Fragility analysis of railway round-ended pier with small shear span ratio in transverse direction
In order to clarify the seismic damage mechanism of round-ended railway bridge piers with small shear span ratio in the transverse direction.Three sets of quasi-static tests with a scale of 1:8 were conducted using a bridge along a certain railway line in China.The ductility,residual displacement,hysteresis energy consumption,and equivalent stiffness of the hysteretic curves were analyzed.Based on the test results,a fiber section finite element model with OpenSees and endurance time analysis dynamic calculations were conducted.Using the displacement ductility ratio of bridge piers as the damage index.The limit values of displacement ductility ratio between five damage states of no,slight,moderate,severe,and complete damage were defined based on the four key points observed in the tests.The damage development process of bridge piers was analyzed through fragility analysis.The research results are drawn.1)The reinforcement ratio has been increased from 0.3%to 0.7%,the bearing capacity of the bridge pier has been increased by 1.37 times,the ultimate displacement has been increased by 1.22 times,the final residual displacement has been increased by 1.55 times,the dissipated energy has been increased by 1.80 times,the initial stiffness has been increased by 1.08 times,and the final stiffness has been increased by 1.12 times.Improving the reinforcement ratio can improve the seismic performance of bridges.2)When the reinforcement ratio of bridge piers is increased from 0.3%to 0.7%,the probability of minor damage under frequent earthquakes decreases from 87.2%to 29.8%.The probability of moderate damage under design earthquakes has decreased from 63.5%to 30.0%.Under rare earthquakes,the probability of severe damage has decreased from 61.7%to 16.4%.The longitudinal reinforcement ratio can significantly reduce the probability of damage to bridge piers and improve their seismic performance.3)When the ductility coefficient allowed by current railway regulations is 4.8,all three bridge piers are in the stage of severe damage.When a rare earthquake occurs,the probability of complete failure of the three bridge piers is 6.4%,0.0%,and 1.4%.Small shear span ratio circular end railway bridge piers have a certain seismic safety reserve under strong earthquake action.
万方数据
维普
