Grand Housing Development Program Volume III - Gtz

Prologue 3Contents 5Design basics and dimensions 6Basic Measurements and Masonry Bond......................................................................................6Building Parts ...............................................................................................................................7Schematic construction process 10Machinery, tools and basic techniques 14Hollow Concrete Block (HCB) Production...................................................................................14Mortar and masonry work considerations...................................................................................15Bending reinforcement for precast beams..................................................................................16Vibrating table.............................................................................................................................17Clamps for holding parts of formwork together ..........................................................................19Formwork for foundations and slabs...........................................................................................20Concrete spacers for fixing position of reinforcement ...............................................................20The manhole ...............................................................................................................................21Construction guideline step by step 22Ecological sanitary systems 30Basics on ecological sanitation...................................................................................................30Functional description of a dry toilet system...............................................................................32ECOSAN pilot project (PPP) .......................................................................................................35Hints on the planning phase 38Detail drawings for construction .................................................................................................38Detail drawings for sanitary installation ......................................................................................39Detail drawings for electrical installation ....................................................................................40Hints on the execution of work 41Sanitary installation ....................................................................................................................41Ground floor slab........................................................................................................................42Wall construction ........................................................................................................................43First floor slab repair...................................................................................................................44Concrete beam repair .................................................................................................................46Roof framework repair ................................................................................................................48Roof covering .............................................................................................................................49Electrical installation...................................................................................................................50Internal staircase ........................................................................................................................51Plaster work................................................................................................................................53Paint work ...................................................................................................................................54First floor terraces weatherproofing............................................................................................55Flooring with cement oxide screed .............................................................................................57Laying the parquet ......................................................................................................................59Tiling work ..................................................................................................................................61Suspended ceilings ....................................................................................................................63Renewal of doors & windows......................................................................................................64Paving work ................................................................................................................................66Structural design of cost efficient apartements 68Analysis of slab...........................................................................................................................68Analysis of precast beam............................................................................................................69Analysis of beam and column .....................................................................................................71Typical 3D models of residential and appartement buildings ......................................................74Typical drawings for the cost efficient buildings .........................................................................78Credits to the stakeholders 87CONTENTS5

BASIC MEASUREMENTS AND MASONRY BOND40 cm20 cm20 cmThe construction of cost efficienthouses requires reducing wastageof material. Reducing wastagedepends on using modules whichstarts from the smaller parts likethe masonry blocks and repeatsthemselves of longer scale of thewhole housing unit.The basic measurement systemused in the project depends on amodule of 40 x 20 x 20 cm (widthx height x depth), being the outermeasurements of one hollow block(HCB) unit.Three types of measurementshave to be differentiated (ref. to fig.below) and calculated as follows,considering a mortar joint width of1 cm.This system of measurement cal-culation has also been transferredto elevations and sections to dothe height calculations.- Full size:Columns measurements haveto be equal to the module sizeplus one mortar joint multipliedby the number of unitsused (n) minus one mortarjoint.For the calculation of groundfloor plans measurements are:(40 cm + 1 cm) x n -1 cmFor the calculation of elevationsand sections measurementsare:(20 cm + 1 cm) x n- Full size plus one mortar joint:Submissions length is equal tothe unit size plus one mortarjoint multiplied with the numberunits used (n).For the calculation of groundfloor plans measurements are:(40 cm + 1 cm) x nFor the calculation of elevationsand sections measurementsare:(20 cm + 1 cm) x n- Openings:Opening size is equal to themodule size plus one mortarjoint multiplicated with thenumber of units used (n) plusone additional mortar joint.In short, for the calculation ofground floor plans’ measurements:(40 cm +1 cm) x n + 1 cmIn short, for the calculationof elevations’ and sections’measurements:(20 cm + 1 cm) x nIn addition, one can calculate theouter measurements of masonrybondbuilding parts as follows:- Overall measurement equal tothe unit size plus one mortarjoint multiplicated by the numberof units used (n) plus onehalf module size.For the calculation of groundfloor plans’ measurementsare:(40 cm + 1 cm) x n + 20 cmFor the calculation of elevationsand sections measurementsare:(20 cm + 1 cm) x nFull sizeFull size plus one mortar jointOpeningOverall measurementScheme of different types of measurement for a ground floor plan shown as an example6Addis AbabaCity Government

BUILDING PARTSFull HCBThe full hollow block has a size ofL=32 cm x W=16 cm x H=19 cm.This size of the HCB is reducedin comparison to the usual sizesused in Ethiopia. The new size ofthe hollow block reduces the productionmaterial and makes theFull hollow block viewed from top HCB easier to handle, this reduceslabour and material costs.During the wall construction thehollow block is placed up with theclosed bottom facing upwards.Therefore the loss of mortar duringconstruction is reduced and thebond between HCBs is increased.Full hollow block viewed from bottomHalf hollow block viewed from top (left) and bottom (right)U-shaped HCB viewed from top (left) and from bottom (right)One mason can build 170 pcs ofHCB per day on an average.After wall construction, it has to bewatered for at least 7 days.Half HCBThe half hollow block has a size ofL=16 cm x W=16 cm x H=19 cmand represents exactly half of onefull HCB.Usage is similar to the full HCB.U-Shaped HCBThe U-shaped HCB has the samesize as the full HCB; L=32 cm xW=16 cm x H=19 cm. It is usedas a formwork for ringbeams & lintelsand at the same time as a partof the wall.FROM TECHNICAL MANUALS VOL I AND II DESIGN BASICS AND DIMENSIONS7Addis AbabaCity Government

BUILDING PARTS(CONTINUED)Column HCBThe column HCB has a size ofL=32 cm x W=16 cm x H=19 cm.It is used as a formwork for columnsand at the same time as apart of the wall.Column HCB viewed form topSlab HCBThis slab construction system, introducedby the Low-cost HousingProject, avoids formwork, reducesrequirements of skilled manpowerand time. The system has twomajor components: the pre-castbeam and the slab HCB.The production of the slab HCB isdone in the same way as productionof wall HCB.The slab HCB viewed from top / sideColumns made out ofcolumn-HCBsAfter constructing the column outof column HCB’s, one side of theColumn HCB with reinforcementHCB at the bottom of the columnhas to be opened to remove themortar that has fallen down duringwalling up. This has to be done toensure a reliable connection betweenthe cast-in concrete and theslab foundation.After walling up, the column is castwith concrete.Connection in between column andwallColumn HCB with reinforcement8Addis AbabaCity Government

BUILDING PARTS4 U-shaped HCBs joined together as alintel with reinforcementSection of HCB with typical placementof reinforcementThe pre-cast beam (bottom) and thereinforcement itself (above)Detail of the reinforcementLintels and Ringbeamsmade out of U-shapedHCBsAfter the wall is properly erectedthe U-shaped HCB’s are placedin at the height of the ringbeam;the reinforcement bars and theconcrete will be placed within theU-shape HCB according to thestructural design.Lintels will be prefabricated on aflat ground area in the same wayas the ringbeams.Precast BeamsIn the pre-cast beam production,the reinforcement has to beproperly bent. Especially for thestirrups, the diameter for bendinghas to be 4 times greater than thediameter of the stirrup itself.The stirrups must be welded at thetop with the main reinforcement.The pre-cast beam is then castby using a mould and a vibrationtable so that the concrete is wellcompacted. The beam production(CONTINUED)This technique avoids extra materialfor formwork.The use of wooden formwork hasnegative effects on the environment.Moreover it requires skilledmanpower and time to mantle anddismantle the form work.The concrete used for filling has tomeet or exceed C25.and transport to the place where itis going to be cured can be doneby four people.After having finished the productionof the components, five labourerscan do the proper layingof the pre-cast elements and slabHCB in one day.Considering 40 sqm of slab, thetemperature reinforcement, theelectric and sanitary lines and alsothe formwork around the slab canbe done within 2 days.One can start the construction ofthe walls on the slab three days aftercasting of the concrete.With the usual method one has towait 21 days without dismantlingthe formwork hampering the activitythat could be done above orbelow the slab.FROM TECHNICAL MANUALS VOL I AND II DESIGN BASICS AND DIMENSIONS9Addis AbabaCity Government

SCHEMATIC CONSTRUCTION PROCESS1 2The following describes, how an exemplary constructionprocess is implemented, using the building partsmentioned before.Reinforcement is placed inside the column HCBs. After10 layers of HCBs are erected they have to be filledwith concrete C 25.During walling up, the columns are integrated into thewall by using column HCBs. The positions of the columnshas to be calculated by a structural engineer. Thestructural design depends for example on the numberof storeys to be built and the possibility of earthquakeexposure.Stirrups are placed within the mortar joints as shownin the drawings.3 4When the wall is erected, a ring-beam has to be fixed.Therefore U-shaped HCBs are used as part of the walland even as formwork for the concrete.U-shaped HCBs are placed on top. Where the reinforcementof the columns is placed, the bottom of theU-shaped HCBs have to be cut. The reinforcementbars of the columns have to be bound into the reinforcementof the ring-beam. The overlap length of thecolumn reinforcement has to be at least 80 cm.10Addis AbabaCity Government

SCHEMATIC CONSTRUCTION PROCESS5 6Reinforcement bars are laid into the U-shaped blocks. Stirrups are placed every 20 cm. The length of thesestirrups depends on the height of the slab to be builtand has to be designed by the structural engineer.7 8(CONTINUED)The U-shaped blocks are filled with concrete, min. The upper reinforcement parts for the slab are placedquality C25.in position.FROM TECHNICAL MANUALS VOL I AND II SCHEMATIC CONSTRUCTION PROCESS11Addis AbabaCity Government

SCHEMATIC CONSTRUCTION PROCESS(CONTINUED)9 10In a next step, precast beams are laid upon the ringbeam.The distance between the beams results fromthe width of one slab-HCB at its bottom plus a toleranceof 0,5 cm on both sides. That means clear distancebetween beams of 50,5 cm.Overlap at the end of beams over the ring-beam has tobe at least 10 cm.The distance between the ring-beam and the first beamhas to be 47,5 cm resulting in an overlap for the slab-HCBs of 3 cm.11 12The slab-HCBs are placed between the beams or betweenbeam and ring-beam.One has to be sure of the proper placement of the slabHCB.12Addis AbabaCity Government

SCHEMATIC CONSTRUCTION PROCESS13 14When all slab-HCBs are placed, the result will be also a Concrete filling is done on top of beams and slabformworkfor the concrete-filling of the future slab. HCBs. The quality has to be at least C25.A temperature reinforcement is to be laid on top of theHCBs with properly bent hooks at the ends of the reinforcementbars. The diameter of the reinforcementbars is 6 mm .Formwork panels are placed at the outer edges of ringbeamsto complete the formwork.15 16(CONTINUED)These drawings are schematic drawings of the final construction. A part of the slab’s concrete filling is cut away toillustrate the position of reinforcement and slab-HCBs within the concrete filling.FROM TECHNICAL MANUALS VOL I AND II SCHEMATIC CONSTRUCTION PROCESS13Addis AbabaCity Government

HOLLOW CONCRETE BLOCK (HCB) PRODUCTIONat a time. The HCB is transportedby two people on a wooden pallet.The HCB remains on the woodenpallet for 24 hrs. Then it is becured covered by a plastic sheetto enhance the curing process andpreventing the water from evaporation.The materials required for the productionof HCBs and their mixingratio differs from site to site dependingon the availability of thebuilding materials and the ratiothat fulfils the required strength.This holds true for all types ofHCBs production.The machine used for the productionof HCBsThe machines used to produceHCBs are electrical vibrating machineswhich have 1.5 HP motorto make sure, that the vibration isstrong enough to compact the concretesufficiently in the moulds andto achieve the required strength.Curing-time is at least 10 days beforeusing the HCBs for construction.It is important to write the date ofproduction on the HCB so thatthe mason can easily identify theHCBs, ready for construction.The average overall production is1200 HCBs per day per machine.The pictures show machines, usedby LCH-Project.Before starting production the differentmaterials used to producethe HCB will be dry-mixed thoroughlyon a clean and dry groundby hand. Then the mixture will beput in the mixer with the appropriateamount of water required (water tocement ratio of 0.49 – 0.55). Themixture is inserted into the mouldand vibrated for about 60 secondsbefore extruded as HCBs.Filling in concrete while the machine isalready vibratingConcrete is filled up during compactinguntil the mould is filledExcept for the slab-HCB, the machinescan produce three piecesThe mould viewed from the topClearing the topRemoving the mould upwards14Addis AbabaCity Government

MORTAR AND MASONRY WORK CONSIDERATIONSSection showing mortar spreadinginto holes of the HCBMortar should be used economically.Therefore it is put on the top of theprevious layer of HCBs in approx.2 cm height. It has to be spread tothe edges properly. A plain pieceof wood helps to prevent the mortarfrom falling down. The uppersurface of the mortar has to berather rough to get a proper connectionbetween the HCBs and toallow the mortar to spread into theholes of the upper HCB. It has topressed down until the height ofthe mortar is reduced to 1 cm.Walls constructed in this way canbe considered as load bearingwalls.Mortar qualityThe mortar used for walling up alltypes of HCBs has to be tested.The minimum pressure resistanceof the mortar mixture has to be 170Kg\sqcm or higher on the 7th day.Putting the mortar ontop of the last layerSpreading the mortarto the edge, using apiece of woodPlacing the HCB withthe closed bottom upFROM TECHNICAL MANUALS VOL I AND II MACHINERY, TOOLS AND BASIC TECHNIQUES15Addis AbabaCity Government

BENDING REINFORCEMENT FOR PRECAST BEAMSForming the stirrupModel of the formwork with readybentstirrup on itBending of reinforcement canquickly be done by using formworkconsisting of a metal plate withbolts welded on it.Removing a finishedsegmentThe bolts must have a diametercorresponding to the minimalbending radius of the used reinforcement-bars.Normally the diameters of the boltshave to be four times bigger thanthe diameter of the bars used.After the stirrup is formed over thelength of the mould, the stirrup canbe put off and re-fitted so that anylength of stirrup can be produced.Starting the newsegment16Addis AbabaCity Government

VIBRATING TABLEDrawings of the vibrating tableThe vibrating table is used during casting of the concretefor the precast-beams.It consists of the vibrating-machine, which is similar tothe one used for HCB-production, and a metal table asshown in the drawings below.The table is trussed at the edges by four billiard balls lyingin hollows to enable it to move horizontally free.In addition, a mould is used to cast seven beams at once.It is also shown in the drawing below.FROM TECHNICAL MANUALS VOL I AND II MACHINERY, TOOLS AND BASIC TECHNIQUES17Addis AbabaCity Government

VIBRATING TABLESupportswith billiardballs(CONTINUED)Filling inconcrete byhandThevibratingmachineSpreadingthe concrete,usinga bend barMould forthe pre-castbeamsTheprecastbeamsafterremovingthe mould18Addis AbabaCity Government

CLAMPS FOR HOLDING PARTS OF FORMWORK TOGETHERClamps are used to hold parts of formwork together.One side is rounded and tapered to make insertioninto the drill-hole easier. The other side isbent by 180 degrees and flattened. This side ofthe clamp provides a pressure on the parts of theformwork to hold them tightly together.a clampInserting the clamp into a drill-hole of the formwork...... And locking it by rotating it by 90 degreesClamps mounted in edge-position using an angle barTwo clamps mounted on formwork for foundation19FROM TECHNICAL MANUALS VOL I AND II MACHINERY, TOOLS AND BASIC TECHNIQUESAddis AbabaCity Government

FORMWORK FOR FOUNDATIONS AND SLABSThe formwork for foundations and for slabs is the same. It consists of a metal panel with a frame welded on it toachieve stability. The frame has got drill-holes for the clamps.In conjunction with angle bars, two pieces can be used to form an edge. They can be mounted side by side or ontop of each other.A formwork for a slab, fixed by additionalwires bound to the reinforcementof the slabThe edge of a formwork-assembly forfoundationA formwork for foundation, panelsmounted on top of each other, side byside and at the edgeCONCRETE SPACERS FOR FIXING POSITION OF REINFORCEMENTIn the execution of foundations and slabs concrete spacers are used to hold reinforcement in position and to assurethe required cover. Cast-in wires are used to fix them to the reinforcement bars.The spacers are produced using a metal mould. Concrete is filled in and during compacting with the vibrating table,the wires are inserted.The concrete spacers with wires for fixing themThe mould for the concrete spacers20Addis AbabaCity Government

THE MANHOLEBottom-view (left) and top-view (right) of the mould withfrog for the chuteThere is also a formwork for the manholes. It consistsof four metal side-panels, two plastic pipes and a rectangularpot. The side-panels are fixed by four anglebars in the corners using clamps as described above.The pipes are fitted on different levels, so that backpressure can not reach the intake.Formworkfor themanhole,viewedfrom theside ofintake(front panelremoved)Viewedfrom top(panel ofintake-sideremoved)The pot is slightly tapered and has a groove at the bottomto form a chute for the future catch drain.All parts are treated with waste oil to make removaleasier.One has to be sure to make the pit for the manholebig enough to be able to draw out the pipes after castingthe concrete. Moreover, one has to foresee enoughspace in the pit for 3 persons to place and remove theformwork.The mouldviewedfrom theside of thecatch drain(front panelremoved)The castmanholeand thepit for themanholeFROM TECHNICAL MANUALS VOL I AND II MACHINERY, TOOLS AND BASIC TECHNIQUES21Addis AbabaCity Government

CONSTRUCTION GUIDELINE STEP BY STEPExcavation for foundation with terracesExcavation & EarthworkAfter the top soil is removed and the dimensions of thefoundations are set out the excavation work for foundationscan start.Lean ConcreteThe lean concrete must be levelled precisely (waterlevel) and kept clean from all organical materials.• The structural drawings have to be checked carefully- width of excavation- depth of excavation- types of excavated materials- type of soil at foundation level.• If the foundation is deeper than 1 m it is recommendedto build terraces were the workers canstand on to reach the bottom of the foundationwithout problems (see picture).• The angle of slope depends on the soil and theweather conditions.• Terraces and the right angel of slope will preventthat loose material can fall to the bottom of thefoundation.• The foundation pits and trenches must be free ofgroundwater and roots.• If the excavated material can not be used as backfill material it should be cart away immediately.• Excavated material which will be used as backfillmaterial should not be stored beside the excavationpits or trenches.Reinforcement & Formwork (Footings)The most important parts of the building are the foundations.All structural drawings must be studied carefully, andshould be understood in all written and drawn parts. Ifthis is not the case, the structural or resident engineershould give explanations !!!!The foundation work should be checked according tothe following list:22Addis AbabaCity Government

CONSTRUCTION GUIDELINE STEP BY STEP(CONTINUED)• Is the quality of the reinforcement bars proofed ? • Is the formwork for the footings well installed• Is their quality according to the structural design ? (height and width)?• Are all reinforcement bars installed accordingly to • Are enough supports for the formwork installed?the structural drawings?• Is the bottom clean and free from organical material?• Are the right bar diameters installed?• Are the spacers in between the reinforcement and • Is the lean concrete watered (cured)?the lean concrete installed?• Are the test cubes prepared for concrete checking?• Have the spacers the right dimensions (height)?• Are enough spacers installed (middle and outsideparts)?Before starting the concrete work for the footings, awritten approval from the resident engineer must be• Are additional stirrups on top of the re-bars installedso that the re-bars cannot bend during theconcrete work?given.Footings, lean concrete and column formworkFoundation with footing columns and backfill up to terrace levelFROM TECHNICAL MANUALS VOL I AND II CONSTRUCTION GUIDELINE STEP BY STEP23Addis AbabaCity Government

CONSTRUCTION GUIDELINE STEP BY STEPConcrete workThe required strength of the concrete should be givenin the structural drawings. The mixing rate for the requiredstrength varies according to different conditions.There is no general mixing rate. The rate and thewater-cement ratio depends on:• weather conditions (sunny and hot - rainy andcold),• dry aggregates / wet aggregates• sizes of aggregates,• condition of sand (washed, silty, dry, etc.),• type of cement.It is recommended to prepare test cubes with differentmixing rates which have to be tested in an official laboratoryin order to find out the right mixing rate underlocal conditions.Footing columns1.5 m , the aggregates will be separated duringthe filling!• Is the formwork for the footing columns well installed(height and width)?• The formwork should not be higher than 20 cm ofthe finished concrete level!!!!• Are enough supports for the formwork installed?• Is the bottom (footing) clean and free fromorganical material?• Are all reinforcement bars installed accordingly tothe structural drawings?• Are the right bar diameters installed?• Are the spacers in between the reinforcement andthe formwork installed?• Have the spacers the right dimensions (distancebetween bars and formwork min.= 2.5 cm)?Before starting the concrete work for the footing columns,a written approval from the resident engineermust be given.(CONTINUED)The construction of the footing columns should bechecked according to the following list:B ACKFILL OF EXCAVATED AREA AROUNDFOOTINGCOLUMNS• Spacers should not be higher than the upper levelof the concrete!!!!• Is the future height of the concrete (filling height)levelled and visibly marked at the formwork?• If the filling height of the concrete is more thanBefore starting the back fill work the resident engineermust approve the materials (selected material) for theback fill work.Lean concrete and grade beams24Addis AbabaCity Government

CONSTRUCTION GUIDELINE STEP BY STEP(CONTINUED)Grade beams with backfill, hardcore, temperature reinforcement without expansion jointsIn order to get a regular compressive strength of theback fill, the steps of back fill should be marked atconcrete will have consequences (level differences) forthe formwork and later for the grade beam.the columns every 20 cm. This means 20 cm of fillingmaterial (selected material), compaction and another20 cm of filling material till the excavated hole is filledThe construction of the grade beam should be checkedaccording to the following list:and compacted. The heights for compaction should bemarked at the footing columns in order to control the • Is the quality of the reinforcement bars proofed?right compaction.• Is their quality according to the structural design?When the excavated holes are filled and compacted• Are all reinforcement bars installed accordingly tothe structural drawings?the whole area for the construction of the grade beams • Are the right bar diameters installed?has to be backfilled and compacted (roller). This backfillhas to be levelled (theodolite) in order to get the• Are the spacers in between the reinforcement andthe lean concrete installed?required height and a smooth surface for the lean concrete• Have the spacers the right dimensions (height)?under the grade beams.• Are enough spacers installed (middle and outsideparts)?Grade Beams• Is the formwork for the grade beams well installed(height and width)?• Is the formwork straight and levelled?After the backfill is well compacted and levelled, the • Are enough supports for the formwork installed?lean concrete for the grade beams can be placed. • Is the bottom clean and free from organical material?It is important, that the lean concrete is levelled because• Is the lean concrete watered (cured)?it will give the right height in between the spac-ers and the re-bars of the grade beam.• Are the test cubes prepared for concrete checking?Before starting the concrete work for the footings, aAlso the formwork of the grade beam will stay on thelean concrete. Every difference in height of the leanwritten approval from the resident engineer must begiven.FROM TECHNICAL MANUALS VOL I AND II CONSTRUCTION GUIDELINE STEP BY STEP25Addis AbabaCity Government

CONSTRUCTION GUIDELINE STEP BY STEP(CONTINUED)Grade beams with ground floor concrete, expansion joints and columns up to first floorSanitary installationThe sanitary installation (waste water line) has to beinstalled at this time. If the waste water line goes belowthe grade beam the pipes should be installed beforethe lean concrete is in situ.The same procedure as with the backfill of the footingsshould be followed.Hardcore & Lean ConcreteThe best solution is that the waste water pipes crossthe grade beam in the middle. In the formwork for thegrade beam an opening has to be prepared so thatthe waste water pipes can pass through. The openingsmust be bigger than the pipes in order to avoid anycontact with the grade beam e.g. when the waste waterpipe has a diameter of 110 mm the opening shouldhave a diameter of 160 mm.As the waste water line has a slope of 2%, the openingin the grade beam should follow this slope.The hardcore consists of broken basaltic stones. Thestructural or resident engineer can change the specificationto trachidic stones.The hardcore has to be levelled so that it’s height isequal on all parts.On top of the hardcore lean concrete (C 5) has to beplaced and levelled. The lean concrete avoids that theconcrete on top (C 25) enters into the spaces betweenthe hardcore.Backfill between Grade BeamsAfter the deinstallation of the formwork for the gradebeams the backfill of the areas in between the gradebeams can start.It is very important that the lean concrete is levelled inorder to get later on the right distance (equal distance)in between the spacers and the temperature reinforcement.26Addis AbabaCity Government

CONSTRUCTION GUIDELINE STEP BY STEPExpansion jointsIn between the grade beams and the floor concreteexpansion joints have to be provided. The floor concretedoes not have any direct contact to the gradebeams. Fore the expansion joint styro foam of min. 0.5cm should be used. Organic material like chipwood isnot recommendable, because it will expand when itgets wet.Floor ReinforcementWhen the expansion joints (styro foam) are fixed thereinforcement bars for the floor can be installed. Theexact positions are shown in the structural design. Itis important that enough spacers are installed and theheight of the spacers is kept accordingly to the design.Under normal soil conditions the spacer will have aminimum height of 2.5 cm while in black cotton soil thereinforcement is 2.5 cm below the floor finishing level.ColumnsBefore starting the erection (construction) of the columns,the structural design has to be studied carefullyin order to avoid future construction problems. Espe-Temporary support for precast beams (slab construction)cially the position of the re-bars is very important becausethe pre-cast beams sometimes are laying ontop of the columns. If the re-bars are not in the rightposition the pre-cast beam will not fit in between there-bars.The column work should be checked according to thefollowing list:• Are all reinforcement bars installed accordingly tothe structural drawings?• Are the right bar diameters installed?• Are the spacers in between the reinforcement andthe formwork installed?• Do the spacers have the right dimensions (distancebetween bars and formwork min.= 2.5 cm)?• Spacers should not be higher than the upper levelof the concrete!!!!• Is the future height of the concrete (filling height)levelled and visibly marked on the formwork?• If the filling height of the concrete is more than 1.5m, the aggregates will be separated during thefilling!• Is the formwork for the footing columns well installed(height and width)?• The formwork should not be higher than 20 cm ofthe finished concrete level!!!!(CONTINUED)FROM TECHNICAL MANUALS VOL I AND II CONSTRUCTION GUIDELINE STEP BY STEP27Addis AbabaCity Government

CONSTRUCTION GUIDELINE STEP BY STEP(CONTINUED)Installation of pre-cast beamsPre-cast beams and slab-hollow blocks installed28Addis AbabaCity Government

CONSTRUCTION GUIDELINE STEP BY STEP• Are enough supports for the formwork installed?• Is the bottom (footing) clean and free fromorganical material?Before starting the concrete work for the footing columns,a written approval from the resident engineermust be given.Block Work (Wall construction)Before starting with the block work all measurements(level of grade beam, floor height, columns, etc.) haveto be controlled.The height of the first layer has to be given to the masonsand marked at the columns.It is advisable to measure and mark at the columnsall other layers in order to give a guideline to the masons.The wall construction should be checked according tothe following list:• Is the mix proportion of the mortar given?• Is the mortar well mixed?• Is the strength of the hollow blocks controlled??• Are the HCB’s well stored beside the constructionarea to avoid longer transportation ways?• Is the working place for the masons prepared?• Do the masons have enough hand tools to erect astraight, upright wall?• Are the corner angels correct (90 degrees)?• Is the wall straight and upright?• Are the conduits for the electrical installationinstalled accordingly to the electrical design?Especially the U-blocks for the ringbeam must be absolutelystraight levelled because on top of the ringbeam the pre-cast beams will be laid. If there is anylevel difference, the slab will not be straight and thepre-cast beams will be bent.Slab ConstructionThe slab construction starts with the installation of theslab support. Three supports have to be installed, onein the middle of the slab and two on both sides of theslab 1 m in front of the walls. The support line shouldbe given in the structural drawings. The pre-cast beamsshould lay on a squared timber (sawn timber). Eucalyptuspoles are not the adequate material for the horizontalsupport because they are not straight enoughand hence can be bent. Every deflexion of the pre-castbeams should be avoided.Before the beams are laid on top of the support, theyshould be checked. Especially the part where theslab hollow block will be placed should be clean andstraight.The correct level of the beams should be controlledbefore the slab hollow blocks are placed.(CONTINUED)The slab HCB´s, hanging between the precast beamsare functioning like a (lost) formwork. They give only atemporary support during the installation phase. Onlythe pre-cast beams and the slab concrete (C 25) areload bearing parts of the slab. When all the HCB´s arelaid, the electrical installation can be installed. After theelectrical installation (conduits, etc.), the temperaturereinforcement will be installed accordingly to the structuraldesign. Spacers have to be installed in order tokeep the reinforcement in the right position. It shouldbe avoided, that too many people are walking on top ofthe ready installed slab before the concrete is cast.All open spaces in between the hollow blocks have tobe closed by mortar in order to avoid that the cementwater is dropping down. If this happens, the load bearingcapacity of the slab will be dramatically reduced.The concrete work should only be started after the writtenapproval of the resident engineer. He has to checkif all installations are well done and all reinforcementbars are installed accordingly to the structural design.FROM TECHNICAL MANUALS VOL I AND II CONSTRUCTION GUIDELINE STEP BY STEP29Addis AbabaCity Government

BASICS ON ECOLOGICAL SANITATIONwhereas the striking majority of theexisting treatment facilities are drypit latrines and septic tanks, whichcannot be considered as sustainablesolutions.Shortcomings of conventional wastewater systems (left) and advantages of ecologicalsanitation systems (right)Alarming sanitationsituationLack of adequate sanitation facilitiesremains one of the main transmittersof disease in the world’ sdeveloping countries. Sanitationinadequacies also hinder economicand social development,constitute a major impediment topoverty alleviation, and lead to environmentaldegradation.In the major cities of Africa as manyas two-thirds of the population arewithout adequate sanitation.The majority of the populationof Ethiopia, urban and rural alikedoes not have access to safe andadequate sanitation facilities.Three-fourth of the health problemsin Ethiopia are communicablediseases attributed to unsafeand inadequate provision of waterand unhygienic waste management,particularly sewage.A study carried out indicates thatthree-fourth of the health problemsof children in Ethiopia are communicabledisease originating fromthe environment. Other studies revealedthat only 11.5 % of the populationhas access to sanitationfacilities while 88.5 % are withoutproper sanitation facilities.The purity and quality of Addis Ababa’s water sources is decreasingat an alarming rate. Tanneries andfactories built alongside the riversare the main industrial polluters.The water however mainly containsharmful micro-organisms (especially“e-colli”), which are foundin human excrements.The current sanitation and wastewatersituation in Addis Ababa isnot satisfactory. About half of thepopulation uses shared sanitationfacilities and almost a quarter ofthe population has no toilet facilitiesat all. Only about 40,000 peopleout of more than three millionare connected to the central sewersystem and the wastewater treatmentponds (A.A.W.S.A., 2002),With this water problem in mindAddis Ababa cannot give itself theluxury to build more flushing toiletsbeing flushed with drinking water.Addis Ababa has to strongly economizeon the use of drinking waterin order to save the little they havefor the absolutely necessary watersupply for drinking and washing.For toilets and washing of clothesetc. innovative devices have to beintroduced and applied in order tomanage and use the scarce waterresources in the most effectivemanner.Decentralized waste water systemsrecycling the water (grey water)and dry sanitation have to beintroduced in order to demonstratecost-efficient and environmentallyfriendly sanitation moreover reducingthe wastage of preciousand scarce drinking water.Centralized versusdecentralized waste watersystems- 80% of costs in sewerage isinvested for sewer lines.- Centralized sewerage systemsare very costly.- Within centralized sewersystems the nutrient cycle isbroken.- Decentralized systems createmore management problems.- Decentralized system createmore jobs.- Decentralized systems can bebuilt in phases/successively.30ARGE Otterwasser GmbHTUTech Innovation GmbHAddis AbabaCity Government

BASICS ON ECOLOGICAL SANITATION- Operation of decentralizedsystem is key issue.- Decentralized systems reducethe import of fertilizer - reuseoptions by source separation(fertilizer, soil conditioner,biogas).DefinitionsThe term wastewater is used inthis report as the total flow of humanfaeces, urine as well as kitchenwastewater and wastewatergenerated through bathing andshowering. The latter ones aresummarised in the term greywater,whereas faeces are termedbrownwater and urine yellowwater.Faeces and urine together arecalled blackwater. For an overviewof the volumes of the differentstreams as well as their respectivecontent of organic matter and nutrientsplease refer to the followingfigure on this page.Stormwater is not included in thisinvestigation and should be conveyedand treated in a separatedsystem. Storage and use of rainwateras additional water supplyshould be considered.Production of waste waterper person per annum- Grew water: 25.000 - 100.000kg (low nutrient)- Yellow water (urine): 500 kg(high nutrient)- Brown water (faeces): 50 kg(high nutrient)Dry toilettes - Why?- Resource efficient sanitationmust consider relation to waterVolumel/(P*year)Yearly Loadskg/(P*year)Greywater25.000 -100.000Flushwatercan be saved6.000 - 25.000Urine~ 500(CONTINUED)Feaces~ 50(option: addbiowaste)N ~ 4-5 ~ 3 % ~ 87 % ~ 10 %P ~ 0,75 ~ 10 %~50 % ~ 40 %K ~ 1,8 ~ 34 %~ 54 % ~ 12 %COD ~ 30 ~ 41 % ~ 12 % ~ 47 %S, Ca, Mg and trace TreatmentTreatment Biogas-PlantelementsCompostingReuse / Water Cycle Fertiliser Soil-ConditionerGeigy, Wiss. Tabellen, Basel 1981, Vol. 1, LARSEN and GUJER 1996, FITSCHEN and HAHN 1998Wastewater volumes and nutrient loadssupply.- Flushing toilettes waste highlyvaluable drinking water.- Black water cannot be reused.- Dry toilettes separate urineand faeces.- Dry toilettes allow reuse ofurine and faeces as nutrientsin agriculture.- Nutrients (urine & faeces) donot require additional treatment.- Urine is a high value fertilizer.- Faeces have to dry and canthen be used as soil conditioner(composted excreta).- Fertilizer contains phosphate.- The deposits of phosphate arebecoming exhausted.- To recover phosphate onerequires sulfate.- Sulphate deposits are becomingexhausted.- Prices for phosphate, sulphateand fertilizer are rising.Experiences with drytoilettesExperiences in rural areas areavailable in example from Kenya,Uganda and India as the link toagriculture in rural areas is directand obvious. Also first experiencesof dry toilets in mass housing constructionhas been made in DongSheng (Inner Mongolia) / China.Designs for dry toilettes for apartmentsare ready to be implementedas well as pilot projects as bestpractices. Awareness creationcampaigns are required.ECOLOGICAL SANITARY SYSTEMS BASICS ON ECOLOGICAL SANITATIONARGE Otterwasser GmbHTUTech Innovation GmbH31Addis AbabaCity Government

FUNCTIONAL DESCRIPTION OF A DRY TOILET SYSTEMSEPARATINGTOILETURINALDry toilet units are arranged in pairs:- one separating toilet- one urinalThe separating toilet contains two moulds:FAECESURINE- one for faeces- one for urineThe separation of urine and faeces is essential for theproper drying process.It has to be taken care of that no bigger amount of wateris spilled into the faeces mouldFor the urine, a tank is attached to the system. The tankis connected to the urine mould of the separating toiletas well as to the urinal.FAECES´CONTAINERSFor both, toilet and urinal, one container each for faecesis situated below the floor.URINETANKURINEDue to the separation of urine and faeces, two workflowshave to be considered:- one for urine- one for faecesWhen urine is entered to the urine mould of the toilet itis led to the urine tank.32Addis AbabaCity Government

FUNCTIONAL DESCRIPTION OF A DRY TOILET SYSTEMWhen faeces are entered to the faeces mould of thetoilet they are stored in the drying container situatedbelow.After 6 months of use, toilet and urinal are exchangedNew faeces are now only entered into the second containerbelow the toilet.During the following 6 months, the urinal is used onthe left side container. Therefore no more faeces areentered. Previously deposited faeces can dry out duringthis period of time.New faeces are now entered only into the second container(shown on the right side).DRYINGFAECESFAECESFAECES(CONTINUED)URINEECOLOGICAL SANITARY SYSTEMS FUNCTIONAL DESCRIPTION33Addis AbabaCity Government

FUNCTIONAL DESCRIPTION OF A DRY TOILET SYSTEM(CONTINUED)SHUTTERTo remove the dried faeces, a shutter on the backsideof the container is opened and the dried faeces aredropped from the drying container to a transport containerthat is carried away.Also the urine tank is emptiedThe dried faeces as well as urine are sold for agriculturaluse.DRIEDFAECESThe shutter of the emptied container is closed again.The urinal and the toilet are restored in the same positionsas before.Another 6 months’ cycle is now newly started.34Addis AbabaCity Government

ECOSAN PILOT PROJECT (PPP)The private sector and development policy have acommon interest in shaping political, legal and socialframeworks that promote development in developingcountries. Within the framework of the public-privatepartnership (PPP) concept, private companies and officialdevelopment cooperation work hand in hand. Theobjective-oriented combination of the two partners´ 83greywater pipeØ40mmgreywater basinwith plants Ground floor plan 15 10 69,5 20 69,5 10 1583urinalwash basinwash basin70parapet90 cm20various strengths creates new opportunities for positivedevelopment impetus in the partner countries.The Project aims at introducing environmentally friendly,improved sanitary devices by enhancing the capacityof local institutions, consultants and companies toget acquainted with ECOSAN (dry toilet system sepa-floor draindepot for ash,sawdust, soil15 85 10 100 15 22 15262154041 43,515 84,5 10 84,5 15 80 15 84,5 10 84,5 15209 80 209depot for ash,sawdust, soilcomplete floor areawith inclined floorscreed to the floor drainECOLOGICAL SANITARY SYSTEMS PILOT PROJECTARGE Otterwasser GmbHTUTech Innovation GmbHPlanungsgruppe Prof. Krusche35Addis AbabaCity Government

ating urine and faeces). In the long run the project willstrengthen the private sector in the field of wastewatermanagement in Ethiopia. Furthermore the no waterconsumption of the new sanitation system will reducedrinking water resources consumption and facilitatethe use of natural organic fertilizers in agriculture.These drawings show the first pilot ECOSAN public toiletto be constructed on construction sites for testingpurpose. revision openingurine tanksgreywater basinwith plantsgreywater pipeØ40mm 80revision openingurine tanksrevision openingurine tanks cylinderical verticalurine-tanksROTO PLCRCVT 25-1(250 litres)cylinderical verticalurine-tanksROTO PLCRCVT 25-1(250 litres)dry vault 1dry vault 2pipe Ø 40 mmdry vault 1dry vault 2pipe Ø 40 mmopening forfaeces removalopening forfaeces removal20 77 15 77 20 80 20 77 15 77 20209 80 209revision openingurine tanks20 80 15 145Subbasement26236ARGE Otterwasser GmbHTUTech Innovation GmbHPlanungsgruppe Prof. KruscheAddis AbabaCity Government

8189 126Sections wash basin22faeces inletfloor drain100urinalpipe Ø 40 mmcorrugated sheet rooffluereinforced with2Ø8mmbelow(revision openings)greywater basinwith plants(e.g. reed)+4,10corrugated sheet roof+2,84+0,95+0,80+0,00-0,10corrugated sheet roofwood columnopeningwash basincylinderical verticalurine-tanksROTO PLCRCVT 25-1(250 litres)strip foundation30 x 30 cmcorrugated sheet roofadditional reinforcement2Ø8mmtop and belowreinforced withØ 8 mm beloweach 8 cmfloor drain5faeces inletwood columns+4,10flueblack painted+2,84concrete beamreinforced with2Ø8mmtop and below+0,95+0,80opening forfaeces removal+0,00-0,10 ECOLOGICAL SANITARY SYSTEMS PILOT PROJECTARGE Otterwasser GmbHTUTech Innovation GmbHPlanungsgruppe Prof. Krusche37Addis AbabaCity Government

DETAIL DRAWINGS FOR CONSTRUCTIONSection A-ASection B-BFloor planA4.0 cm2.0 cm2.5 cm 2.5 cm?0.8 cm2.0 cm0.2 cm12.5 cm0.2 cm10.0 cm4.4 cm4.4 cmB B?1.5 cm4.4 cmMounting saddle of a balcony’s posts in the detail drawing ...16.9 cmA10.0 cm4.0 cm4.0 cm10.0 cmDetailsscale 1:1BALCONY024A: 16.44 m2TILESH: 3.00 mR 1,31144 30 220 18 118 3 125 30TOILET026A: 8.50 m2MOZAICH: 3.12 m10 18 173 3 170 30 129 10 5SECRETARY025A: 11.06 m2MOZAICH: 3.12 m... and their locations in the first floor plan26 305 10 129 30 220 18 140 8020030 30 80200The preparation of detail drawings is crucial for easyand precise communication on the construction siteand also for producers of building parts.It is also necessary for the planner for checking thespacial and geometrical correctness of the construction.Dimensions, levels and heights can only be ensuredprecisely in sections and elevations.Different tolerances of the small, medium and largescale building parts and their analogous trades haveto be considered.The mounted saddles and post on the balconyDia 14mm REINFORCEMENT VERTICAL POSTDia 50mm CHS handrail50x30 RHS VERTICAL POST40x30 RHS VERTICAL POSTANCHORED TO HCB WALL Dia 50mm CHS HAND RAILDia 50mm CHS HORIZONTALRAILDia 50mm CHS HORIZONTALRAILDia 50mm CHS HORIZONTALRAILDia 50mm CHS HAND RAILDia 30mm CHS HORIZONTAL RAILDia 30mm CHS HORIZONTAL RAILDia 30mm CHS HORIZONTAL RAILThe posts after manufacturing.Exemplary detail drawing for a external staircase38Addis AbabaCity Government

DETAIL DRAWINGS FOR SANITARY INSTALLATION3-dimensional visualization of thetoilets’ and hand basins’ connectionsin ground floor and first floorPlanning the sanitaryinstallationMaking a freehand sketch of thelavatory and it’s sanitary furnituregives a basic idea of the futurelocations of the furniture. Partitionwalls as well as the height of tilingand it’s layout are considered.Proper sloping of the wastewaterpipes in mind, the locations andthe dimensions of pipes are specified.For installations that passno solid wastes into the systema diameter of 55 mm is normallysufficient. For others, like toilets,a diameter of 110 mm is needed.Connectors and reducers have tobe chosen and properly specified.Fall pipes have to be plannedstraight and unbroken through allstoreys. They should have a ventilationopening at the upper endand have to extend up to the roof.Proper ventilation of the fall pipesand the house drain is importantto prevent the siphon traps formemptying when flushing toilets.The first sketch of the sanitary installation in the ground floor toiletThe connection of the pipes to thehouse drain should be rounded toprevent clogging.Sanitary designs have to be doneor approved by an engineer.The final detail drawing with all necessary measurements and technical descriptionsTHE KASANCHIS RENOVATION PROJECT HINTS ON THE PLANNING PHASE39Addis AbabaCity Government

DETAIL DRAWINGS FOR ELECTRICAL INSTALLATIONPlanning the electricalinstallationWhen planning electrical, wastewater / fresh water installationsand other installations as telecommunications,all pipes, conduitsand cables have to be consideredin their 3-dimensional spacial locationsand have to be coordinatedto prevent intersections or overlapsof pipes or conduits.For the electrical installation, properplanning is needed to ensurethe correct assignment of switchesto lighting fixtures or other fixturesthat should have switches.Lighting fixtures, sockets and otheroutlets for additional installationshave to be reasonably grouped toelectrical circuits. A dry and centrallocation for a fuse box has to beplanned according to the interiordesign.Cables have to be protected formoverload by fuses. Cables’ dimensionsand fuses’ specificationshave to be defined by the electricalengineer according to the designof the circuits.All installations have to be connectedto earth for safety. Therefore allcables, for example PVC sheathedcables, have three conductors.Wiring with live, neutral andearthed cable within conductors- one live, providing power- one neutral- one earthedConduits enable a system to be rewiredwithout damage or interferenceof the fabric of the building.The cables used within conduitsare usually insulated only, whereasin non-rewireable systems thecables have a protective outersheath.The live, neutral and earthedcable seen at a conduit’sconnection boxIn some cases, i. e. for lighting,only the live and neutralcable is needed.Drawing of the ground floor, showing switches, sockets and the assignments of cables and conduits40Addis AbabaCity Government

SANITARY INSTALLATIONTo ensure correct lengths and angles, it is wise to mountsanitary pipes and joints for testing purpose.Sanitary pipes areplaced. One has toensure the correctpositions of openingsof the pipes.In the groundfloor pipes have tobe placed belowthe slab withinthe hardcore, toprevent load frombeing delivered tothe pipes, as theyare not able tocarry load.Proper opening in foundation strip of the wall to avoid loadon the pipe. Reaching the main sewer line on correct level.- Ensure enough space to the slab and foundations,as pipes cannot bear load.- Keep minimum distance to walls for plastering.- Ensure correct slope of pipes. Secure openings witheasy removable paper from used cement bags.Sometimes the spacial geometry can be complex. Keep inmind, that you will need space for plaster work on the wall!Securing openings with easy removable paper. Ensure thecorrect slope of the pipes and enough space for the slab.Sometimes also pipes have to be mounted hidden under theplaster. Channels for the pipes have to be made in the walls.THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK41Addis AbabaCity Government

GROUND FLOOR SLABOn top of the hardcore layer, a leanconcrete (C-5) anda reinforced concreteslab (C-25) isplaced.Before putting thecement screed,a plastic sheet isplaced to preventmoisture from beingsoaked by thecement screed.To hold the reinforcement of the cement screed in position, itis placed on top of concrete rulers before casting concrete.Plaining the cement screed with a levelling board.The finished cement screed.The finished cementscreed. Theseparating plasticsheet has also toseparate the cementscreed fromthe walls. Overlappingplastic sheet iscut off later.Whenever the area to be covered by the cement screedreaches a certain size, expansion joints have to be placed.- In case of high level of groundwater a plastic sheethas to be placed between lean concrete and cementscreed to prevent the screed form soaking moisture- Precise levelling of the cement screed eases futureflooring work. Consider expansion joints!42Addis AbabaCity Government

WALL CONSTRUCTIONExisting exterior walls are made out of natural stone, whereasinterior walls are made of brick.In some cases,cracks can beseen due touneven settlementof foundations.These cracks arerepaired by installingreinforcementbars around thecorner within themortar joint beforeplastering.Cracks can beeven more seriousbetween interiorand exterior walls,where no properjoining of the wallshas been made.- Remove old plaster- Repair cracks, insert reinforcement if necessary- Close openings according to design drawings- Wall up new walls according to designReinforcement bar within the mortar joint.Existing plaster isremoved.Thereafter lintelsand beams can bemore thoroughlychecked for damage.Cracks in walls arenow accessible andcan be repaired.Openings no longer needed are closed and new walls arewalled up.THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK43Addis AbabaCity Government

FIRST FLOOR SLAB REPAIRRotten beams werediscovered whenexamining the firstfloor slab.Parts of the pumiceconcrete filling hadto be removed toget access to thedamaged beams.This had to bedone especially inareas, where theroof cladding wasdamaged or lost,allowing rainwaterto infiltrate.One of the rotten beams of the first floor slab.Supports for the damaged beams. The beams are cut andshafted.Rotten parts of beams were removed and the remains werecut clean.Joint of a shafted beam, made by cutting along the beam’saxis and fixing with screws.A substructure made out of a lathing with a mesh reinforcementis placed underneath the beams.- Support beams with posts. Securing and supportingthe beams is crucial for building stability and safety.- Take out concrete filling between beams.- Cut and shaft damaged wooden beams.- Place substructure and formwork.44Addis AbabaCity Government

FIRST FLOOR SLAB REPAIRA lintel is made, replacingthe existingwalls of the café’scorridor.The concrete iscast through thefirst floor slab intothe formwork.To ensure propercompaction of thecast concrete, avibrating cylinderis used. Sufficientcompaction is especiallynecessaryfor load bearingbuilding parts.Formwork is placed below the damaged area to hold thepumice concrete.The pumice is carefully compacted by hand not damaging orbending the steel wire mesh substructure.- Place reinforcement if needed. It has to be negotiatedwith the structural engineer, if reinforcement hasto be placed or not.- Place and compact pumice concrete. Concrete forThe lintel below the first floor slab after removing theformwork.(CONTINUED)The pumice concrete is placed. According to the structuralengineer’s calculations reinforcement was not needed.The repaired part of the slab seen from below. The wiremesh also serves as a base for the plaster.load bearing parts as lintels has to be compactedcarefully. Use a vibrating cylinder.THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK45Addis AbabaCity Government

CONCRETE BEAM REPAIRDamaged beam’s reinforcement in the two rooms that haveterraces above, which are no longer waterproof.The terrace tiles are removed to gain access to the concreteslab.The slab is supportedby posts sothat the concreteof the beam canbe chiseled outwithout facing anydanger.The uncovered reinforcement of the beam. As it is bound intothe slab, all concrete has to be chiseled out up to the top.Additional chiselingfor a better joiningof the old slab andthe new concretebeam has to bemade. Additionalreinforcement isplaced in theseopenings to the leftand the right side.As the reinforcementbars of thebeam are corroded,the load bearingcapability of thesebars is no longersure. Additionalbars are insertedfor safety reasons.This picture showsthe connection tothe wall, where theconcrete of the oldbeam had to bechiseled out intothe depth of thewall (new bars aremarked red).- Support the slab by posts.- Chisel out concrete of the beam. Check for necessaryrepair work on the beam’s reinforcement.- Place additional reinforcement bars.- Place formwork.46Addis AbabaCity Government

CONCRETE BEAM REPAIRInserting the new reinforcement bars between the existingones.Detail of the reinforcement and the mounted formwork.Ensure sufficient concrete cover for the bars!The fresh concrete should be fully covered and moisturizedafter casting to avoid cracks due to shrinkage.- Cast concrete. Prevent the freshly cast concrete fromdrying out. This would lead to shrinkage and cracks,resulting in reduced load bearing capacity and watertightness.The connection of the beam’s reinforcement to the groundfloor wall’s ring beam.The mounted formwork for the concrete as seen from below.The final result after plastering.(CONTINUED)THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK47Addis AbabaCity Government

ROOF FRAMEWORK REPAIRThe existing roof framework as seen through the lathing ofthe existing suspended ceiling.Overview of the roof framework’s rafters and ridge purlins(computer model).Joint of the existing roof structure’s rafters made with bolts.Rafters (right side), rafters with lathing (left side) and trussedbeam with ridge purlin (middle).Old framework and new lathing.Rafters and lathing of the hipped roof structure.- Dismantle existing roof cover- Repair work on roof’s framework- Place new lathing48Addis AbabaCity Government

ROOF COVERINGRoofing shingle made of coated corrugated iron sheet.Shingles are mounted by screwing on the lathing.The hooks for the gutters (marked red) are mounted byscrewing or nailing to the rafters.The mounted gutters, painted with the final coat. Down pipeswill be mounted after finishing the external plaster work.- Mount roof cover on lathes.- Mount hooks for gutters- Mount down pipes after finishing the plaster workson the exterior walls.The finished roof framework and cladding seen from belowPrefabricated gutters in segments, primed and ready formounting.Mounted downpipe. The fixture(marked red) isembedded to thewall.The upper part ofthe down pipe ismade out of softzinc metal sheet.To avoid damageon the pipe, thelower two metersare made out ofcast iron.THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK49Addis AbabaCity Government

ELECTRICAL INSTALLATIONChiseled channelfor electrical installationending in abox for a switchor a socket. Theswitch or socketwill be put withinthe box, so only thefront of it can beseen after mounting.Conduits for electrical installation can be easily bent whenheated.The wires are fixedtemporarily withgypsum. The wiringwork was done afterapplying the firstcoat of plaster.Also a multitude of conduits for telecommunications andelectricity can be put under plaster, hiding them.Mounted box forswitch or socket,fixed with gypsum.Box for a switch mounted behind tiles. Screw holes for thefixture of the switch are also provided with the box.- Installation of electrical conduits and cables accordingto the electrical design. Hiding cables and conduitsunder plaster gives the walls a high quality appearance.50Addis AbabaCity Government

INTERNAL STAIRCASEThe handrail before dismounting. All parts are marked toease assembling after repair.One of the original steps is broken. By turning it 180 deg. itcan be reused. Edges are rounded with a grinder.The metal holdersof the handrail areembedded to thewall and fixed withmortar.- Ensure exact position of mounting saddles for thehandrail.- Broken steps can be repaired using the same materialby turning the step 180 deg.- Terrazzo steps can be grinded with angle grinderPlacing the reused step in mortar bed.The staircase withouthandrail. Thehandrail is repairedand broken piecesare renewed. It isalso sanded andpainted.Plaster work on thestaircase and repairwork on the stepsare carried out.The handrail’s saddles, made of wood, mounted on the wall.Openings will be filled while plastering the second coat.- Use acid water mixture for cleaning terrazzoTHE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK51Addis AbabaCity Government

INTERNAL STAIRCASE(CONTINUED)The renewedhandrail’s postis mounted andenclosed by aconcrete basis.While casting theconcrete a spaceto the upper levelof the step is left(approx. 2,5 cm).The space is filledwith a mixtureout of mortar andmarble chips.Fixture of the old handrail at the lowest point. A part of thelast step is broken and missing.After curing thesurface can begrinded and polished.The result looksquite similar to theoriginal terrazzosteps.The mixture of mortar and marble chippings.The original terrazzosteps arecleaned with amixture of waterand acid.The ceramic skirting board is mounted.52Addis AbabaCity Government

PLASTER WORKApplying fist coat (splash targeting) of cement plaster onrough wall surfaces like natural stone walls.Preparation of cement lime plaster in a self-made trough outof HCBs and plastic sheet.A proper thickness of the first and second plaster coattogether is around 2,5 cm.- Place plaster on natural stone walls by splash targeting.- Plaster fist coat on all walls (cement plaster).- Plaster second and third coat on all walls (cementlime plaster).Applying the first regular coat of cement plaster using troweland plasterer’s float.The second plastercoat is applied.Lime cement plasteris used. Nowthe surface is muchsmoother.Precise work isneeded whenplastering edges.Use plumb line andspirit level to ensurestraight edges.- While plastering, keep edges straight.- Avoid over plastering frames of doors or windows.- Ensure correct thickness of the coats.THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK53Addis AbabaCity Government

PAINT WORKThe final coat in theinterior corridors isa plaster-like paintthat is applied similarto a fine plaster.The surface of the plaster-like paint in the corridors in detail.Also for the exteriora similar paint wasused. It’s surface isa bit more rough.The picture showsthe second coat ofpaint on the rightside and the finalcoat on the left.Painting work ondoor frames.To avoid spilling ofpaint on the walls’surfaces, the useof adhesive tape isrecommended.The adhesive tapecan be stuck ontothe wall surface,covering it whereneeded and protectingit from freshpaint.The interior brokenwhite final coat,the blue windowsframe and the exteriorgreenish paintseen together.While choosingcolors, consider allnecessary colors ofa building together.Avoid over painting or plastering door and window frames,as cleaning is more time consuming than precise working.- Paint walls with three coats of paint.- Paint final coat on frames of doors and windows.- Paint final coat on handrails of stairs, balcony andterraces.- Avoid over painting, use adhesive tape to coverbuilding parts not to be painted- Use correct mixtures for the first, second and finalcoat of paint according to color and the kind ofpaint.54Addis AbabaCity Government

FIRST FLOOR TERRACES WEATHERPROOFINGCement screed for levelling and correct sloping to preventwater from permanent stay.Pillars have aplastered foot, thateases welding thebitumen sheet andkeeps the masonrywork out of thereach of rainwater.By covering thepillar with a biggernatural stone plate,the pillar is protectedfrom rainfall.Bevel edges withmortar between theslab and the pillar’sfoot.Openings for lightsare provided.To prevent wallsfrom soaking waterfrom the terrace, itis recommendedto also cover thelower 15-20 cmof walls with thebitumen sheet.To prevent thematerial from futurecracking, the edgebetween wall andslab is bevelledwith mortar.- Place cement screed- Wall up pillars, plaster lower 20 cm- Prepare beveled edges where the bitumen sheet hasalso to cover walls- Prepare water intakes, outlets and guttersBuilding up the pillars for the balustrade. Handrails aremounted and electrical conduits are placed within the pillars.The pillar’s cover stone has a drip off edge to prevent rainwaterfrom reaching the masonry work.Water intakes haveto be preparedbefore bituminouspaint is applied.The bituminouspaint providesbetter connectionbetween the bitumensheet and thecement screed.Take care not tocover the waterintakes!THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK55Addis AbabaCity Government

FIRST FLOOR TERRACES WEATHERPROOFINGWhere no guttersare used, metalwater outlets withsufficient lengthhave to be inserted,keeping the fallingwater from reachingthe wall andkeeping the walldry.(CONTINUED)Before heating and glueing the bitumen membrane, a bituminouspaint is applied, also to the walls up to 20 cm.Bituminous paint (seen on the foot of the pillar) and bitumensheet at the moment of welding.The bitumen sheet is also covering the lower parts of thewalls. Ensure proper overlaps and sealing at the edges!The correct overlappingof the bitumenwaterproofingmembrane hasto be ensured. Toprevent future leakage,each bitumenmembrane must beoverlapped by thenext membrane.With a gas burnerthey are then gluedtogether. This workhas to be donecarefully and accurate,to ensure awaterproof terrace.Finished pillar withcover for lighting.Also the cementoxide screed ismade.The lower part ofthe pillar still showsthe bitumen sheetand bituminouspaint to ensurewater tightness.- Apply bituminous paint on all surfaces that have tobe covered by bitumen sheet- Heat and glue the bitumen waterproofing membrane- While heating and glueing the bitumen waterproofingmembrane, ensure correct overlaps of the material.Reduce number of joints is crucial. Any joint or overlapcan be a future leakage. Do not cut or puncturethe membrane until necessary.56Addis AbabaCity Government

FLOORING WITH CEMENT OXIDE SCREEDCasting of cement oxide screed on the ground floor slabwithout reinforcement or plastic sheet.Glass wool is mixedinto the cementoxide screed. Thefibres of the glasswool act as reinforcementto avoidcracks caused bymaterial shrinkageand temperaturechanges.To further avoidcracks caused bymaterial shrinkage,the continuous areacovered by the cementscreed has tobe kept small.Expansion jointsare introducedaccording to thefoundation stripesof the walls.- Cast cement oxide screed- Cover to prevent drying out- Cut additional expansion joints where necessary- PolishTo avoid cracks,5 mm Styrofoamhas to be placed inbetween the wallsand the cementscreed.OverlappingStyrofoam is cutafter curing of thescreed and coveredby the skirtingboards.Curing period. Toprevent cementscreed from dryingout, it is covered byplastic sheet.Too fast drying ofthe cement screedwould result incracks.In some areas the screed is cut providing an expansion jointto avoid uncontrolled cracking.- Because the cement oxide screed is considered asa high quality finish, irregularities in the finish andcracks have to be avoided.- Mix glass wool into the cement screedTHE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK57Addis AbabaCity Government

FLOORING WITH CEMENT OXIDE SCREED(CONTINUED)The expansion joint is filled with cement oxide concrete orsilicone.The cement oxide screed is polished with this machine witha rotor and four blades.The cement oxide screed was also applied on the café’s terraceon top of the bitumen waterproofing membrane.Wooden skirting boards are placed matching the color of thecement oxide screed.The finished screed on the café’s terrace ...... and in the exhibition room.- Expansion joints can be filled with cement oxide concreteby hand58Addis AbabaCity Government

LAYING THE PARQUETFor some rooms,for example the studio,the placementof a cement screedwas not possible.The woodenbeams in the slabconstruction ofthese rooms have aminimal movementdue to the naturalmaterial. A cementscreed wouldquickly crack.Therefore sandwas dried in thesun and used as alevelling screed.To ensure exact levels, lathes were placed within the drysand. Levelling with levelling board, cord and spirit level.Sorting dismantled parquet planks for reusability.- Preparation of skirting boards and planks- Use sub construction with dry sand and chip woodboards in areas, where a wooden slab constructionis situated below.- Laying parquet. Glueing parquet’s planks has to beThe dry sand is placed onto the rough first floor slab in thestudio, made out of wooden beams and pumice concrete.The dry sand afterlevelling. Only thelathes used as ameasure for thelevelling can beseen.Chip wood boardsare placed on topof the dry sand toprovide a constructionground forthe glueing of theparquet planks.Cutting old parquetplanks to exactmeasurements forthe new parquetdesign.At this time sandingis not necessary.done on a clean and dry surface. Any loose materialhas to be avoided.- Sanding (rough)- Filling rabbets with resin filler- Sanding (fine)THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK59Addis AbabaCity Government

LAYING THE PARQUETTo work quickly,a package of theplanks is laid outand prepared withglue from oneside...(CONTINUED)... and laid directly onto the cement screed or chipwoodboard, facing with the glueing side downwards.After sandinguneven levels areremoved and theparquet’s surface issmooth.Also old paint anddirt are removed asit can be seen atthe inner part of theparquet floor on thepicture.Within door openings, special ornaments are laid. Rabbetsare filled with resin filler.The parquet after second sanding and impregnation. Polishingwill be the final step.The parquet after polishing.- Impregnation and mounting skirting boards- Polishing60Addis AbabaCity Government

TILING WORKTiles can be cut with an angle grinder achieving preciseedges and openings.Before starting thetile setting, it iswise to check themeasurements ofthe tiles.Depending onbrand and quality,huge tolerancesare possible.To achieve highquality results onlyuse tiles with minimumtolerance.Spacers are usedto exactly place thetiles. This proceduremakes workfaster and moreprecise.Some spacersare marked in thepicture,- It is preferable to glue tiles on a precise cementscreed instead of laying them in mortar bed. Usecement screed and glueing whenever possible.- Use spacers for setting the tiles.- Check the tiles’s dimensions before setting them.Exceeding openings can be closed if the remaining part ofthe tile is kept (marked red).Tiling work in thetoilets. The tiles areplaced in mortardirectly onto theplastered wall.Be sure that theplaster and themortar is made precisely.Tiling workon uneven surfacesis very difficult andleads mostly to aninsufficient result.The finished tiled wall. Notice the exact and even size of therabbets.THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK61Addis AbabaCity Government

TILING WORKAs mosaic tiles arevery small, workon mosaic floors orwalls is difficult andtime consuming.Most of the mosaicfloors had to berepaired using oldand also some newtiles.(CONTINUED)Use only little amount of mortar to place tiles, as the volumeto fill with mortar is small.Proper mixture of old and new tiles, resulting in a harmonicimpression of colors.Sanitary furniture and installations in bathrooms should besealed with silicone to make cleaning easier.The finished mosaicfloor gives aharmonic impressionof colors.Wooden skirtingboards are placed,matching the colorof the flooring.Expansion jointsin the groundfloor can be easilyintegrated, as themosaic tiles havesmall sizes. No tileshad been cut orextra large rabbetsintroduced.- Sealing rabbets of sanitary china to the floor- Sealing rabbets between wall tiles and floor tiles- Sealing rabbets with silicone makes future cleaningeasier, important in kitchens, toilets and bathrooms.62Addis AbabaCity Government

SUSPENDED CEILINGSLathing for the suspended ceiling of the first floor. The ceilingis carried by the roof’s framework.Prefabricated chipboard panels ensure exact measurements.Cables and conduits can be easily hidden behind a suspendedceiling.- Prepare lathing and framework, cut chipboard panels- Mount panels according to lathing- Mount ceiling stripes- Paint and rabbets’ workPlaster is used to fill gaps and irregularities between thelathes and the walls.Mounting of chipboard panels.Filling rabbetsbetween the ceilingand the wall withsilicone provides asmooth rabbet-lessfinish of the ceiling.Cracks due toshrinkage of theceiling are avoidedin future.- Fill rabbets with silicone to achieve a permanent rabbet-lessfinishing of the connection between wall andceiling.THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK63Addis AbabaCity Government

RENEWAL OF DOORS & WINDOWSRemoving old paintwith hot air dryerand trowelThe glazing has to be removed before work on the window’sbody is carried outCareful cleaning ofornaments of doorsand windows usinga wood chiselIn most cases the wood was found in good condition underthe old paintAlso frames arecleaned using hotair and a specialtrowel. These trowelsare self-madeto especially reachinto edges andcorners.Renewal of damagedparts onwindow shutter. Asmany as possibleof the old woodenparts have beenreused.- Take out all doors and windows for repair works- Burn off paint from doors, windows and frames- Renew damaged parts and check for distortion andshear64Addis AbabaCity Government

RENEWAL OF DOORS & WINDOWSChecking for exact overall measurements to eliminate distortionDovetailed joint of awindow shutterAll you need for a glazed door: door frame, door casementand shutters- Repair works of frames, doors, windows and shutters- Production of new frames, doors and shuttersGlueing of window shutter(CONTINUED)Painting the shutterin two coats. Thefirst coat containswood protectiveadditives.Glazing is mounted into the door’s casement. Putty seals thewindows and gives also proper fixture to the glass.THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK65Addis AbabaCity Government

PAVING WORKCrush and chisel natural stones to exact dimensions. Do notchisel conic stones!Main lines as rainwater ditches, borders and openings forgreenery are laid first. Ensuring overall level and slope.Edging has to be placed at the borders of the pavement tokeep the stones together.Prepare ground on exact level. Use cords, levelling boardand spirit level to ensure exact level and slope of the surface.Laying of stones in sand. The stones are pressed into thesand by careful hammering.Use cords to keep straight lines.- Preparation of ground- Laying of main lines- Laying of paving stones- Flushing with fine gravel and water- Use proper material for ground preparation andflushing. Ensure minimum slope to prevent rainwaterfrom staying- Ensure proper flushing to achieve durability of thepavement by well compacted fine gravel in rabbets.66Addis AbabaCity Government

PAVING WORKKeep similar sizesof rabbets. Therabbets are flushedwith fine gravellater.Flushing fills therabbets with finewell compactedgravel that holdsthe stones in theirposition.Proper choice ofthe gravel for flushingis important forthe durability of thepavement.The flushed stones in detail.Installations like water intakes can be integrated in a decentmanner.A multitude of ornaments and patterns are possible withsmall size paving stones.Left side of picture shows the already flushed pavement.Proper flushing will give permanent fixture to the stones.The sun ornament of the pavement in the middle of thecourtyard.(CONTINUED)THE KASANCHIS RENOVATION PROJECT HINTS ON THE EXECUTION OF WORK67Addis AbabaCity Government

STRUCTURAL DESIGN OF COST EFFICIENT APARTEMENTSANALYSIS OF SLABSTRUCTURAL SYSTEMThe floor system is composed ofpartially pre cast rib beams castmonolitically with a topping slab of6cm deep. HCBs of special shapeare used as fillers and formworkbelow the topping slab, separatingthe ribs.HCB SLAB DETAILCAST INSITU CONCRETEPRECAST BEAMHOLLOW BLOCKTYPICAL SLAB SECTIONTYPICAL SLAB SECTIONTOPPINGREINFORCEMENTP dThe topping is a one way slabthat is supported on the pre-castbeams.L=625 mmTaking a one meter strip and analyzingthe slab it could be shownthat the area of steel to be providedisHCB SLAB DETAILminimum. The shear should alsobe checked because of local sheardevelopments due to small slabdepth.Fig. 1: Section of slab at final conditionThe maximum shear developedv max= pdl/2 is checked against thecapacity of the section and it isdetermined whether shear reinforcementshould be provided ornot. In the present example noshearreinforcement is provided sincethe applied shear is less than thecapacity of the section.Minimum reinforcement from thecode suggests that a reinforcementmesh providing in each directionacross sectional area not less than.001 of the section of the slabshould be provided.A typical section of a slab withminimum reinforcement is shownin FIG-1.68Addis AbabaCity Government

ANALYSIS OF PRECAST BEAMThe analysis of the pre-cast beamis divided into two parts.1. Initial condition2. Final conditionINITIAL CONDITIONThe initial condition is one whenthe pre cast beams are laid on themain beams supporting them,overlain by the slab HCBs, beforetopping slab concrete is cast.For spans greater than 4m a concretesection of 80mm depth and120mm width has been used.For initial condition this pre castbeam is laid on the main beamssupporting it. Since the initialcondition is a transitory period thedepth of the pre cast beam is chosenfulfilling the flexuralrequirement which is shown later.A typical pre cast beam section isshown in Fig.2.Fig. 2: Detail of precast beamFig. 3: Precast beam and HCB arrangementbefore top slab casting(initial condition )HCB SLAB DETAIL AT INITIAL CONDITIONThis precast beam is to be supported at midpoints in order to meet it’s designrequirements typical section of a pre cast beam with the hollow blocksat initial condition is shown in Fig-3.The pre cast beam at initial condition is designed to carry the live load anddead load. It is provided with shear reinforcement in accordance with thecode requirements.Typical analysis of a precast beam at initial condition: STRUCTURAL DESIGN OF COST EFFICIENT APPARTEMENTS CALCULATIONS69Addis AbabaCity Government

ANALYSIS OF PRECAST BEAM(CONTINUED)Checking for shearThe compressive force cs shouldbe multiplied with the buckling The shear force in the beam is calculated for maximum value. (v max)ratio of the reinforcement and it’sdivided with the area of the re-bar V maxis distributed to the diagonal reinforcements and the appropriate re-barwhich is checked with the allowablestress . The bottom reinforce-is selected which can carry the induced stress.ment should be able to carry thedesign moment.FINAL CONDITIONIn cases where the span is longer,the pre cast beam isn’t able tocarry thedesign moment and an intermediatesupport is provided and theanalysis is done as shown before.The section of the slab at final condition is shown in FIG-4.HCB SLAB DETAIL Fig-4 Section of slab at final condition Loading:dead load (g k ) :pre cast beam : 0.12*.08*25= xThe corresponding c sis calculatedand it’s divided with by thearea of the reinforcement whichis checked against the allowablestress capacity of the reinforcement. This is provided as a bottomreinforcement. This is the negative moment developedat the temporary support.In the same case the stress comingto the reinforcement should beless than the allowable stress.Lconcrete block + cast in situ concretefloor finish + partition= y_ g klive load (q k ) :- depends on the purpose of structureDesign load :m max = Pp d = 1.3* g k + 1.6* q d *L 2k8System:P d us = m df cd *b*d 2= z- for this value of us a graph is readfrom EBCS code and the value of k x isread.70Addis AbabaCity Government

ANALYSIS OF BEAM AND COLUMNThe depth D varies depending onPRECAST BEAMthe span.A depth of 280 mm was used forappartements with 5.0 m span inAddis Ababa.The longitudnal section of a typicalprecast beam is shown in fig-4.FIG-4 typical longitudnal section of precast beamPRECAST BEAMk x= x/dfrom this we can get the value ofx.This value is checked against thecentroidal axis of the beam and itdetermines whether the beam actsas a T-beam or a rectangular section.mine the value of k z.A S=M/K Z*d*f ydThe above equation is used to determinethe area of steel.check for shearThe shear force that comes to thestructure equalsv sd= p d*l/2This value is compared with thecode requirements of the sectionand then the appropriate shearforce equation is used to determinethe reinforcement to be provided.The longitudnal section of a typicalprecast beam is shown in fig-4.The same graph is used to deter-ANALYSIS OF BEAM AND COLUMNThe beam is the primary structurethat supports the precast beams .There are two types of beams usedin this approachit to wall under and columns.Given a masonry stiffening wallthat is constructed into the frameit can be expected that due to therestraints of the frame to the stiffeningBut due to imperfect constructionof the wall & also quality of hollowblocks it will be difficult to assumethat the wall will totally carry& transfer the load from pre-castbeam & the wall above. And therefore- Beam in U shaped HCB (supportedby the wall)-These were wall the wall will act as a di-agonal within the frame and significantlyin designing the girder beams, the wall is assumed to carry someused in class B HCB wallsreduces the loads imposed percentage of the vertical load.- Beam with out wall support on it. The function of the stiffenerwall is only limited by the shear Additional horizontal reinforcementBeam in U shaped HCBAs it is mentioned above it carriesload that comes from the precastbeam and wall above and transfercapability . Tension forces will bemainly eliminated by the framevertical members if the mortar jointb/n the horizontal frame member &the wall provides sufficient contact.within the hollow block maybe considered to upgrade the wallshear load bearing capacity.STRUCTURAL DESIGN OF COST EFFICIENT APPARTEMENTS CALCULATIONS71Addis AbabaCity Government

DDCCBBAAA'A'116001200 5580120035700PB-122500226420 1200 5580120035700PB-12952033120035700PB-14412002345971920055120035700PB-1661200120028320PB-155807735700 3570012006420PB-122500885975580 12001200ANALYSIS OF BEAM AND COLUMN(CONTINUED)Beam without wall supportThis beam is used when1. There is no wall support due to openings and cantilever positions 2. CLASS C HCB walls are used due to unavailability of class B HCB.3. To speed up the construction of suspended slabs by constructing wallHCB after beam and slab construction.A typical section of the U-beam supporting a pre cast beam as shown inFIG-5.FIG-5The layout of the pre cast beam is shown for a typical Apartement.682179837 25800234609120FFB-13750 3750 3750 3750 3750 3750 3750 3750 3750 37503750 3750 3750 3750 3750 3750 3750 37501370x300x5mm THICK PLATEFFB-21200Ø6/300 meshFFB-41370x300x5mm THICK PLATEFFB-23750 37501200Ø6/300 meshFFB-4FFB-11370x300x5mm THICK PLATE375037503750 3750 37503750 3750 3750 3750 37503750 3750 3750 3750 3750 3750 3750 375012003750 3750 37503750 3750 3750 3750 37503750 3750 3750 3750 3750 3750 3750 3750FFB-3FFB-33750 3750 3750 3750 3750 3750 3750 3750 3750 37503750 3750 3750 3750 3750 3750 3750 3750FFB-11370x300x5mm THICK PLATE1200FFB-1FFB-3FFB-3The pre cast beams are provided with edge reinforcements in order to takecare of small negative moments that might develop and to insure stability.In the same waypre cast beams at edge are provided with additional negative reinforcementsto take care of cracks that might develop by a negative moment.The additional re-bar is shown in FIG-6. FIG-6 Additional re-bar at edge72Addis AbabaCity Government

ANALYSIS OF BEAM AND COLUMNCOLUMNSwall is considered as a non loadFor columns with load bearing bearing wall .wall, lateral loads (earth quakeload) coming to the structure areresisted by both the columns and Type of foundationthe wall. The column is totallybraced by the wall. To consider The type of foundation is chosenthis effect the wall is modeled togetherwith the frame element in of foundations. These are footing,by making analysis for three typesthe analysis.mat and trench masonary foundationand a cost analysis is made toFor columns without load bearingwall, lateral loads (earth quakechoose the most economical one.load) coming to the structure are The type of foundation chosen dependson the type or size of struc-resisted by the columns.ture and the soil condition.The analysis of this beam and columnsand the frame as a whole ismade by using a software in a 3-D SUMMARYmodel. (SAP 2000 was used in thiscase) .All in all the purpose of the designis to make a safe and economicalFor the smaller residential buildingsup to two stories vertical loads purpose.structure that meets its intendedare governing. For stories higherthan two stories lateral loads are The design of the buildings meetsusually governing in the design the standard code of practice ofof columns. The whole design is the country.based in guaranteeing a ductilesystem that is both safe and economical.Lateral load analysis of the buildingswas done according to theprovisions of the Ethiopian BuildingCode Standards.Usage of the hollowblock wall as a structuralelementThe hollow block used in the constructionof the cost efficient housingis used in the analysis as a loadbearing wall for walls which areclass B. It is assumed to have 20%of Modulus of elasticity of concrete. For walls which are class C the(CONTINUED)STRUCTURAL DESIGN OF COST EFFICIENT APPARTEMENTS CALCULATIONS73Addis AbabaCity Government

TYPICAL 3D MODELS OF RESIDENTIAL AND APPARTEMENT BUILDINGS3D MODEL OF A TYPICAL G+3 BUILDING( WITHOUT A LOAD BEARING WALL)3D MODEL OF A TYPICAL G+2 BUILDING( WITHOUT A LOAD BEARING WALL)74Addis AbabaCity Government

TYPICAL 3D MODELS OF RESIDENTIAL AND APPARTEMENT BUILDINGS3D MODEL OF A TYPICAL G+2 BUILDING( WITH AND WITHOUTOUT A LOADBEARING WALL)3D MODEL OF A TYPICAL G+1 BUILDING( WITHOUTOUT A LOAD BEARING WALL)(CONTINUED)STRUCTURAL DESIGN OF COST EFFICIENT APPARTEMENTS CALCULATIONS75Addis AbabaCity Government

TYPICAL 3D MODELS OF RESIDENTIAL AND APPARTEMENT BUILDINGS(CONTINUED)3D MODEL OF A TYPICAL G+4 BUILDING( WITH A LOAD BEARING WALL)3D MODEL OF A TYPICAL G+4 BUILDING( WITHOUTOUT A LOAD BEARING WALL)76Addis AbabaCity Government

TYPICAL 3D MODELS OF RESIDENTIAL AND APPARTEMENT BUILDINGS3D MODEL OF A TYPICAL G+5 BUILDING( WITHOUTOUT A LOAD BEARING WALL)3D MODEL OF A TYPICAL G+5 BUILDING( WITH A LOAD BEARING WALL)(CONTINUED)STRUCTURAL DESIGN OF COST EFFICIENT APPARTEMENTS CALCULATIONS77Addis AbabaCity Government

TYPICAL DRAWINGS FOR THE COST EFFICIENT BUILDINGS78Addis AbabaCity Government

STRUCTURAL DESIGN OF COST EFFICIENT APPARTEMENTSTYPICAL STRUCTURAL DRAWINGS79Addis AbabaCity Government

TYPICAL DRAWINGS FOR THE COST EFFICIENT BUILDINGS(CONTINUED)80Addis AbabaCity Government

STRUCTURAL DESIGN OF COST EFFICIENT APPARTEMENTSTYPICAL STRUCTURAL DRAWINGS81Addis AbabaCity Government

TYPICAL DRAWINGS FOR THE COST EFFICIENT BUILDINGS(CONTINUED)82Addis AbabaCity Government

STRUCTURAL DESIGN OF COST EFFICIENT APPARTEMENTSTYPICAL STRUCTURAL DRAWINGS83Addis AbabaCity Government

TYPICAL DRAWINGS FOR THE COST EFFICIENT BUILDINGS(CONTINUED)84Addis AbabaCity Government

STRUCTURAL DESIGN OF COST EFFICIENT APPARTEMENTSTYPICAL STRUCTURAL DRAWINGS85Addis AbabaCity Government

TYPICAL DRAWINGS FOR THE COST EFFICIENT BUILDINGS(CONTINUED)86Addis AbabaCity Government

CREDITS TO THE STAKEHOLDERSTsedale MamoAAHDPOmanageroverall coordinationAmare AsgedomAAHDPOland, infrastructure and designdepartment headland provision, design and utilitiescoordinationRuth ErlbeckGTZ / LCHproject managersociologist / economistoverall coordinationDipl.-Ing. Ralph TrosseGTZ / LCHtechnical advisorarchitectdesign, coordination, site supervisionand documentationDr. Messele HaileMH-Engineering PLCmanaging directorstructural supervisionDipl.-Ing. Carsten StammeierGTZ / LCHarchitectproject documentation and illustrationsIngo Oexmann landscape designer training of natural stone pavement,exterior designKifle GutemaGTZ / LCHsite managerconstruction site management,construction supervision, purchaseGetechew DugoGTZ / LCHsite managerconstruction site management,construction supervision, purchaseARGE Otterwasser GmbH/TUTech Innovation GmbH/Planungsgruppe Prof. KruschePPP ECOSANRalph Bäcker professional photographer presentation photographs87