Research On Hierarchical Safety Assessment Technology Based On Deformation Analysis Of Suspension Bridge Tower

Cable support tower deformation is one of the key factors affecting the state ofsuspension bridge since if excessively deformated, it will not only be a security threat tocable support tower, but also be an influencing factor on the performance of thefull-bridge structure. At present, there is a lackage of effective and direct assessmentmethod on the service state of deformed cable support tower in current norms and nomature program is put forward by domestic and foreign scholars. Therefore, it has aremarkable significance to establish a direct and effective assessment model to evaluatethe service state of deformed cable support tower. Based on the impact analysis of thecable support tower deformation of suspension bridge on bearing capacity of thefull-bridge, this paper establishes an assessment method to evaluate the working state ofdeformed tower.First, based on the suspension bridge static analysis theory and the structural layoutand mechanical characteristics of cable support tower, relied on Zhongxian YangtzeRiver Bridge, this paper builds finite element model and analyses the deformationbehavior of cable support tower in operational period under the action of wind load,temperature load and live load. A monitoring method on suspension bridge cablesupport tower deformation based on inclinometer measuring method is also introducedin this paper.Second, this paper thoroughly analyses the impact of cable support tower deformationon the bearing capacity of the whole bridge. Combined with the suspension bridge staticanalysis theory and based on the study of Zhongxian Yangtze River, this papercalculates separately the bearing capacity changing conditions of cable support tower,boom, main cable, stiffening girder and some other key components of suspensionbridge under the action of longitudinal deformation working condition combinationand transverse deformation working condition combination. Thus the variationregulations between tower deformation and the effect variation volume of eachcomponent are obtained. On this basis, the objects with the most significant bearingcapacity change is selected to study the influence of longitudinal deformation on thewhole bridge bearing capacity after suspension bridge sag ratio, side span ratio and tower height change. Also the sensitivity degrees of those three parameters to the effectof suspension parts bearing capacity are compared.Third, based on the influence of cable support tower deformation analysis on thewhole bridge bearing capability and according to the hierarchical assessment theory, anassess model is established, which takes the sensitive factors on constructionalcomponent bearing capacity in cable support tower deformation as indicator system, anda cable support tower deformed state assessment system is put forward.At the end of this paper, the cable support tower deformation monitoring data ofZhongxian Yangtze River in April2013is taken as an example. The assess method isapplied to assess its technical condition level after cable support tower deformed. Theresults show that this assess method can be used to evaluate the service condition ofdeformed cable support tower and it is operable and logical.This article made studies on deformation analysis of suspension bridge tower andsafety assessment technology of preliminary conclusions,and provide a positivereference for devise and safety assessment of suspension bridge tower.