Steel Section Design and Connections Tutorial - Kxcad.net

T2 Multi-Bay Portal Frame Tutorial Demonstrating the Use of,
MasterFrame
MasterKey Steel Sections Design
MasterKey Connections
Welcome to MasterFrame for Windows: Plane, Grillage and Space Frame
Analysis. This tutorial provides an introduction on the use of MasterFrame for
Windows in the elastic-plastic analysis and design of portal frames. You are
provided with a step by step rational method for dealing with portal frames and
are introduced to the most important concepts and features along the way.
As you work through the tutorial references are made to relevant
sections in the main manual.
In this tutorial, you will create, analyse and design the same portal frame
example used in the Class 1 : Multi-Bay Portal Frames ShowMeHow Video. We
recommend that you take a few minutes to view this video before proceeding
with the tutorial. This will quickly help you become familiar with the screen
layout and toolbars.
3 MasterFrame
4 MasterKey Steel Sections Design
Steelwork and Portal Frames - Multi-Bay Portal Frames
T2 Multi-bay Portal Frame Design Tutorial
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T2.1 MasterFrame
T2.1.1 Loading MasterFrame
T2 Multi-bay Portal Frame Design Tutorial
To start this tutorial:
Double click on the
MasterSeries for
Windows icon to start
the MasterSeries.
Select Frames from the
top menu and then
‘MasterFrame : Analyse
Design Drafting’ from
the drop down menu.
T2.1.2 The File Selection Menu
The MasterFrame File Selection menu will now be displayed.
This menu enables you to load existing files or create new data files. As each
existing file is selected, a picture of the frame is displayed in the window to
assist your selection.
Select the New File button to clear and set the focus to file name input box.
Type “Tutor03”.
The Get File button has changed to Create New
Select Create New.
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2.2 General File Management
T2.1.3 The Frame Generation Menu
In most cases you will be able to select a start-up
frame and then tailor it to your specific requirements.
In this case we shall generate a multi-storey frame,
edit the co-ordinates of the roof beams and then add
the two parapet walls.
The Frame Generation Menu (Frame Wizard) is now
displayed as shown.
TIP! If the frame you are generating does not match
one of the pre-processor frames, choose a frame that
is similar to, but larger than, your frame. It is easier to
delete members than to add them. If in doubt a multistorey
frame makes a good basic grid.
Select the Multi-Bay Portal Frame button
3.3.2 Frame Generation Procedures and Templates
The Start-up Frame
The multi-bay portal frame pre-processor is now displayed.
This option enables you to generate a wide variety of single and multi-bay
portal frames including all the basic information such as the rafter and column
sections, haunch dimensions, the values of the dead and live loads and base
fixity.
You can select equal or unequal bays.
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Click on Span (m)
Type 24
Click on Height to Eave
(m)
Type 6
Click on Rise (m)
Type 3
Click on Haunch depth
(m)
Type .625
Click on L @ Eaves (m)
Type 2.4
Click on L @ Apex (m)
Type 1
Click on Partial Fixity %
Type 10
As we change the input in the pre-processor the graphical display is always
updated. This is because the ShowNewFrame button is depressed.
Select Proceed to generate the frame. The frame now turns to black as it
has been generated.
This option generates a Multi-Bay Portal Frame of varying spans, rises and
haunch depths.
Notes on Changing the Sections in the
Pre-processor
3.3.2 Frame Generation Procedures and
Templates
Click to paste section
from sections list
T2.1.4 Portal Frame Loading Cases
In the process of generating a new frame, two loading cases are automatically
created, namely:
Loading Case 01 : Dead plus Live (Ultimate)
1.4 D1 + 1.6 L1
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Where:
D1 Dead Loads
L1 Live Loads
Loading Case 02 : Live Only (Serviceability)
0.0 D1 + 1.0 L1
Adding a Sway Stability Loading Case:
The following few steps demonstrate how to:
1. Add a new loading case (Sway Stability)
Use the Find Notional Loads option (.5% of the factored loads in case 1)
Use the Add Notional Loads option (add the notional loads to loading case 3)
Select Loading Case Titles (Number of)
from the Cases menu
Click on Add Case
Click on the Quick Word button (Sway
Stability)
Select the Loading Combinations Tab
Use the Spin Button to view the
Loading Combination for the first two
loading Cases
Move to Loading Case 01 : Dead plus
Live (Ultimate)
Select the Notional Loads & P-Delta Tab
Click on Find Notional Load
Type .5 in the Percentage Box
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Using the Spin Button move to Loading
Case 03 : (Sway Stability)
Click on Add Notional Load
T2.1.5 Analysing the frame
Select Analyse from the top menu.
Select Plane Frame.
3.14 Analysing the Frame
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T2.2 MasterKey: Sections
We will now move into MasterKey Steel Sections and use the AutoCheck to
determine the state of all the members under local capacity and overall buckling
checks.
Select Steel Design from the
Design menu
From the Options menu, select
Display MasterKey Menu
MasterKey Sections offers three
design menus, namely Elements,
Independent and Integrated.
The Independent menu offers the
same type of checks as the
Integrated menu to be used without
frame link. The Options menu
enables you to convert an
Integrated design to an
Independent design check.
The Elements menu offers basic design checks such as Compression
Resistance, Lateral Buckling Resistance Moment, Local Capacity Check, Axial
Load with Moments, Web Bearing and Buckling Capacities, Section Properties
and Classification.
T2.2.1 Using the Integrated Menu
From the Options menu, de-select Display MasterKey Menu
Select AutoCheck - Group Check from the Integrated Design menu
Draw a window around the frame to select all members
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The results of the AutoCheck are colour coded as follows:
1. Red members are locally over stressed (plastic hinge location)
2. Cyan members require additional lateral restraints
3. Black members pass the local and buckling checks
4. Grey members are not checked (e.g. concrete or sections not
licensed)
The above results show that the members are over-sized. We will use the
Axially Loaded Members with Moments check, to select suitable sections.
T2.2.2 Designing the Outer Column Sections
An ideal column section is that which creates a small amount of over-stressing
under the haunch (local capacity not greater than 1.25)
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Select Axially Loaded Members
with Moments from the Integrated
Design menu. The Apply To
mode is activated
Click on the lower part of the outer
left hand column
Let us use the Sections AutoChange
to select and then store a suitable
column section.
Click on the section list down
arrow and select section 457x191
UB 67
With a Local Capacity value of 1.061,
this new section now shows a small
amount of overstressing.
Click on the Store button
Select Current Group to change the
section for all the outer columns
Select Current Group
Click on Change
It is advisable to change the rafter
section before we re-analyse the
frame
Click on Exit Store
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T2.2.4 Designing the Rafter Section
We will use the same design brief to
select a suitable rafter section in
which the bending moment and
moment of resistance are as close as
possible.
Select Axially Loaded Members
with Moments from the Integrated
Design menu
Click on the outer left hand rafter
Click on the section list down
arrow and select section 457x152
UB 52
Note the bending moment diagram.
Click on the section list down arrow and select section 406x140 UB 46
Please note that the small amount of over-stressing at the end of the haunch
will be eliminated when the plastic hinges are formed and the moments are
redistributed.
Click on the Store button
Select Current Group
Click on Change
T2.2.6 Designing the Inner Column Sections
We will use the same design brief to select a suitable rafter section in which the
bending moment and moment of resistance are as close as possible.
Select Axially Loaded Members with Moments from the Integrated Design
menu
Click on the inner left hand column
Change to Copy Current Brief Mode
Click on other (right hand) inner column
Return to Search for Next Brief Mode
Click on the ‘AutoSize Current Member’ button
Click on the Store button
Select Selected Members
Selected members are highlighted in red. Select only the two inner columns,
deselecting any other members highlighted.
Click on Change
Click on Re-Analyse
T2.2.7 Review the AutoCheck
Having re-analysed the frame with the new sections, let us view the results of
AutoCheck
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Select the AutoCheck - Group Check from the list of existing Design Briefs:
Design Brief 1 of 2 (bottom left hand corner of screen)
The results indicate that the outer columns are slightly over stressed (shown in
red). Other values indicate that the sections selected for the various members
are all appropriate for plastic analysis (please note that plastic analysis is a
form of moment re-distribution).
T2.2.8 Placing the Plastic Hinges
Select the Axial With Moments check for the outer left hand column from the
list of existing Design Briefs: Design Brief 2 of 2.
From the Options menu, select
Plastic Hinges
Select Apply To Mode
Click on the lower part of the
right hand column
Click on the Add button
Click on the lower part of the
left hand column
Click on the Add button
Click on the Re-Analyse button
T2.2.9 Changing the Haunch Dimensions
Click on 1 st , 2 nd and 3 rd rafter in turn
The applied moment at the end of the haunch is
very close to the section capacity. This is likely to
require lateral restraints at close intervals. To
avoid the above, let us increase the haunch
length by say 400 mm.
Click on the Section AutoDesign tab
Click once on the top of the spin button to increase the haunch Dep1(H/D) to
2.05
Click several times on the top of the spin button to increase the increment to
0.400
Click on the top of the spin button to increase the haunch length XH1(m) to
2.8
Click on the Store button
Select Current Group
Click on Change
Click on Re-Analyse
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T2.2.10 Column Lateral Restraints
Ensure you are in Search for
Next Brief Mode
Click on the lower part of the
outer left hand column
The cyan background indicates
that the column requires lateral
restraints. Let us specify the side
rail positions (1.4 m centres) and
then check the various portions
for axial with moments.
Click on the Lateral Restraints
tab
Type 1.4 in the Portion 1 input
box
Click on the 3rd and 4th portions on the bending moment in the output area
Change to Copy Current Brief Mode
Select right hand outer column to copy the Axial with Moment brief including
the lateral restraints information to the other outer column
The side rail spacing is satisfactory. Let us now check the column stability and
determine the positions of the torsional restraints.
T2.2.11 Column Torsional Restraints
Select Appendix-G : Stability Checks from the Integrated Design menu
The cyan background indicates
that the column requires
additional torsional restraints.
Please note that the column
must be restrained at the plastic
hinge location in all cases.
We shall now increase and
decrease the length between the
points of torsional restraints
(Portion 1).
Click the Torsional Restraints
tab
Enter a value of 4.2 in Portion
1
Change to Copy Current Brief Mode
Select right hand outer column to copy the Appendix-G brief including the
torsional restraints information to the other outer column
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The outer columns require two torsional restraints each, one at 4.200 m and the
other under the haunch at the plastic hinge locations.
T2.2.12 Rafter Lateral Restraints
We will now check the rafter for a purlin spacing of 1.8 m.
Ensure you are in Search
for Next Brief Mode
Click on the outer left hand
rafter
Click on the Lateral
Restraints tab
Enter a value of 1.8 in the
Portion 1 input box
Click on the critical
portions of the bending
moment in the output area
Purlin spacing of 1.8 m is
satisfactory for the first rafter.
Varying the Purlin Spacing
The purlin spacing will need to be reduced in some areas. It is therefore
necessary to enter the spacing for all portions and then reduce it in the critical
locations.
Enter a value of 1.8 in Portion 2 to Portion 7
Let us now reduce the spacing in the critical portions using an increment of 0.1
m.
Click on Portion 2 in the Input Data
Click on the left part of the horizontal spin button to the right of the Portion 2
value to reduce the length of Portion 2 from 1.8 to 1.7m
Purlin spacing is now satisfactory. However, let us reduce the first and second
portions to 1.4 m, so that a purlin is coincident with the end of the haunch.
Use the horizontal spin button to reduce Portion 1 and 2 to 1.4, or
alternatively
Directly type the values in Portion 1 and 2 to 1.4
Let us check the 2 nd and 3 rd bay rafters using the same brief.
Change to Copy Current Brief Mode
Select rafter members 2, 3, 4, 5, and 6 to copy the Axial with Moment brief
including the lateral restraints information to all other rafter members
Click on Search for Next Brief Mode
Click on the critical portions of the bending moment in the output area
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T2.2.13 Rafter Torsional Restraints
Ensure you are in Search for Next Brief Mode
Click on the outer left hand rafter
Select Appendix-G : Stability Checks from the Integrated Design menu
To determine the position of the torsional restraints required in the rafter, we
first check the stability over the first two portions (2 @ 1.4 m = 2.8 m length
starting @ 0 m).
If this fails then provide a torsional restraint at 1.4 m and check the stability over
the second and third portions (1 @ 1.4 + 1 @ 1.8 = 3.2 m length starting @ 1.4
m).
If this also fails then provide a second torsional restraint at 2.8 m and check the
stability over the third and forth portions (2 @ 1.8 = 3.6 m length starting @ 2.8
m).
Click on the torsional restraint tab
Enter the value of 2.8 in Portion
1
This portion is unstable, so we
provide our first torsional restraint
@ 1.4 m
Enter a value of 1.4 in the ‘Start
at’ just before Portion 1 the Input
Data
This portion is still unstable, so we
provide our second torsional
restraint @ 2.8 m
Enter a value of 2.8 in the ‘Start
at’ just before Portion 1 the Input
Data
Enter a value of 3.6 in Portion 1
This provides torsional restraints at 2.8 and 3.6 m. Let us check other rafters by
copying and applying this design brief.
Change to Copy Current Brief Mode
Select rafter members 2, 3, 4, 5, and 6 to copy theAppendix-G brief including
the torsional restraints information to all other rafter members
Click on Search for Next Brief Mode
Important Note:
Although the length of portion 1 is defined as 3.6 m, it will automatically check a
portion between the torsional restraint at 2.8 and the point of contraflexure in
each rafter.
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T2.2.14 Checking for Failures
Click on the Section AutoDesign Tab
Click the ‘Fail’ button to search all design briefs for design failures.
All design briefs are scanned and stops at any design failures encountered
allowing you to rectify the problem. In the current example no failures should
be present, and the dialog box as shown below is displayed.
T2.2.15 Printing Design Checks
The following few steps demonstrate the selective printing options of the design
checks.
Select Print Design Output from the Print menu
Click on Include All to activate all checks
Click on AutoSelect
The “AutoSelect” automatically selects the critical portions from each check.
The “All above” option allows to print only those checks with utilisation above
the specified value.
You can select to print a list of all the design checks (summary of results) and
then print detailed results for critical portions.
You can also print the checks one per page for ease of reference and partial reprinting.
Click on the Print List (Summary) button to print a list of all the checks that
were covered
Click on the Printer button in the Job Reference form
Click on the Print button to print detailed output for the selected checks
Click on the Printer button in the Job Reference form
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T2.2.16 Deflections and Sway Stability
We will now view the frame deflection under serviceability and sway stability
conditions.
Select ‘List of Selected Nodal Displacements’ from the Edit-View menu.
The Nodal displacements check is also accessible by selecting the AutoCheck
design brief.
Serviceability and Sway Stability nodal displacement are automatically
extracted for eaves and apex nodes. The Sway Stability displacement limit of
h/1000 is also automatically inserted.
The maximum horizontal sway is only 2.95 mm which is less than half the
permissible value of h/1000 (6 mm).
Other analysis information can be viewed using ‘View Analysis Output’ and
‘Bending, shear and deflection’ from the Print menu.
3.15 View and Print Results
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T2.3 MasterKey : Moment Connections
Let us now move to MasterKey Moment Connections.
T2.3.1 The Eaves Connection
Select Connections Design from the Design menu
The Connection Pre-processor is
displayed.
Click O.K. to design an Eaves
Connection
Click on the outer left hand rafter
near the eaves
Scroll the design output to view
failures
Click on the button
from the top tool bar for an
explanation of the failure
symbols.
Click on the AutoDesign button at
the top of the edit area
T2 Multi-bay Portal Frame Design Tutorial
The All and Ult. buttons are active
to design for only all ultimate
loading cases. In this example only
loading case 1.
Click on the Auto button in Auto
Design dialog box
Close the Auto Design by clicking
on the X on the top right of the
dialog box
Feel free to examine the results and modify the joint details as you wish.
Please also feel free to use the top toolbar to display dimensions and to zoom
on various parts of the connection.
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T2.3.2 The Apex Connection
Click on the Add button in the
top toolbar
Select Apex (Beam to Beam)
Click O.K. to design an Apex
Connection
Click on the outer left hand
rafter near the apex
This joint is satisfactory with the
minimum bolts. AutoDesign can
also be carried out on an Apex
connection, as shown in the
previous Eaves design.
T2.3.3 The Base Plate
Click on the Add button in the
top toolbar
Select Base Plate
Click O.K. to design a Base
Plate Connection
Click on the outer left hand
column near the base Scroll
the design output to view
failures
Click on the button
from the top tool bar for an
explanation of the failure
symbols.
Select Design Options from
the Options tab
Click on the Base Plates tab
For a description of all design
options;
Click on Close
6.11 Design Options
Click on the AutoDesign
button at the top of the edit
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area
Click on the Auto button in
Auto Design dialog box
Close the Auto Design by
clicking on the X on the top
right of the dialog box
T2.3.4 Printing Results
Select ‘Print…’ from the Print menu
Click on any of the items in the
connection brief listing to include or
exclude from printing.
Click on the Printer button (or the
Word export button if you have
PowerPad)
Check that the print orientation is
Portrait
Click on the Printer button inside the
Job Reference form
Feel free to experiment and print any output as you wish.
T2.3.5 DXF Output
Select DXF Output from
the DXF Output menu
Click on the Page
Layout tab
Select A2 from the Page Size List
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Drag the objects on the screen and place them anywhere you like
Check the AutoCAD box to auto start AutoCAD upon export.
Check the Border and L’Scape boxes
Click Export, and the drawing is automatically imported to AutoCAD
Close
We hope you have enjoyed working through this tutorial, you will have learned
the basics of using MasterFrame, MasterKey I-Section and MasterKey Moment
Connections in the elastic-plastic analysis and design of portal frames.
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