huangyhg

modelling floor diaphragms on computer
hey there!
i hope someone out there can shed some light on this one: is there a simple ("quick & dirty") way to account for floor diaphragm stiffness when computer modelling a multi-story building? i have a concrete slab on standard bar joists, but that seems awfully time-consuming to model accurately by parts. is there a conservative and reliable way to account for this without detailed modelling to the nth degree?
thanks,
david
most programs have built-in options to model concrete slabs as rigid diaphragms. the nodes at each floor level are slaved together so that they translate and rotate as a rigid body. this is the quickest method and gives reasonable results for load distribution. the drawback is that diaphragm strut and chord forces are not automatically calculated and need to be done by hand. if you want to more accurately account for the actual stiffness of the diaphragm, you can use shell elements.
i know this is late; but better late than never.
i use ataad pro and i model diaphragm as plate element. provide proper properties (thickness, strength, possion ratio, etc as required by your software). i found this to give good and reasonable results even with corrugated steel roof deck.
i hope this helps

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