FRP-混凝土-钢双壁空心桥墩分析及设计方法研究

Fiber-reinforced-polymer (FRP) composites are a class of high-performance materials that is strong, lightweight and corrosion-resistant. FRP-concrete-steel double-skin tubular members (DSTMs) are a new type of hybrid structural members invented by Prof. Teng Jin-guang of The Hong Kong Polytechnic University. DSTMs consist of an outer FRP tube, an inner steel tube and a layer of concrete sandwiched between them. Their advantages include ease of construction (e.g., the FRP tube and the steel tube serve as the stay-in-place formwork for concrete), superb corrosion resistance and excellent seismic resistance. Since the first publication of the concept of DSTMs in 2004, extensive research, including both experimental and theoretical studies, has been carried out. As a result, a good understanding of the structural behavior of DSTMs has been established, leading to design provisions in a national standard of China (GB50608-2020), but the practical implementation of DSTMs has not yet been reported to date. Against the above background, this paper presents a study on their analysis and design issues in connection with the first practical implementation of DSTMs as bridge piers recently completed by the authors' team. A nonlinear analysis method based on the fiber model for section analysis was employed to carry out in-depth investigations on a number of significant issues such as design methods for the ultimate limit state and the serviceability limit state. Furthermore, the detailing of joints (between a DSTM bridge pier and the foundation, as well as between a DSTM pier and the bridge superstructure) is examined, and a comparison of construction cost between the DSTM bridge piers and other types of bridge piers is presented. The design principles and methods, as well as areas needing further research, are summarized towards the end of the paper, which provides a valuable basis for future research on and application of DSTMs.