基于损伤塑性模型的混凝土双K断裂参数确定  

Determination of Double-K Fracture Parameters of Concrete Based on Damage Plasticity Model

作　　者：符永康 许修亮 Fu Yongkang;Xu Xiuliang(Poly Changda Overseas Engineering Co.,Ltd.,Guangzhou 510620,China)

机构地区：[1]保利长大海外工程有限公司,广东广州510620

出　　处：《市政技术》2022年第3期12-18,共7页Journal of Municipal Technology

基　　金：国家自然科学基金青年基金项目(51908168)。

摘　　要：利用混凝土损伤塑性模型,对混凝土三点弯曲梁(TPB beam)损伤-断裂过程进行数值模拟;再通过数值模型,从损伤起始临界时刻定义起裂荷载,由峰值荷载时刻损伤因子的分布确定裂缝失稳扩展时刻的临界等效有效裂缝长度,提出了确定混凝土起裂断裂韧度、失稳断裂韧度的新方法。研究结果表明:基于损伤塑性模型的混凝土三点弯曲梁数值模型,能较准确地预测单次荷载作用下混凝土三点弯曲梁的荷载-位移曲线,模拟混凝土的准脆性断裂破坏过程,即裂缝起裂、稳定扩展和失稳扩展3个阶段;采用数值模拟方法确定出的起裂断裂韧度和失稳断裂韧度与原有方法确定出的结果吻合性良好,误差均在10%以内,符合工程规范要求。该研究结果证明了新方法简单、实用且有助于推动双K断裂模型在混凝土结构裂缝稳定性分析和安全性评价中的应用。Based on the concrete damaged plasticity model,the damage-fracture process of three-point bending concrete beam(TPB beam) was numerically simulated.The initial cracking load was determined from critical time of damage initiation by the numerical model.The critical equivalent effective crack length of crack instability propagation time was determined by the distribution of damage factors of the peak load time.A new method was proposed to determine the initial fracture toughness and unstable fracture toughness of concrete.The results show that the numerical model of TPB beam based on damage plasticity model can accurately predict the load-displacement curve under monotonic load,simulate the quasi-brittle fracture process of crack initiation,stable crack propagation and unstable crack propagation.The initial fracture toughness and unstable fracture toughness obtained by the proposed method are in good agreement with the results determined by the former methods,all the relative errors are within10%,which meets the requirements of engineering specifications.The proposed method is proved to be relatively simple and practical,which can promote the application of double-K fracture model in crack stability analysis and safety evaluation of concrete structures.

关 键 词：三点弯曲梁 损伤塑性模型 双K断裂模型 起裂断裂韧度 失稳断裂韧度 

分 类 号：U416[交通运输工程—道路与铁道工程]