Optimization On Design Parameters Of Double Thin-Wall Piers Based On General FEM Program

With the progress of science and technology and the development of bridge engineering construction, long-span continuous rigid-frame bridges have been widely applied apparently, and have become an important bridge style in modern bridge engineering. There are many cross-section forms in this bridge style. The form of double thin-wall piers is popularly used among of them. The key problem is how to choose the thickness of one single pier and the distance between two single piers from center to center. Depending on technical experience or trial analogism, the conventional technical methods have some limitations.In this paper the features of constructional details and behaviors of double thin-wall piers of continuous rigid frame bridges were firstly analyzed. According to the condition of deformation compatibility, a relationship between the inner forces on the coping of pier and the single inner forces of the double thin wall pier was established. Considering the restraint of strength and stability of the single pier, a mathematic model of optimization of double thin-wall pier design parameters based on ANSYS program was established. Then the feasibility of this method was verified by a simple example of plane rigid frame structure. Finally, according to the optimization theory and method of general FEM software , an actual bridge example of optimization design of Santan Yellow River Bridge was given to represent the process of the proposed method, in which the model building, result getting, the command follow programming functions and the optimization methods of zero-order and first-order were used. The results of optimization design can not only meet the specification, but also can make full use of the materials and yield good economic returns.Comparing with the actual design data of the Santan Yellow River Bridge, the method of this paper indicates preferable precision and feasibility for the optimization analysis on double thin-wall piers of long-span continuous rigid-frame bridges.