Bencardino Francesco, Nisticò Mattia
Department of Civil Engineering, University of Calabria, Via P. Bucci, Cubo 39B, Rende, 87036 Cosenza, Italy.
Materials (Basel). 2021 Aug 31;14(17):4961. doi: 10.3390/ma14174961.
This paper shows a theoretical model for predicting the moment-curvature/load-deflection relationships and debonding failure of reinforced concrete (RC) beams externally strengthened with steel reinforced geopolymeric matrix (SRGM) or steel reinforced grout (SRG) systems. Force equilibrium and strain compatibility equations for a beam section divided into several segments are numerically solved using non-linear behaviour of concrete and internal steel bars. The deflection is then obtained from the flexural stiffness at a mid-span section. Considering the appropriate SRGM-concrete bond-slip law, calibrated on single-lap shear bond tests, both end and intermediate debonding failures are analysed. To predict the end debonding, an anchorage strength model is adopted. To predict intermediate debonding, at each pair of flexural cracks a shear stress limitation is placed at concrete-matrix interface and the differential problem is solved at steel strip-matrix interface. Based on the theoretical predictions, the comparisons with experimental data show that the proposed model can accurately predict the structural response of SRGM/SRG strengthened RC beams. It can be a useful tool for evaluating the behaviour of externally strengthened RC beams, avoiding experimental tests.
本文展示了一个理论模型，用于预测用钢纤维增强地聚合物基体（SRGM）或钢纤维增强灌浆料（SRG）系统进行外部加固的钢筋混凝土（RC）梁的弯矩-曲率/荷载-挠度关系以及脱粘破坏。利用混凝土和内部钢筋的非线性行为，对划分为若干段的梁截面的力平衡和应变协调方程进行数值求解。然后根据跨中截面的抗弯刚度得到挠度。考虑在单剪粘结试验中校准的合适的SRGM-混凝土粘结-滑移规律，分析端部和中间脱粘破坏。为了预测端部脱粘，采用锚固强度模型。为了预测中间脱粘，在每对弯曲裂缝处，在混凝土-基体界面设置剪应力限制，并在钢带-基体界面求解微分问题。基于理论预测，与试验数据的比较表明，所提出的模型能够准确预测SRGM/SRG加固RC梁的结构响应。它可以成为评估外部加固RC梁性能的有用工具，避免进行试验测试。
