Elasto-plastic Stability Analysis Of Leaning-type Arch Bridge

The leaning-type bridge is a novel arch bridge which comprised of four arch ribs: twoparallel vertical ones or extroversion ribs in the center and the leaning-type ones on both sides.The parallel arch ribs are the main load-bearing structural components of the bridge and otherarch ribs contribute to the lateral support for the arch bridge. This novel and artistic bridgeswith unique shape and wide deck have obvious technical advantages compared withconventional arch bridges. However, due to the absence of lateral bracing between the ribs,this arch bridge has a relatively low bending stiffness and it is important to ensure its stabilityunder service and limit loads. There have been few leaning-type bridges built around theworld and few studies on their stability (mostly focused on elastic stability analysis orgeometric nonlinear analysis). In this thesis, a three dimensional finite element model forZengcheng Bridge is established with the software ANSYS. Detailed analysis on theelasto-plastic stability is carried out, and the factors that influence its elasto-plastic stabilityare studied comprehensively. The main work of this thesis is listed as follows：1. The state-of-the-art of the arch bridge and arch bridge stability were reviewed. Somerelevant analysis methods and the basic theory of finite element stability for arch bridges arediscussed.2. Base on the three dimensional finite element model of Zengcheng bridge with ANSYS,the elastic and elasto-plastic stability analysis were carried out. Linear elastic, geometricnonlinear and elasto-plastic stability analysis are studied and compared with each orther.Influence on the structure internal force and deformation by the nonlinear geometric factor isalso compared with that by material nonlinear factor.3. Through the finite element model, the thesis studies the three kinds of designparameters, namely the ratio of rigidity of inclined arch to main arch, quantity and distance ofthe boom, quantity and rigidity of cross-brace between main arch and inclined arch, and twokinds of load factor, uniform load and lateral wind load that affect the ultimate bearingcapacity of leaning-type bridges. What’s more, the stability analysis of leaning-type bridgesand normal arch bridges is compared. Thus, it gives more comprehensive understanding onthe elasto-plastic stability of leaning-type bridges.Zengcheng bridge is a typical leaning-type bridges. Some discussions and results fromthis thesis may provide some reference for the future bridge engineering.