纤维编织网-ECC加固RC梁受弯性能试验

为研究纤维编织网-ECC联合加固RC梁的受弯性能，对1根普通RC梁和9根加固梁进行了四点弯曲加载，分析了ECC高度和纤维编织网层数对加固梁破坏形态、裂缝分布和承载力等受弯性能的影响。试验结果表明：加固梁受弯破坏时裂缝细而密，且呈现ECC中多、混凝土中少的分布特点；和普通RC梁相比，加固梁纯弯段混凝土裂缝数量增加33.3%~66.7%；增加纤维编织网层数或ECC高度对提高加固梁裂缝数量影响较小；加固梁承载性能随纤维编织网层数和ECC高度增加而提高，当ECC高度与加固梁截面高度之比为0.5且布置3层纤维编织网时，加固梁开裂荷载、屈服荷载、极限荷载和普通钢筋混凝土梁相比分别提高111.11%、37.86%、36.13%；ECC高度和纤维编织网层数对加固梁抗弯刚度影响较小，但影响作用不同；加固梁抗弯刚度随纤维编织网层数增加略有增加，随ECC高度增加略有减小；增加纤维编织网层数或ECC高度可降低加固梁钢筋应变。受弯加载过程中加固梁截面仍保持平面，满足平截面假设。基于正截面受弯承载力计算理论，并考虑纤维编织网利用率，建立了加固梁受弯承载力计算公式。由该公式得到的计算结果与试验结果吻合较好。最后，基于该公式分析了加固梁极限弯矩对ECC高度和纤维编织网层数的敏感性，发现加固梁极限弯矩对纤维编织网层数变化敏感性较低。

Experimental Study on Flexural Behavior of RC Beams Strengthened with Textile and ECC

In order to study the flexural performance of RC Beams Strengthened with textile and ECC, one ordinary RC beam and nine strengthened beams were subjected to four point bending loading. The effects of ECC height and textile layers on the flexural performance of reinforced beams such as failure mode, crack distribution and bearing capacity were analyzed. The test results show that the cracks of TRECC-RC beam are fine and dense, and show the characteristics of more cracks in ECC part and less in concrete part. Compared with ordinary reinforced concrete beams, the number of cracks in the concrete part of pure bending section of TRECC-RC beams increases by 33.3%-66.7%. Increasing the number of textile layers or ECC height has little effect on increasing the number of cracks in TRECC-RC beams. The bearing capacity of TRECC-RC beam increases with the increase of the number of textile layers or ECC height. When the ratio of ECC height to the section height of strengthened beam is 0.5 and three layers of textile are used, the cracking load, yield load and ultimate load of TRECC-RC beam are increased by 111.11%, 37.86% and 36.13% respectively compared with ordinary reinforced concrete beam. ECC height and the number of textile layers have little effect on the flexural stiffness of TRECC-RC beams, but the effects are different. The flexural stiffness of TRECC-RC beam increases slightly with the increase of the number of textile layers and decreases slightly with the increase of ECC height. The steel strain of TRECC-RC beam decreases with the increase of the number of textile layers or ECC height. The section of TRECC-RC beam remains plane during bending loading, which meets the plane section assumption. Based on the calculation theory of flexural capacity of normal section and considering the utilization rate of textile, the calculation formula of flexural capacity of strengthened beams is established. The calculated results obtained by this formula are in good agreement with the experimental results. Finally, based on the formula, the sensitivity of the ultimate moment of the strengthened beam to the ECC height and the number of layers of textile is analyzed. It is found that the ultimate moment of the strengthened beam is not sensitive to the change of the number of layers of textile.