Numerical Modelling Of Structural Behaviour Of RC Frames With And Without Infill Walls Subjected To Progressive Collapse

Progressive collapse is a calamitous structural event that can be caused by man-made and natural hazards.Regardless of the cause,only a single local failure can induce a significant chain of damage in structure which can eventually lead to the entire collapse.When such an element,e.g.a column,is lost,the loads that are supposed to pass through the lost column need to be safely transferred to the adjacent elements to prevent progressive collapse.This research aims to provide a review on the most common triggering factors of progressive collapse of RC structures.Well documented timeline with major progressive collapse events and the evolution on development of design codes or standard are presented.Furthermore,overview of existing design codes and guidelines for progressive collapse events and the process of progressive collapse along with the prevention strategies are presented.Some prevailing design methods of progressive collapse of building structures,i.e.event control,the direct design methods and indirect design methods are studied under threat dependent and threat independent design methods.Also four alternative analytical procedures such as linear static,non-linear static,linear dynamic and non-linear dynamic are studied under the framework of the direct methods.For aiming to minimize the risk of causing progressive collapse,some structural traits need to consider in the design of building structures are also presented.This research work presents a computational investigation on the failure modes and structural behavior of RC beam column sub-frames subjected to progressive collapse.To this end,finite element models are developed for six cases in ABAQUS,each comprising two span beams and three columns and the mechanism of progressive collapse resistance in the middle column missing scenario is analyzed under the mid span point loading in different stages of deflections.The finite element models are validated by comparing the results with the experimental results in literature.Good agreement is observed,which validates the accuracy of models to predict the structural behavior of RC beam column sub-frames in progressive collapse event,in lieu of performing costly,time consuming experimental works.Furthermore,a parametric study is performed to examine the effects of percentage of beam top longitudinal rebar,percentage of bottom longitudinal rebar and the beam span-to-height ratio on the global structural behavior of beam-column sub-frames.Structures with higher energy absorption capacity possess high progressive collapse resistance.Energy absorption capacity of finite element models are compared and analyzed.In addition,RC frames with infill walls are also modeled in ABAQUS/Explicit.The masonry wall is modeled using simplified micro modeling procedures.The model is validated comparing force-displacement curve,crack patterns and stress and strain variation results with that of experimental results in the literature.