Research On Resilient Concrete Continuous Bridges Under Earthquake And Over-Height Truck Collision

Bridge plays an important role in life line engineering,therefore improvement of bridge resilience under disaster is of significant engineering value.This thesis focuses on the concrete continuous bridges,and a resilient bridge system with improved shear keys and piers to realize the structural resilience under seismic hazard and over-height truck collision.The main research works of this thesis are listed as follows:(1)8 exterior concrete shear key specimens with different dimensions and reinforcement layouts are designed based on a real bridge,and the mechanism of the shear keys is studied via pseudo static test.The results indicate that the shear capacity is improved with the increase of concrete strength,the height of shear key and the top layer reinforcements of bent cap have little influence on the shear key capacity,the shear key capacity can be enhanced by increasing the reinforcement ratio through the interface between the shear key and the bent cap,and the ductility can be improved by using closed stirrup which is recommended in design.(2)6 interior sacrificial steel plate shear key specimens(3 with initial groove,3 without initial groove)are designed.The failure mode and mechanism of these speciments are studied by horizontal monotonic loading experiment.The results indicates that the steel interior shear keys with good plastic deformation capacity play a role in buffering and energy absorption.Besides,the shear keys with initial groove show better performance compared with the ones without initial groove due to definite damage position facilitating repair and shear capacity improvement caused by plastic hinge area elevating.(3)The experiments of both exterior concrete shear key and interior sacrificial steel plate shear key are simulated,the results show good accordance with experiments.Parameters of interior sacrificial steel plate shear key are further analyzed.Based on the parameter analysis,initial grooved steel plate shear keys with a notch(r = 0.3~0.4de)positioned at 100 mm height from the shear key bottom are recommendated.Besides,the design formulas of capacity and energy dissipation are regressed simulation results.(4)Finite element simulation of the procedures that the bridge superstructure collides with exterior concrete shear key and interior sacrificial steel plate shear key are performed,respectively.For exterior concrete shear key,the relationship between the maximum impact force and the superstructure related parameters(i.e.,collision mass,initial velocity)are obtained on the basis of parameter analysis.(5)The finite element method of double-rocking-coloum pier with shear links is proposed and validated.The deformation process under reciprocating load is simulated and critical design parameters are further discussed based on the numerical model.The result indicates that initial tension provided by steel strand has a significant influence on pier stiffness while the yield capacity of shear link has a significant influence on energy dissipation and residual displacement of bridge pier;the influence of shear link stiffness is limited;and the distance between two coloum has a certain influence on the mechanism of pier.Furthermore,the computational formula to describe the skeleton curve of pier is derived and corresponding verification is carried out.(6)Based on aforementioned research results,detailed design methods and analysis procedures of key components(i.e.,exterior concrete shear key,interior sacrificial steel plate shear key and double-rocking-coloum pier with shear links)are provided.