Research On Ultimate Capacity Of High-strength Bolt Connection Of Steel Structure At High-temperature

The application of steel structures becomes increasingly more with fast development of our national economy and increasing of steel product quantity. However, considering that steal structure has the character of non-resistance fire, so it is necessary to make a research of mechanical property and bearing capacity of the whole structure, components, connections and material at high temperatures. High-strength bolt connection is a kind of connecting methods of the steel structure which is applied widely, and connection property of the steel structure has an important influence on working property of the whole steel structures. Once connection is damaged, the whole working property of structure would be affected, and even completely lose bearing capacity. So property of high-strength bolt connection of steel structures at high temperatures is an important part of researches against fire of steel structures. Because mechanical character and failure mechanism of high-strength bolt connection at high temperatures is very complex, and by now research in this field is not much throughout and outside the country.The influence of high temperatures on the mechanical property of steel materials, components and structure is summarized and current research of high-strength bolted connection both abroad and domestic in recent years is introduced in this paper. Basing on results of experiments of high-strength bolted tension and shear limit capacities at high temperatures, three dimensional solid finite element model is set up and non-linear analysis of finite element method is done on high-strength bolted tension and shear ultimate capacities of at high temperatures by adopting ANSYS software. Limit capacities of high-strength bolted connection are gained at different temperatures and the validity of the finite element model is verified by good agreement between the analytical and test results. And simulation formula of limit capacities is presented according to numerical calculation data that can provide some references for design against fire of high-strength bolted connection.At the same time, mechanical property and destruction mechanism of high-strength bolted connection is analyzed by calculation results completely inthis paper, the relationship between losing factor of prestressing force and temperature is gained and conclusion is drawn that the main reason why slip load of high-strength bolted connection against shear reduces results from losing of friction factor and prestressing force at high temperatures.The research work in this paper possesses certain practical value. The analysis results could provide references and basis for congener research and amendment of steel structure code in future.