Shaking Table Test Design And Seismic Performance Analysis Of FRP Reinforced Concrete Frame Structure

At present,the research of FRP reinforced concrete structure at home and abroad is mainly focused on the aspect of component,and the study on the seismic performance of FRP reinforced concrete frame is less.And researchon the seismic performance of FRP reinforced concrete members mostly based on pseudo static test and finite element analysis,lack of dynamic analysis.Therefore,it is certainly need to research seismic performance of FRP reinforced concrete frame structure in the earthquake dynamic loads.Shaking table test is the most direct and effective structure earthquake-resistance dynamic test method,which can truly representate the earthquake process to study structural dynamic response and damage mechanism,seismic performance,and it is one of the most widely used methods in structure seismic test.In this paper,the mechanical performance test of FRP bars and the concrete materials properties test are carried out and the shaking table test scheme of FRP reinforced concrete frame structure is designed.This is based on the literature of the mechanics of FRP tendons and FRP reinforced concrete structures seismic performance.According to the similarity relation between the prototype structure and model,a FRP reinforced concrete frame structure model with 1/4 scale factors was designed and constructed.And the additional weight and measuring system arrangement of model structure were also carried out to prepare for shaking table test.Then,the finite element model of FRP reinforced concrete frame structure was established using SAP 2000.And 4 earthquake waves were selected to carry on dynamic time history analysis of 52 working condition,including one-way,two-way and three-way earthquake excitation.The acceleration response,displacement response and dynamic characteristics of the structure under different earthquake waves and different peak acceleration were obtained.Based on the existing seismic code that take inter story drift angle as evaluating indicator,the seismic performance of the structure was assessed.And it provides theoretical support for the follow-up shaking table test.The paper mainly comes out the following conclusions by numerical simulation analysis:(1)In the acceleration response: the maximum acceleration of each floor is on the whole inverted triangle distribution,and maximum acceleration occurs at the top.Under the same peak acceleration,the acceleration response of Wenchuan earthquake is the largest,showing that the maximum seismic response of the model depends not only on the peak value of the ground motion,but also on the earthquake wave frequency spectrum.The vertical seismic wave has little effect on the horizontal seismic behavior of the model structure in X and Y directions.(2)In the displacement response: Under the same peak acceleration,Wenchuan wave caused the largest floor displacement,followed by the Lanzhou artificial wave and EL-Centro wave,and model structure have minimum displacement when encountering Taft wave.It shows that the maximum displacement response of the model structure is not only related to the peak value of the ground motion,but also to the frequency spectrum of the seismic wave.When subjected to the same seismic wave,the larger the peak acceleration,the greater the displacement response of the model structure,which shows that the structural stiffness decreases gradually and the deformation increases.The vertical seismic wave has little effect on the horizontal displacement of the structure.(3)From the perspective of structural stiffness,the stiffness of bottom column is smaller than that of two or three floor column,which is most likely to be damaged under the action of earthquake.Therefore,in the design of FRP reinforced concrete frame structure,the stiffness of the bottom column should be taken into account,and the bottom column stiffness should be increased by increasing the size of the column.(4)From the view of story drift angle,the maximum inter story displacement angle mainly concentrated in the bottom,which indicates that the first story of structure is more prone to deformation and more easily damaged than the two or three story under the ground motion,and the constructional measures for earthquake resistance should be strengthened.Under different levels of earthquake,the structural response is more intense,and the damage is more serious with Wenchuan earthquake wave than other waves.It is further shown that the seismic response of the structure is closely related to the seismic wave frequency spectrum.The structure basically meet the seismic performance objectives of “no damage under low-level earthquake”,“repairable under moderate earthquake”,“no collapsing under strong earthquake”.(5)When shaking table test is carried out,the excitation sequence of seismic wave is Taft wave,EL-Centro wave,Lanzhou artificial wave,Wen Chuan wave.