Analysis About The Response Of Gabled Steel Frames During Overall Fire Process Of Heating And Cooling

This paper mainly analyzes the response of plane gabled steel frames and the wholestructure of gabled steel frames during overalll fire process of heating and cooling bynumerical analysis method. According to the results of the analysis, fire-resistant designproposal is proposed.At first, a program considering heterogeneous distribution of large space fire iscomposed for calculating temperature field. Using the program, temperature field of planegabled steel frames during overalll fire process of heating and cooling is studied. According tothe results of the analysis, simplified calculation method for temperature field of plane gabledsteel frames during overalll fire process of heating and cooling is proposed. The results ofanalysis show that: temperature gradient along section height direction of members is tiny, sothat the temperature of cross-section can be replaced by the temperature of cross-sectionshaped heart; the temperature disparity during cross-section shaped heart and atmosphere istiny, so that the temperature of cross-section can be replaced by the temperature ofatmosphere.After that, a program, which considers geometric large deformation, materials nonlinearand heterogeneous distribution of large space fire, is composed for thermal-stress analysis.Using the program, the variation of internal force and deformation of plane gabled steelframes during overalll fire process of heating and cooling is studied. The parametric studyanalysis is carried out to mainly determine the effect of fire location, protection measures,stress ratio, column foot constrain, the growth rate of the fire and the cooling rate of the fire.The results of analysis show that: the reaction of plane gabled steel frames will be greaterwhen fire location is deviated from the center, beam is not protected, stress ratio is greater,column foot constraint is strengthened; the effect coursed by the growth rate of the fire andthe cooling rate of the fire is not significant and temperature of structure plays a decisive role;when fire location is deviated from the center, the extremum of some response of sructureappears during process of heating and cooling; when fire location is in the cente, theextremum of all response of sructure appears at the highset temperature. Finally, a program, which considers geometric large deformation, materials nonlinearand heterogeneous distribution of large space fire, is composed for thermal-stress analysis.Using the program, the variation of deformation of the whole structure of gabled steel framesduring overalll fire process of heating and cooling is studied. The results of analysis show that:out-of-plane deformation of main rigid frame will occur under fire，and out-of-planedeformation will be greater when the main rigid frame is close to the end of the structure.Based on the results of the analysis, fire-resistant design proposal is proposed: theresponse of structure during overalll fire process of heating and cooling is complex and it isdiffcult to calculate exactly, so the concept design must be paid more attention; analysis aboutthe whole structure during overalll fire process of heating and cooling must be carried out andworking condition of different locations must be considered; structural redundancy can bereduced as much as possible; heat insulation measures of steel beam should be strengthened.