Mechanical Behavior Study On Inclined Pylon Cable-stayed Bridge During Construction And Operation

The type of inclined pylon cable-stayed bridge is widely used in the city. The inclined pylon and wide deck bring a lot of difficulties for structural computation, such as computational method of the girder, non-load effect, cable tension optimization theory, and the construction control of inclined pylon and girder. Based on Banfu No.2 Bridge in Zhongshan city, this thesis studies the spatial computational theory and the mechanical behavior during construction and operation. The main research work in this thesis is as follows:(1) Based on the characteristics of structure and mechanics, the two side main ribs are considered to be Timoshenko beam sub-element, and the deck is considered to be plate beam sub-element. According to the compatibility of deformation among elements, one assembled plate beam element is obtained, and this element can take into the shear lag effect. Through the secondary development of UPFs, the user element is realized on the finite element software platform.(2) On the basis of assembled plate beam element, the computational method of thermal effect, shrinkage and creep effect is studied. The non-load effect of side main rib and deck is equivalent to be the node load of sub-element. Then the node load of each sub-element is converted into the assembled plate beam through transition matrix. Then structural analysis uses the equivalent nodal load, and the thermal effect, shrinkage and creep effect are obtained.(3) The temperature field experiment of Banfu No.2 Bridge is performed. According to the measured data, the regional temperature field is presented. That is: according to the temperature distribution rules of girder and pylon, the temperature field of each member is presented, including one-dimensional and two-dimensional temperature field. Based on the measured data, the parameters of each temperature field are fitted. Then it can provide reference for the thermal effect analysis of the similar section in Guangdong province.(4) The reasonable finished state is determined through the minimum bending energy and influence matrix methods. For the Banfu No.2 Bridge, the single method can not obtain reasonable cable tension. Therefore, twice optimum approach is presented. The process is: the initial finished state is determined through the minimum bending energy, and then the influence matrix method is used to adjust some cable tension. After the reasonable finished state is determined, the backward analysis is carried on, and the reasonable construction tension is obtained, the shrinkage and creep are considered through the equivalent node load. As a result, the reasonable construction tension can be obtained through only once analysis, and the cable tension optimization efficiency is increased.(5) Based on above analysis approach, the spatial finite element model is built to analyze the mechanical behavior during construction and operation. The contents are the shear lag effect of girder, the structural temperature effect, and the forecast of long-term deformation and internal force. Besides, the local stress among pylon, pier and girder is analyzed. Duo to the assembled plate beam element is weak in analyzing local stress, the analytical area selects solid element, the other area selects assembled plate beam element. Through all the research, it provides reference for the design and construction of inclined pylon cable-stayed bridge.