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They are doing it right. It depends on you. It is the beauty of the structures that they will behave the way you designed them. When reducing the torsion modifier for beams that are failing to a value approx equal to 0 then watch for the increased moments in slabs. If you put the reinforcement in slab for additional moment then it is ok! It depends upon the relative stiffness of beam and slab that how much load beam will take (Torsion, moment etc).

Dear mhdhamood, 1- In case of seismic loading, the shearwall will take high moment and high shear. In case of seismic, it is not necessary that the design combination will be tension. If you talking about alone seismic load case, it can be tension. but when you design for load combs, it can be tension if seismic increases from DL and compression if not. 3- First of all you need to check the punching of slab for gravity loading. The thing which you are saying is 100% correct. But what your senior saying is also correct. I ll explain. What your senior are saying: This is right but not for code based design. You do not need to design the thickness of slab for seismic as in ACI code, you can design the members for gravity loading for the structures which are in high seismic areas ACI 21.13. You are designing the slab for out of plane forces. AND these out of plane forces as per ACI 21.13 we can design for gravity loading including shear and flexure. What you are saying: BUT you need to design the slab (diaphragm design) for inplane forces which are based on seismic demand. So yiu are not required to provide the thickness of slab for seismic loading as it will be out of plane forces. But you need to design this slab near shearwall are for inplane forces Now what you are saying is the next step. After providing the thickness of slab on gravity loading, we need to check the thickness of slab by checking it on slab beam behaviour and checking its rotation which is the next step and its details are not given in any code. There are guidelines which can be used to check these details like ATC 72. Thanks Muneeb

I am not sure what your query is. I infer that you are talking about dealing with shear strength of floor slab around the shear wall. My question is: are you using flat plate as floor, or beam-slab system? If you are using flat plate, then you need to be worried about the shear failure of slab.

One thing that I learned while dealing with above mentioned building is that area of the floor has significant effect on structural system to resist seismic loads. The building, under discussion, has an area of about 45000 sqft/floor. The building is 4 stories, the bay length is 26ft, the column size is 30 inches, and beams are 15x30 inches. Even then, one requires shear walls of about 130 ft length in both direction to satisfy strength and serviceability requirement of code. The shear in one wall exceeds the maximum limit set by the code if one uses lesser shear walls. The problem is base story shear, which is about 5000 kipps at second level.

Dear How r u designing the shearwall in shear? If shearwall is failing in shear then you can do following things as told by Mr. Umar 1- Try to increase the length of shearwall. The thickness increase will not matter too much. But if you can increase length that will be helpful to design shearwall in shear. 2- Try to increase the shear reinforcement in shearwall. 3- Try to increase fc' 4- Try to add some more shearwalls to reduce the total shear demand by structure. I think by these points of these four points you will be able to solve the issue because everything depends upon the shear force in shear wall. You also need to provide confinement in the confined zones as well for flexural reinforcement. Thanks Muneeb