Study On Seismic Behavior Of CFST Arch Bridge With Steel Tube Filled With Rubberized Concrete

Rubber concrete is a kind of composite material with strong ductility but less strength than ordinary concrete.Many studies suggest it is suitable for structures with seismic requirements.In order to verify the seismic behavior of rubber concrete,this paper applies it to the arch rib of CFST arch bridge to form RuCFST arch bridge.The seismic response of the arch bridge with different rubber content is studied.Taking an actual CFST arch bridge as an example,finite element models are established.The rubber content in the arch rib is 0%(NC),5%(RuC5),10%(RuC10)and 15%(RuC15),respectively.Firstly,the dynamic characteristic analysis,modal sensitivity analysis and modal contribution coefficient analysis of the arch bridge are carried out.Then,the response spectrum analysis and nonlinear dynamic time-history analysis are carried out.Response spectrum analysis is used to calculate the responses of arch bridges under lateral,longitudinal and vertical seismic actions,and the combination of three directions is considered.The nonlinear dynamic time-history analysis takes into account the effect of uniform excitation and traveling wave on the seismic response of the arch bridge.When NC,RuC5 and RuC15 are used respectively,the effect is analyzed by calculating the internal forces and displacements of arch foot,arch rib 1/4 and arch roof in the range of wave velocity 50~2500m/s.Finally,the damage degree of the arch bridge under earthquake is studied based on the double failure criterion of deformation and energy.The damage index(DI)is calculated under earthquake with peak acceleration of 0.2g and 0.4g.The results show that: With the addition of rubber in the arch rib,the vibration modes of the arch bridge are invariable,and the natural frequency is slightly reduced.The sensitivity and contribution rate of the main modes are almost unchanged.The seismic response of the arch bridge decreases.At the same time,the stresses in the steel pipe increase while the ones in the core rubber concrete decrease under the earthquake.The RuC5 arch rib has minimum seismic damage with peak acceleration of 0.2g and 0.4g,the next is NC,while damage of the RuC15 arch rib is maximum,that is,the arch rib with rubber content of 5% has better seismic performance.