Disease Analysis And Study On The Consolidation By External Per-stressed Technique In Rigid-frame Arch Bridge

Nowadays, as traffic volume increased, bridges built in last century cannot matchthe need of vehicle flow anymore. In addition, because of bad integrity and weakness inpotential of bearing capacity, a lot of disease occurred in Rigid-Framed arch bridge, thatcannot meet the requirements of normal use. It is very important to strengthen this typeof bridge. This paper based on Guangdong highway administration bureau science andtechnology project<Concrete rigid frame arch bridge reinforcement and reconstructiontechnology and applied research in in Guangzhou>, researched the diseases ofRigid-Framed arch bridge and the strengthen methods, main research contents andconclusions are:This paper analyzed the component and stress characteristics of Rigid-Framed archbridge. Based on the research results of this paper, it can summarize that diseasecentralized in mid-span of external chord, big and small nodes, vault, skewback, bridgedeck and micro-bend plate. Main disease characteristic that influence the structure is themassive cracks, especially on the lower margin of vault, mid-span of external chord andmicro-bend plate.Analyzed the cause of disease in design, construction period and management.Combined with real bridge calculation results, this paper analyzed the reason of designperiod. The results showed that value of load impact coefficient, transverse distributioncoefficient and temperature exchange were small. In design period, stress was notchecking, the crack width was not calculated, so it was hard to grasp the performance ofbridge in using period.According to main disease of Rigid-Framed arch bridge, this paper compared usualmethods to strengthen it, emphasis analyzed and pointed out applicability of differentstrengthen methods. These papers recommended strengthen methods to strengthenchord, arch legs, lateral ties, and decks. It also pointed out that increasing sectioncombining with external pre-stressing was the optimum scheme to strengthen solid-websecion.This paper built FEA model of50m span Rigid-Framed arch bridge to calculate,the results showed that bearing capacity and stress of solid-web section cannot meetdemand. Analysis pointed out that solid-web section was under large eccentriccompression.External pre-stressing method improved the stress state, but not the bearing capacity.When using increasing section combining with external pre-stressingmethod, bearing capacity, stress and deformation performance was greatly improved, itwas to say, this method completely suitable for strengthen Rigid-Framed arch bridge.