土木外文翻譯--高溫下鋼筋混凝土中鋼筋的性能-文庫吧
2025-04-17 14:23 本頁面
【正文】 be recognized that the temperature of the steel member(s) will not usually be the same as the fire temperature in a partment or in the exterior flame steel will experience a much slower temperature rise during a fire exposure than unprotected steel. Also, fire effect on steel member is influenced with its distance from the center of the fire, and if more ventilation occurs near the steel in a fuelcontrolled condition, wherein the ventilation helps to cool the steel by dissipating heat to the surrounding environment [4]. Especially, temperature increase of steel and concrete in posite steelconcrete elements leads to a decrease of mechanical properties such as yield stress, Young39。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 engineering profession to the possibility of connection failure under fire conditions [6]. In this study, S220 and S420 ribbed concrete steel rebars were subjected to 7 different temperatures to determine the high temperature behavior of reinforcement steels. 2. Experimental Study Experimental studies were conducted with 10 and 16?mm in diameter and 200?mm in length S220 and S420 reinforcement steel rebars. Test specimens 19 were subjected to 20, 100, 200, 300, 500, 800, and 950176。C temperatures in a high furnace for 3 hours, respectively. At the end of the curing process, steels were cooled naturally to the room temperature. Subsequently, tensile tests were applied to steel reinforcement rebars. According to EN 100021 tensile strength, yield strength and elongation of the steel rebars were determined for elevated temperatures [7]. The steel specimens tensile strength tests were performed with 60 tons of loading capacity universal tensile strength test machine. The loading speed of the test machine is adjusted according to TS 708 code [8]. 3. Test Results and Evaluations . StressStrain Relations The average values for stressstrain relationship for specimens that were exposed to various temperatures are given in Figures 1 and 2. The curves in Figures 1 and 2 were drawn with the average test results of 10 and 16?mm in diameter steel specimens. The test conditions were meant to simulate a building that had a fire so the changes in the mechanical properties of reinforcing steels used in structures exposed to high temperature could be determined. As seen from Figure 1, temperatures below 500176。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
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