Prestressed Concrete Continuous Beam Arch Combination Bridge Derrick Loading Performance Analysis

In recent years,with the rapid development of bridge construction in our country,prestressed concrete continuous beam arch combination bridge has been widely used in all parts of the country,the combination system bridge combines the bridge advantages of curved and arch bridge compression,using suspender of arch rib and the beam of the force transmission that is a typical three element structure on the stress characteristic,namely is composed by the live load distribution component,force transmission component and the main load-bearing.The combined bridge has advantages of material saving,low cost,the foundation requirements low,strong adaptability,simple construction process and superior structure properties,is a type of development potential bridge However in this three element stress structure,due to corrosion,fatigue and other reasons booms become rod breakage,induce redistribution of internal force of suspender,and the influence of the hanger rod axial force,displacement and reliability changes.So it is necessary to analysis about force change of structure due to boom fracture.This paper as the background with two different structures of beam arch bridge to study the structural response of the fracture of the boom,the main contents of the following:(1)By simply supported beam arch combination bridge model,analyzing the uniformly distributed load of suspender force distribution for calculation model of the equivalent membrane tension that is derived suspender tension of film and beam stiffness ratio,suspender arch ribs generation stiffness ratio,the arch rise span ratio and other parameters by force method equation.(2)By using the finite element software to establish finite element model engineering 1 and engineering 2 and analyze the suspender fracture under the different location,also analyze the axial force and displacement changes of two seat suspension bridge before and after,in the engineering 2 which regards boom fracture of axial force and displacement amount before and after as the analysis object,it is compared boom around the fracture of the axial force and displacement variation,finally obtained the different structural forms of the two background bridge suspender fracture for effects and differences of the remaining rod axial force and displacement.(3)In the state of ultimate bearing capacity,calculating normal section bending security surplus degree of engineering background 1,and then calculating the normal section bending safety margin in different positions after the fracture rod,getting variation of bending the safety margin with different positions fracture rod before and after;in Engineering 2,the fracture of different position of suspender the safety margin of cross-section change before and after was calculated,using the data,indicating the situation of beam arch composite bridge flexural safety margin for Engineering 2 under the state of ultimate bearing capacity,finally getting the influence and the difference of rod bending fracture for two different structural forms of bridge crane the bearing capacity.(4)The reliability indexes of two background bridges before and after of the boom fracture were calculated,and the influence of the fracture on the reliability index of the remaining boom was analyzed.Obtaining the strength of the coefficient of variation of booms which were 0.05,0.1,0.15,0.2 of derrick reliability index and the relationship between different boom material strength coefficient of variation and the derrick reliability index by changing the boom material strength coefficient of variation.