为确定混凝土材料的真实断裂韧度,分析了几种混凝土断裂韧度尺寸效应规律,提出了三点弯曲粱测试的起裂韧度KiniIC和失稳韧度KunIC尺寸效应表达式及真实断裂韧度的趋势线外推法.采用在建桥梁上部结构用高强混凝土制作了6组几何相似,最大尺寸为长×高×宽＝1280 mm×320 mm×160mm,总共18根带预制缺口的素混凝土平面应变三点弯曲试件,由载荷-加载点位移、载荷.裂缝口张开位移曲线和裂缝前沿应变等计算得到双K韧度值.结果表明,混凝土双K韧度符合现在提出的尺寸效应规律,而趋势线外推法可用于测定工程中大尺寸混凝土的断裂韧度.%A trend extrapolation method to determine the double-K fracture toughness(initiation toughness and unstable toughness)is put forward through size effect expression of double-K toughness deduced by the existing size effect laws.The three-point bending beams were carried out with 6 groups of notched beams in various geometric similarity.which had the maximum dimensions being length×height × width=1280 mm×320 mm × 160 mm.The double.K toughness was calculated from curves of load-crack mouth opening displacement and load-displacement at loading point and the true toughness were evaluated by Rend extrapolation.Results showed that the double-K tough.ness is good agreement with the size effect expression of this article and the Rend extrapolation method can be used in the evaluation of fracture paraments of concrete structure in engineering.
展开▼
