土木外文翻譯--高溫下鋼筋混凝土中鋼筋的性能-文庫(kù)吧資料
2025-05-22 14:23本頁(yè)面
【正文】 are lower than the design strengths of these steels. Consequently, the remaining strength of the steel rebars in structures is influenced with the exposure time and type of fire depending on the heat transfer through concrete cover to steel parts [10]. Figure 4: Tensile strength of steel rebars against temperature. . Elongation The relation between high temperature and splitting elongation ratio can be seen from Figure 5. The figure is demonstrated that both steel rebars show a same elongation behavior under elevated temperatures. The elongation ratios of S220 steel rebars are higher than S420 rebars depending on the ductile fracture behavior of this steel. After a fire inside the reinforced concrete building, the deflections of the structural members increase with the ductile behavior of the steel reinforcement at high temperatures. 21 Figure 5: Elongation ratios of steel rebars against temperature. The elongation ratios were slightly increased up to 300176。C exposure temperature, respectively. For the highest exposure temperature at 950176。C, yield strength decreases were 64% and 89%, respectively. According to these results, the remaining yield strength of S220 steel reinforcing rebar is higher than S420ribbed steel rebar after hightemperature exposure. Figure 3: Yield strength of steel rebars against temperature. . Tensile Strength The tensile strength variation of steel reinforcement rebars exposed to elevated temperatures is given in Figure 4. On the light of these results, there was no significance reducing of tensile strength for both types of steel rebars up to 500176。C there is no 20 decrease in yield strength, but after this temperature a significant yield strength loss occurs [9]. The yield strength losses of both S220 and S420 steel rebars were 46% and 84% for 800176。C. Figure 1: Stressstrain curve of S220 steel rebar. Figure 2: Stressstrain curve of S420ribbed steel rebar. . Yield Strength Yield strength of both reinforcing steel rebars was affected with the elevated exposure temperatures. It can be concluded from Figure 3 that there is no variation in yield strength of reinforcing steels with cover up to 300176。C have no significant effect on mechanical properties of preheated and cooled S220 steel rebars. The yield strength and splitting tensile strengths of S220 steels were similar up to this temperature. However, the yield strength and splitting tensile strength of the S220 steel rebars are reducing with the increase of temperatures over 800176。s modulus, and ultimate pressive strength of concrete [5]. Thus, load bearing of steel decreases when steel or posite structure is subjected to a fire action. If the duration and the intensity of the fire are large enough, the load bearing resistance can fall to the level of the applied load resulting in the collapse of the structure. However, the failure of the World Trade Centre on 11th September 2020 and, in particular, of building WTC7 alerted the engin
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