升降温全过程混凝土梁截面抗弯承载力分析

为解释升降温全过程中约束混凝土梁在较大的梁端弯矩作用下而没有发生明显破坏的现象,使用FORTRAN语言自编程序考察了混凝土梁截面抗弯承载力的变化情况.结果表明:(1)轴向约束产生的轴压力使梁截面抗弯承载力有一定程度的提高;(2)单调升温时,随着时间的增加,N-M包络图逐渐内缩,且前期内缩较快随后逐渐减缓,而截面N-M曲线的不对称性越来越明显;(3)对于升降温全过程的情况,降温阶段N-M曲线内缩速率逐渐减缓,降温一段时间后N-M曲线趋于稳定和对称.

Sectional Bending Capacity of Restrained RC beams during Heating and Cooling Phases

In order to explain the phenomenon that restrained RC beams subjected to large bending moment do not fail significantly during heating and cooling phases, sectional bending capacity of restrained beams is studied, using the program developed employing FORTRAN. Simulation results show that: (a) bending capacity of RC beams is improved under the axial force generated by axial restraint; (b) with time increasing, N-M envelop diagrams of beams exposed to fire without cooling phase, reduce inward gradually, and especially rapidly in early period, and become more asymmetric; (c) After a period of cooling, N-M envelop diagrams of beams exposed to fire with cooling phase tend to be stable and symmetric.