Abstract: Aiming at the problem that pre-cast beam generated cracks in course of laying aside it，the mechanics knowledge Was utilized to deduce the formula，and the tensile stress under different descending value of temperature Was calculated according to the engineering，and the finite element software ANSYS Was used to verify the formula.The conclusion Was put forward that if the bearings of pre-cast beam were incorrectly installed when it Was laid aside，and the sudden descending of temperature may result in cracks ，then the corresponding avoidance measure was suggested .

Key words: pre-cast beam, crack, temperature, bearing

摘要： 针对预制梁存放时开裂的问题，运用力学知识推导公式，结合工程实例计算下降不同温度时产生的拉应力大 小，并运用有限元软件ANSYS分析验证，指出预制梁存放时支承处理不当，温度骤降是导致梁体开裂的原因，并提出 了处理意见．

关键词: 预制梁, 裂缝, 温度, 支承