【摘要】 钢筋混凝土联肢剪力墙或联肢筒壁中的连梁是抗震关键部件。小跨高比连梁因剪弯比高,不采取特殊措施难以满足高剪力条件下的高延性要求。现行设计规范使用的交叉暗撑连梁虽抗震抗剪能力及延性好,但钢筋绑扎困难;现行规范降低抗剪能力上限、强化配箍要求的普通配箍连梁则抗剪能力过低、延性依然不足。为此,有必要寻求一种不需内力或刚度折减的高抗剪能力、高延性、便于施工的小跨高比连梁设计方案。为适应小跨高比连梁的受力特征,提出一种由交叉斜筋和上、下L形斜筋复合配筋的新设计方案,并完成19个具有不同跨高比、不同剪压比和不同斜筋———L形筋用量比的足尺连梁低周交变加载试验。试验结果表明,采用新方案配筋的连梁具有良好的抗震性能;剪跨比为0.8~2.5的该类连梁在剪压比高达0.3及以上时仍具有不低于4.0~5.0的位移延性,且施工难度明显降低。这种新的连梁配筋方案可推荐用于高抗震等级的建筑结构。更多还原

【Abstract】 Coupled beams in reinforced concrete structural walls or tubes are key anti-seismic members.In general,coupling beams of small aspect ratios cannot meet the requirement of high ductility in the context of high shear forces due to the large ratio of shear to flexural moment,unless specific reinforcement arrangements are implemented.Although coupled beams reinforced with two intersecting groups of diagonally placed bars can provide satisfactory seismic shear capacity and excellent ductility,it is always very difficult to place the reinforcements in construction.The current codified reinforcement scheme of coupled beams,with enhanced ordinary closed-stirrups and with reduced upper limit of shear capacity,results in significant reduction of shear capacity and insufficient ductility.Therefore,there is an impetus to find a reinforcement arrangement scheme that can provide high seismic shear capacities and excellent ductility for coupled beams and make construction convenient,under the condition that no reduction of internal forces or stiffness is needed in design.In this paper,a new reinforcement arrangement scheme,namely combined cross slanting reinforcements and upper and lower L-shaped inclined reinforcements,is presented on the basis of internal-force characteristics of such small-aspect-ratio coupled beams.Nineteen full-scale specimens with different shear-compression ratios and different ratios of diagonal to L-shaped inclined reinforcements were tested under reversed cyclical loading.The results show that with this new reinforcement scheme,the coupled beams exhibit excellent seismic behaviors.For this type of coupled beams with shear-span ratios ranging from 0.8 to 2.5,the displacement ductility coefficients are higher than 4.0 even when the shear-compression ratios are as high as or higher than 0.3,and at the same time,the difficulty in placement of reinforcements is remarkably alleviated.Such a new scheme of reinforcement arrangement is feasible for coupled beams of high seismic grades in reinforced concrete buildings.更多还原