Abstract The flexural strengthening of reinforced concrete (RC) beams by bonding external composite materials has proved to be an effective and convenient technique. Several works, focus on mechanical behaviour of continuous reinforced concrete beam with two spans strengthened by composite materials, were reported in literature. This paper presents the flexural capacity of continuous RC beams with three spans strengthened or repaired by bonding carbon or glass fibre reinforced polymer (CFRP or GFRP) sheets. Experimental program consists of eight continuous RC beams strengthened by CFRP or GFRP sheets and one beam of reference. The dimension is the same for all beams with a length 9 m and a section 15x25 (cm). Experimental tests with monotonic loading were carried out by varying damaged level of the beams, composite material type and strengthening thickness. Five failure modes of strengthening beams were observed. The results show that the ultimate bending moment of the beam can be improved between 14.8 and 26.6% in case of the beams by bonding CFRP sheets and between 7.2 and 11.8% by bonding GFRP sheets. The beam, which was pre-damaged under pre-loading level 100% of the failure load, can be repaired as strengthened continuous RC beam. The optimal strengthening thickness in the positive and negative bending moment region was obtained. The variation of the strain in the positive and negative bending moment was analysed.

中文翻译：

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CFRP/GFRP片材加固或修复的连续钢筋混凝土梁的抗弯能力

摘要 通过粘接外部复合材料对钢筋混凝土（RC）梁进行抗弯加固已被证明是一种有效且方便的技术。文献中报道了几项工作，重点是复合材料加固的两跨连续钢筋混凝土梁的力学性能。本文介绍了通过粘合碳或玻璃纤维增​​强聚合物（CFRP 或 GFRP）片材加固或修复的具有三个跨度的连续 RC 梁的抗弯能力。实验程序由 8 根由 CFRP 或 GFRP 片材加固的连续 RC 梁和一根参考梁组成。长度为 9 m 且截面为 15x25 (cm) 的所有梁的尺寸都相同。通过改变梁的损坏水平进行单调加载的实验测试，复合材料类型和强化厚度。观察到加固梁的五种破坏模式。结果表明，梁的极限弯矩在梁的情况下，通过粘结CFRP 板可提高14.8% 至26.6%，而粘结GFRP 板可提高7.2% 至11.8%。梁在100%失效荷载的预加载水平下预损坏，可以作为加强连续钢筋混凝土梁进行修复。得到了正负弯矩区的最佳强化厚度。分析了正负弯矩中应变的变化。2 和 11.8% 通过粘合 GFRP 片材。梁在100%失效荷载的预加载水平下预损坏，可以作为加强连续钢筋混凝土梁进行修复。得到了正负弯矩区的最佳强化厚度。分析了正负弯矩中应变的变化。2 和 11.8% 通过粘合 GFRP 片材。梁在100%失效荷载的预加载水平下预损坏，可以作为加强连续钢筋混凝土梁进行修复。得到了正负弯矩区的最佳强化厚度。分析了正负弯矩中应变的变化。