Research Of Bridge Strengthened By High-tensile Bolt

The bridge is the most important spanning structures in the field of road transport and has a very significant position in the modern highway system.It is necessary to strengthen and maintain the bridges timely and effectively which have aged,split and damaged.The typical bridge strengthening approaches are: deck reinforcement layer reinforcement methord,outsouring concrete reinforcement methord,gunite concrete reinforcement methord,paste steel reinforcement methord,paste the carbon fiber reinforcement methord,transforming the structural system reinforcement methord and exteral prestressing reinforcement methord.The paper proposes a new brdige bonded prestressing reinforcement methord applicable to the small&medium span bridge,which combines with increasing section reinforcement methord and exteral prestressing reinforcement methord on the basis of the existing bridge reinforcement methords.This methord is not only simple,but also can ensure the integrity of the structures.Old and new systems can work coordinately, and it has overcome the stress hysteresis of other methods.In addition it can also reduce the structural deflection and crack width, improve the structural carrying capacity,the resistance of cracks significantly and the stress state of the structures effectively.The design idea of this method is as follows: thus the tension of the level linear prestressing tendons(high-tensile bolts) under the beam to realize the application of the exteral reinforcement prestressing,use the anchor for anchorage in the anchor-side,make the use of prestressing provided by the vertical tendons(high-tensile bolts) to press the transmisssion equipment behind the anchors on the beam,transfer the level prestressing to the beam rely on friction between the beam and transmisssion equipment,at last,spray the polymer mortar on the bottom of the beam ,the reinforcement has completed at tins point.The paper mainly covers the research not only on the material , mathord of the tension and layout of the prestressing tendons,but also the anchoring device,performance of the polymer mortar and corrosion of the prestressing system.The paper makes a checking on the normal and oblique section separately on the basis of design specification of highway bridges and culverts. The concrete of the transmission region and the transmisssion equipments are calculated in the context of elasticity.All of these provide the theory foundation for the design.On the basis of the theory, the paper also carried out a destructive load comparative experiment on the beams.In the experiment,the new method which is put forward in the thesis is regarded as the core of the strengthening program,the precast hollow slabs which are very staple in the civilian construction are strengthened for use as the carrier, the precast hollow slabs are strengthened by high-tensile bolts,and the destructive tests are separately carried on the slabs which have been strengthened and not.In the tast,the hogging,destruvtive load value and destructive form are registered under the different load.The outcome of the experiment is indicated that the new mothod is feasible and reasonable.The test concludes that:1. the new mothod is effective and feasible;2. the method have the higher reinforcement efficency and can increase the carrying capacity of the structure apparently;3. the new and old system can work together well and have a good combination;4. the new anchor device is effective and can anchor the prestressing tendon effectively;5. it is feasible to regard the high-tensile bolt as the prestressing tendons.Because the new reinforcement method is never used,so this paper mainly do a research on the applicability ang validity of the new way.In addition,there are still some problems need to resolve:1. the object of the new reinforcement mothod is the upper structure of small&medium span bridge,it is worth of verifying that if it applies to the long&medium span bridge;2. it's need to be confirmed that ultralong high-tensile bolt wtether or not can be produced to meet the needs of the actual reinforcement;3. it is need to opyimize the size of anchoring device;4. the key part of the transmission region is need to have a more accurate counting; 5. the of influence the polymer mortar towards the structure;6. reinforcement system need to be futher optimized and improved.