中文摘要：

结构钢材的韧性随温度降低而下降，其破坏形态也由塑性屈服向脆性断裂转变，构件的承载力也由强度控制变为材料的韧性控制．本文以裂纹尖端张开位移（CTOD）为指标试验研究了钢结构低温断裂行为，并提出了基于CTOD指标的钢结构防脆断设计方法．研究表明，该方法以考虑裂纹扩展而提高部分的最大承载能力作为构件的承载力，引入了温度和厚度对钢材断裂韧性的影响，通过裂纹扩展量的参数使设计方法与试验结果相吻合．

英文摘要：

The toughness of steel decreases as temperature drops, its breakage transfers from plasticity to brittleness and the loading capacity is controlled by the toughness, not the strength. This paper experimented with the fracture behavior of steel structures at low temperature with the criteria of crack tip opening displacement （CTOD）, and proposed a design method for the resistance of fracture for steel structure. This method took the max loading resistance including the increase after the crack extension, considered the influences of temperature and thickness, and introduced the crack extension parameter to coincide the calculation with the experimental results. This design method could be applied in the fracture prevention design and could be used as the basis for further research.