摘要
The fracture processes of concrete were described by a cohesive crack model based on initial toughness criterion. The corresponding analytical method to predict the instability state was proposed. In this model, the initial toughness was adopted as the crack propagation criterion and the weight function method was used to calculate the stress intensity factor and the crack opening displacement caused by the cohesive stress. The unstable toughness can be easily obtained using the proposed method without measuring parameters at the critical state that was necessary in traditional methods. The proposed method was verified by existing experimental data of wedge splitting specimens with different grades of concrete and the sensitivity of the results on the tensile softening curve was discussed. The results demonstrate that the proposed method can well predict the peak load, the critical effective crack length, and the unstable toughness of concrete specimens. Moreover, the calculated unstable toughness is not sensitive to the tensile softening curve.
研究目的:研究混凝土失稳韧度的理论预测方法。创新要点:1.提出混凝土失稳韧度的理论预测方法;2.利用楔入劈拉试件计算不同级配混凝土的失稳韧度;3.研究失稳韧度受拉伸软化曲线的影响。研究方法:1.基于起裂韧度扩展准则,采用理论分析手段研究混凝土的失稳韧度计算方法;2.利用楔入劈拉试件(见图3)计算不同级配混凝土的失稳韧度。重要结论:1.基于起裂韧度准则可合理地预测峰值荷载状态及失稳韧度;2.混凝土失稳韧度受断裂能的影响较小;3.拉伸软化曲线对混凝土失稳韧度的影响较小。
基金
Project supported by the National Natural Science Foundation of China （Nos. 51309073 and 51309203）, the Specialized Research Fund for the Doctoral Program of Higher Education （No. 20131317120012）, and the Open Research Fund Program of State Key Laboratory of Hydroscience and Engineering （No. sklhse-2014-C-02）, China
