Study On Prestress Control Of Simply Supported Girder Bridge

Since 1978,China's road transport infrastructure construction developed rapidly with each passing day,the overall level of which increased rapidly,during which a large number of new simply supported girder bridges were build.With the wide application of this type of bridge,many bridge diseases have been produced,which has caused huge losses.Among these diseases,the girder's subsidence is one of the most important and serious problems,and and the continuous prestress loss is the main cause.In order to reduce the prestress loss in the girder bridge and achieve the purpose of improving it's durability,safety and reliability.This paper,based on the existing engineering experience,takes the girder of the assembled simple girder bridge as the research object,Based on the finite element software simulation,the influence of various factors on the prestress loss is studied in the production process of the prefabricated girder field.The following conclusions are obtained:Based on the existing engineering experience,this paper analyzes the consideration of prestress loss in engineering specification,and finds out that the control of prestress under the condition of intelligent tensioning process is mainly to control the prestress loss.Aiming at the typical 30 m T girder in the production process,the prestressed tendons and the channel friction,the prestressing tendons retracting and retracting the anchor deformation and the joint compression,the prestressing tendons and the prestressing tendons,the elastic modulus ratio of concrete,the relaxation coefficient of prestressed tendons,and the age of concrete loading on the prestress loss are studied by means of orthogonal experiment design and Midas software simulation.Based on the data analysis of 16 kinds of prestress losses,it is found that the most important factor affecting the prestres loss is the friction between the prestressing tendons and the tunnel during,then the production of the prefabricated girder,followed by the concrete loading age,The relaxation coefficient of the prestressed tendons is followed by the ratio of the prestressing tendons to the elastic modulus of the concrete.The least is the prestressing tendons retracting and retracting the anchors and the compressions of the joints,The optimal combination of these five factors to the prestress loss is given when the effect is minimal.According to the principle of main control and secondary factors,the application of analysis results in engineering practice is discussed.The design of the best level combination of engineering design ideas were given,the first friction test were carried out to control the main factors,and then consider the secondary factors of the auxiliary control,and finally do anchor under the prestress test to determine the true loss of the control of the situation program.