Study On Failure Mechanism Of Reinforced Concrete Frame Structure Under Earthquake

A reinforced concrete frame structure(RCFS) has good shock resistance quality whenthis structure shows the yield mechanism of strong column and weak beam as standardizedunder earth quake action. Whereas, seen from the past earth quake events, many of the RCFSshowed column-hinge but not beam-hinge which failed to live up the designers’ expectation.This not only threatened people’s safety, but also caused great property loss. Factors for thefailure of RCFS’s yield mechanism of strong column and weak beam are:1, the enhancementthe cast-in-place slab gives to the frame’s stiffness and flexural capacity;2, the values of thebending moment coefficients of the frame’s endpoint;3, the limiting value of the framecolumn’s axial compression ratio as well as the unreasonable layout of the infilled wall, andetc.. This paper tries to analyze the factors mentioned above in the following aspects andproposes relevant advices.(1) Through modal analysis and pushover analysis of common frames of noncast-in-place slab, frames of double girder cross-section rigidity, frames of cast-in-place slab,and frames of different reinforcement ratio in the cast-in-place slab, the influences of thecast-in-place slab to the RC frame structure’s yielding mechanism under an earth quake eventare analyzed. As the result shows, the cast-in-slab is the prime factor of whether RC framestructure can fulfill the yielding mechanism of strong column and weak beam.(2) Through pushover analysis of the RC frame models with for different endpointbending moment intensification factors, the influences of the endpoint bending momentcoefficients to the RC frame structure’s yielding mechanism under an earth quake event areanalyzed. As the result shows, when the endpoint bending moment coefficient goes up to1.7,the RC frame structure of cast-in-place slab can work with the standard yielding mechanismof strong column and weak beam which has better anti-seismic property.(3) Through modal analysis and pushover analysis of the RC frame models with differentaxial compression ratio limiting values, the influence of the structure’s axial compression ratio limiting values to the RC frame structure’s yielding mechanism under an earth quakeevent are analyzed. As the result shows, although decreasing the structure’s axial compressionratio limiting values can improve the structure’s anti-seismic property to some degree, theaxial compression ratio limiting values is not the prime factor of whether RC frame structurecan fulfill the yielding mechanism of strong column and weak beam.(4) Thorough modal analysis, non-linear time-procedure analysis, and non-linear staticanalysis of the frame models of non infilled walls, infilled walls of all around, and infilledwalls of vertically nonuniform layout, the influence of the infilled walls to the RC framestructure’s yielding mechanism under an earth quake event are analyzed are studied. As theresult shows, the infilled walls should be layed out as reasonably as possible and that theframe should be adjusted in accordance with the actual layout of the infilled walls.