یک سیستم مهاری جدید و موثر برای افزایش ظرفیت خمشی تیرهای RC
Abstract
1- Introduction and background
2- Research significance
3- Experimental work
4- Test set-up and instrumentation
5- Experimental results
6- Conclusions
References
Abstract
Previous experimental studies revealed that anchorage systems were able to increase the efficiency of fiber reinforced polymers (FRP) in terms of the flexure or shear enhancements and ductility performance of the structural members. This study was conducted to investigate the suitability and effectiveness of two anchorage systems for enhancing the bond performance of fiber reinforced cementitious matrix composite (FRCM), a more recent strengthening technique using a cementitious-based binding system. In the interest of improving its flexural performance, two anchorage systems were examined here: a glass spike anchor and a novel U-wrapped anchor. The novel U-wrapped anchor is a PBO strip where its’ ends had only the fabrics in the longitudinal direction that gathered and anchored into the concrete using epoxy adhesive agent. The idea behind anchoring the ends of the U-wrapped PBO strip into RC beams was to rely on the high tensile strength of the PBO strip to control the premature debonding of the FRCM composite. Real-scale simply supported RC beams were examined under the effect of strengthening with different reinforcement ratios and with and without anchorage systems engagement. Test results revealed the contribution of anchorage systems in preventing or delaying the FRCM debonding failure mechanism and enhancing the flexural performance of strengthened beams.
Introduction
and Background Different types of anchorage systems have been used to delay the premature debonding failure mode associated with FRP composites. The successful anchorage systems have allowed the FRP’s composite materials to continuously carry a load in shear or flexure in which extra benefits from high-strength fabrics were achieved. Thus, proper anchorage systems can reduce the required cross-sectional area of the expensive fabric materials or provide a better structural performance with respect to increasing in the fabrics reinforcement ratio. Some of the important anchor types are mechanical anchorages, U-wrapped sheets, anchor spikes, and FRP rods. Many experimental studies have illustrated the efficiency and applicability of these anchorage systems. Khalifa et al. [1] invented a novel anchor that was used to reduce the stress concentration of FRP systems at the ends. The novel anchor consisted of FRP sheets that were extended through a groove filled with epoxy that may or may not include an FRP rebar. Khalifa et al. [1] stated that “the u-anchor system provides an effective solution for cases in which the bonded length of FRP composites is not sufficient to develop its full capacity.’’ Wu and Huang [2] and You et al.