Mechanical Behavior Analysis Of V-type Double Arch-tower Cable-stayed Bridge

Since the first modern cable-stayed bridge,Stromsund Bridge,was built in Sweden in 1955,the cable-stayed bridge has become the preferred structure type for designing long-span bridges because of its advantages such as reasonable force,light shape,remarkable landscape and large spanning capacity.At present,more and more engineers love to design and construct it.It has been rapid developed in recent decades,the main span has also increased from the original 182 m to 1104 m.However,with the increasing span length of the cable-stayed bridge,the structure is more and more flexible.The cable-stayed bridge belongs to the high order statically indeterminate tall-space structure,so the three-dimensional effect is more remarkable,the force is extremely complex.It is very important to analyze the static and the dynamic behavior of the whole and key parts of the bridge structure,in order to inspect the rationality of the design and the safety of the bridge operation.Based on the theory of cable-stayed bridge analysis,this thesis takes the V-type double-arch cable-stayed bridge as an engineering example,the analysis of the static and dynamic behavior and the local critical parts' stress are carried out.The main contents in this thesis are as follows:1.Based on the theory of finite element analysis and cable-stayed bridge,the three-dimensional finite element model of the bridge to analyze the whole static and dynamic behavior is established.The key points are to accurately simulate the bridge structure and ensure the reliability and accuracy of the analysis results,and lay a foundation for the subsequent static and dynamic calculation.2.The overall static behavior of the bridge structure is analyzed to study its static performance and lay a foundation for the subsequent local stress analysis.The overall static analysis shows that the maximum tension(compression)stress for main concrete girder and the steel structure of tower under the most unfavorable load combination meets the requirements of the code,and the maximum stress amplitude caused by the maximum stress of cable and live load meets the design requirements.3.The dynamic behavior of the bridge is analyzed and its dynamic characteristics are studied.The seismic response of the bridge is analyzed by using the response spectrum method and the dynamic time history method to obtain the seismic response.The dynamic time-history response analysis shows that different seismic input modes have different effects on the internal force of the control section.Generally speaking,the axial force response value of the control section under the longitudinal + vertical combination is larger than that under the lateral + vertical combination,while the shear force is smaller and the bending moment is larger or smaller.At the same time,the response value of E2 earthquake is larger than that of E1 earthquake.Additionally,the safety factors of control cross-sections are both >1 under E1 and E2,it will only emerge repairable damage,and the structure meets the seismic performance of code requirements.4.The local modeling of the steel-concrete composite joint of the V-type arch tower is carried out to obtain the local stress behavior of the key part.The stress level of each member of the steel-concrete composite section of the main tower is low under each static load condition,and the steel structure is in elastic state under the combination of the most unfavorable load conditions,without yielding phenomenon.No stress concentration for concrete base was found.The principal tension and compression stress of concrete is low.The safety reserve is high enough.