Book Description

Horizontally curved girder bridges have been used considerably in recent years in highly congested urban areas. However, although significant research on physical testing and advanced analysis has been underway for the past decade, the practical employment of many recommendations has not been achieved by the engineering community nor have standards reflecting this work been brought into practice. The design process of curved composite bridges involves tracking the stresses and the potential failure change in the girders during erection, construction and service loading stages. For structural safety and serviceability, the designer estimates the stresses induced within the bridge and assure that they do not exceed the applicable specified limit state as required in bridge design standards. However, the designer may be concerned about the level of approximation that is used in his estimate or even the applicability of the underlying theory. To answer this question and provide the designer with more insight into the behavior of the curved bridges, the field testing during construction and service loading of a curved bridge located near Baltimore, Maryland is re-examined here using linear elastic three-dimensional finite element modeling. Comparisons are made between the finite element results and the measured results. Finally, to facilitate the finite element modeling effort for use by a designer, ANSYS Parametric Design Language (APDL) capabilities are used here to develop an analysis/design tool for "Bath-Tub" style curved steel girder bridges. This tool is then used to evaluate the effects of several important design variables on the response and behavior of the girders during the construction phase. This study demonstrates the ability of finite element modeling to assess the stiffness, serviceability performance, buckling behavior and ultimate strength of curved bridges during construction and it is a major step towards a performance based approach to design for stability. The level of safety or reliability that would be available during the erection and the construction processes of horizontally curved girder bridges represents another major concern for the designer. A three span continuous curved box girder bridge in Houston, Texas is used in this study as an example reflecting current detailing and fabricating practice and it is chosen for a detailed evaluation of the structural safety/reliability during the erection and construction process. This task involves simulating the girder erection and concrete slab placement sequence of the bridge using comprehensive nonlinear three dimensional finite element modeling.