I tried following your directions and I am still getting and awkward deflection. What kind of earthquake loads are you applying? response spectrum? RE: SAP2000: Modeling Roof and Floor in Building (SMRF) CWEngineer (Civil/Environmental) and after you run it it all looks nice and pretty. Its easy to make mistakes when using computers. you should be seeing movement of the structure as a whole on the firsts shapes. Check the mode shapes to see if they are as they should be. so you will get equal deflections in X or Y for all joints within the same constraint. By doing this you are assuming that all joints in the same floor will move in X or Y together. For flexible diaphragms, such as roofing and such, this is not valid as this systems are always considered to be too flexible. I have used this in the past for steel decks. You must make sure that this assumption is valid for your particular structure. here select diaphragm and then create a new one. dont add joints from different floors to the same constraint) you go to assign. to do this you select all the joint in a floor (make sure they are on the same floor. If I understand correctly, you need to assign a diaphragm constraint to the joints. Again, I stress the need to double and triple check that the loads are being distributed correctly.Ģ. This will save you the hassle of having to distributes the loads manually to each beam. this usually quick and easy for simply supported beams.
I suggest you verify this with some hand calcs to make sure you got it right. check again to see if the loads are being distributed properly. you do this by selecting it and going to assign and then local axes.
If the loads are not distributed to the frames you want, you will have to rotate the area object.
In a 3D view you should now be able to see the loads distributed over the frames. After you assign the loads you can check how they are distributed by going to "display" and then area and then load assigns, on the window choose the load case to display and then check the option for one-way loads. In the case of steel decks you want the area to load only beams that are perpendicular to the deck. the trick is to assign the load as one-way distributed to frames, this way the loads will only transfer to beams which are oriented in a certain direction with relation to the area object. After you draw the are you assign a load to it. Load transfer: You can use an area of type "none", this will give you no load on the beams since the area has no material.