内填Y形钢支撑加固多层钢筋混凝土框架结构滞回性能试验研究

为了研究内填Y形钢支撑多层RC框架结构的抗震性能，进行了3榀2层单跨1/2缩尺试件的低周反复荷载试验。分析试件在循环荷载作用下的破坏机理、滞回性能、延性、刚度退化规律以及耗能能力。研究结果表明：应用Y形钢支撑加固RC框架合理可行，Y形钢支撑承担了大部分水平荷载，梁柱连接节点破坏程度较轻；耗能段与混凝土梁的连接构造合理，没有发生破坏；Y形钢支撑破坏，导致结构失效；加载初期，试件荷载 侧向位移比滞回曲线具有一定程度的捏缩，耗能段屈服后，试件滞回曲线相对饱满；试件2层的荷载-层间位移比滞回曲线比1层饱满，2层的侧向变形程度比1层大；楼板的存在增加了框架梁的刚度，减少了梁上的裂缝数量；节点构造对结构抗侧刚度影响较小，对变形能力影响较大；加固震损后的结构，应该考虑结构刚度退化程度。在试验的基础上提出了内填Y形钢支撑的设计方法。

Experimental study on size effect of flexural behavior of reinforced high-strength concrete beams subjected to cyclic loading

Six reinforced high-strength concrete beam-type specimens of different sizes with stubs columns in the middle were fabricated，and tested under low-cycle reversed loading to investigate the effect of depths on flexural behavior of reinforced high-strength concrete beams. The parameters of specimens varied in depths and ratios of longitudinal reinforcement on the top of cross sections, while the depth-width ratios of cross sections, shear span-to-depth ratios and ratios of longitudinal reinforcement on the bottom of cross sections and stirrups were constant. C70 concrete was used to cast the specimens and HRB 400 steel bars were used as longitudinal reinforcement. The influence of beam depths on nominal cracking moment, nominal yield moment, nominal ultimate moment, displacement ductility, plastic rotation capacity, stiffness degradation and energy dissipation capacity of high-strength concrete beams were investigated. It is shown that there is no apparent size effect observed on nominal cracking moment, nominal yield moment and nominal ultimate moment of reinforced high-strength concrete beams, and that all specimens subjected to cyclic loading clearly show similar stiffness degradation which is independent of beam depths, while the displacement ductility factors，rotational capacity as well as work index of specimens decrease with increasing of depths, showing significant size effect.