Analysis On The Influencing Factors Of Dynamic Effect In Progressive Collapse Dynamic Effect And Collapse Resistance Of RC Structure

The concern about the progressive collapse began in the 1968 collapse of the Roman point.Especially after the "911 incident" in 2001,a lot of research work on progressive collapse began.Some countries also began to formulate relevant norms to guide the design for preventing progressive collapse.The progressive collapse is due to the local failure of the structure after the accidental load is encountered,and the original equilibrium state is broken.If the bearing capacity of the remaining structure is insufficient to withstand the unbalanced load,the damage range will be expanded,and eventually the other parts of the structure will be destroyed,even the overall collapse of the structure.The entire collapse process is often a complex nonlinear dynamic process.Most of the current research results are based on the static force method to study the mechanism of the structure.This paper uses finite element software to decompose the RC structure.The nonlinear dynamic analysis analyzes the dynamic effects of the residual structure and the factors affecting the collapse performance.The main research contents are as follows:(1)In this paper,the Explicit and Standard modules of ABAQUS are used to numerically simulate the dynamic test and static test of column failure in reinforced concrete beam-column substructures,and the correctness of modeling,material constitutive and unit selection in the model is verified,which enables the reliability of further research.(2)Further parameter analysis was carried out on the basis of successful verification of the column removal dynamic test in the beam-column substructure.By changing the failure time and the load on the beam,the time-history curves of the nodal dynamic analysis are compared and analyzed.The effects of failure time and load on the beam on the dynamic effect of the structure are discussed..(3)The nonlinear static analysis of the beam-column substructure under different loads is carried out by the ABAQUS/Standard module,and the corresponding static displacement of the joint is obtained.The dynamic displacement is removed by static displacement,and the displacement-based dynamic amplification factor DIF is obtained.The effects of failure time and load on the beam on DIF are further analyzed.The results show that DIF decreases with the increase of failure time,and the load on the beam has little effect on DIF.Subsequently,the collapse dynamic analysis of the beam-column substructure based on the single degree of freedomsystem was carried out.(4)The influence factors of continuous collapse dynamic effect of RC plane frame were analyzed by SAP2000,including the number of floor layers,structural span and failure column position,beam reinforcement ratio,and failure time.The above factors were discussed for the influence on the maximum vertical displacement of the remaining structural failure column nodes and load-based dynamic amplification factor.(5)The RC space frame structure without considering the slab and considering the slab was established by SAP2000.The bottom corner column,the long side middle column,the short side middle column,and the inner column were respectively removed for nonlinear dynamic analysis.For the two models with and without floor slabs,the influence of the slab's ability to resist collapse is studied by comparing the vertical displacement of the failure column joints with the development degree of the plastic hinge of the remaining structure;in addition,considering the slab and not considering the slab,The axial force changes of the adjacent column and the diagonal column at the position where the column is removed are compared.