Research On Fatigue Design Parameter And Structural Details For Orthotropic Deck

Orthotropic deck as a structure style, its fatigue issues have been the key points and research focus in the bridge construction since its putting into use, scholars across the world have conducted researches on the problems arising in operating process and made a series of research results. These results have effectively solved some of the problems of deck, which are really worthy to learn and use. From the end of the century to now, large-span steel bridges are built in a large scale in China, in terms of the orthotropic deck, it is still in the process of problem-emerging and problem-solving, so we need to find problems continuously, fully incorporate the foreign research results and conduct systematic researches on the fatigue of deck according to the conditions in China.In this paper, the fatigue issues of orthotropic deck are studied with the bridge deck design parameters and construction details as the main line, and from the aspects of the fatigue properties, fatigue loads, design parameters optimization and anti-fatigue design methods of the load bearing conditions and structure details, and through analysis of relevant standards and literature, carrying out real bridge test, full scale model test, structure details test, analog simulation analysis and a combination of theoretical analysis.The main research results are as follows:â‘ fatigue tests are carried out on the fillet weld between deck and longitudinal rib web, arc-shaped opening of diaphragm, the embedding section of rib, the fatigue resistances of various structural details are slightly higher than Eurocode3 and Japanese standards. In terms of the variable thickness butt welding structures between the bolted position of the main truss chord cover and the deck, the pre-stretch element, target element and contact element analogy high-strength bolts are used to connect the friction surface, which realizes the finite element analysis of the stress of mixed joints of bolt and welding for the first time.â‘¡Carry out contrast analysis of the related researches on fatigue loads by various countries, and determine standard fatigue truck model, impact factor for the bridge deck fatigue checking calculation and predict traffic flow in accordance with the situation of China.â‘¢Make analysis of the calculation results of the finite element model of nine kinds of bridge decks, when the thickness of the panel is selected between 14 ~ 16 mm, rib thickness is 8 mm, diaphragm thickness is 12 mm, the appropriate diaphragm arc shaped opening shape is studied and determined.â‘£Through the proposed life circle design of deck fatigue resistance, the fraction is introduced to be as the parameter for fatigue resistance equation of structure detail, which reflects the thinking of the life circle design.There are innovations in this paper:â‘ In terms of the variable thickness butt welding structure between the bolted position of the main truss chord cover and the deck, the pre-stretch element, target element and contact element analogy high-strength bolts are used to connect the friction surface, which realizes the finite element analysis of the mixed joints of bolt-welding for the first time, which firstly realizes the finite element analysis of the stress of mixed joints of bolt-welding, its calculation results are basically consistent with measured values. The finite element analysis of the stress of bolt-welding joints provides efficient method for studies on the mixed structure details of bolt-welding.â‘¡Bring forward the life circle design method of deck fatigue resistance, and the fraction is introduced to be as the parameter for fatigue resistance equation of structure details, which reflects the thinking of the life circle design. The importance, replacement circle and cost for replacement and other factors of the various structure details of deck are taken into consideration, which divides the study of the paper into two categories, fatigue equations with different fractions are used for the different structure category, consequently achieve life circle design.