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Bond investigations of prestressed, near-surface-mounted, ribbed memory-steel bars with full bond length
Materials & Design ( IF 8.4 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.matdes.2020.109145
Bernhard Schranz , Christoph Czaderski , Thomas Vogel , Moslem Shahverdi

Abstract The effectiveness of iron-based shape memory alloy (Fe-SMA, ‘memory-steel’) reinforcements has been proven in several studies and site applications. Due to the novelty of ribbed memory-steel reinforcement bars, limited research has been performed on their application in structural engineering, however. In this study, the bond behaviour of memory-steel bars in a near-surface-mounted configuration designed for prestressed strengthening of concrete structures was investigated. Memory-steel bars were installed on concrete blocks and activated by resistive heating before being subjected to pull-out load. The effects of heating and hence prestressing, bar ductility, bond length and rigidity of the fixation were studied based on obtained prestress, crack development, slip and bar strain. During activation of the bars, a longitudinal splitting crack with insignificant crack width occured. Two failure modes were observed during subsequent external loading, including tensile rupture of the bar when less ductile material was used, or bond failure when material with higher ductility was under investigation. Initial prestressing did not result in a reduced bond capacity. Based on the differential equation of bond behaviour, an analytical calculation procedure was developed that enables prediction of bond shear stress, slip, bar strain, pull-out load, as well as the use of a non-linear material behaviour.

中文翻译:

全粘合长度的预应力、近表面安装、带肋记忆钢筋的粘合研究

摘要 铁基形状记忆合金(Fe-SMA,“记忆钢”)增强材料的有效性已在多项研究和现场应用中得到证实。然而,由于带肋记忆钢筋的新颖性,对其在结构工程中的应用进行了有限的研究。在这项研究中,研究了为混凝土结构的预应力加固而设计的近表面安装配置中记忆钢筋的粘结行为。记忆钢筋安装在混凝土块上,并在承受拉出载荷之前通过电阻加热激活。基于获得的预应力、裂纹发展、滑移和钢筋应变,研究了加热和预应力、钢筋延展性、粘结长度和固定刚度的影响。在酒吧激活期间,出现裂纹宽度不明显的纵向劈裂裂纹。在随后的外部加载过程中观察到两种破坏模式,包括使用延展性较低的材料时钢筋的拉伸断裂,或研究延展性较高的材料时的粘结破坏。初始预应力不会导致粘合能力降低。基于粘结行为的微分方程,开发了一种分析计算程序,可以预测粘结剪切应力、滑移、钢筋应变、拉出载荷以及非线性材料行为的使用。初始预应力不会导致粘合能力降低。基于粘结行为的微分方程,开发了一种分析计算程序,可以预测粘结剪切应力、滑移、钢筋应变、拉出载荷以及非线性材料行为的使用。初始预应力不会导致粘合能力降低。基于粘结行为的微分方程,开发了一种分析计算程序,可以预测粘结剪切应力、滑移、钢筋应变、拉出载荷以及非线性材料行为的使用。
更新日期:2020-11-01
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