Initial Equilibrium State Analysis Of Self-anchored Suspension Bridge With Spatial Cable

Recently,a number of self-anchored suspension bridges are constructed at home and abroad.Because cable anchorage forces influence stress and deformation of the girder,and the girder is constructed before the main cable,self-anchored suspension bridge has a large diffence with earth-anchored suspension bridge on static and dynamic characteristic.Furthermore,as a kind of new cable shape,spatial cable system have different angle between each cable segment and bridge axis.For its hangers are declining , sag effect have tu be taken into account.The main cable and the hanger couple together during solving process of shape and force.Spatial cable is more complex than plane cable configuration.At present,in the world there are only 3 self-anchored suspension bridges with spatial cable which have been in use.This paper bases on these new issue,analyses cable-hanger system and tower-girder system,solve a series of problem in the initial equilibrium state of the self-anchored suspension bridge with spatial cable and supply complete data for subsequent structure effect analysis.Above all,after reviewing computational theory and non-linear influential factor of self-anchored suspension bridge,the paper studies its cable-hanger system.Aiming at spatial cable,the paper quotes detailedly Japanese doctor Ohtsuki's straight line segment theory and tongji university doctor Luo xi heng's elastical catenary theory,and further studies the latter's calculation method of programme. After presenting crucial parameters:solution method of the hanger lower end vertical force and adjusted values,elastical catenary algorithm of spatial cable is deduced.Secondly,according to the previous algorithm,using MATLAB language,the paper writes the programme called as self-anchored suspension bridge initial equilibrium state calculating programme(SASB-IESA).The Yongjong Grand Bridge is calculated with SASB-IESA.By comparing the analysis result with literature[34], SASB-IESA is demonstrated high accurate and efficient.Thirdly,the paper indicates that besides the cable-hanger system tension,self-anchored suspension complete bridge analysis model has to introduce the initial forces of the tower-girder system to suppress their deformations,so the current model satisfied not only the target design configuration but also the self-equilibrium between the full dead loads and internal member forces. The paper propose iterative method of the initial forces and zero displacement, calculation method of tower and girder's zero-stress dimension.Then,the paper founds a complete state analysis model using MIDAS civil program with SASB-IESA's output data and makes structure effect analysis.At last,the paper takes a kilometer level earth-anchored suspension bridge as an example,founds separately plane cable and spatial cable analysis modle using MIDAS civil program,compares respectively their natural vibration frequency and mode,obtains following conclusion:spatial cable advances obviously the whole bridge's transverse stiffness and torsional stiffhess,improving structural dynamic stability.