Seismic Response Analysis And Vibration Mitigation Research Of Continuous Beam-Arch Composite Structure

The continuous beam-arch composite structure fully utilizes the advantages of continuous beam bridges and arch bridges,and has become an urban and regional landmark by virtue of its excellent structural force characteristics and unique beautiful shapes.It is widely used in the construction of long-span railway bridges and highway bridges.in.In this paper,the continuous beam-arch composite structure,which is representative of the Nanzhonghuan Bridge in Taiyuan City,is used as the research object.The dynamic characteristics,seismic response,overall structural shock absorption measures and local vibration reduction measures of the continuous beamarch composite structure are analyzed.The main research contents of this article are as follows:1.The development history of the continuous beam-arch composite structure at home and abroad is briefly described.The research status of the seismic performance of the continuous beam-arch composite structure is analyzed.The seismic damage characteristics of the continuous beam-arch composite structure are summarized.The main problems existing in the continuous beam-arch composite structure are discussed.2.The main engineering overview of the Nanzhonghuan Bridge is introduced.A three-dimensional finite element model of the Nanzhonghuan Bridge is established using Midas / Civil,and the structural frequency and main mode characteristics are calculated and analyzed.The research results show that the structure has a long natural vibration period,a small lateral stiffness,a reasonable arrangement of mode shapes,and is not prone to coupled vibration and modal recombination.The structure design is more reasonable;the anti-symmetric mode of the structure appears earlier than the symmetrical mode.The appearance of the structure indicates that the integrity of the structure is better,and the in-plane stiffness is better than the out-of-plane stiffness.3.Determine the structural acceleration response spectrum based on the engineering geological report and the " Seismic ground motion parameters zonation map of China",and generate three artificial seismic waves based on the SIMQKE＿GR wave selection software as dynamic time history curve inputs,using dynamic response spectrum method and dynamic time history analysis,respectively.The method is used to calculate the seismic response of the structure,and the results obtained by the two methods are compared.The influence of traveling wave effect on the earthquake of this type of bridge is studied.The research results show that: under the two calculation methods,the maximum ground motion response of the structure appears at the control section of the arch foot(B5),and the maximum displacement response appears at the control section of the main arch rib 1 / 2L(B3);the structure is under 11 kinds of apparent wave speeds The internal force response of the control section is slightly larger than that under the uniform excitation.In general,the traveling wave effect has little effect on the seismic response analysis of the structure.4.The finite element model of the lead-core rubber isolation bearing of the Nanzhonghuan Bridge was established,and the displacement response,internal force response and internal force response of the main arch rib under the E2 ground motion were compared and analyzed.The cross-sectional area of the lead core,The influence of the lead-core hardening ratio and the size of the isolated bearing on the vibration damping effect of the bearing.Finally,the damping effect of the lead-core rubber isolated bearing under the optimal parameter combination of the bridge was studied.The research results show that after the lead-core rubber shock-isolating bearings are installed,the displacement response values of the main arch control section are reduced to varying degrees,but the lateral isolation rate of the transverse bridge is low,which is mainly affected by the external stiffness of the main arch rib surface;Only a part of the isolation support is provided,so at the arch foot B5 section,compared with other control sections,the internal force response value of the structure decreases less;when the bridge uses a lead-core rubber isolation support for seismic isolation design,take lead When the core diameter is D = 180 mm,the hardening ratio α = 0.154,and the bearing diameter is 1200 mm,the other structures with the same mechanical properties have the best vibration damping effect.5.The ABAQUS / CAE finite element software is used to establish the local stress model of the arch,and the dynamic elastoplastic time history analysis method is used to comprehensively consider the structural and material nonlinear factors.Point response,find the yield point and stress concentration area of the structure,and discover the elastoplastic deformation law of the structure to identify the weak link and the yield mechanism of the structure.The research results show that the weakest part of the arch is the concrete near the joint between the top of the arch and the ribs,and below the main rib;the three-way restraint of the outer steel plate greatly improves the plasticity of the concrete.They can be perfectly coupled to cope with earthquakes,but the bond strength between the outer steel plate and concrete needs to be improved;increasing the strength level of concrete and the yield strength of steel within the appropriate range can enhance the plasticity of the structure and reduce the displacement response in all directions of the structure;When the local model of the arch is subjected to the force optimization analysis,the concrete strength grade is C55,the outer steel plate model is Q370 q,and the common steel section area is 1.10 S.When the other mechanical characteristics are consistent,the structure’s local vibration reduction effect is the best.