Static And Dynamic Characteristics Analysis Of A Single Long-Span Suspension Bridge Under Completion State

In various bridge systems,suspension bridges are known for their ability to conquer large spans.In particular,it is competitive in the range of 500 to 3000 m in span(span of the self-anchored suspension bridge is 100 m to 500m),covering 85% of the span of all suspension bridges.With the rapid development of bridge technology today,more and more suspension bridges continue to appear before people.Although the suspension bridge design theory is continuously improving,there are few studies on its system.Based on the relevant research at home and abroad,this paper studies the static and dynamic characteristics of a suspension bridge using the single span large suspension bridge as the engineering background in the following three aspects:(1)Introducing the theory of static and dynamic characteristics in the development of suspension bridges.According to the relevant specifications,the model components are simplified equivalently,the structure is discretized,and the appropriate element forms are selected according to their force characteristics.The full-bridge calculation finite element model is established using Midas/civil(2011)software.,the static characteristics of a suspension bridge under six kinds of load combinations(Combination one: dead load + settlement + moving load;Combination two: dead load + settlement + moving load + temperature;Combination three: dead load + settlement + moving load + lateral wind load(with vehicle)+ temperature;Combination four: dead load + settlement + moving load + lateral wind load(with car)+ temperature + braking force;Combination five: dead load +settlement + lateral wind load(one-hundred-year event);Combination six: dead load+settlement+longitudinal wind load(one-hundred-year event)are studied,and the related laws are provided to provide reference for practical engineering.Considering the structure in six load combinations.(2)Analyze the natural vibration characteristics of long-span suspension bridges.At the same time,in order to study the influence of structural parameters on the dynamic characteristics of suspension bridges,the span ratio,the constant load concentration,the stiffness of the main beam,the tensile stiffness of the boom,and the tensile strength of the main cable are considered separately.The influence of stiffness changes on the dynamic characteristics of suspension bridges has led to a series of conclusions that provide powerful references for design.Calculate response spectrum analysis of suspension bridge under three load conditions(Case one: longitudinal + 0.3 times transverse + 0.3 times vertical;Case two: 0.3 times vertical + horizontal + 0.3 times vertical;Case three: 0.3 vertical + 0.3 times horizontal+ vertical).It is concluded that the axial and lateral bending moments of the tower of the suspension bridge and the lateral displacement of the tower top and the longitudinal displacement of the beam end are indicators that need to be strictly controlled during design.The effects of uniform excitation on the dynamic characteristics of suspension bridges are studied.The combinations of EL Centro waves,Taft waves and James waves are considered.(Case one: EL Centro+0.3 Taft +0.3 James;Case two: 0.3EL Centro+ Taft +0.3 James;Case three: With the unanimous encouragement of 0.3EL Centro+0.3 Taft + James,some important indicators(displacement,shear force,bending moment history curve)of the south tower top,south tower bottom,beam end,and midspan are obtained.Comparative analysis leads to practical conclusions.(3)Non-uniform incentive theory formula is derived in this paper.Because of the large span of suspension bridges studied in this paper,the influence of traveling wave effect on its dynamic characteristics was studied.It was assumed that the apparent wave speeds were 500m/s,1000m/s,2000m/s,3000m/s,and 4000m/s respectively.The influence of the dynamic characteristics of suspension bridges has led to the displacement(longitudinal,lateral,vertical)across the suspension bridge,the south tower and north tower(vertical and lateral displacements),and the internal force response across the central and south and north towers(bending moment,shear force,axial force),and compared with the results calculated under the same incentive,to get the relevant laws.