Rules for the Classification of Floating Docks - Boat Design Net

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Chapter 4Table 7 : Table 7 : Grades of steel to be used for elements contributing to longitudinal strength, not includedamong those considered in Tab 2, but of particular local importanceThickness s ≤ 30 mm 30 < s ≤ 40 mm s > 40 mmNormal strength A and B B EHigher strength steels AH AH DHTable 8Lifting capacity ≤ 40000 t 50000 t 60000 t 70000 t 80000 t 90000 t 100000 tCoefficient C 0,8 0,85 0,89 0,92 0,95 0,97 0,993.2 Docks in reinforced concrete or in prestressedreinforced concrete3.2.1 Docks in reinforced concrete or in pre-stressed reinforcedconcrete are considered by RINA on a case-by-casebasis.4 General requirements for scantlings4.1 General4.1.1 The scantlings of the dock are to be such that theindicative values of the state of the structure obtained byapplying the requirements for the check of the longitudinal,transverse and local strength given in the following itemsare no greater than the values of the allowable state.The scantlings of docks in reinforced concrete or in prestressedreinforced concrete are considered by RINA on acase-by-case basis.States exceeding the allowable state, but not in excess ofthe limit state, may be permitted at RINA's discretion underparticular exceptional circumstances.4.2 Allowable state and limit state4.2.1 Definitionsa) Allowable state: the whole of the allowable stresses andglobal and local deformations.b) Limit state: the whole of the stresses and global andlocal deformations beyond which the structure loses itsfunctional characteristics.c) State of the structure: the whole of the stresses and globaland local deformations of the structure.The allowable state and limit state are defined with referenceto the mechanical characteristics of materials and thestability conditions of elastic equilibrium of the structure.4.2.2 Steel docksa) Allowable stresses:σ id amm = 160/K, in N/mm 2τ am = 90/K, in N/mm 2The values of the coefficient K are those indicated inPart B of the Rules, in respect of the steel grade.b) Limit stresses:σ id lim = 0,9 σ snτ am = 0,52 σ snwhere σ sn is the nominal yielding stress of the material.Stress values less than those indicated in items a) and b)may be assumed, at RINA's discretion, with respect to therequirement of granting adequate safety for possible instabilityphenomena.4.3 Direct calculations4.3.1 When checking the constructional drawings, RINAmay consider material distribution and scantlings other thanthose obtained applying the requirements for the check oflongitudinal, transversal and local strength given in the followingitems, provided that it is demonstrated, by means ofdirect calculations based on theoretical assumptions and/orexperimental results, that the allowable state or, for exceptionalload conditions, the limit state is not exceeded.Direct calculations made in accordance with the mostadvanced techniques are to be carried out wheneverrequested by RINA and in general in the case of unusualstructures or docks of large dimensions or particular characteristics.RINA reserves the right to require structural checks, alsotaking into account particular conditions which may exceptionallyoccur during the dock operation.The direct calculations are to be carried out for the mostsevere anticipated realistic load conditions.In particular, if the hydrostatic loads on the local structuresare determined with respect to the differential heads anticipatedduring operation and it is possible that, due to damage,said heads may be exceeded, the check with the loadcondition due to the extreme hydrostatic head which maybe assumed on the structure is to be carried out.4.4 Longitudinal strength4.4.1 Load conditionThe longitudinal strength is to be verified for dock operativeconditions, with the waterline corresponding to the pontoonfreeboard B le , with a structure with load equal to thedesign lifting capacity of the dock arranged on the floorand, as far as practicable, symmetrically on length.In the absence of more precise data, the conventional distributionof ship loads shown in Fig 2 may be assumed for drydocks.18 Rules for floating docks 2010
Chapter 4abFigure 2parablebe reported in the operating manual, the dock deformationsare compatible with the safety of the lifted structure.4.5 Transverse strengtha = 5,3 P / (CL ) (kNm)cb = 6,3 P / (CL ) (kNm)cCL cL c4.5.1 GeneralThe transverse strength of the dock is to be checked both inthe middle and in the end areas and scantlings are to besuch that, with the dock in the load conditions indicated in[4.4.1], the state of the structure does not exceed the allowablestate.Whenever more exact data are not available and heavierload conditions are not anticipated, the conventional checkcriteria given in the following items may be assumed.L c : length of the dock (see [1.2.6]), in mP : design lifting capacity of the dock (see Ch 2,[2.3.2]), in tC : coefficient given by the ratio between the lengthof the shortest ship intended to be lifted and thelength of the dock, to be assumed not more thanthe values given in Tab 8 as a function of the liftingcapacity.4.5.2 Dry Docksa) Load on floor1) For continuous pontoon dry docks with liftingcapacity P ≤ 40000 t, the load condition indicatedin Fig 3 is to be considered.Figure 34.4.2 Scantlings of the midship sectionThe scantlings of the midship section of the dock are to besuch that, in the presence of the bending moment derivedfrom the load condition described in [4.4.1], the state of thestructure does not exceed the allowable state.Whenever more accurate determinations are lacking, thevalues of bending moment given by the following equationsmay be conventionally assumed:a) sagging bending moment, in kN·m:M sag = (1,25 - 1,10 C) P L cBFF = 11 P / (CL c ) (kNm)b) hogging bending moment, in kN·m:M hag = 5 M inswhere P, L c , C have the meanings given in [4.4.1].Where a non-uniform ballast distribution is foreseen, it is tobe checked that, in the same load condition but with uniformlydistributed ballast, the structure state does notexceed the limit state.2) For continuous pontoon dry docks with liftingcapacity P > 40000 t, the heavier of the load conditionsindicated in Fig 4 and Fig 5 is to be considered.B uFigure 44.4.3 Extension of the end scantlingsThe scantlings of the main section are to be kept over alength equal to at least to 0,4 L c in the middle, and thenmay be gradually reduced in way of the ends.B mFF=8P/(CL ) (kN/m)c4.4.4 Non-continuous pontoon and walls docksFor non-continuous pontoon and walls docks the bendingmoment and shearing stress are to be determined takinginto account the connections between the various elements.The Interested Parties are to supply documentation certifyingthat in the most severe conditions of actual operation, toB3) For non-continuous pontoon dry docks, the loadcondition F indicated in Fig 3 is to be considered forthe whole length of the dock.Rules for floating docks 2010 19
Page 1 and 2: Rules for the Classificationof Floa
Page 3 and 4: Definitions:"Rules" in these Genera
Page 5: RULES FOR THE CLASSIFICATION OFFLOA
Page 8 and 9: CHAPTER 2 CLASSIFICATION1 Premise 1
Page 10 and 11: CHAPTER 4 HULL, STABILITY AND MATER
Page 12 and 13: CHAPTER 6 FIRE PROTECTION1 Applicat
Page 14 and 15: Chapter 2CHAPTER 2CLASSIFICATION1 P
Page 16 and 17: Chapter 3scope of the annual machin
Page 18 and 19: Chapter 4Table 1 : Documentation to
Page 20 and 21: Chapter 4C = 0,373 + 0,023 B/T 1 -
Page 24 and 25: Chapter 4Figure 5Figure 6h 1ihFFF=5
Page 26 and 27: Chapter 5CHAPTER 5MACHINERY AND SYS
Page 28 and 29: Chapter 6only, may reach every part

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