Thin-wall High Piers Highway Girder Bridge Structure Mechanics Performance Analysis

Bridge as a transportation hinge in ensuring smooth flow of traffic plays a vital role, but the bridge structure might sueffer from many kinds of diseases during the service life which threaten the safety of the bridge. In this thesis, relying on the Xi Zhang Cun Bridge, established by the use of grillage finite element model,Calculated the structural performance influence of Overloading, temperature, wind, and bearings failure;Finally, given some suggestion for Safety management and maintenance of,the Xi Zhang Cun bridge.1.Overloading mainly influence the upper structure of bridge.In the overload situation,the internal force increase 50%-90%;the cross section of mid-span subjected to tensile stress,the stress value will surpass Concrete tensile strength and Cause section cracking in Eccentric loading.Overloading lead to Counteracting force increases,what will accelerate the bearing damage.Overloading effect on the bridge related to the vehicle type,The more concentrated vehicle axle weight, the greater the impact.To ensure the safety of the bridge, the Bridge managers should strengthen the management of passing vehicle,Prohibit the overload vehicles passing the bridge.For some heavy vehicles,Overloading detection should be done earnestly before it passing the bridge.Simultaneously should avoid the heavy vehicles keeping to the side to go crowdedly,prevents the bridge partial stress oversized.2.The wind load is primary factor which causes the bridge lateraldeformation,the maximal displacement of the pier top is 57.51mm under wind load.Because of the lateral deformation of the bearings, the girder and the bent cap have displacement difference,the Maximum value is 98.38mm,this might lead to the girder run in to the anti-knock block.The maximal lateral deformation of piers is 7.28 mm under temperature gradient load,The maximum stress at the side toward the sunis-4.34MPa. When the wind blows to the bridge pier back positive side,The bridge pier stress is most disadvantageous,The stress at the back positive side may reach to-10.45MPa and the side toward the sun appears the tensile stress.Therefore,we should strengthen the bridge examination and maintenance,we Should pay attention to the bearings especially whether has the lateral shear distortion,the girder and the bent cap whether has the contact,Whether the bridge pier does appear the crack.3. Bearing failure mainly affect bridge local stress.At the same pivot,when a bearing hanging in the air,the counteracting force of adjacent bearings increase and other Counteracting force reduce.while peripheral bearings hanging in the air is most disadvantageous,coMPared to the original bridge, counteracting force can be increased to 2.7 times. bearing hanging in the air caused the shear and bending moment of the girder increasing, the maximum shear can increased to 2.76 times and the maximum bending moment can increase 20% when the side of bearing failed, the maximum shear can increased to 1.75 times and the maximum bending moment can increase 6% when the middle of bearing failed. The ratio of the largest shear after and before bearings hanging in the air is between 6.919～19.266 and the ratio of maximum positive and negative bending moment were 18.9 times and 70.76 times.