Measurement of Fracture Toughness of Conrete Using the Short-Rod Procedure

9414243插图本研究的目的是评估用于混凝土断裂韧性标准化测量的短棒(SR)试件的配置。解决的关键问题是：1)线弹性断裂力学(LEFM)测试程序对低、中、高强度混凝土的ASTM C39标准圆柱体尺寸的适用性；2)基于内聚断裂力学的测试程序对低、中、高强度混凝土的适用性；以及3)简化的尺寸效应调整程序对估计有效断裂韧性(KLC)的适用性该项目包括两项主要任务：测试和模拟。将对三种尺寸的试件和三种强度的混凝土进行两级SR测试。级别1将采用LEFM行为。II级将考虑大范围的无弹性，也可以从子尺寸的样本中测量KLC。SR结果将与使用欧洲标准进行测试的结果进行比较。计算机模拟将用于：测试II级测试中使用的非弹性修正系数的有效性；评估该方法对所有测试的尺寸和强度的一致性和准确性；以及重新校准当前标准的SR几何形状，以进行混凝土的最佳测试。该项目的结果可能导致一个可靠的，简单的，廉价的混凝土属性的标准测试程序，其测量越来越重要。***

9414243 Ingraffea The objective of this research is to evaluate the short-rod (SR) specimen configuration for use in the standardized measurement of fracture toughness of concrete. Key issues addressed are: 1)Applicability of Linear Elastic Fracture Mechanics (LEFM) testing procedures to ASTM C39 standard cylinder size for low, medium,and high strength concrete; 2)Applicability of cohesive fracture mechanics-based testing procedures for low, medium, and high strength concrete; and 3)The applicability of simplified size-effect adjustment procedures to estimate valid fracture toughness (Klc) The project consists of two principal tasks, testing and simulation. Two levels of SR testing will be performed on three sizes of specimens, and three strengths of concrete. Level 1 will assume LEFM behavior. Level II will account for large scale inelasticity, and could also measure Klc from sub-size specimens. The SR results will be compared to those obtained from testing using the European standard. Computer simulation will be used to: test the validity of the inelasticity correction factor used in Level II testing; assess the consistency and accuracy of this approach for all sizes and strengths tested; and recalibrate the current standard SR geometries for optimal testing of concrete. The results of this project could lead to a reliable, simple, and inexpensive standard test procedure for a concrete property whose measurement is of increasing importance. ***