Analysis Of Time Varying Seismic Vulnerability Of Beam Bridge With ECC-RC Composite Pier

Under the action of earthquake,the earthquake damage of bridge is mainly the displacement and collision of the superstructure and the destruction of the substructure and foundation.The pier is an important component of the bridge to resist earthquake,and its damage is mainly caused by the yield of steel and the collapse of concrete in the plastic hinge area.Ordinary concrete has low tensile strength and poor crack resistance,which is difficult to be solved by improving the material.Engineering cement matrix composite(ECC)is a fiber-reinforced cement matrix composite,which dissipates seismic energy through high ductility,strain hardening and multi-seam development.In addition,the use of high strength reinforcement has a significant impact on the seismic performance of the structure.However,the seismic behavior of ECC and high strength reinforced bridge piers is seldom studied.In view of the influence of ECC and high strength reinforcement on the time-varying seismic vulnerability of bridge members and bridge systems in the plastic hinge area of bridge piers during the whole life cycle,the following research work is mainly carried out in this paper:(1)The constitutive relationship model of ECC and high-strength reinforcement is analyzed,and the constitutive model of ECC01 and Steel02 in Open SEES software is used to simulate ECC and reinforcement respectively,and the models of RC beam bridge,common reinforced ecc-rc composite pier bridge and high-strength reinforced ecc-rc composite pier bridge are built respectively.(2)The moment-curvature analysis of pier section was carried out by using XTRACT software,and the relative displacement ductility ratio and relative displacement were selected as seismic damage indexes of pier and support.According to the chloride ion erosion mechanism,considering the bridge site environment and considering the normal maintenance of the bridge,the influence of the corrosion of longitudinal bar on the pier damage index was studied.(3)Using incremental dynamic analysis method for RC beam bridge,the common steel ECC-RC composite beam bridge piers and high strength steel ECC-RC composite beam bridge piers earthquake vulnerability analysis,build the bridge into the bridge seismic vulnerability curve of component and system,contrast analysis shows that the plastic hinge using ECC and ordinary steel,high strength reinforced ECC can improve aseismatic ability,bridge structures and system which improve the degree of more significantly,improve the degree and the size of the PGA;The rigid pier is more sensitive to the ECC performance,and the plastic hinge with high strength reinforcement ECC improves the seismic performance of the rigid pier more.(4)The seismic vulnerability of members and systems of corroded RC beam Bridges and ecc-rc composite bridge piers is analyzed,and the corresponding time-varying seismic vulnerability curves and surfaces are drawn.The results show that the seismic vulnerability of members and systems of the two types of beam Bridges increases with the increase of service life,but the increment of probability of surmounting is related to the size of PGA.The influence of steel corrosion on the seismic vulnerability of ecc-rc beam Bridges is lower than that of RC beam Bridges.