Research On The Mechanical Properties Of Twin-Towers Curved Beam Suspension Bridge With One-cable Plane

As a new type of bridge,the twin-towers curved beam suspension bridge with one-cable plane of self anchored is becoming more and more popular in the construction of large span pedestrian bridge,for its smooth line,three dimensional penetration,and matching with the landscape and road.Because the curved beam suspension bridge with one-cable plane not only has the flexibiltiy aspect of the cable system,but also has the rigidity aspect of the curved beam bridge system.It is necessary to combine the theoretical analysis with the geometric calculation in the establishment of the three dimensional finite element model.And the calculation of space iteration is carried out until the finite element model of twin-towers curved beam suspension bridge with one-cable plane of self anchored under the dead load state is completed.The static and characteristics characteristics of the finite element model are analyzed.And the identification of the damage index of the main cable are distinguished.First of all,the development of suspension bridges at home and abroad are summarized in this paper.The influence of suspension modes and the number of cable towers on the curved beam suspension bridge are summarized.In order to find the shape finding method of space main cable of the twin-towers curved beam suspension bridge with one-cable plane of self anchored,the basic calculation theory of suspension bridge is studied.The balance equation of main cable alignment is also analyzed.Based on the calculation of the alignment of the main cable,the theoretical calculation of the main cable shape and the finite element analysis method of the curved girder bridge are discussed and modified.These theories establishes the basis for creating finite element modeling and mechanical performance analysis of the twin-towers curved beam suspension bridge with one-cable plane of self anchored.Then,depending on one kind of finite element software--Midas/Civil,a finite element modeling method of twin-towers curved beam suspension bridge with one-cable plane of self anchored is established.By expanding Midas/Civil finite element software analyzed function to find this formfinding for main cable of curved beam suspension bridge of self anchored,combining with geometric numerical analysis.The numerical value,main cable coordinate and the internal force of main cable and sling,which are calculated iteratively until the three-dimensional finite element model of the twin-towers curved beam suspension bridge with one-cable plane of self anchored is established.It is proved with an example that the main cable line of this twin-towers curved beam suspension bridge with one-cable plane of self anchored.The main cable line is smooth,and the internal force of main cable and sling are reasonably distributed..The example also proves the correctness of the finite element modeling method of the twin-towers single-cable plane curved beam suspension bridge of self anchored.The static characteristics of the twin-towers curved beam suspension bridge with one-cable plane of self anchored are analyzed based on the finite element model.The main cable,sling and stiffening girder of the twin-towers curved beam suspension bridge with one-cable plane of self anchored meet the requirements of standard design under the condition of dead load.Under the different population load conditions,the twin-towers curved beam suspension bridge with one-cable plane of self anchored has complex characteristics,which are suspended cable,curved beam and stay cable.And in particular cases,some characteristics are more significant.These problemes need to be focused on.Under the condition of overall warming,the displacement of stiffening beam changes little.However,under the condition of overall cooling,the displacement of stiffening beam changes obviously.It is necessary to pay attention to the changing trend of main cable's shape of the twin-towers single-cable plane curved beam suspension bridge of self anchored under the condition of overall cooling.And the lower basic frequency and soft structure of the pedestrian bridge are easy to cause the vibration response problem under the specific flow density.It is necessary to consider the human vibration condition in use.And the TMD damping device should be installed to solve the problem of comfort.The damage identification of main cable of the twin-towers curved beam suspension bridge with one-cable plane of self anchored are analyzed based on the finite element model.The damage identification of main cable is judged according to damage indexes of in plane directions and in transverse directions based on relative modal flexibility and modal flexibility differences of in plane directions and in transverse directions.The damage degree of the main cable is more serious,the damage condition in the tower is more obvious than that in the side span and middle span.Damage indexes of in plane directions and in transverse directions based on relative modal flexibility are more accurate than modal flexibility differences of in plane directions and in transverse directions to identify the damage of main cable.