Hello,
I am modeling a floor slab (1 ft thick) with concrete beams (all 24" wide x 36" deep). These beams will be cast monolithically with the floor slab, therefore the beams are modeled as 24" deep.
My question is how does STAAD determine the following beam deflections? What are the formulas? What criteria is taken?
(The particular beam in question is highlighted in blue. The red beam selected is the one segment determined with the max deflection. The circled deflections on the right of the image is what I'm questioning how STAAD obtained these values.)
Any help will be greatly appreciated. Basically, I want to check these values, perhaps by hand, and conform my STAAD output is reasonable.
Best,
Pascual
The displacement you circled is the Global displacement in Y at the start of the beam. So basically this is the displacement at the node at the start of the member. For the beam and the slab to be considered as monolithic, please make sure that the beam is broken up into segments in line with the plate mesh.
Details on how the stiffness analysis is carried out by STAAD.Pro is available at
https://docs.bentley.com/LiveContent/web/STAAD.Pro%20Help-v11/en/GUID-3ED02290-F1A5-4EA7-8313-8A23C75A9F19.html
By saying "displacement at the node at the start of the member", do you mean for this case the deflection is at node 1660? If so, yes I understand that. What I don't understand is how STAAD is getting that deflection.
There are several beam segments along the line in red. I modeled beams between nodes with the plate mesh along the red line I show.
The literature on the stiffness analysis you shared didn't help on understanding how STAAD is getting the deflection of -0.230 in. Trying to do hand calcs to compare, I am not getting anything close.
Yes -0.23 in is the deflection at node 1660. The literature I referred you to describes how stiffness analysis is carried out by STAAD.Pro. I am not sure how you can hand calculate and match the value of -0.23 inches because it is not just a simply supported beam in isolation but rather one that is connected to a slab which is a two way type element ( transferring load in both directions) and directly influences the displacement of the beam. Moreover the element matrices/global matrices also involve terms related to shear deformations which are not accounted for in hand calculations. If you want to do some verification on the software, there are a number of verification examples that you can find at
https://docs.bentley.com/LiveContent/web/STAAD.Pro%20Help-v11/en/GUID-8C62E6A3-4470-4E9E-92DB-4878EB27DF9D.html