Tawfik Ahmed Bahgat, Mahfouz Sameh Youssef, Taher Salah El-Din Fahmy
Construction and Building Engineering Department, College of Engineering and Technology, Arab Academy for Science, Technology and Maritime Transport (AASTMT), B 2401 Smart Village, Giza 12577, Egypt.
Professor of Concrete Structures, Structural Engineering Department, Tanta University, Tanta 31527, Egypt.
Materials (Basel). 2021 Nov 30;14(23):7349. doi: 10.3390/ma14237349.
The numerical simulation of concrete fracture is difficult because of the brittle, inelastic-nonlinear nature of concrete. In this study, notched plain and reinforced concrete beams were investigated numerically to study their flexural response using different crack simulation techniques in ABAQUS. The flexural response was expressed by hardening and softening regime, flexural capacity, failure ductility, damage initiation and propagation, fracture energy, crack path, and crack mouth opening displacement. The employed techniques were the contour integral technique (CIT), the extended finite element method (XFEM), and the virtual crack closure technique (VCCT). A parametric study regarding the initial notch-to-depth ratio (a/D), the shear span-to-depth ratio (S.S/D), and external post-tensioning (EPT) were investigated. It was found that both XFEM and VCCT produced better results, but XFEM had better flexural simulation. Contrarily, the CIT models failed to express the softening behavior and to capture the crack path. Furthermore, the flexural capacity was increased after reducing the (a/D) and after decreasing the S.S/D. Additionally, using EPT increased the flexural capacity, showed the ductile flexural response, and reduced the flexural softening. Moreover, using reinforcement led to more ductile behavior, controlled damage propagation, and a dramatic increase in the flexural capacity. Furthermore, CIT showed reliable results for reinforced concrete beams, unlike plain concrete beams.
由于混凝土具有脆性、非弹性非线性的特性，混凝土断裂的数值模拟具有一定难度。在本研究中，对带缺口的素混凝土梁和钢筋混凝土梁进行了数值研究，以使用ABAQUS中的不同裂缝模拟技术来研究它们的弯曲响应。弯曲响应通过硬化和软化阶段、抗弯能力、破坏延性、损伤起始和扩展、断裂能、裂缝路径以及裂缝口张开位移来表示。所采用的技术包括轮廓积分技术（CIT）、扩展有限元法（XFEM）和虚拟裂缝闭合技术（VCCT）。研究了关于初始缺口深度比（a/D）、剪跨比（S.S/D）和体外后张预应力（EPT）的参数研究。结果发现，XFEM和VCCT都产生了较好的结果，但XFEM具有更好的弯曲模拟效果。相反，CIT模型未能表达软化行为，也未能捕捉裂缝路径。此外，减小（a/D）和降低S.S/D后，抗弯能力有所提高。此外，使用EPT提高了抗弯能力，显示出延性弯曲响应，并减少了弯曲软化。此外，使用钢筋导致了更具延性的行为，控制了损伤扩展，并显著提高了抗弯能力。此外，CIT对钢筋混凝土梁显示出可靠的结果，这与素混凝土梁不同。
