钢-混凝土结合梁试件降温与升温过程的数值计算

根据非稳态导热的控制微分方程,建立了钢-混凝土结合梁试件降温与升温过程的数学模型.将恒热流的三维导热问题视为相应的3个一维导热问题的叠加,并采用有限差分法对控制微分方程进行离散,对钢-混凝土结合梁试件在强迫对流环境下的降温(25～-45 ℃)和自然对流环境下的升温(-45～25 ℃)中的温度分布进行了数值计算.研究结果表明:在降温与升温过程中,钢-混凝土结合梁试件内部各点温度变化速率不相同,导致试件内温度分布不均匀,形成了温度梯度;气温的较大变化会使钢-混凝土结构内部温度分布不均匀,由此产生的温度应力可能会破坏桥梁结构.

Numerical Calculation of Steel-Concrete Composite Beam Specimen in its Temperature Dropping and Rising Process

According to the differential control equations of three-dimensional unsteady thermal conduction, a numerical model was developed for calculating temperature distribution in temperature dropping and rising process of steelconcrete composite beam specimen. A three-dimensional unsteady thermal conduction was treated as three one-dimensional unsteady thermal conductions, and the process of temperature dropping in force convection and temperature rising in natural convection was calculated. The calculation results indicate that different temperature changing velocities of different points cause the temperature not to be distributed well in the specimen, which induce temperature gradients. Great variations of air temperature will make temperature not well distributed in steelconcrete constructions, and temperature stress caused by temperature gradients will make great crevices on bridges.