Research On Under-Anchor Effective Prestress Measurement And Control Indices Based On The Reliability Theory

With the scientific progress,the bridge engineering is rapid development,and prestressed concrete bridge is occupying a very large proportion in bridge engineering.Some of the prestressed concrete bridges in the operation of a few years have had emergence various diseases.Such as beam deflection,cracking.Reason can be attributed to the design,construction,maintenance and other aspects of conservation.The traditional prestressed tension construction process is extensive,and the control index is lacking,and the index standard value is unreasonable,etc.,,which as the main reason for prestressed concrete bridge disease,after the prestressed tension is anchoring,leading to the anchor pre-stress is difficult to achieve the specifications and design documents expected to be buried,poor uniformity,lately prestress loss is too large and other hidden dangers.Therefore,for the prestressed beam tension and monitoring of the construction process has been continuously improved.From the beginning of the manual operation of hydraulic jack tension,to the semi-automatic and intelligent tension system in recent years,the various aspects of the prestress tension were improved,including equipment,process,control method.So the current norms in accordance with the early tension experience and the old measured data,which are selected the anchor effective prestress measurement and control indicators,are gradually failed to apply in modernization prestressed bridge engineering.Therefore,according to the modernization prestressed bridge construction technology,based on reliability theory and prestress Loss effect of effective prestressed of the the same beam uniformity,And based on the principle of prestress loss control and convenient application of construction,the standard value of the anchor effective pre-stress measurement and control index is used to detect and guide the pre-stress fine construction.And it is important to analyze the stress distribution of the anchor prestressed tendons.And this has a very important engineering application value and theoretical significance.This index should include the anchor effective prestressed size,control accuracy,and the unevenness of the same beam and the some section.The prestressed bridge with a tensile stress of 0.75 fpk is designed,which is commonly used on bridges,and the effective prestressing data are measured andanalyzed according to the length of steel beam.Based on the theory of reliability,the index of prestressed bridge is studied by reliability theory,which including the anchor effective prestress standard value,control precision,unevenness of the some beam and the standard value of the same section.The calculate method of the same beam and the same section unevenness in the construction field has been modified.In addition,the construction monitoring and control technology of the anchor effective prestressed has been briefly introduced,which is in the background of pre-stress fine construction.Including the unevenness of the same beam and the same section control method.Such as finely combing the beam and the extracorporetic cable in vitro suspension tension,synchronous symmetry tension and other construction technology,which ensures the accuracy of anchors effective prestressed tension,and introduces the application of monitoring and control indicators standard.