Analysis On Partial Safety Factor Of The Loads Basic Combination Of Small And Medium Span Bridges

Since the study for reliability of highway works were carried out in 1988, after nearly 20 years of change and development, a number of important factors influencing highway bridges load models, such as the proportion of vehicle models, load capacity, traffic flow have changed a lot. Correspondingly, the statistical parameter of vehicle load effect is bound to change. These statistical parameters have significant impacts on the reliability index of structure. Therefore, on the basis of statistical data of existing vehicles, it is necessary to carry out new vehicle load effect partial safety factors research.As an important part of the western transport projects (2008 318 494 04) "Study of bridge designing load and security experiment load ", This paper takes the short and medium span bridges as examples to evaluate position of Chinese load effect partial safety factors and their combination effect,then researches calculation methods of the partial safety factors. First,to get the new partial safety factors of vehicle load effects, this paper conducted a survey of the short and medium span bridges,distinguished the similarities and differences between the standard in highway bridges from different countries,and confirmed the reasonable position of Chinese standard in the world. Then,based on the actual traffic flow statistical analysis, this paper obtained the new statistical parameters, proposed four methods to calculate the partial safety factors vehicle loads effect of highway bridges.These method included linde 0.75 linear separation method, normal linear separation method, the least square of resistance method and the least square of reliability index method, followed by the comparison of their results. Based on the above work, this paper finaly studied the coefficient for importantance of structure with calibration method.The methods and conclusions can give reference to revision of code.