Abstract The efficacy of the NSM technique using prestressed CFRP laminates for the flexural strengthening of RC slabs was assessed experimentally. The results obtained indicated that the application of NSM CFRP laminates with a certain level of prestress is a suitable strategy to increase the load-carrying capacity of slabs in terms of service limit state (SLS) conditions. The higher is the CFRP prestressed level the larger is the performance of the NSM technique in the improvement of the behavior of the slabs at SLS conditions, but the deflection at the maximum load of the slabs decreased with the increase of the prestress level. The prestressed NSM CFRP laminates were more effective in the slabs with the lower concrete strength class, mainly at SLS conditions. The increase of the percentage of the flexural reinforcement had a detrimental effect on the performance of prestressed NSM CFRP laminates. An analytical formulation was developed for predicting the cracking, yielding and maximum loads of RC slabs flexurally strengthened with prestressed NSM CFRP laminates and a very good predictive performance was obtained. An upper limit is proposed for the prestress level for ensuring a compromise of ductility and strengthening effectiveness of this type of structural elements.

中文翻译：

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用预应力 nsm cfrp 层压板进行弯曲加固的单向钢筋混凝土板的性能 - 影响参数的评估

摘要 通过实验评估了 NSM 技术使用预应力 CFRP 层压板对 RC 板进行抗弯加固的效果。获得的结果表明，在使用极限状态 (SLS) 条件下，应用具有一定预应力水平的 NSM CFRP 层压板是一种合适的策略，可以提高板的承载能力。CFRP 预应力水平越高，NSM 技术在改善 SLS 条件下板的性能方面的性能就越大，但板在最大载荷下的挠度随着预应力水平的增加而减小。预应力 NSM CFRP 层压板在混凝土强度等级较低的板中更有效，主要是在 SLS 条件下。弯曲钢筋百分比的增加对预应力 NSM CFRP 层压板的性能产生不利影响。开发了一种分析公式，用于预测用预应力 NSM CFRP 层压板弯曲加固的 RC 板的开裂、屈服和最大载荷，并获得了非常好的预测性能。提出了预应力水平的上限，以确保对此类结构元件的延展性和加强有效性进行折衷。