Analysis Of Influence Of Transverse Beam On Seismic Performance Of Double Column Piers

Highway and municipal bridge often used in the form of beam bridge in China,with the corresponding substructure of double column piers.Double-column piers are generally multiple static-indeterminate structures consisting of pier columns,cover beams and inter-column girders.The transverse girder between columns can directly affect the horizontal internal force distribution of the structure,which will affect the seismic resistance of the double-column piers and destruction modes.At present,in the conventional design,the transverse beams is set according to the structural requirements.However,under the action of transverse earthquake,engineers have no clear understanding of the impact of the transverse beams on the seismic performance of the double-column piers.In this paper,the main purpose is to study the influence of transverse beam on the seismic performance of double-column pier.By using the nonlinear fiber elements in OpenSees finite element software,the finite element model of double-column pier with 12 m,18 m and 24 m high-Based on the quasi-static analysis method,the anti-seismic performance of transverse beams with double-column piers was analyzed and compared.The number of the transverse beams,the installation position and the ratio of the rigidity of the tie-beam to the columns were discussed and optimized Analysis,including the following:(1)Based on the OpenSees finite element software,the non-linear fiber elements were used to simulate the collapse test of four frame columns and frames in Tsinghua University.The experimental results and the numerical simulation results were contrasted and analyzed.The nonlinear fiber unit numerical model used for analyses later,established by Concrete02 concrete model and Steel02 steel reinforcement model has great correlation with test data,and can reasonably and effectively simulate the frame column and frame structure loaded by pseudo-static test.(2)Quasi-static analysis of three types of cross-beams,no cross-beam,one cross-beam and two cross-beam,were carried out in the double-column piers.The seismic performance,internal forces and node displacements of double-column pier are studied.The results show that,under the action of transverse reciprocating load,compared to no cross-tie beams,the double-column pier with horizontal tie beams can increase the equivalent heel damping coefficient he value of double-column pier,reduce the bending moment values at pier top and bottom,and increase the transverse flexural rigidity of the structure to reduce the lateral displacement of the pier column.The conclusion is that the transverse beam is provided to increase the transverse bearing capacity of the double-pier with a covered beam and enhance its energy dissipation effect is obtained.(3)Considering different pier high of 12m,18m and 24m,the finite element models of double-column pier with covered girder were established.By using the quasi-static analysis method,the position of transverse girder and the stiffness of transverse girder in double-Stiffness ratio were discussed,including the equivalent viscous damping coefficient,equivalent stiffness,the parameters of the skeleton curve,the displacement ductility coefficient and the internal force distribution,which shows that the location of the horizontal beam will affect the internal force distribution of the double-column pier under the action of transverse reciprocating load.But the effect on the seismic energy dissipation is not significant.For the single-lane transverse beam is located at the middle position of the double-column pier or the double-transverse beam,the first transverse beam is set in the range of 0.3～0.4 times of the pier height,and the second transverse beam is located at 0.6 times of the pier height,which is the best position to achieve great energy dissipation effect and ductility.The stiffness of transverse beam has a significant effect on the internal force distribution of double-column pier under horizontal horizontal force.The increase of the rigidity of the tie beam will result in the increase of the bending moment of the pier body and the decrease of the bending moment of the pier top and bottom under horizontal force.Setting a single transverse beam or double transverse beam,the optimal ratio of the transverse beam stiffness to the pier stiffness is 0.3-0.7,which achieves a great effect of seismic energy.