钢绞线网片-聚合物砂浆加固钢筋混凝土梁受弯性能试验研究及破坏机理分析

通过6根采用钢绞线网片-聚合物砂浆加固技术加固的钢筋混凝土梁和1根未加固对比梁的受弯性能试验，研究了钢绞线配置数量(加固率)、聚合物砂浆类型和钢绞线预应力水平等参数对加固试件受弯性能的影响。基于试验结果，重点分析了加固试件的承载力、变形能力、破坏形态和破坏机理等。结果表明：试件受弯承载力随加固率的提高而提高，但加固试件的变形能力有所降低；采用该加固技术对试件的初始刚度影响不大；钢绞线施加预应力可提高加固梁的抗裂性能，减小裂缝宽度，但在相同加固率下，试件的变形能力随预应力水平提高而降低，采用预应力水平0.05的加固试件可获得较好的变形性能；单、双组份聚合物砂浆对加固试件界面黏结性能和承载力无明显影响；对加固率较大的试件，需进行端部锚固件验算。基于平截面假定，提出了采用钢绞线网片-聚合物砂浆加固钢筋混凝土梁受弯承载力的计算式，计算结果与试验结果吻合较好。

Experimental study on flexural behavior and failure mechanism of RC beams strengthened with SSWM-PM

Six RC beams strengthened using steel stranded wire mesh and polymer mortar (SSWM-PM) and one un-strengthened RC beam were constructed and tested to investigate the flexural performance. The main parameters included the reinforcement ratio, type of polymer mortar (PM) and prestress level of stranded wires. Based on the test results, the bearing capacity, deformation, failure modes and failure mechanism of the strengthened specimens were analyzed. The results indicate that the flexural capacity of strengthened specimens increases with the increase of the reinforcement ratio, while the ultimate deformation and ductility of strengthened specimens decrease compared with un-strengthened specimen. The strengthening technique has little influence on the initial stiffness of specimens. The prestress of stranded wires could restrain the crack and reduce the width of cracks, while higher prestress level led to a decrease of the ultimate deformation capacity of specimens under the same reinforcement ratio. The strengthened specimen with a prestress level of 0.05 has satisfactory deformation capacity. In addition, strengthened specimens with two-component PM don’t show significant difference in bonding behavior and bearing capacity compared to those with single-component PM. For strengthened specimens with a high reinforcement ratio, the capacity of end anchorage components needs to be checked. Based on the plane-section hypothesis, the design formula of flexural capacity was proposed, and the calculated results agree well with the test results.