Investigation Of Overall Buckling Behavior Of High Performance Fire-resistance Steel Welded I-section Columns At Elevated Temperatures

With the development of economy and society as well as the concentration of urban population,the possibility and damage of fires in buildings become bigger and bigger.As a kind of construction material,steel has amounts of advantages such as high strength and light deadweight.However,due to the poor performance at elevated temperatures,the investigation of fire resistance of steel is of great significance for the steel structures design.The mechanical properties of WGJ high-performance fire-resistance steel,developed and manufactured by Wuhan Iron and Steel(Group)Company,at ambient and elevated temperatures were investigated in this paper.What's more,the overall buckling behavior of welded I-section columns at ambient and elevated temperatures(includ ing small space fires and large space fires)was also investigated and corresponding design methods were proposed.The main work of this paper includes following aspects:(1)The standard static tensile tests of WGJ high-performance fire-resistance steel were conducted at ambient and elevated temperatures.The mechanical properties including initial elastic module,yield strength and tensile strength at differe nt temperatures were acquired.Besides,the reduction factors of mechanical properties and stress-strain curves at ambient and elevated temperatures were also shown in this paper and compared with suggested values of different design standards as well as experimenta l results of other papers.(2)On the basis of overall buckling tests results of 7 welded I-section columns at ambient temperature,the accurate finite element models were established.By using the verified finite element models,the influence of initial imperfection,welded residul stress and constitutive models to the overall buckling behavior of columns at ambient temperature was investigated.According to the numerial calculation results,the design method of Chinese standard was modified and new design curve was proposed.Comparision show that modified design curve matched well with the numerial calculat io n results,which means the modified design curve could be appiled in the design of overall buckling behavior of columns at ambient temperature.(3)12 welded I-section columns with different slenderness ratios and steady load raios were axial y compressed at elevated temperatures and the buckling modes as well as critical temperatures were investigated.(4)Finite element models of axial-compressed columns at elevated temperatures were established.The test results of this paper and other reference papers were used to verify the accuracy and reliability of these finite element models.By using the verified finite element models,the influence of cross-section,slenderness ratio,steady load ratio,initial imperfection,welded residul stress and constitutive model to the overall buckling behavior of columns at elevated temperatures was investigated.(5)On the basis of the numerial calculation results,design methods of overall buckling behavior of welded I-section columns at elevated temperatures,including small space fires and large space fires,were proposed.Comparision show that design results matched well with the numerial calculation results,which means the proposed design methods could be appiled in the design of overall buckling behavior of columns at elevated temperatures.