Numerical Simulation Of Progressive Collapse Performance Of Multi-Storey Planar Steel Framed Structure Under Debris-Impact Scenarios

Progressive collapse is a consequent reaction caused by the failure of local structural components of building structures subjected to accidental load,which leads to the disproportionately large part collapse of the whole structures.The unexpected collapse of the Ronan Point apartment in the U.K.firstly caught the attention of researchers on the robustness of structures.Subsequently,such research area drew an increasing amount of attention after several catastrophic events,including the collapse of the Murrah Federation building in Oklahoma City in 1995 and the World Trade Center in 2001.More and more accidents caused by progressive collapse make us realize that after the local failure of some key components,the debris-impact caused by the upper storey is a vital important explanation accounting for the progressive collapse of the structure.However,till now,major research carried out experiment related to sub-structures under columnremoval-scenarios,without considering that the debris-impact from the upper failed components.Furthermore,for blasting demolition works,taking debris-impact into consideration can save a large amount of human and financial resources.Hence,aiming at this problem,this thesis tend to find out the most dangerous location of a special multistorey planar steel frame,explore how to make debris-impact occur and put forward best demolishing scheme.To achieve these goals,carry out the following works:(1)Establish macro finite element models of two-column-one-beam substructures with WUF-B connections and FP connections,verify the accuracy of the model by comparing the modelling results with outcomes of the impact experiments of relevant substructures.To some extent,the simplified method and modelling approach are verified.(2)Establish finite element models of a 10-storey planar steel structures with different beam-column connections.Obtain two more prototype structures by modifying the connections and the beam section of this 10-storey planar steel structure.Carry out 60 different simulations under single-column-removal-scenarios.Based on the modelling results,it is found that if the removed column is located at higher floors,it is more dangerous;along the horizontal direction,the removal of column at side or column that with relatively weak connections would lead to more adverse performance of the structures.Furthermore,if the removed column is located at the floor where there exists the change of the cross-section of beams,a greater vertical displacement of the upper joints of the removed column will appear.(3)Carry out 10 simulations of the model with RBS connection and FP connection under two-column-removal-scenarios,8 simulations under three-column-removalscenarios,2 simulations under beam-removal-scenarios and 3 simulations under jointremoval-scenarios.Based on the response of the structures and extent of failure,such simulations are classified.Finally,discuss the most efficient way to make the whole structure collapse with the consideration of the effect of debris-impact under multicolumn-removal-scenarios and figure out whether it is feasible to make the structure collapse via removing beams or joints.It is found that removal of vertical bearing member can efficiently destroy the anti-progressive collapse performance of a structure.Removal of multi-column at the middle storey of a structure enables superstructure with sufficient mass strike on the understructure.Sufficient impact energy enables the occurrence of the local failure of the understructure during the impact process,which increases the possibility of the progressive collapse of the whole structure.