The Factor Of Influence On Long Span Cable-stayed Bridge Dynamic Characteristics

Large bridges, which as an important part of the transportation infrastructure andlifeline engineering, have been entered a flourishing phase of research and construct. However,the large-span bridges have flexible, low quality and low damping characteristics, that makebridge wind resistance, seismic resistance and performance of vehicle-bridge couplingvibration becoming main controlling factors in the design. Bridge security control isinevitable and significant technical problem. Nevertheless, these problems have a closedrelationship with dynamic characteristics of the structures. Most of the long-span cable-stayedbridges are built on the rivers with rains and winds, it is very easy to cause vibrations of cable,and cable vibrations have a great impact on the bridge safety, durability, comfort and economy.So the studies on mechanism and control of cable vibrations become a focus in recent years.Therefore, it is critical and meaningful for study on dynamic characteristics of bridgestructure.This paper studies and analyses the effect factors of dynamic characteristics in long-spancable-stayed bridges, the main work are showed in several ways:1、Collecting information on the bridge structure and dynamics characters, introducingthe basic theory of natural vibration of bridge structures, and summarizing the commonstructural damping in engineering.2、On the basis of reading extensive references, summing up the effect of differentmodeling methods on dynamic characteristics. And by applying appropriated method ofmodeling, analyzing effect on structural dynamic characteristics of different cross-sectiontypes.3、Because of lacking limiting displacement on the end of middle tower, it increases theflexibility of multi-tower cable-stayed bridges. Nowadays, references about the effect ofstructural stiffness on the stability of bridges are mainly static. This paper analyzes the effectof tower stiffness on dynamic characteristics of multi-tower cable-stayed bridge with a largespan.4、 To make the studies feasible, dynamic characteristics of the cable must be accuratelysimulated, so this paper also discusses the effect of unit division in super long stay cables ondynamic analysis results.