Seismic Performance Analysis Of Self-reset Double-column Pier Bridges

Earthquake disasters not only endanger human life and health,but also cause economic losses that can not be ignored,such as the collapse of houses,the repair and reconstruction of roads and bridges.And the failure of the functions of these construction projects has further increased the development of rescue work,indirectly affecting the health of the affected people.As one of the most important transportation corridors after the earthquake,the function of bridge structure after the earthquake greatly affects the success of disaster relief work.In order to protect people’s life,health and reduce economic losses as much as possible,we should try our best to make the bridge which is the main road of transportation,be able to quickly resume use after the earthquake.Therefore,the consideration of seismic design of bridges includes not only the safety of human life,but also the economic situation and the ability of rapid recovery.The introduction of self-resetting structure can make the structure hardly suffer from serious damage under earthquake,or quickly restore its usability after earthquake.At present,this kind of structure is the focus of scholars’ research in the field of architecture.What’s more,it has been studied to a certain extent,but most of this kind of structure is concentrated in the building shear wall or single-pier bridge.And it has not been applied in the actual bridge structure.Therefore,there is still a lack of relevant research in the field of bridge,especially in double-pier bridges.The main research contents cover the following aspects:(1)The self-resetting structure is introduced into the double-column portal pier.The tension prestressing force is set as 80 kN,90 kN,100 kN,120 kN,130 kN,150 kN and 200 kN respectively for time history analysis under earthquake.The results show that with the increase of tension prestress,the residual displacement of self-resetting double-column pier bridge decreases first and then increases;the energy dissipation capacity decreases gradually;and the maximum stress of prestressing tendons increases gradually.Therefore,the large tension force in the prestressing tendons as self-resetting components should not be too large.When the tension force is 120 kN,the seismic performance of the bridge is better.(2)One(tension force is set as 480 kN),two(each tension force is set as 240 kN)and four pre-stressed tendons(each tension force is set as 120 kN)were set up in the self-resetting double-column portal frame pier for time history analysis.The results show that when the tension prestressing force is equal,with the increase of the number of prestressing tendons,the residual displacement decreases;the maximum stress decreases gradually.Besides,when only one prestressing tendon is installed,the maximum stress exceeds the effective stress of the prestressing tendon of 1488 Mpa.The number of prestressing tendons has little effect on the energy dissipation capacity of the self-resetting double-column pier bridge.Therefore,the seismic performance of self-resetting double-column pier bridge with four prestressing tendons is better.(3)The spacing of symmetrically distributed prestressing tendons is set as 400 mm,600 mm and 800 mm for time history analysis.The results show that with the increase of the spacing of the prestressing tendons,the residual displacement decreases;the energy dissipation values of the three working conditions are similar in the range of 0.3g-0.7g local vibration peak value;the energy dissipation capacity decreases with the increase of the spacing of the prestressing tendons in the range of 0.8g-1.0g local vibration peak value.The maximum response of the prestressing tendons increases with the increase of the spacing of the prestressing tendons.But the increase rage is very small,far less than the failure stress.Therefore,when the spacing of prestressing tendons is set as 800 mm,the seismic performance of self-resetting double-column pier bridge is better.(4)This paper compares the time history analysis under two conditions.One is to arrange 12 energy-dissipating steel bars evenly at the bottom of pier,the other is to arrange 6 energy-dissipating steel bars evenly at the top and bottom of pier.The results show that when 6 energy-dissipating steel bars are set at both the top and bottom of pier,the maximum displacement of pier top is smaller;the residual displacement decreases obviously.And the maximum stress of prestressing tendon is larger,but the increase is not obvious,far less than the failure value of prestressing tendon(1488 MPa).Besides,the plastic hinges are less and the yield degree is lower.Therefore,the seismic performance of the self-reset double-column pier bridge is better when six energy-dissipating steel bars are arranged at the top and bottom of the pier.(5)In this paper,the self-resetting structure is introduced into the actual double-column pier bridge.Considering the economic factors,only 2# pier is set as the self-resetting double-column pier.The time history analysis of El-centro seismic wave,Taft seismic wave and artificial seismic wave input along the transverse direction of the bridge is carried out.The results show that under the action of three kinds of seismic waves,the maximum displacement of the pier top and the participating displacement of the self-resetting double-pier bridge are both smaller than those of the ordinary double-pier bridge.Besides,the plastic hinges are less and the yield degree is lower.Therefore,after introducing self-resetting structure,the seismic performance of the bridge is significantly improved.