Abstract Many existing concrete buildings worldwide require improvement in structural integrity. Previous research has proven the effectiveness of iron-based shape memory alloy (Fe-SMA or memory-steel) reinforcements for the prestressed strengthening of structures. The unique function of the material, i.e., the so-called shape memory effect, enables cost-effectiveness and presents simple ways to prestress defective building components. Ribbed memory-steel bars have only been available recently. This study aimed to investigate their performance in a novel strengthening technique, named near-surface mounted (NSM) method. Bond experiments with short bond lengths were performed to investigate the feasibility of this configuration and to identify the effects of several design parameters including: groove dimensions, bar diameter, bar material, cover depth, mortar strength, and concrete strength. The use of a digital image correlation system enabled detailed measurements of slips, crack width, and surface strain. An analytical procedure based on the differential equation of bond behaviour was developed, which enabled the calculation of slip, strain, bond shear stress, and load capacity. The results show that ribbed memory-steel bars can be used in an NSM configuration due to high bond capacity. The cover depth, substrate strength and elastic modulus had a significant effect on the failure mode and bond capacity.

中文翻译：

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短结合长度的带肋近表面安装铁基形状记忆合金棒的结合行为

摘要 世界上许多现有的混凝土建筑都需要改善结构完整性。先前的研究已经证明了铁基形状记忆合金（Fe-SMA 或记忆钢）增强材料对结构预应力加固的有效性。材料的独特功能，即所谓的形状记忆效应，可实现成本效益，并提供简单的方法来对有缺陷的建筑部件进行预应力。带肋的记忆钢棒最近才出现。本研究旨在研究它们在称为近表面安装 (NSM) 方法的新型强化技术中的性能。进行了短粘合长度的粘合实验，以研究这种配置的可行性，并确定几个设计参数的影响，包括：凹槽尺寸、钢筋直径、钢筋材料、覆盖层深度、砂浆强度和混凝土强度。使用数字图像相关系统可以详细测量滑移、裂缝宽度和表面应变。开发了一种基于粘结行为微分方程的分析程序，可以计算滑移、应变、粘结剪切应力和承载能力。结果表明，由于高粘结能力，带肋记忆钢棒可用于 NSM 配置。覆盖深度、基材强度和弹性模量对失效模式和粘合能力有显着影响。这使得能够计算滑移、应变、粘结剪切应力和负载能力。结果表明，由于高粘结能力，带肋记忆钢棒可用于 NSM 配置。覆盖深度、基材强度和弹性模量对失效模式和粘合能力有显着影响。这使得能够计算滑移、应变、粘结剪切应力和负载能力。结果表明，由于高粘结能力，带肋记忆钢棒可用于 NSM 配置。覆盖深度、基材强度和弹性模量对失效模式和粘合能力有显着影响。