Comparative Analysis on Seismic Performance of Reinforced Concrete Frame with Demolished Columns at the Top Floor
Demolishing columns at the top floor is common in reconstruction project of demolishing columns in concrete frame structure because of the minimum load and the floors involved in the modification and the least impact on the original frame.Most engineering technicians pay much attention to how to make the structure bear the increased load after demolishing columns,but the overall seismic performance of the frame after columns being demolished seldom become focus.In consideration of this situation,taking a demolishing columns project at the top floor of an existing teaching building as an example,three frame models were established by using ABAQUS finite element software,which were the original frame model,the enlarged beam section frame model and the prestressed beam frame model.The reversed cyclic loading test were simulated on the three frame models,and the seismic performance indexes such as the hysteretic curve,the skeleton curve,the stiffness degradation curve and the viscous damping coefficient of the three frame models were obtained.The seismic performance of the three frame models was compared and analyzed.The analysis results showed that compared with the original frame model,the horizontal bearing capacity of the enlarged beam section frame model and the prestressed beam frame model decreased as well as the ductility.Moreover,the initial stiffness of the original frame was the greatest,and the stiffness degradation rate of the three frames was similar at the later stage of loading but the stiffness of the original frame was slightly greater than the other two frames.In terms of energy consumption,the equivalent viscous damping coefficient of the prestressed beam frame was the highest at the later stage of loading,which indicated the energy consumption capacity of the prestressed beam frame was superior to the enlarged beam section frame.In general,the seismic performance of the frame decreases after the inner column on the top floor were demolished.The seismic performance of the enlarged beam section frame and the prestressed beam frame had their own advantages and disadvantages,but the prestressed beam frame was superior to the en-larged beam section frame on the whole.
original frameenlarged beam section frameprestressed beam framereversed cyclic loading test simulationseismic performance