Study On The Common Defects And Reinforcement Technique Of The Widen Prefabricated Bridge

With the development of our national economy and sharply increase of highway traffic, some main freeway can not meet the traffic requirements, and need be broadened. Of the prefabricated slabs of the bridge with longitudinal cracks in one or two years, reinforced concrete slabs take up 18%, prestressed concrete slabs 64%, among which capping beam of the abutments with vertical cracks account for 59%, and the abutments with vertical cracks 65.8%. Studying on the causes of the broaden bridge diseases is important to maintain and reinforce the prefabricated bridge, which can be guidance to the design and construction of broaden bridge.This paper makes an introduction of the bridge broaden ways, gives an evaluation method about the broaden effectiveness, and summarizes long-term effect analysis for built-up bridge. And this paper reseaches the lateral force in the prefabricated slabs with the hinged panels beam method, analyzes the relationship between the lateral force and automobile load, and bridge spans, and the width of the bridge; studied the additional stress in the abutment foundation with the subgrade self-weight load, puts forward a calculation method to uneven settlement of pile foundation in the widen bridge.Then through the finite element analysis, this paper researches the causes of longitudinal cracksin the prestressed concrete slabs with 20 meters long, analyzes the stress changes in the slabs on the condition of the normal supports or one pedestal out of work, and the condition of the load with slab self-weight, prestressed load, or automobile wheel load; studies the abutment vertical cracks, analyzes the stress changes in the abutment with the load of the upper structure weight, driveway load on the deck, foundation displacement load and soil pressure behind the abutment.At last, the maintenance and reinforcement mothods for the longitudinal cracks of hollow slab bridges, coping of bridge abutments and vertical cracks of thin-walled abutments are put forward, which have been applied in the projects. The well effects have been obtained which indicated that the methods worth to be popularized.