Study of Cyclic Behavior of Confined High-Strength Concrete Moment-Resisting Frames

本报告提出了约束高强混凝土（HSC）抗弯矩框架的循环响应的实验信息，并提出了一种分析方法来评估约束高强混凝土框架的破坏模式以及极限侧载能力。试验涉及6个一湾一层HSC抗弯矩框架，该框架由2根受钢管约束的200x200mm方形柱和1根受常规箍约束的180x300mm矩形梁组成。所有框架均采用设计强度为80MPa的高强度混凝土，并在周期性横向力和恒定轴向载荷的联合作用下进行了试验。试验结果表明，在高轴向荷载作用下，钢管约束柱仍能保证钢结构框架非常稳定的循环性能。由于钢管约束可以将整个混凝土包含在一柱中，因此在大变形的情况下，钢结构框架的滞回环不会发生突然的强度退化。对方钢管进行内加劲加固，可以显著提高方钢管的约束效果。宽厚比（B/t比）为87加内加劲方钢管的约束效果与不加内加劲B/t比为33的方钢管相同，但方钢管的用钢量仅为后者的55%。本报告还提出了一种设计方法，使结构工程师能够简单地评估受约束钢结构框架的极限横向荷载和变形能力。该方法考虑了方钢管的约束效应，简化了极限计算程序。受约束钢结构柱和梁的荷载和变形能力。理论结果与实测结果的比较表明，所提出的设计方法可以很好地预测实验结果。此外，所有的试验框架都按照设计的延性方式进行，这意味着所提出的设计方法也使工程师能够在设计阶段可靠地预测受约束HSC框架的破坏模式。少

This report presents experimental information on the cyclic response of confined high-strength concrete (HSC) moment-resisting frames along with an analytical method to evaluate the failure mode as well as the ultimate lateral load capacity of the confined HSC frames. The tests involved six one bay and one-story HSC moment-resisting frames, which consisted of two 200x200mm square columns confined by steel tube and one 180x300mm. rectangular beam confined by conventional hoops. All of the frames were made of HSC with designed strength of 80MPa and were tested under combined cyclical lateral force and constant axial load.Test results have indicated that confinement of the columns by steel tube could ensure very stable cyclic performance to HSC frame even when it was under high axial load. Since confinement by steel tube can contain the whole of concrete in a column, no abrupt strength degradation occurred in the hysterestic loops of the HSC frames till large deformation. It has also beco … More me clear that strengthening the square steel tube with inner stiffener could enhance its' confinement effect significantly. The square steel tube, which had width-to- thickness ratio (B/t ratio) of 87 and was strengthened with inner stiffener, provided the same confinement effect as the steel tube with B/t ratio of 33 but without inner stiffener, while the steel amount of the former is only 55% of the latter.This report also presents a design method enabling structural engineer to simply evaluate the ultimate lateral load and deformation capacity of confined HSC frames. This method involves consideration of confinement effect by the square steel tube and simplification of calculation procedure for the ultimate. load and deformation capacity of confined HSC columns and beams. Comparison between the theoretical and the measured results has indicated that the proposed design method could predict experimental results very well. In addition, all of the test frames performed in a ductile manner as designed, which implies that the proposed design method also enables engineers to reliably predict the failure mode of the confined HSC frames at the stage of design. Less