Experimental Study On Progressive Collapse Of RC Frame Structures With Lateral Restraint

In recent years,the study of the collapse-resistant performance of the RC structure has attracted the attention of scholars both here and abroad.The collapse-resistant mechanism related to the beam cross section size,the high span ratio,the reinforcement ratio,the floor slab,and the lateral restraint stiffness of the frame column.At present,less experimental study on the collapse-resistant of structure consider the influence of the the lateral restraint stiffness on the structure.Therefore,it is necessary to carry out the experimental study on the collapse-resistant of beam-column sub-assemblages with the lateral constraint.The effect of the lateral restraint stiffness in the performance and transformation mechanism of collapse is studied.This thesis intends to study the collapse-resistance of beam-column sub-assemblages by experiment method and numerical simulations.(1)? A static experiment method was used to test the collapse-resistant performance of four beam-column sub-assemblages,three of them are cast-inplace structures with different lateral restraint stiffness,and the other one is the assembly structure of the welded joint with the specification design.The experimental results of load displacement,lateral restraint,horizontal displacement,strain change,crack initiation and failure mode of reinforced concrete beam column sub-assemblages are obtained.It provides data for the analysis and numerical simulation of structure.(2)? The results are analysed by comparing three different lateral restraint structures.The effect of different restraint on the collapse-resistance of the structure is studied.Discussed the influence of different side span restraints on the structure.Solved the problem of restraints in collapse-resistant performance and transformation mechanism.The method in the collapse-resistant standard is discussed,and the influence of the lateral restraint on the calculation of the bearing capacity is analyzed.(3)? The results are analysed by comparing assembly monolithic structure and cast-in-place structure.Discussed the differences in the collapse-resistance performance such as failure mode,bearing capacity,and deformation ability.Studied the collapse-resistant design mechanism of assembled monolithic structure based on an "equivalent cast-in-place" design.(4)? This thesis is based on OpenSEES nonlinear finite element software for studing the influence of lateral restraints on structural collapse-resistance performance.Selected suitable steel and concrete constitutive models and nonlinear displacement-based beam-column fiber units to perform numerical simulations on the test results of cast-in-place structures.Based on the above OpenSEES calculation model,the influence of factors such as the perimeter restraint stiffness and the size of the side column on the collapse-resistance performance of the structure is analyzed.The mechanism analysis of the collapse-resistance performance of beam column sub-assemblages is carried out.