Analysis Of Influence Of Auxiliary Pier On Dynamic And Static Mechanical Performance Of Long Span Composite Girder Cable Stayed Bridge

With the improvement of technology and the continuous advancement of transportation system,cable-stayed bridges are widely used in highway bridges due to their large span and small impact on the clearance under the bridge.At the same time,the bridge span gradually increases.The auxiliary pier which is an very important component of the bridge.When the span is large,the auxiliary pier is usually set to improve the overall rigidity of the bridge.In this paper,based on the Yumenkou Yellow River Bridge,the influence of the auxiliary pier on the dynamic and static mechanical properties of the long-span composite beam cable-stayed bridge was studied.The model was established by CSiBridge software,and the optimal position of the auxiliary piers was analyzed,and the influence on their dynamic and static mechanical properties was analyzed.The research content of this paper is as follows:1.The development history and structural characteristics of the composite cable-stayed bridge,the research status of the auxiliary pier and the research status of the dynamic performance of the long-span cable-stayed bridge are briefly introduced.2.Based on the cable-stayed bridge that it relies on,an additional auxiliary pier and add two auxiliary piers models were builded in this paper.The reasonable position of auxiliary piers when adding an auxiliary pier and adding two auxiliary piers were studies.3.Accorded to the research determined the reasonable position of the auxiliary pier.The finite element models of the three schemes are established.The cable forces under various bridge conditions are calculated using the bending energy minimization method.The influence of the number of auxiliary piers on the stress of the main beam,the main tower,the cable and the deformation of the main girder under the action of live load is calculated and analyzed.The most favorable solution for the static performance of the cable-stayed bridge was obtained.4.The commonly used dynamic analysis methods of the long-span cable-stayed bridge are introduced.The natural vibration characteristics of the cable-stayed bridge under the three schemes are calculated,included the natural frequency and mode characteristics.And the influence of the number of auxiliary piers on the dynamic characteristics of the cable-stayed bridge is compared.5.The commonly used seismic performance analysis methods for long-span cable-stayed bridges are introduced.Response spectrum method and time-history analysis are used to analyze the seismic response.Each method of ground motion were used two input forms: 1)vertical and vertical;2)horizontal and vertical.Compared the number of auxiliary piers to the internal forces of the key sections of the main tower,auxiliary piers,transition piers and main girders of cable-stayed bridges.Simultaneously compared the changes of seismic responses of various key points of cable-stayed bridges.The most favorable solution for the dynamic performance of the cable-stayed bridge was obtained.The research results and conclusions of this paper are as follows: Based on the design of the unsupported pier of the original cable-stayed bridge,the reasonable position of the auxiliary pier in the auxiliary pier and the two auxiliary pier models is determined;the installation of the auxiliary pier can improve the static force of the cable-stayed bridge.Mechanical properties,but after adding an auxiliary pier to continue to add auxiliary piers,the static improvement of the cable-stayed bridge is limited;the auxiliary pier can improve the overall stiffness of the bridge,the frequency of the first four modes significantly,increase the auxiliary pier can be obvious Effectively improve the vertical stiffness of cable-stayed bridges,improve the ability to resist vertical deformation,and then can effectively reduce the longitudinal girder of the main girder;response spectrum analysis and time-history analysis of the changes in the key cross-section response of cable-stayed bridges Generally,the overall analysis of the rate of change shows that increasing the number of auxiliary piers can significantly increase the seismic response of certain parts of the cable-stayed bridge.