Study On Seismic Fragility Of Tall Reinforced Concrete Structures

For the increasement of the economy and the development of cities,more and more tall reinforced concrete buildings have been built in China.If a tall reinforced concrete building is severely damaged or collapsed during an earthquake,there would be costing lives and economic loss.The study on the seismic fragility of tall reinforced concrete buildings is fundamental and important to study on citeration for seismic precaution,hazard evaluation and prediction of reinforced concrete tall reinforced concrete buildings.As a result,the study on the fragility of tall reinforced concrete buildings have high values on seismic engineering principles and practice.This dissertation mainly focuses on the seismic fragility of tall reinforced concrete buildings,and the main contents are listed in the below.Damage intensity measuring models of concrete walls are built through machine learning program based on the experiments of high-span concrete walls.Models built by machine learning are commonly more accurate than the models based on traditional statistic techniques.And among all the models built by machine learning,the model based on Adaboost method is the most accurate and the stablest.So the model based on Adaboost method is recommended to measure the damage intensity of concrete walls.Based on the damage intensity measuring models of concrete walls,the effect of structural systems on the relationship between the maximum drift and the damage intensity of tall reinforcement buildings is studied through the statistics of dynamic time-history analysis on eleven tall reinforced building nonlinear finite element models.The variance analysis on the results of dynamic time-history analysis on eleven nonlinear finite element models suggest that the structural systems have no effect on the relationship between the maximum drift and the damage intensity of tall reinforced buildings.Considering the results of dynamic time-history analysis on eleven nonlinear finite element models,the measurement of damage intensity of tall reinforced concrete buildings by the maximum drift is constructed.Considering the results of the above studies,fragility curves of tall concrete buildings are studied based on the results of the dynamic time-history analysis on seven nonlinear finite element models which is built considering actual tall reinforced buildings.Analysis suggests that the fragility of tall buildings is sensitive to the characteristics of seismic spectrums.And although the levels of tall reinforced concrete buildings have a little effect on the fragility,the effect is so small that could be ignored in practice.The fragility curves of tall reinforced concrete buildings are drawn rest on the results of the dynamic time-history analysis,including 120 timehistory records on seven finite element models.For the reason that he fragility of tall buildings is sensitive to the characteristics of seismic spectrums,the fragility curves considering the characteristics of seismic spectrums are drawn which is based on the result of ground motion groups divided by the mean periods.In practice,when the characteristics of the seismic spectrum can be speculated,the fragility curves considering the characteristics of seismic spectrums could be used.