The Research Of Influnce Of Construction Site On Thick Steel Plate Welding Stress

In the quality control of practical engineering, quality defects will aroused if the influence elements at construction field. It is most important in welding technology and quality management of steel structure that analyzing the affecting factors in construction field, formulating effective measures of welding technology, ensuring welding quality being up to specification. The environment of construction field plays an important role in welding quality of steel structure, so it should be given enough concern in order to avoid harm it could be lead to. There is instability in the environment of construction field, and structure material an component joint structure also changes. It is in qualitative analysis stage for all kinds of influence factors of welding defect. At the present time it is still using test combining engineer experience to research effective measures for preventing and eliminating various welding defects. Therefore, it is necessary for engineers and technicians to innovate continuously and perfect gradually in the method research for welding technology parameters, quality control and safety protection under specific construction environment.With the development of technology of steel structure, thick plate is used more and more in steel structure bridge. Although stiffness of thick plate is large, residual stress is easily to generate in the process of welding, which seriously affecting the performance of structure. At present, there are not much scientific research achievements on thick plate welding, all these that the size,the distribution and the cause of residual stress need further study.This paper is based on the welding research subject of a super-large in Daning, Chongqing. In this paper, analog simulation of welding line of bridge structure and heat affected zone is put forward by using finite software MSC.Marc2005, various of boundary conditions and the influence elements is also loaded. The influence degree to the residual stress of welding line is especially analyzed according to environment feature at construction site. Then the influence degree of some influence elements (such as air temperature, humidity, wind and so on) to the welding stress is draw from the analysis. According to the conclusion, the influence of temperature is most important, the consequences is most serious, and it is most difficult to control, then humidity comes second .The influence of wind can be control in local microenvironment by useful methods. The research result of this paper offers reliable references for quality control of construction welding. According to the feature and welding difficulties of steel structure, environment characteristics of steel structure construction field in the new period, welding quality defects caused by environment of construction field are analyzed in this paper, corresponding safeguard is also put forward, which provides certain reference value for constructors in steel structure welding. Then the method of welding residual stress test and effective measures to minimize or eliminate residual stress is proposed according to the construction condition of project field, in order to ensure the safety of the bridge structure.