多轴强度安全系数的定义及应用

针对基于古典强度理论的传统安全系数定义不能确切地表示材料在多轴应力状态下的安全度，也很难直接应用于一般的多参数强度准则的问题，引入失效距离的概念，给出了多轴强度安全系数的定义及其计算方法。以混凝土材料为例，选择常用的5种强度准则，分别给出了多轴强度安全系数的计算公式。选取3组较为典型的应力组合，分别计算了5种强度准则对应的多轴强度安全系数，所反映的混凝土材料强度状态与三轴试验结果相当吻合。结果表明，所定义的多轴强度安全系数有利于改变现行设计准则中经常采用单轴强度安全系数的习惯，为更加科学合理地进行结构强度设计和校核提供了有效的工具。

Definition and Application of Safety Factor for Multiaxial Strength

The conventional safety factor based on classical strength theory could not exactly express the safety for materials in multiaxial stress states, and it was difficult to apply the general multi-parameter strength criteria directly. The definition and calculation method of the safety factors for multiaxial strength were proposed by using the concept of failure distance, which was applicable in any stress state and multi-parameter strength criteria. Taking concrete materials as an example, 5 common strength criteria were selected, and the calculation formulae of the safety factors for these criteria were discussed, and the safety factors of concrete in 3 types of stress state were computed for each criterion. The numerical examples for concrete show that the states of strength described by the safety factor proposed agree with the results of triaxial test. The results indicate that the safety factor for multiaxial strength has advantage of changing present design criterion which is used to apply the safety factor for uniaxial strength, so as to provide more reasonable and scientific tools for strength design of structures.