既有建筑由于结构功能要求的提高、可靠度的降低、耐久性等问题的出现而需要进行加固改造。目前，混凝土结构加固中加大截面法是常用的一种方法，对加大截面法加固受弯构件，其新、旧混凝土结合面是一个薄弱的受力面且结合面的工作性能将直接影响加固构件的变形及受力性能。因此，提高和改进加大截面法加固受弯构件新、旧混凝土结合面的连接方法及受力性能，对既有建筑加固改造理论与技术及工程应用具有重要的研究意义。 本论文通过分析加大截面法加固受弯构件的工作性能及新、旧混凝土结合面的粘结机理，提出了在新、旧混凝土结合面采用人工凿毛处理和增设构造植筋的连接方法。考虑不同的植筋布置方式，共设计制作了两组4个受弯构件，并进行了单调静力加载试验及有限元的数值模拟分析，得出四点研究结论：（1）加大截面法加固受弯构件时，需在结合面进行人工凿毛及增设构造植筋处理，形成改造的加大截面法加固受弯构件结合面的连接方法；（2）构造植筋可显著提高新、旧混凝土结合面的粘结力学性能及结合面的开裂性能，大大提高了新、旧混凝土共同工作能力，使得结合面的无裂缝出现；（3）改进结合面的连接方法，采用布置构造植筋，使得加固试件受力性能接近一次性整浇试件；（4）根据试件的破坏特征、增设构造植筋且植入旧梁混凝土孔中深度为15d，以及试验数据的研究与分析，提出加大截面法加固受弯构件斜截面抗剪承载力计算公式及正截面抗弯承载力计算公式。 上述研究成果对进一步研究加大截面法加固受弯构件的受力性能及新旧混凝土界面的连接方法，完善混凝土加固改造设计规范具有一定的参考价值，并可供实际加固改造工程的设计与施工参考。

The improvement of existing buildings due to the structure of the functional requirement, the emergence of the problem such as low reliability, durability and need reinforcement renovation. At present, the reinforced concrete structure in enlarging section method is a method in common use, strengthening flexural member of enlarging section method, combining with the new and old concrete surface is a weak bearing surface and combining with the working performance will directly affect the deformation and stress distribution of reinforcement component performance. Therefore, enlarging section flexural member reinforced increase and improve the new and old concrete and the connection method and mechanical performance, theory and technology of existing buildings reinforcement and reconstruction and the engineering application has important research significance. This paper through the analysis of enlarging section method to reinforce the performance of flexural member, and combined with the new and old concrete bonding mechanism, puts forward the new and old concrete surface by using artificial cut wool processing and adding structural steel connection methods. Consider different ways of planting bar decorate, total design made two sets of four flexural member, and the monotonous static load test and finite element numerical simulation analysis, four research conclusion: (1) Enlarging section method to reinforce flexural member, should be carried out in combination with surface artificial planting bar cut hair and add structure processing, enlarging section flexural member reinforced form transformation of joint surface connection method；(2) Planting bar structure can significantly increase the new and old concrete and the bond performance and joint surface cracking performance, greatly improving the ability to work together old and new concrete, combining with no cracks appear below ; (3) Improve the method of combining the connection, adopt planting bar decorate construction, reinforced specimen stress performance close to the one-time concrete specimens ；（4）Planting bar according to the failure characteristics of the specimens, adding structure and inserted in the old concrete beam hole depth of 15 d, and the research and analysis of test data, and put forward enlarging section method for inclined section flexural member reinforced shear bearing capacity calculation formula and calculation formula of normal section flexural capacity. The above research results for further study on enlarging section method to reinforce the forced properties of flexural member, and new and old concrete interface connection methods, perfecting the design code of concrete reinforcement and reconstruction has certain reference value, It also can supply consult for the design and construction of the reinforcement and modification engineering.