Investigation of Rigid Floor Diaphragm Effects in Reinforced Concrete Structures

Floor and roof systems are designed to carry gravity loads and transfer these loads to supporting beams, columns or walls in addition they have a key role in distributing lateral loads to vertical resisting systems and act as a diaphragm. Even though the assumption of rigidity of floor diaphragm is used frequently, it can cause some error in some cases so investigation of this assumption seems necessary. The main purpose of this paper is to compare failure mechanism in reinforced concrete structures by using assumption of flexible and rigid diaphragm and also Comparison of their response and comparing drifts, columns and shear walls forces could be result of this paper. In the present study, five main parametric models are used to investigate effects of rigidity of floor diaphragm in behavior of reinforced concrete structures, these parameters are number of spans, thickness of slab, existence of shear wall as a lateral load resisting system and thickness of shear walls, all of the instances are modelled in two way, first with assumption of rigid diaphragm and then with assumption of flexible diaphragm and linear and nonlinear time history analyses are performed for each model and then their results are compared. It is found that failure mechanism, with assumption of rigid diaphragm, is different from the failure mechanism with assumption of flexible diaphragm in addition forces and drifts are different when those two distinct assumption are used in modeling.

Keywords:

Diaphragm , Rigidity , flexiblity , Time history linear and nonlinear analysis