The Influence Of Suspension Bridge Main Cable Anchoring Method On Structural Mechanics Performance

As the suspension span becoming smaller, the cost ration of Anchorage goes greater. And then in some cases, the cost of suspension bridge is bigger than other types of bridge. At this moment, the main cable may anchor at the end of stiffened girder, then the form of Anchorage becomes self-anchored from anchored. The structural mechanics system is changed by change of anchor method. Comparative research on the static-dynamic mechanics performance is done on the base of ANSYS Models, and the results provide direction to suspension bridge deign. The main contents and achievements are described as follows:(1) In terms of suspension bridge design theory, the paper designs the parameters of the two types of bridge models consulting the structural design of Xiamen Haicang Bridge and Changsha Sanchaji Bridge. Shape-finding programme is programmed by FORTEAN language and the main cable's initial stress is optimized based on ANSYS language. And then accurate dimensional finite element models of suspension bridge are built;(2) The paper finds the disadvantageous sectional load locations via calculating the influence lines of 7 key sections including the stiffened girder sections above towers, bottom sections of towers and stiffened girger sections of main span to compare the bending moments and vertical displacements. The bending moments of anchored structure are bigger than self-anchored structure by 26% when the loads are disadvantageous loads of stiffened girger sections above towers, while the bending moments of anchored structure are smaller than self-anchored structure in other cases. The distinction rates are from 12.9% to 67.5% variously; the deflections of mid-span of anchored structure are smaller than those of self-anchored structure in most cases;(3) Structural parameters studies including stiffened girder vertical bending rigidity, tensile rigidity of main cable, longitudinal bending rigidity of bridge tower, structural system, vertical curve curvature of stiffening girder and rigid connection between main cable and stiffened girder are carried out to investigate their influence on the static behavior of the two different types of bridge such as tower stress, suspension rod rigidity, bending moment and deflections at mid-span and so on. All above may provide reference for suspension bridge design;(4) The dynamic mechanics performance of anchored structure and self-anchored structure is compared. Meanwhile, structural parameters analysis are carried out in three aspects including the structure system, vertical curve radius and rigid connection between main cable and stiffened girder in order to study their influence to dynamic mechanics performance. It is concluded from the calculating results that the main vibration frequencies of anchored structure are higher than those of self-anchored structure. The basic frequences of the two types of bridges are heightened by increasing vertical curve curvature of stiffening girder, setting vertical supporting members and stiffing connection.The influence of main cable anchoring method on static-dynamic mechanics performance for suspension bridge is obvious and we should consider cautiously from many aspects.