Checking max deflection?

Question

Hello all, 
 I'm a student learning STAAD.Pro this semester. 
 
 I've done a beam model with two point loads applied. I've analyzed the model, but I haven't seen an output for what the actual value of max deflection in the beam is. 
 How does STAAD display this? 
 Thank you.

Sye · Answer

The section displacements that you see in the analysis output file are all global displacements and these are reported at 13 equally spaced sections along the length of a member (including the start and end). The L/DISP however is reported for the max local displacement only and not for the global section displacements because when checking the deflection in a member and satisfying the allowable deflection requirements ( L/240, L/360 etc) you should use the local displacements.

Sye · Answer

To keep things simple here is a sample file ( EXAMP01_rev.STD ) with respect to which I have explained the calculations. I have highlighted the max local displacement for member 6 for load case 1 obtained in different ways. If you look at the member section displacements output from the PRINT SECTION DISPL and PRINT SECTION MAX DISP output, both show the max local disp as 0.13606 inches as highlighted below

A rough calculation based on the section displacements reported in the output above also matches the value as shown next 
 Local Displacement at mid section = 1.0087 &ndash; (0.9048 + 0.8405)/2 = 0.13605 inches 
 The Maximum Relative Displacement table reports the same value as well as marked below

Amitava · Answer

To view the value of deflection in the output file (.ANL File) add the command "PRINT SECTION MAX DISP LIST (member number)" after the analysis command. Please refer the section 5.44 of the Technical Reference Manual of STAAD.Pro.

Sye · Answer

In case you are interested in checking the deflection graphically, you can double click on the member and check the values as shown next. The diagram is annotated with the max deflection value.

DSANJU · Answer

In addition to the suggested answers below, you may select the member, go to the Post-processing mode. You may go to menu Report >Section Displacement and choose shorting option as max displacement. You may choose the load case for which the displacement is to be reported. You may create a repor for the same

Sye · Answer

The displacements that you see at the 13 section locations for each member and for each load case, are the global displacements of these points from their initial positions to their finally displaced positions. So if you consider the member 212 and load case# 12, the 7th section which is at the middle of the member, has displaced in global Y by -0.2007 inches. The Max LOCAL DISP on the other hand, reports the maximum displacement of the section measured relative to a straight line joining the displaced positions of the start and the end nodes. That is 0.02482 inches in this case and a quick and approximate way to verify this is by subtracting the global displacement of that point from the average global displacement of the start/end nodes ( or the first and the 13th sections). So in this case the Max local displacement = 0.2007 - (0.1755 + 0.1764)/2 = 0.0248 in. The L/DISP is the ratio of the total member length and the max local displacement. So L/DISP = 100/0.02482 = 4029

Checking max deflection?

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