Experimental Study Of Small Radius Curve Bridge Space Prestressed Friction

With the rapid development of our country highway and city road, overhead road and interchange project in more and more. Curve prestressed concrete girder bridge because of its can well adapt to the terrain restrictions on bridge site, reduce the project cost, satisfy the route overall linear continuity and urban landscaping design requirements and is becoming more and more widely used. For prestressed concrete bridge structure, design and tensioned prestressed construction technology is directly related to the stress of bridge structure under the operating state and the durability of the structure. Therefore, study on a large number of scholars at home and abroad. At present, in tensioning of prestressed concrete components control mainly adopts two-way control of stress effect, namely the tensioning stress control and zhang stretch long volume control. But in engineering practice, the prestressed ShiJiaShi double charged with tension control stress and elongation are stipulated in the specification of data access is larger, mainly is the actual hole and hole deviation coefficient of friction coefficient with the data given by specification, the deflection formula specification of parameters selection can better reflect the actual project in the process of the tensioning of the prestressing tendons prestressed friction loss and the size of the elongation.In the code for this topic from the highway prestressed friction loss formula, by relying on the project for prestressed friction test and the test beam bell test, research and analyze the data from the new formula is derived, coefficient and coefficient of curvature increases the material, the friction loss for a variety of small radius curve bridge prestressed method calculation have been compared with the actual measured value, the main research contents are as follows:Small radius curve bridge prestressed loss theory research. In the tensioning process, the loss of prestress content five:loss of pipe friction stress, anchorage deformation reinforced retraction and joint loss of compressive stress, the stress loss caused by elastic compression of concrete, steel bar and concrete shrinkage and creep relaxation caused by loss caused by stress. Test content: prestressed friction loss experiment research, bell prestress losses in the main, long-term loss of prestress with the study. Based on damage theory foundation, introduced the many kinds of method for prestress losses, which focuses on the loss of prestress of multi-span continuous beam is calculated.Research of prestressed stretching long. Prestressed reinforcement in prestressed tension before and after process, respectively in four kinds of condition, the tensile process is divided into three stages, at different stages of tensioning prestressed reinforced in a different state. Small radius curve bridge tensioning prestressed reinforcing steel bar in each stage of the elongation to some extent, the influence of subject three factors of affecting the prestressed elongation was studied.Relying on the construction of prestressed friction loss determination and analysis of data. According to the practical engineering situation, according to the test scheme of friction loss experiment, bell loss test and long-term loss test, the test data are collected. Using the standard formula calculates the testing friction coefficient and deviation coefficient of the beam. Calculates the parameter with the given parameter specification were analyzed, calculated parameters significantly larger.Formula derivation and analysis of parameter selection. Small radius curve bridge prestressed reinforcement is a long beam angles, friction loss and the length of the prestressed reinforcement and prestressed Angle all have relations, in the process of derivation, found between curvature and deviation coefficient, the relationship between material and friction coefficient.In the new formula is derived, increase the curvature coefficient and coefficient of materials used for deviation correction coefficient and friction coefficient, and compares the value of each specification parameter analysis, discuss the values of parameters in the new formula is derived.Loss of prestressed calculation method of the simulation analysis and multiple comparison analysis of calculation results. Apply Dr Bridge finite element software, based on a project for the actual simulation of the prestressed friction loss data extracted from the model and tensile length measured data, and comparing the measured values; On method for calculating friction loss using a variety of prestressed prestressed reinforcement fixed end effective prestressing force calculation in the process of the tension and the calculation of friction loss, compare the calculated value of each method analysis, verify the reliability of the new formula is derived.