Research On Design Of Cable-stayed Bridge’s Scale Model Based On Stiffness Similarity Theory

Since the end of last century, more and more large-scale bridges have been built all over the world. The world record of their span length has been broken by one after another. Long-span bridges, especially cable-stayed bridges and cantilever bridges, are more and more preferred as the first choice of river-crossing bridges, or even sea-crossing bridges. However, as years pass, various types of structural damages, mainly caused by the improper use and maintenance, and natural disasters such as earthquakes and storms, will occur to bridges unavoidably. This will lead to a significant reduction in bridges’load carrying capacity and durability, and finally will affect the operation security. If we pay enough attention to bridge’s health status and evaluate it by monitor damages and structural integrality in real time during the operation period, we could know about the structure’s status in time and adopt corresponding safety measures.In order to study better on the application of modern testing and measurement technology and structural safety monitoring strategy in cable-stayed bridges, our research group has built a cable-stayed bridge model in reduced scale of1/40of the Badong Changjiang Bridge. Based on this structural test model, this paper discusses its design and fabrication process, and verifies whether it fits the patterns of cable-stayed bridges by static tests and dynamic tests. The main achievements are presented as follows:(1)On the basis of a brief introduction about the model testing similarity relationship theory, and aiming at the characters of cable-stayed bridges and this model test, ideas about the model’s design and fabrication are put forward. An ideal model which is exactly similar to the Badong Changjiang Bridge is designed.(2)By using the finite element software ANSYS and MIDAS, an analysis of the ideal model’s static and dynamic characters is made. The comparison between ideal model and the Badong Changjiang Bridge shows that stiffness similarity method is suitable when there are two different elastic modulus similarity ratios(3)With limits in materials and spaces, the actual model cannot meet all similar relationships. Thus, under the test’s purposes, a simplified model is designed. The zero displacement method also helps in optimizing its’cable tension. Result shows that cable-stayed bridge’s internal force conforms to the floating system’s force characters.(4)Then the cable tension is debugged with fiber grating sensors. Trial results show that the actual model fits cable-stayed bridge’s characters, and meets the test’s design requirements.