Study On Weight And Application Of Fire Resistance Factors Of Large-space Single-span Steel Portal Frame Buildings

The large-space steel structure is a kind of important building structure system. Among these, the portal frame structure is representative of light steel structure inland presently, and it is one of the mostly used steel structure system. While, like the other steel structure, the portal frame structure is also have the shortcomings of low strength at high temperature and poor fire-resistant. Thus, the studies of the fire resistance design are of great practical importance. Many researchers have started the studies of the fire resistance of structures and their response under fire.This thesis considered both the temperature of large-space building unprotected steel components in the fire and fire-resistant critical temperatures of steel portal frames, and studied the objective weights of different factors of the fire resistance of large-space single-span portal frame. The major contents are list below:(1) Based on the calculation of air temperature and steel components temperature in large-space building, we analyzed the influence of heat release rate, building volume, cross-section shape coefficient of steel component on the temperature of large-space single-span steel for 2 hours after the fire. And through the dimensionless processing and regression analysis, a fitting formulae relative these factors was also presented.(2)Based on the previous studies on the analysis of the fire-resistant critical temperatures of steel portal frames, we analyzed the influence of Loading Rate, column high and coefficient K on it. And through the dimensionless processing and regression analysis, we got another fitting formula that contain Loading Rate, column high and coefficient K.(3) According the basic thought of the bigger disparity of indexes the bigger weight, use of factors change affect the safety of large space single portal frame differently to reflect the objective weights of factors, analysis the objective weights change with various factors, and used them in specific cases.Under the condition of this paper research, the results show that Loading Rate is the most important factor from the viewpoint of the fire-resistant critical temperatures of steel portal frames, it′s about 0.4 which is the largest among the six factors; The weight of Coefficient K is bigger when it is smaller, and reduces along with own increase. Heat release rate is another important factor from the viewpoint of steel components temperature in the fire. When the building volume, cross-section shape coefficient is small, their weight value is great. The weight decreases rapidly with the increases of either the building volume or cross-section shape coefficient.This study offers a reference for large-space single-span steel portal frame buildings fire risk assessment, and a guide for fire resistance design and fire fighting management.