Bidirectional Shaking Table Test And Seismic Analysis Of FRP Retrofitted Nonductile RC Frame

In previous earthquake events, a number of existing reinforced concrete (RC)frames structures suffered severe damage. Most of these frames designed accordingto pre1970codes which bears gravity loads only, and none considering seismic load,or can not stisfy the present siesmic requirements due to the revision of design code.These structures are called nonductile frames. The nonductile RC frames withdissymmetric building plane suffered more severe damage, torsional will exacerbatethe seismic response and made them even collapsed. Therefore, retrofitted thenonductile and dissymmetric RC frame is necessary.In recent years, FRP virtue of its superior mechanical properties and ease ofconstruction are widely used in reinforcement project. However, comparing with theactual application in engineering, the theoretical investigation of seismicperformance of nonductile RC frames strengthened with FRP is obviously laggedbehind. At present, there is no seismic design method in structural level for RCframes retrofitted by FRP. Consequently, the investigation of seismic performanceand design method of FRP strengthend nonductile RC frames has importanttheoretical significance and engineering value. It is the basis work that providingtechnical support for modifieding the seimic design code and the strengthen designcode for concrete structures of our country.FRP strengthend nonductile and asymmetrical RC frames is the research objectof this study. In order to address current research gaps, this thesis carried out thefollowing work.First of all, shaking table test of4storeys and2bays FRP strengthenednonductile RC frames was conducted to investigate the variation of failure mode,seismic response and performance between unidirectional and bidirectionalearthquake input, and the development process from initial damage to failure ofstructures under different eathquake levels was also discussed. The result shows that:when the earthquake input is small, there is little difference of the seismic responsebetween unidirectional and bidirectional earthquake input, but when the earthquakeinput is become larger, torsional response of the structure increased underbidirectional earthquake input.Then the finite element model of shaking table specimen and nonlineardynamic analyses were conducted using OpenSees software. The simulation resultsagreeing well with test results show the correctness of modeling approach andaccuracy of analysis results.On the basis, the seismic performance of nonductile and asymmetrical RC frames three FRP rehabilitation schemes were evaluated analycitcally. Time historyanalysis were conducted for the studied cases. And the result shows that, afterretrofitting the seismic performance of dissymmetric frame significantly improved.And retrofitted the columns of lower two storeys is the best strengthening scheme.