火灾后钢筋混凝土损伤程度的灰关联分析

由于火灾对钢筋混凝土结构的影响存在不确定性,使得人们不能准确地确定火灾后钢筋混凝土结构的损伤程度,给评估和加固修复带来很大困难。本文运用灰色系统理论中灰关联分析数学模型定量分析了高温下钢筋混凝土梁的3种影响因素,并确定了各因素间的主次关系,为高温后钢筋混凝土结构的安全评估及修复加固提供了理论依据。

Analysis for Damage Degree of Reinforced Concrete after Firing Based on Grey Degree of Incidence

Three factors influence reinforced concrete beams after firing are analyzed, and primary and secondary relations between these factors are determined using the mathematical model of in grey degree of incidence in grey theory, which provides a theoretical basis for evaluation of the safety of the reinforced concrete after firing. Damage degree of reinforced concrete structures after firing is difficult to be determined accurately because the influence of fire on the reinforced concrete structures can not be precisely evaluated. This paper attempts to find out the most important factors influencing the development of the system and grasps the primary character through the comparison of many factors and the analyses of their relative orders. In this paper, the relevant factors of the damage degree of reinforced concrete structures after firing have been put in order through calculation of related degree between "mother" factors (surplus bearing capacity) and "children" factors (ultimate temperture, primary loads, and firing time). The primary load has a primary influence on the residual bearing capacity of the reinforced concrete members, the ultimate temperture is the secondary and the firing time is the last. The analysis in this paper argue that the influence of the primary loads is the most important factor due to Load Induced Thermal Strain(LITS). Concrete structures will be cracked by LITS. Meanwhile, damage of concrete members could not be restored when ultimate temperate exceeds 600°C and has a significant influence on residual bearing capacity. It is shown that the theory of grey degree of incidence is worth to be applied in finding out the primary and secondary relations among many factors due to its simple calculation.