高强钢绞线网-高性能砂浆加固混凝土柱的受力机理研究

Concrete column is the key member in the construction framework which affects its safety and durability greatly. Enlarging concrete section by using new concrete, enveloping steel and strengthening with fiber-reinforced polymer (FRP) are three widely-used methods to strengthen concrete column, but these methods have their own disadvantages, such as construction complex and volume increase of enlarging section method, high technical needs and poor durability of enveloping steel, and the high cost and poor fire proof of FRP method. In order to improve the seismic performance, ductility and durability of concrete columns significantly while improving the bearing capacity greatly,this researth will put forward a new method for strengthening concrete columns with ferrocement including steel wire rope mesh， and its experimental study will be carried out. a. The axial compression performance.Some circular concrete columns will be strengthened by using the ferrocement including steel wire mesh. Comparative test is performed under axial compressive load, the effect such as different strengthening methods and the area ratios between steel bar and wire mesh are studied according to the index of bearing capacity and ductility. The formula of the ultimate load of the columns is proposed. b. The eccentric loaded performance. Some concrete columns strengthened are tested under eccentric loading, and the effect of the eccentricity is studied. c. The seismic performance. An experimental study of some square concrete columns strengthened is carried out under the cyclic loading. The ferrocement can not only improve the hysteretic energy dissipation and ductility of concrete column significantly, also enhance the bearing capacity and rigidity greatly. The plastic hinge length at the column bottom is discussed. A reasonable evaluation could be drawn out based on a comprehensive analysis. Further research issues are put forward at the end of the research. The strengthhening technology using high strength steel wire mesh and high- performance mortar is a reliable method,coupled with low cost,construction easily,which is suitable for seismic retrofit of the buildings in urban and rural China.With broad application prospects,this method will probably get different concrete results.The mechanical properties of confined concrete columns are necessary.

研究内容：（1）分析钢筋混凝土柱采用高强钢绞线网-高性能砂浆加固后的力学性能； （2）研究不同的加固参数（包括不同的加固方式、加固材料用量、锚固措施、持载大小等）对混凝土柱承载力、刚度、裂缝和抗震性能等性能改善的影响程度； （3）通过上述实验分析与理论研究，建立钢绞线网-高性能砂浆加固钢筋混凝土柱的设计计算方法。.研究意义：我国是受地震、火灾等影响的地区，灾后受损的房屋需要进行有效地加固。我国也有大量的历史性重要文物建筑需要采用高性能材料进行加固维修。采用高性能材料高强钢绞线网-高性能砂浆对钢筋混凝土柱进行加固不但具有相当高的经济效益，而且是保障人民生命财产安全的重要措施，具有重要的社会效益和经济价值。因此进行钢绞线网-高性能砂浆加固混凝土柱受力性能和设计方法的研究有着重要的意义和应用前景。

我国是受地震、火灾等影响的地区，灾后受损的房屋需要进行有效地加固。我国也有大量的历史性重要文物建筑需要采用高性能材料进行加固维修。采用钢绞线网-聚合物砂浆加固混凝土结构，无论从加固层的材性、被加固构件的性能，还是从加固施工的难易和投资费用的高低等方面来看都显示出了明显的优越性。. 研究内容：（1）分析高强钢绞线网-高性能砂浆加固钢筋混凝土柱后的力学性能；（2）研究不同的加固参数（包括不同的加固方式、加固材料用量、锚固措施、预应力水平等）对钢筋混凝土柱的承载力、裂缝、变形和抗震性能等性能改善的影响程度；（3）通过综合实验分析与理论研究，建立高强钢绞线网-高性能砂浆加固钢筋混凝土柱的受力机理。. 本研究推导了适用于钢绞线网约束混凝土柱峰值应力的计算模型；建立了钢绞线网约束混凝土柱的应力-应变关系分析模型，把提出的应力-应变关系模型应用到钢绞线网-聚合物砂浆加固钢筋混凝土柱在低周反复荷载作用下以及偏压作用下的力学性能研究中。进行高强钢绞线-高性能砂浆加固偏心受压柱试验研究，表明横向预应力钢绞线-聚合物砂浆加固后小偏压RC柱的极限承载力和变形性能均得到了明显提高和改善对加固小偏压RC柱进行受力机理分析，借鉴所适用的约束混凝土的基本原理及模型，提出约束混凝土峰值应力、应变的计算方法；并推导出加固小偏压柱极限承载力简化计算公式。完成了8根加固柱试件在低周往复作用下的抗震性能实验，探究了钢绞线预应力水平、钢绞线特征值、轴压比等参数对加固RC柱抗震性能的影响。分析了各试件在往复荷载作用下裂缝开展模式、刚度退化、耗能能力、延性变化等抗震参数的发展规律，以及各实验参数对加固RC柱抗震性能的影响，得到的恢复力模型曲线与实验曲线相吻合。采用有限元软件对低周反复荷载作用下的预应力钢绞线网-聚合物砂浆加固柱进行模拟分析，考虑轴压比、预应力水平、混凝土强度和配箍率等参数对加固柱抗震性能的影响。通过引入钢绞线约束折减系数对混凝土本构模型进行修正，并对钢筋采用非线性随动强化模拟，使模拟结果与试验结果吻合较好。利用灰色关联理论进行模型输入变量选择，建立了基于径向神经网络模型的延性分析模型并进行预测，研究轴压比、钢绞线间距、预应力水平因素对加固柱延性的影响规律。分析轴压比、预应力水平和配箍率对钢绞线约束折减系数的影响，给出加固柱正截面承载力的理理论计算方法。