1用什么方法确定达到的强度等级与否评判是否达到设计要求的强度等级,首先要明确用什么来确定达到的强度等级。是用强度标准值,还是用强度平均值。GB 50010—2002《混凝土结构设计规范》规定:“混凝土强度等级按立方体抗压强度标准值确定”。如现场抽取或试验室试验实测得试件强度平均值f_μ=37.0MPa,预估得强度标准差σ=5.0MPa,则估计该批混凝土强度标准值f_(cu,k)=37.0-1.645 5.0=28.8MPa,于是估计该批混凝土的强度等级为C25。(强度标准值多用f_k代表,f_(cu,k)代表立方体强度标准值) 1 What method should be used to determine the strength level reached or not? Whether the design meets the strength level of the design requirements, we must first specify what level of strength to achieve. Is the strength of the standard value, or the strength of the average. GB 50010-2002 “Code for Design of Concrete Structures” stipulates: “The concrete strength grade is determined according to the cubage compressive strength standard value”. For example, the average value of the strength of the test piece measured on site or in the laboratory test is f_μ = 37.0MPa and the standard deviation of the expected strength σ = 5.0MPa, then the standard value of the concrete strength f_ (cu, k) = 37.0-1.645 5.0 = 28.8MPa, so the strength of the batch of concrete is estimated to be C25. (Intensity standard f_k multi-purpose representatives, f_ (cu, k) represents the cube strength standard value)