局部采用纤维增强混凝土梁柱节点抗震性能试验研究

为了提高梁柱节点受剪承载力、变形能力及耗能能力,同时避免节点钢筋拥挤而导致的施工困难,采用纤维增强混凝土(FRC)代替普通混凝土作为节点核心区基体材料,考虑轴压比和节点核心区配箍率的影响,进行了7个FRC梁柱节点和1个钢筋混凝土(RC)梁柱节点对比试件的拟静力试验,分析其破坏形态、承载力、变形能力、耗能能力、节点核心区剪应力-剪应变曲线和梁端塑性铰区弯矩-转角曲线。结果表明,在节点核心区主斜裂缝出现前,试件已具有很高的受剪承载力和变形能力;当轴压比试验值为0.07~0.28时,随着轴压比增大,FRC试件的受剪承载力、侧向变形能力、耗能能力及节点核心区的剪切强度和剪切变形能力增加;增加节点核心区配箍率,承载力退化有所减缓;FRC试件梁端塑性铰转动能力有较大提高。

EXPERIMENTAL STUDY ON SEISMIC PERFORMANCE OF BEAM-COLUMN JOINTS WITH FIBER-REINFORCED CONCRETE IN JOINT CORE AND PLASTIC HINGE ZONE OF BEAM AND COLUMN END

Fiber-reinforced concrete (FRC) was used in this study to replace normal reinforced concrete (RC) for beam-column joints to improve the shear strength, deformability and energy dissipation capacity of beam-column joints. This was also to avoid severe reinforcement congestion and construction difficulties. Quasi-static tests of seven FRC beam-column joints and one RC beam-column joint were conducted with varying axial load ratio and stirrup ratio in joint cores, to analyse the failure modes, shear strength, deformability, energy dissipation capacity, shear stress-strain curves in joint cores and moment versus rotation curves in plastic hinge zones at beam ends. Experimental results indicated that FRC joints exhibited high shear strength and deformability before the main diagonal crack occurred at the joint core. As the test axial load ratio increased from 0.07 to 0.28, shear strength, energy dissipation capacity, shear strength and deformability of the joint core increased. As the stirrup ratio of joint core increased, shear capacity degraded slowly. The plastic hinge rotation capacity of beam ends was improved considerably.