Analysis Of The Mechanical Behavior Of A Type Inclined Tower Cable-stayed Bridg

Cable-stayed bridges are a type of high-order hyperstatic structural system composed of a main beam,bridge towers,and diagonal cables.The three-dimensional spatial effect is significant,and the load behavior is particularly complex.As a unique type of cable-stayed bridge structure,the A-type diagonal tower cable-stayed bridge has a distinctive shape and its load behavior under external loads is different from that of conventional cable-stayed bridges.The A-type diagonal tower structure differs significantly from single-column towers,arch towers,and inverted Y-shaped towers,and its structural design poses certain difficulties in the industry.Different cablestayed bridges have different load characteristics and are not universal.In addition,Atype diagonal tower cable-stayed bridges are relatively rare both domestically and internationally,and few scholars have conducted in-depth and comprehensive analysis and summarization.Therefore,it is necessary to conduct a specialized analysis of the load behavior of A-type diagonal tower cable-stayed bridges.In this study,relying on the Guizhou Provincial Science and Technology Plan Project,and using the Bijie Daotianhe Bridge as the engineering background,the stress behavior of A-type inclined tower cable-stayed bridges was investigated through theoretical analysis,numerical simulation,and on-site experiments.The main contents of the study include:(1)Based on the relevant theories of finite element analysis and cable-stayed bridge stress analysis,a spatial static and dynamic model of the A-type inclined tower cable-stayed bridge was established,and the overall static stress behavior of the bridge structure was analyzed.The deformation and mechanical responses of the bridge structure were obtained during the construction phase,bridge operation phase,and under the condition of cable breakage during the operational period.The static performance was comprehensively studied,and the cable tension values were applied to the local stress analysis of the tower anchor zone.(2)The overall dynamic stress behavior of the A-type inclined tower cablestayed bridge was investigated,mainly including two aspects: firstly,the sub-space iteration method was used to analyze the natural vibration characteristics of the entire bridge structure and determine its dynamic characteristics;secondly,the seismic response of the entire bridge structure under the E2 earthquake was analyzed using the response spectrum method and time-history analysis method.Furthermore,based on the P-M-φ analysis theory,the seismic performance of the bridge structure was evaluated to obtain its seismic performance.(3)By combining the structural construction of the tower anchor zone and the construction process,the local refined model of the tower anchor zone of the A-type inclined tower cable-stayed bridge was established using the midas FEA.Local stress analysis of the tower anchor zone was conducted,and the main stress parts of the tower anchor zone were monitored for real-time stress during the key construction phases.The distribution of the axial stress at the C1 and C15 cable anchorages was compared and analyzed,and the real stress distribution law of the concrete under the regional area was studied.(4)The effect of moment stiffness was considered,and the natural vibration characteristics of two cable systems were analyzed.Firstly,a double-beam model was used to construct the mechanical model of the two cable systems.The two cables were considered as Euler beams with axial force effects,and springs were used to connect the double beams to simulate the interference factors between the cables.In addition,vertical and rotational springs were used to simulate boundary conditions at both ends of the cables.Based on this mechanical model,this study presented the theoretical solution for the free vibration of the cable system and the iterative algorithm for solving the natural frequency of the system.The validity of the proposed method was verified by comparing it with the finite element results.Finally,this study analyzed several typical external factors that may affect the natural vibration characteristics of the cable system.