99. Select the eight beams as shown in Figure 30. You can use the Tools->Display Node to Node Distance menu command to measure the distances as shown in Figure 30. To remove the node dimensions, click on Tools->Remove Dimension menu command.
100. Select the UNI GY -0.2083 kip/ft command in Vertical Load 1 and select the Assign to Selected Beams assignment method.
101. Click the Assign button. Click the OK button on the confirmation dialog box.
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Note: If you want to remove loads from a member, you could use the Toggle Load check box in the Load & Definitions dialog box.
Figure 30: Location of Uniform Load for Vertical Load 1
102. Select the eight beams as shown in Figure 31.
103. Select the UNI GY -0.2083 kip/ft command in Vertical Load 2 and select the Assign to Selected Beams assignment method.
104. Click the Assign button. Click the OK button on the confirmation dialog box.
105. Select the two mid-span beams as shown in Figure 32.
106. Select the UNI GY -0.025 kip/ft command in Lateral Load case and select the Assign to Selected Beams assignment method.
107. Click the Assign button. Click the OK button on the confirmation dialog box.
108. Select the Nodes cursor and select mid-span node as shown in Figure 33.
109. Select the FZ 0.05 kip/ft command in Lateral Load case and select the Assign to Selected Nodes assignment method.
110. Click the Assign button. Click the OK button on the confirmation dialog box.
Note: If the loads are too small in the graphics window, right click in the graphics window and choose labels->scales and provide appropriate scales for the loadings.
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Figure 31: Location of Uniform Load for Vertical Load 2
Figure 32: Location of Uniform Load for Lateral Load 2
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Figure 33: Location of lateral load application node point for Lateral Load case
28 Analysis:
111. Click on Analysis/Print control tab on the left. The Analysis/Print Commands dialog box will appear.
112. Select the All option in the Perform Analysis tab and press the Add button.
Figure 34: The Analysis/Print Commands dialog box
113. Click the Close button.
114. Click on Analyze->Run Analysis command. The STAAD Analysis and Design dialog box will appear.
115. You should not have zero errors in the STAAD Analysis and Design dialog box.
116. Select the Go To Post Processing Mode option button and click on the OK button.
29 Results:
117. Select the Node->Displacement tab. The displacement of each and every node can be determined by simply clicking on a node point in the graphics window and looking at the
displacement table on the right.
Figure 35: Displacements
118. Select the Node->Reactions tab. The support reaction of each and every support node can be determined by simply clicking on a node point in the graphics window and looking at the support reaction table on the right.
Note: Make sure that the Difference row for each load case in the Statics Check Results window is close to zero. A non-zero value usually indicates instability in the structure. You may use the 0.99 MPX 0.99 MPY 0.99 MPZ at the joints to avoid using a completely released joint.
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Figure 36: Support Reactions
119. Select the Beam->Forces tab. The bending moment diagram will be displayed. The user may turn on the deflection and loading diagrams using the icons.
Figure 37: Beam end and section forces
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Figure 38: Moment, deflection and load diagram
120. Select the Beam->Stresses tab. The combined axial stress distribution diagram can be seen for any member.
Figure 39: Combined Axial and Bending Diagram
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121. Select the Beam->Graphs tab. The moment, shear, and axial force diagram can be seen for any member.
Figure 40: Moment, shear, and axial force diagram
122. Click on the Modeling tab.
123. Right click in the graphical user interface and select Labels. Suppose you wanted to see the members that had a combined axial and bending stress of 500 psi.
124. Select the Force Limits tab and provide the inputs as shown in Figure 41.
125. Click on the Apply button. The beams shown in red in Figure 42 have exceeded the combined axial and bending stress of 500 psi.
126. This procedure can be used to find which members are exceeding the 30 ksi criteria.
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Figure 41: Force Limits
Figure 42: Combined axial and bending stress contour
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Experiment with the model and try changing some of the strut connections to partial moment releases.
Try changing the section sizes of the members along the x-axis 1 in x 1 in rectangular sections and the rest of the members to 0.75 in x 0.75 in sections. You will note that some bars have exceeded the 30 ksi limit as shown in Figure 43 for the lateral load case. Keep connection design in mind also. Section cross section will be reduced in tension.
Figure 43: Combined axial and bending stress contour
35 Design (Not Applicable to this example):
Note: STAAD.Pro cannot perform code checking on square prismatic steel sections defined in this model. The user could define a general section or create a tube section using the section database to perform the code checking as per the AISC 360-05 code.
127. Click on Design->Steel control tab on the left.
128. Select the AISC 360-05 code in the Current Code selection box in the data area.
129. Click the Define Parameters button in the data area. The Design Parameters dialog box will appear as shown in Figure 35.
130. Select the FYLD design parameter and enter and assign the yield strength of steel to be used for the bridge if not 36 ksi. In the case of this tutorial, the default yield strength (i.e. 36 ksi) will be used.
131. Click on the Close button
132. Click the Commands button. The Design Commands dialog box will appear.
133. Select the Check Code command and press the Add button 134. Assign the Check Code command to all members.
Figure 42: The Design Parameters dialog box
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4.0 Help, Questions, Comments
There is a lot of help available for STAAD.Pro in electronic format. You may press the F1 key in the STAAD.Pro interface to look the help documents. You may send your STAAD.Pro related questions or comments to [email protected].