The Static And Dynamic Analysis Of Through Arch Bridge-Continuous Rigid Frame Composite Bridge

With the development of the bridge undertaking,a single load-bearing structure can no longer meet the requirements of designers for traffic functions and aesthetics,and the combined system bridge will be an inevitable trend for future bridge development.The emergence of the composite system bridge not only reduces the amount of work,but also optimizes the structural stress and plays an innovative role in the appearance of the bridge.The advantages of through arch bridge—Continuous Rigid Frame Composite Bridge make it have a broad prospect in this type of bridge.In this paper,the static characteristics and seismic response of the bridge type in the use phase are studied based on the Jinghong Lancang river double-track bridge of the new railway from Yuxi to Mohan Line.The main research contents and conclusions of this article are as follows:(1)This paper describes the structure,construction and stress characteristi-cs of large-span continuous rigid frame bridges,as well as common diseases.Through bridge layout,structure size,reasonable reinforcement and adoption of combined system bridges and other measures to avoid related diseases,a continuous-rigid-framed composite system bridge through arch bridge—contin-uous rigid frame composite bridge was introduced.(2)The theory of deflection and the finite element theory of the space analysis of through arch bridge—continuous rigid frame composite bridge are introduced.It provides the theoretical basis and the specific calculation analysis method for the structural analysis and calculation.(3)The internal forces,stresses and displacements of the main components of the bridge type under dead load and medium live load are analyzed.According to the analysis,the dead load plays a dominant role in the design of the bridge type.Similar to the ordinary arch bridge,the arch ribs are under pressure and bending,the main beam is mainly compressed,with side spans and middle spans;under the action of medium live load,the arch ribs are mainly subjected to compression,the main girders are mainly bent,and the most unfavorable position occurs at the arch feet.Therefore,the stress on the joints of the beam arches should be the focus of consideration when designing.(4)Studying the influence of different earthquakes on the seismic response of structures,the analysis shows that because of the box-shaped cross section of the entire structure,the torsional stiffness is large,and no torsional vibration occurs in the first ten vibration modes;under the action of longitudinal earthquakes,only the longitudinal and vertical displacements are affected,but the vertical displacements are more affected;under the action of lateral earthquakes,there is almost no effect on longitudinal and vertical displacements,but lateral displacements are significant due to the weak transverse stiffness of the ribs;vertical seismic action has a great influence on the internal force of the structure and cannot be neglected during design.(5)Through comparison of time-history analysis and response spectrum analysis,we found that time-range analysis of displacement and internal forces generally exceeds response spectrum analysis.Due to the standard response spectrum curve used in the response spectrum analysis,the spectral characteristics and the actual seismic wave have large differences.At the same time,the time-course analysis of the randomness of seismic wave selection is also a factor that causes differences in the results.For large-span continuous beam arch bridges,the seismic response analysis can be estimated by the response spectrum method,and the time-history analysis method should be used for verification.