Experimental Study For The Performance Of Friction High Strength Bolt Connection Nodes Under Eccentric Pull Force In High Temperature

With the wide use of steel structure, as an important way of connection, high strength bolt connection is have been widely used. Although the steel is not burning material, it is not fireproof, high temperature could suffer a sharp cut in its bearing capacity, steel structure fire resistance research in China has made many achievements, but, under the high temperature, the research of high strength bolt connection under eccentric force has almost no effect.This article mainly research on mechanical properties of high strength bolt node by the eccentric force effects under high temperatures, the emphasis was on the modulus of elasticity of high strength bolt steel, high strength bolt pretension change under high temperature and the damage form of bolt connection node, slip load and sliding coefficient, make fitting analysis according to test results.Under high temperature, the intensity and modulus of elasticity will change; therefore, under the high temperature, the determination of the elastic modulus is an important part of steel structure fire resistance design. This is the uniaxial tensile test for20MnTiB steel under different temperature,get the stress-strain relations of20MnTiB and the modulus of elasticity index, and make mathematical fitting, get the change rule of elastic modulus of20MnTiB when the temperature changes.Temperature is one of the most important factors that affects the high strength bolts pretension change, under the high temperature, the stress of high strength bolt easily relaxes, and stress relaxation phenomenon directly leads to the decrease of the bearing capacity of high-strength bolt and slip load of high strength bolt connection node drop down. This experiment was carried out on the high strength bolt node of own design under the high temperature to monitor the strain, concluded the strain change rule, fited the temperature-strain curves and temperature-pretension curve, summarizes the change law of pretension.The mechanical properties of High strength bolt connection at high temperature is important, in this paper, ten groups of high strength bolt connection with eccentric force under the high temperature would take part in the tensile test, studying its failure pattern, slip load and the coefficient of slip resistance. Experiment shows that:with the increase of temperature, the sliding damage of High strength bolt connection nodes become more and more early,slip load and slip displacement of connection node are gradually decreased, and combining with the elasticity modulus of20MnTiB steel and the change of the high strength bolts pretension, concludes that slip coefficient decreases with temperature increasing, too.Finally, the author use ABAQUS to establish finite element model for high strength bolt connection with eccentric force effect in high temperatures, to make simulation analysis and compare with the test results analysis.