18 / 10 外文原文： Research Letter Properties of Reinforced Concrete Steel Rebars Exposed to High Temperatures İlker Bekeel, at high temperature. Both concrete and steel undergo considerable change in their strength, physical properties, and stiffness by the effects of heating, and some of these changes are not recoverable after subsequent cooling [ 18 / 10 1]. It is necessary to have safe, economical, and easily applicable design methods for steel members subjected to fire. However, without fire protection, steel structures may suffer serious damage or even collapse in a fire catastrophe. This is because the mechanical properties of steel deteriorate by heat during fires, and the yield strength of conventional steel at 600°C is less than 1/3 of the specified yield strength at room temperature [2]. Therefore, conventional steels normally require fire-resistant coating to be applied [3]. The temperature increase in the steel member is governed by the principles of heat transfer. Consequently, it must 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 ventilati
