Abstract

This paper presents an experimental and numerical model of carbon fiber reinforced polymer (CFRP) retrofitted concrete beams with and without intermediate notches, developed to predict the impact load, energy response, cracking pattern and interfacial stress distribution under drop-weight impact. Considering a drop-weight falling from different heights, a CFRP sheet was bonded to the bottom surface of the beam. The specimen’s drop-weight impacts were established for retrofitted and un-retrofitted simply-supported notched concrete beams. A nonlinear finite element model was developed and calibrated to analyze the interfacial stress field, failure modes, cracking patterns and damage sequences. The results obtained numerically in terms of load–time, load–displacement and energy–time curves were compared to those given by the authors’ experimental tests and also to those given in the literature. For un-retrofitted beams, the impact time was very short, with failure at the center of the beam. For notched beams, the impact load decreased as notch depth increased, owing to the local loss of rigidity at the center of the concrete beam. For the retrofitted beam, however, the impact time was quite long, with a very high impact load, because the beam was more resistant, with rebound.

摘要

本文提出了一个带有和不带有中间切口的碳纤维增强聚合物 (CFRP) 加固混凝土梁的实验和数值模型，用于预测落锤冲击下的冲击载荷、能量响应、开裂模式和界面应力分布。考虑到从不同高度落下的落锤，在梁的底面上粘合了一块 CFRP 板。试件的落锤冲击是针对改装和未改装简支缺口混凝土梁建立的。开发并校准了一个非线性有限元模型，以分析界面应力场、失效模式、开裂模式和损伤序列。在加载时间方面以数值方式获得的结果，将载荷-位移和能量-时间曲线与作者的实验测试和文献中给出的曲线进行了比较。对于未改装的梁，冲击时间很短，梁中心失效。对于开槽梁，由于混凝土梁中心的局部刚度损失，冲击载荷随着开槽深度的增加而降低。然而，对于改装梁而言，冲击时间相当长，冲击载荷非常高，因为梁更耐久，有回弹。