huangyhg

pile cap modelling
hi,
i am trying to model a 4-storied concrete building on piles with staad pro.
i have modelled the slabs as palte elements. i have grade beams in my ground floor. can anyone please suggest what is the best way to model the pile cap in this situatuation. assume, there is going to be 4 piles under each column attached to a pile cap.
any explanation will be very helpful.
thanks in advance,
benjaman

you might have better luck on the geotechnical site of this forum or the bently website.
you probably can try to model the joint between the pile cap and column as a pin connection, so that you do not have moment transferring to piles. once the building has been analyzed, you may design the caps using strut and tie method.
model the pile caps as pinned boundary conditions. connect the grade beams to the nodes that you created to represent the pile caps. than use a rigid-end offset that is the distance from the center of your pile cap to the face of the beam that is framing into it. for pile cap design use shin25 recommendation or the crsi handbook
dear ash060,
your reply was very helpful..... yet there remains another problem..........as i have told earlier i intend to model the ground floor slab as plate elements. i can use a rigid-end offset at the joint node for my grade beams. but what about my plate elements resembling the ground floor?
if your ground floor slab is not to thick, than you can probably just connect your plate elements node to node and it should not effect the results of your beams too much. just make sure that they are meshed as needed so the load will transfer to the beams than the point supports.
i am not familiar with staad so i am not sure how the program meshes plates.
if the geometry is not very complicated than it may be better to not model the floor slab at all. use trib area to put loads on each beam, and than run the model to get your pile cap reactions

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