Research On Seismic Performance Of Continuous Rigid-framed Steel-concrete Composite Bridge

In recent years,crack and excess deflection of rigid frame bridges became a serious problems in our country.Steel-concrete composite continuous rigid-frame bridge can not only avoid such diseases,but also has the advantages of good holistic capability,convenient and quick construction.With the promotion of the steel and composite bridge,there will be wide development for steel-concrete composite continuous rigid-frame bridge in highway and railway construction.In addition,during use of the bridge,it is inevitable to encounter natural disasters such as earthquakes,cars or ship collision,fire,explosion and other extreme accidents.The effects of multi-hazard load is not taken into account in the existing design specification.Therefore,the study of the mechanical performanc of steel-concrete composite continuous rigid-frame bridge under multi-hazard has great theoretical significance and great practical value.In this dissertation,based on quasi-static experiment,explosion experiment and nonlinear finite element model are used to explore the seismic performance of steel concrete composite continuous rigid frame bridge and the antimulti-hazard performance of piers.The main work is as follows:1.A new structural form is designed for rigid joints of steel-concrete composite continuous rigid-frame bridge.The joints with different piers including double-skin steelconcrete composite pier,reinforced concrete pier and steel-concrete composite pier was also designed for comparing their seismic performance.2.Consideration of the effect of explosion damage,the multi-hazard seismic performance of double-skin steel-concrete composite piers with different sections is studied.The explosion experiment has caused damage to the piers and explored the forms of damage to the piers with different sections.The quasi-static experiment has been done to compare the seismic performance with undamaged piers.3.The finite element model of steel-concrete composite continuous rigid-frame bridge has been built to study dynamic response under earthquake and evaluate the seismic performance.The main conclusions are as follows:1.The seismic performance of the joint constructed with double-skin steel-concrete composite pier is better than the joints constructed with reinforced concrete pier of steelconcrete composite pier.Its seismic performance is better while reducing the amount of materials.2.The explosion damage has a great influence on the development of double-skin steelconcrete composite pier under quasi-static experiment.The peak of the load is reduced by the explosion damage;the strength degradation curves shows the asymmetry;its stiffness decreased obviously,but it has little effect on its energy dissipation capacity.3.The seismic performance of steel-concrete composite continuous rigid-frame bridge is good,plastic hinge appears at the bottom of the pier under earthquake.When pier height is not the same,the shorter the pier is,the more vulnerable it will be to the earthquake damage;seismic performance decreases with the increase of the span;there is no obvious relativity between seismic performance and cross number;the bridge with different height of piers is more likely to be damaged than the one with the same height of piers.This dissertation can provide reference for aseismic design,extension and application of steel-concrete composite continuous rigid-frame bridge.