Structural Property Of Super-long Span Cable-stayed Bridge Based On High Performance Materials

Concrete cable-stayed bridge is a competitive structural system in the long-span bridge family in virtue of its good performance such as durability, low cost of construction and maintenance, etc. However, the lower strength of ordinary concrete used in present bridges makes the applicable span length of the existing concrete cable-stayed bridges generally less than 500m. The cable-stayed bridge with larger span must use steel-concrete composite girder or steel girder. However, in comparison with concrete girder, using steel girder would result in a more expensive and less durable structure. In this paper, a new concrete cable-stayed bridge system characterized with CFRP (Carbon Fiber Reinforced Polymer) cable and Reactive Powder Concrete (RPC) main girder was presented to develop a more efficient and durable bridge structure. It was expected to expand the applicable span range of concrete cable-stayed bridge to about 1000m long through the structural system.Based on the scheme design of a cable-stayed bridge with the main span of 1008m, five cable-stayed bridges with different materials were proposed:(1) Bridge 1 (S-S-N), the cable-stayed bridge with steel cable, steel girder and normal concrete tower.(2) Bridge 2 (C-S-N), the cable-stayed bridge with CFRP cable, steel girder and normal concrete tower.(3) Bridge 3 (S-R-N), the cable-stayed bridge with steel cable, RPC girder and normal concrete tower.(4) Bridge 4 (C-R-N), the cable-stayed bridge with CFRP cable, RPC girder and normal concrete tower.(5) Bridge 5 (C-R-R), the cable-stayed bridge with CFRP cable, RPC girder and RPC tower.Five cable-stayed bridge models in three-dimensional were established, using finite element analysis software MIDAS, and then the feasibility of the new cable-stayed bridge system was further discussed based on the results from a comparative analysis about static and dynamic performance of these five bridge models. This thesis involves the following work:1. The significance of this study and the relevant literatures were expounded. Meanwhile, the historical and present background of the research on CFRP and RPC was introduced systematically. Based on the excellent performance of these two materials, the objectives of this paper were put forward.2. Designed a cable-stayed bridge with the main span of 1008m, The principle of replacing CFRP cable, the design of the cross section of RPC girder (considering the stiffness, shear capacity and local stability) was demonstrated.3. The analysis of the static performance (such as the deflection of main girder, deviation of tower, force, and stress, etc.) of five cable-stayed bridge systems under different load (vehicle load, temperature load, wind load, dead load) and combination, showed that the proposed new bridge system has good static performance.4. The comparative study of the free vibration modes and spatial elastic stability of the five cable-stayed bridge systems illustrated that the proposed new bridge system has good dynamic performance and stability.