Study About Detection Technologies Of Vertical Prestressing In Webs Of Prestessed Box Grider Bridge

In recent decades,prestressed concrete continuous box girder bridge (rigid frame)have been developed rapidly for its high stiffness, driving smooth and comfortable, simplemaintenance and mature construction method,easy for engineering unit to master and a seriesof advantages.But among the Bridges which have been built, there are a number ofprestressed concrete box girder bridge produced a series of bridge diseases during the processin construction or in using; among those diseases, the emergence and development ofweb plate inclined cracks in the box girderin is the most common and web inclined cracksdirectly endanger the durability and safety of the bridge. Too much the vertical prestress lossor failure is one of the main reasons which lead tothe crack;So a convenient and effectivedetection methods to control the vertical prestressed reinforcement of effective stress is animportant measures to improve the quality of vertical prestressed tensioning and to preventweb cracking.Based on the vibration testing method to detect th vertical prestressed tensionwhich is the main means of quality control, we have got some research achievements, theresearch work and achievements are as follows:we have programmed and debuged the relatedalgorithm.First, based on the concept of contact stiffness and contact stress which is proportionalto the separation,established a variety of analytical models to compare the sensitivity of thetilt angle of the anchor plate.In some indoor models and site calibration experiments, wefound varying degrees of inclination anchor plate affect the value of the coefficient K.processing inclination of0°,1°,2°,3°,4°five kinds of anchor plates to quantitativelydetermine the degree of influence on the inclination of the K value by indoor trials, proposeda method to amend the tilt angle of the anchor plate.Secondly, by study test method ofcharacteristics and tensile force coefficient curve，provided a theoretical basis for calculationof the effect of calibration tests tendons;verify calibration reliability and stability of the testmethod by indoor model test. Finally，we have used vertical tendons tensile force vibrationtesting method to test multiple bridges vertical tendons tensile force, and we got quantitativeassessment of data which can reflected vertical tensioned prestressed qualitystatus,effectively eliminating the human factor, the retest data show that the quality havebeen significantly improved and vertified the reliability of vibration testing methods.Developed the corresponding detection process and eligibility criteria in order to effectivelyguarantee the quality tensioning tendons.