Relation of Stability Coefficient to Design Parameters for Curved Continuous Rigid Frame Bridges with Long-Span and High-Pier

Abstract

Based on the nonlinear theory, through changing the design parameters, the stability of model curve rigid frame bridges with long-span during cantilever construction was analyzed; The results show that the central angle of the curve dominated the stability coefficient; The nonlinear stability coefficient of bridge is 35% of eigenvalue flexure. Data was collected for a large number of long-span rigid frame bridge which have been built. Through comparison and classifying, the results indicate that the types of piers and its design parameters (the central angle of curve , slenderness ratio of piers, and the main pier types, the number of tie-girder) are related to the stability coefficient. The simple and creditable formulas can be taken as reference in designs. Introduction Long-span curve bridges with high piers are continuous rigid frames in general, which are built by the method of sub-segmental cantilever construction. During the construction stage, the Trigid frames suffer less constrain; their inter-force and deformation are very complex (He and Xiang, 2003). The gravity centers of each section of the curve's supper-structure are not in one line, so that the piers are under eccentric compression. Torque, rotation angle and lateral displacements of piers and beams were formed by gravity. These characteristics make major long-span curved bridge design and construction more complex than a straight bridge (Wang and He, 2005, 2006). In this paper, based on non-linear mechanics, through analysis the stability of long-span high-pier curved bridges, the relationship of stability and curved bridge design parameters was pointed out, which provided the basis for the large span continuous rigid frame bridge design, construction and monitoring. Methods of non-linear analysis To solve the non-1inear mechanics problems, the incremental method is usually used. The structure's critical loads are divided into several increments, each increment load corresponding to the deflection curve can be regarded as the linearity approximation. Such linear treatment can be quite accurate to the original non-linear course. When the structures bear a group of loads, we assume the loads grow in fixed proportion. The critical proportion determines the critical loads. We can determine the critical loads by the critical proportion. The concrete constitutive uses formula(1): c f k3 = σ 2 0 0 2 0 0 ) / ( ) / )( 2 ( 1 ) / )( 1 ( ) / (