| In recent years,with the continuous improvement of transportation capacity in China,the problems such as insufficient bearing capacity of bridges have become increasingly serious,so effective reinforcement of damaged bridges has become a top priority.Carbon fiber material is widely used in bridge reinforcement technology because of its advantages of light weight,high elasticity and good corrosion resistance.The method of reinforcing damaged bridges with prestressed carbon fiber material has been applied more and more.This method needs to install tensioning and anchoring equipment of carbon fiber material on the construction site,which is the most important factor affecting the reinforcement efficiency of prestressed carbon fiber material.Nowadays,the research content of tension and anchorage system of carbon fiber materials at home and abroad is getting deeper and deeper.According to the anchoring principle of the anchoring system and considering the convenience of construction,this paper puts forward a new type of clamping prestressed carbon fiber cloth tension anchoring system,and studies its stress characteristics and anchoring stability.The main results are as follows:First of all,by analyzing the shortcomings of the existing tension and anchorage systems at home and abroad,summarizing the causes of prestress loss,and combining with the existing anchorage systems,a new clamp-type tension and anchorage system for carbon fiber cloth is proposed,which includes the winding shaft,clamp system,fixing plate and other components.The anchoring principle and self-locking ability of the system are verified by differential method,and the angle range of inclined section of fixture is determined by functional relationship.It is obtained that the tension anchoring system can achieve the self-locking purpose of carbon fiber sheet under the action of external force under the tight pressure of 93.3 k N.The stability of the system under the action of external force is verified by the calculation method of the current code on shear and tension of anchor bolt,and the construction procedure of the new tension anchoring system is given.Secondly,the finite element analysis software ABAQUS is used to analyze the thickness of the tension anchorage system and the stress of the clamp under different inclination angles.Under the premise of considering the mechanical properties,manufacturing errors and installation convenience of the system,it is concluded that the mechanical properties of the system are the best when the thickness of the fixing plate is 30 mm and the inclination angle of the clamp is 5.Static simulation was carried out to analyze the mechanical properties and verify the stability of the system.The results show that the greater the prestress applied by the system,the closer the connection between the winding shaft and the fixture,the stronger the self-locking ability of the system,and the uniform stress of the carbon fiber cloth in the fixture will not occur.By studying the law of anchor bolt stress changing with depth,it is concluded that the best anchoring depth of anchor end should be 110 mm and the best anchoring depth of tension end should be 120 mm under the maximum design tension of the system.At last,by analyzing the deformation of the system under different tensile forces and drawing the deformation-displacement curve,it is concluded that the deformation of the system under external forces is almost linear with the increase of external forces.Under the tensile forces of 114 k N,170 k N and 227 k N respectively,the deformation of the system is1.773 mm,2.447 mm and 3.254 mm,which is very small,which is about 20% less than that of the traditional anchoring system.To sum up,the new clamp tension and anchorage system proposed in this paper has the advantages of good mechanical properties and convenient construction,which can provide mechanical basis for carbon fiber cloth to play a better role in reinforcement engineering. |
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