huangyhg

precast fea modelling
i am curious how one would go about modeling the connection between double tees (diaphragm) to my shear walls for my precast structure? my model right now is pretty much no different than what a model for a cast-in-place structure should look like, but i would like to more accurately capture the behaviour of my precast structure where the double tees are connected at about 1.5 m intervals to my shear walls. i'm curious as to how that can be done and what the normal practice is when trying to capture difference in behaviour of precast structures and cast-in-place structures.
thanks,
clansman
a 3d model? suggest to attach a model view, then the suggestions would flow in.
yes it is a 3d model. i will not have access to my model until monday, but it is essentially double tee floor spanning into a shear wall. i'm building this 3d model for lateral analysis, i think that accurately modeling the shearwall/diaphragm interface to that of a precast structure as opposed to that of a cast-in-place structure will give me very different results. i just don't know where to begin modeling that interface.
clansman
at very least, i think the medel shall take into consideration of how the wall/d-tee connection is going to be. usually you would get larger concentrate horizontal loads under the legs, and a pair of vertical loads (in opposite direction) on the end supporting walls to resist the tendency of rotation (lateral load applied on the deck would rotate about the horiz. n.a.). the degree of fixity is largely depending upon the the way the tee is connected to the walls, and the connection details.
are you talking about the bearing / lateral connection at the stem or the non-bearing connection to the flange. for the flange connection i have used rigid links at the spacing of my connections. if you are just looking for the connection forces to the wall you then set the dt nodes as part of the rigid diaphragm but not the walls. this way you will get the connection forces in the rigid link. you can model the bearing connection the same way but put a bearing link a flange depth below the lateral connection. make sure to release the vertical axis with all of the shear connections and the lateral axes on the bearing.

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