歐洲建筑防火規(guī)范(introduction_to_eurocode_structural_fire_engineering)(文件)
【正文】 mal analysis: ? both EC3 Part and EC4 Part ? unprotected and protected steel beams Lower and upper flanges Considerably different temperatures proper calculation of temperatures ! Temperature 28 Temperature increase of unprotected steel thVAc1 e tmaa ???? ?Temperature increase in time step ?t: ? ? ? ?? ?4m4rr e e t 27327310x67,5h ???? ? ????Heat flux has 2 parts: Radiation: ? ?mgcc,n eth ??? ??Convection: Steel temperature Steel Fire temperature 29 Section factor Am/V unprotected steel members perimeter c/s area exposed perimeter c/s area h b 2(b+h) c/s area 90% ! 30 Temperature increase of protected steel Steel temperature Steel Protection Fire temperature dp ? Some heat stored in protection layer. VAdcc ppaapp??? ?? Heat stored in protection layer relative to heat stored in steel ? ? ? ? aapp 1et3/11VAcd/ ???????l?? ? ?????????????? Temperature rise of steel in time increment ?t 31 exposed perimeter Total c/s area exposed plate Total c/s area exposed flange Total c/s area Section factor Am/V inherently protected systems 32 Section factor Ap/V protected steel members Steel perimeter steel c/s area h b 2(b+h) c/s area inner perimeter of board steel c/s area 90% ! 。C) 4000 3000 2022 1000 Steel 26 Other concrete thermal properties NC LC NC LC May assume constant value for NC: 1,60 W/ May assume constant value for NC: 1000 J/ cc * Specific heat cc (J/) 400 800 1000 1200 200 600 1000 176。K) 10 20 30 40 50 60 0 200 400 600 800 1000 1200 Temperature (176。C (x 106) Steel ? Steel thermal expansion stops during crystal structrure change in the 700800176。C) 6 5 4 3 2 1 Strain (%) Strength (% of normal) Strain at maximum strength Degradation of concrete strength and stiffness Normalweight Concrete ? Accurate for norm
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鄂ICP備17016276號-1