Progressive Collapse Behavior Of Composite Frame Structure With Reinforced Concrete Columns And Steel Beams

As the reinforced concrete column-steel beam(RCS)composite frame structure has more prominent advantages.With the increasing of environmental pollution,the engineering sector pays close attention to the development of it.The theoretical basis of such structural system has been improved,but the research on the anti-continuous collapse of the RCS structure at home and abroad is not yet mature.The theory and research of the relevant aspects are in the initial stage in my country.Therefore,the anti-continuous collapse behavior of RCS composite frame structure is studied in this paper.The main works are as follows:(1)This paper introduces the process of analysis,modeling,the parameter value and so on by ANSYS software,and analyzes the catenary theory of the structure,and obtains the allowable displacement of the structure catenary mechanism.Then,taking a single-layer planar RCS composite frame as an example and analyzing the stress mechanism of the structure after the failure of the key column by ANSYS software.The analysis shows that the catenary effect of steel beam can played when the nodes are rigidly connected,and meet the ultimate tensile strain(0.23)of the steel or the relative plastic angle of the node as critical condition of the continuous collapse of the structure.(2)Taking a five-tier RCS structure in accordance with the specification of China as an example,and establishing the finite element model of the slab with the floor by ANSYS software.First of all,the instantaneous unloading method is used to simulate the failure of the columns.The modal analysis of the remaining structures is carried out,and obtaining the basic analysis parameters of structure(failure time,mass damping coefficient,stiffness damping coefficient,etc.).Then the transient dynamic analysis of the remaining structures is carried out,and analyzing the response of the remaining frame.The results show that the RCS composite frame structure cannot meet the design requirements of continuous collapse;as the failure column in the same floor,the anti-continuous collapse of the structure is the weakest when remove the corner column;the higher the failure corner column is,the higher the probability of progressive collapse occurs.(3)Finally the factors that influence the continuous collapse of RCS frame structure are analyzed and summarized.Based on the existing research results and the concrete situation of our country,this paper classifies the important grades of the building structure against the progressive collapse.And putting forward the anti-continuous collapse's related measures and design recommendations about the RCS composite frame structure system.The anticontinuous collapse performance of the RCS composite frame structure is further improved and optimized by using different constructive measures and design methods.