【摘要】 钢纤维已成为土木工程中应用需求不断增长的增强材料，因而钢纤维混凝土(steel fiber reinforced concrete, SFRC)的损伤、断裂也是工程中亟需解决的关键问题。基于最新提出的统一相场理论和内聚力模型，建立由钢纤维、骨料、砂浆及界面过渡区构成的SFRC细观有限元模型并结合试验予以验证。针对单轴拉伸、三点弯曲等工况，考察钢纤维掺量和长度、骨料形状、初始切口缺陷等因素对SFRC抗拉和抗折性能的影响，对SFRC的力学性能及损伤破坏机理进行研究。结果表明：基于相场损伤模型和内聚力模型建立的SFRC细观有限元模型具有较好的准确性和可靠性；SFRC抗拉强度受钢纤维掺量的影响较大，在掺量取2%时性价比较高，比0.5%掺量时约提高34.2%,骨料形状和钢纤维长度的影响较小；SFRC抗折强度受钢纤维掺量及切口深度的影响较大，掺入0.2%、0.35%和0.5%的钢纤维使SFRC切口梁承载力分别提高了20.7%、38.9%和63.7%,相比切口深度为25 mm的SFRC切口梁，切口深度为40 mm和55 mm的SFRC切口梁承载力分别降低了19.9%和39.8%。供钢纤维混凝土工程分析和设计参考。更多还原

【Abstract】 Steel fiber has become a reinforcing material with increasing application demand in civil engineering, so the damage and fracture of steel fiber reinforced concrete(SFRC) is also a key problem that needs to be solved urgently in engineering. Based on the unified phase field theory and cohesion model proposed recently, a meso-finite element model of SFRC composed of steel fiber, aggregate, mortar and interface transition zone was established and verified by experiments. Under the conditions of uniaxial tension and three-point bending, the effects of factors such as steel fiber content and length, aggregate shape, and initial notch defects on the tensile and flexural properties of SFRC were investigated, and the mechanical properties and damage mechanism of SFRC were studied. The results show that the SFRC meso-finite element model based on the phase field damage model and cohesion model has good accuracy and reliability. The tensile strength of SFRC is greatly affected by the content of steel fiber, and the cost performance is higher at 2% content, which is 34.2% higher than that at 0.5% content. The influence of aggregate shape and steel fiber length is small. The bending strength of SFRC is greatly affected by the content of steel fiber and the cut depth. The addition of 0.2%, 0.35% and 0.5% steel fiber increase the bearing capacity of SFRC cut beam by 20.7%, 38.9% and 63.7%, respectively, compared with SFRC cut beam with a cut depth of 25 mm. The bearing capacity of SFRC beam with 40 mm and 55 mm incision depth decrease by 19.9% and 39.8%, respectively. It can be used as reference for steel fiber reinforced concrete engineering analysis and design.更多还原