钢筋混凝土矩形梁的耐火当量时间研究

钢筋混凝土矩形梁的耐火当量时间研究

摘　要：现行耐火设计方法没有充分考虑实际构件所处的火环境，针对性不强，耐火设计结果不够科学合理。根据性能化耐火设计方法的理念，计算出不同火灾荷载和通风条件下的当量时间是解决这一问题的途径之一。本文利用工程学原理研究钢筋混凝土矩形梁在实际火灾中所需耐火性能，以实际火灾轰燃后的房间热平衡和热传导理论为基础，建立了钢筋混凝土矩形梁在火灾中的温度场和承载力计算模型，利用差分方法进行数值分析，以VB为工具，分别编制计算机程序从而计算出钢筋混凝土矩形梁在实际火灾和标准火灾时的承载力。然后，以承载力等效为原则，求得梁在不同火灾荷载和通风系数下的当量时间，并通过分析数据回归得到当量时间与火灾荷载和通风系数的函数关系式。由此可见，当量时间将标准火与实际火联系起来，利用当量时间的计算公式把各种实际情况下的钢筋混凝土结构耐火设计统一到标准升温条件之下，充分考虑了火灾房间的荷载值，通风条件对构件耐火性的影响，使对钢筋混凝土构件耐火设计更为合理。

关键词　钢筋混凝土矩形梁;　当量时间;　火灾荷载;　通风系数


Study on the Fire Resistant Equivalent Time of
Reinforced Concrete Rectangular Beam

Abstract: The real fire environment has not fully been considered in the current fire-resistant design method which results in short of pertinence and sensitivity. According to the performance fire-resistant design method, the problem can be solved by calculating the equivalent time on practical fire load and ventilation. This paper firstly utilizes the engineering principle to study the required fire-resistant performance of reinforced concrete rectangular beam in the real fire. Based on the theory of thermal balance of compartment post-flashover and heat conduction, the calculating model of temperature field and bearing capacity is established. The program of equivalent time is designed with Visual Basic language, based on equal bearing capacity. Finally, fire load and ventilation coefficient are picked out as the parameters and the function of equivalent time is derived. The equivalent time in practical fire conditions can be calculated. So it makes the fire-resistant design of reinf
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