Analysis Of Loss And Effect Of Long Beam Prestress Along Long Path Of T-shaped Rigid Frame Bridge With Large Span

Prestressed concrete structure is widely used in bridge construction because of its unique advantages.The prestress is a very important link in the bridge structure which can not only change the mechanical performance of the structure but also control the linear structure.However,the prestress effect in the structure can be lost due to the construction quality,material properties and some uncontrollable factors,which will lead to the reduction of the prestressing force of the steel beam and have effect on the structure.There are many factors causing the loss of prestress,and there are six main factors that cause the prestress loss according to a large number of experiments and practical research performed by scholars and experts at home and abroad.In order to study the law of prestress loss effect of structure,it is possible to study each loss separately and analyze the stress state of steel beam under each loss along the length direction of steel beam.This study can get not only the regularity of each loss but also the influence factor on the loss.In the actual construction process of prestressed concrete structure,the prestress loss can not be exactly calculated due to the uncertain factors which only can get its estimated value through a certain scientific research methods.In order to study the effect of prestress in the structure that actually works,it is very important to explore the actual stress value of prestressed steel beam.Thus the error analysis of theoretical estimate value and actual stress value is of great research significance.In particular,as the span of the bridge increases,the position of the prestressed pipe and its actual deviation coefficient may be in great discrepancy with the coefficient of the theory,which will make the calculation of the long bundle of steel beam stress different from the actual value,and then distort the result of the structure,so for the Long-span prestressed concrete bridge There is a certain research significance for this error analysis.The main research contents of this paper are as follows:First,introduce and expound the development process of the theory of prestress loss research at home and abroad;Secondly,the theoretical estimating formula of each prestress loss is deduced,then the stress curve of the corresponding steel bundle along the length direction is calculated by means of the structure finite element software,and the main influencing factors are found by the stress curves.Third,depending on the actual project case,combined with the constructionconditions of the site to carry out some related stress detection,testing items include:the effective stress detection under the anchor,pipe grouting density detection,along-path stress detection(through the strain gage and then the conversion of the stress value).The theoretical value is corrected by the error analysis of the theoretical value and the measured value.Fourth,the revised theoretical value and the outstanding theoretical values are brought into the software for analysis,and then comparative study of the structure of the effects of the effects such as displacement and stress,and error analysis.