Analysis Of Seismic Performance And Seismic Reliability Of RC Frame Structures Considering Slab Effect

The influence of the cast-in-place slab on the seismic performance of the reinforced concrete frame structures are mainly divided into two parts.At the component level,the rotation stiffness of the beam is changed and the bearing capacity of the beam is improved.At the structural level,Due to the constraints of the slab,the overall stiffness and seismic performance of the structure are improved.When analyzing the seismic performance of the reinforced concrete frame structures,the slab effect should be fully considered.But how to consider the effect of the slab,there is still a lack of effective and efficient method.This paper aims to find a way to effectively consider the slab effect.The research and the evaluation of the reliability of the concrete frame structures are difficult problems,the difficulty lies in the determination of the structural failure function.How to use macroscopic control parameters such as vertex displacement to represent structural failure function,there is no effective method at the present stage.In this paper,a new method for calculating the reliability of structural system was proposed.The new method used the structural vertex displacement as a reference index to determine whether the structure was safe,and the validity of the new method was verified by Monte Carlo method.The main contents and innovations of the paper are as follows:(1)Based on the ABAQUS finite element analysis software,the finite element analysis model of the slab-beam composite component was established.By modifying of the basic parameters in the model,the variation law of the moment-rotation curves of the slab-beam composite member under different parameters conditions was analyzed.Combining the variation law of the moment-rotation curves and the unique mechanical properties of the slab-beam composite component,a simplified moment-rotation equation was derived to consider the slab effect.The finite element method and the simplified formula were used to calculate the moment-rotation curve respectively,and the results showed that the calculated curves of the two methods had high coincidence degree.(2)Based on the SAP2000 finite element analysis platform,the plastic hinge method was proposed to study the seismic performance of the cast-in-place reinforced concrete frame structures.The core principle of the plastic hinge method was to assign the above mentioned moment-rotation curve to the bar analysis model in the form of plastic hinge property.The conversion problem of the plastic hinge property in the bar analysis model could be corrected by the effective reinforcement area correction coefficient,the bending stiffness increase coefficient and the plastic hinge strengthening coefficient.In the SAP2000 finite element software,the pushover analysis of the reinforced concrete frame model was analyzed by the plastic hinge method,and compared with the analysis results of the entity finite element model,it showed that the plastic hinge analysis method could effectively simulate the slab effect under the action of the earthquake.And the pushover curves calculated by the plastic hinge method were in good agreement with the pushover curves calculated by the entity finite element model.(3)Based on the unique failure mode of the reinforced concrete frame structures,an improved response surface method for calculating seismic reliability of frame structures was proposed.The method taked the structural vertex displacement as the reference standard to evaluate the reliability of the frame structure system.Based on the pushover analysis method and by studying the relationship between the ultimate moment bearing capacity of the bottom column and the corresponding pushover curve,the seismic reliability of the structure could be calculated by the structural failure response surface which was deduced from the reference pushover curves under the defined vertex displacement condition.The seismic response of the reinforced concrete frame structures were analyzed by using the improved response surface method and the results of the analysis were compared with the results of Monte Carlo method(the finite element model used in the Monte Carlo method was modified by the plasic hinge method).The results showed that the improved response surface method was an effective method and can accurately evaluate the seismic reliability of the frame structures.