由四点弯曲试件确定混凝土的断裂与强度参数

Determination of fracture toughness and tensile strength of concrete using four-point-bending specimens

提出了采用四点弯曲试件确定混凝土的断裂参数与强度参数的理论模型与具体应用方法.建立了四点弯曲条件下混凝土试件名义强度的表达式.研究了不同虚拟裂缝扩展长度取值对断裂与强度参数确定结果的影响规律.分析结果表明:仅需采用小尺寸四点弯曲试件的峰值荷载,即可同时确定混凝土无尺寸效应的断裂韧度与拉伸强度.通过不同学者的试验验证,证明了所提模型与方法的合理性与可靠性.研究为混凝土真实材料参数的合理确定提供了新思路.

Presents a theoretical model and an associate specific application method for determining the fracture and strength parameters of concrete using four-point-bending(4-p-b)specimens.An expression of the nominal strength for concrete specimen under 4-p-b conditions is established.The influence of different fictitious crack length on the determination of the fracture and strength parameters has been in-depth analyzed.The research shows that the independent fracture toughness and tensile strength of concrete can simultaneously be determined by using the proposed model and the peak load of the small-size four-point bending specimen.The validity of the proposed model and associate method were confirmed by different experimental results.The results of this study gave a new ideal to determine the true material parameters of concrete.