钢骨超高强混凝土框架节点恢复力模型

为了研究钢骨超高强混凝土框架节点的恢复力特性,设计制作了12个试件,进行了低周反复加载试验。观察、记录了试件的受力过程和破坏形态,基于受力过程中试件表现出的典型特征,提出了三折线骨架曲线模型和恢复力模型,并与试验结果进行了对比分析。研究结果表明,试件从受力至破坏的过程可归纳为开裂、通裂、失效3个阶段;在通裂和失效阶段,试件加载、卸载刚度退化明显,出现明显的卸载残余变形;所建议的三折线骨架曲线模型与骨架曲线试验结果吻合较好,直接反映出了试件的受力破坏过程。由建议的三折线恢复力模型计算得到的滞回曲线与试验得到的滞回曲线变化趋势大致相同,吻合程度较高,很好地描述出了钢骨超高强混凝土框架节点的滞回性能。所建议的恢复力模型可供钢骨超高强混凝土框架结构非线性地震反应分析应用。

STUDY ON RESTORING FORCE MODEL OF STEEL REINFORCED ULTRA HIGH STRENGTH CONCRETE FRAME JOINTS

In order to study the restoring force model of steel reinforced ultra high strength concrete frame joints, twelve specimens were fabricated and tested under low cyclic loading. The loading process was observed and failure modes were recorded. Three-line models of skeleton curves and restoring force models are presented based on typical characteristics of specimens, and compared with experimental results. The results show that loading process of specimens can be summarized with three stages; first cracking, full cracking and failure. Loading and unloading stiffness degenerates obviously in the stages of full cracking and failure. Residual deformation appears in the hysteretic curve after unloading. The presented three-line models of skeleton curves agree well with the experimental ones, which clearly indicate the failure process of specimens. Additionally, the hysteretic curves from the presented restoring force model agree well with experimental ones, and their trends are approximately identical to experimental ones. The hysteretic behavior of steel reinforced ultra high strength concrete frame joint is described better by the three-line restoring force model. The presented restoring force model can be adopted to analyze nonlinear seismic response of steel reinforced ultra high strength concrete frame.