装配式双拼槽钢-混凝土开孔组合梁试验研究

Experimental Study on Prefabricated Double-Channel Composite Beams with Web Openings

装配式建筑行业渗透率不断提升,针对装配式工业化的需求,提出了一种新型装配式双拼槽钢-混凝土开孔组合梁(DCCP),由高强螺栓连接装配模块形成,实现完全干式连接,兼具节省钢材、便于敷设管道及增大建筑使用空间等优点.对具有腹板圆形开孔的DCCP和4根不同腹板圆角矩形开孔长度的DCCP进行了静力弯曲试验,探究了腹板开孔长度对组合梁受弯性能的影响,分析了试验梁的破坏模式,跨中挠度、应变、平面外位移、界面滑移随荷载变化规律,提出了DCCP极限承载力的理论计算模型.结果表明:腹板开孔长度对组合梁的力学性能有显著的影响,腹板开圆孔的组合梁表现为槽钢翼缘屈服失效,混凝土板在跨中压碎即弯曲破坏,而腹板开长圆角矩形孔的组合梁因腹板开孔处四角产生塑性铰和开孔处高弯矩端对应位置的混凝土板压溃而发生空腹破坏(Vierendeel mechanism failure);腹板开孔长度由150 mm增加到900 mm时,组合梁的承载力和延性分别降低了20%和23%;具有腹板开孔的DCCP平均延性系数值为8;高强螺栓约束下的装配模块间分离微乎其微,整体协同工作性能良好.钢梁与混凝土板间最大滑移为0.34 mm,新型组合梁采用的钢板连接件可有效传递钢梁和混凝土板间的纵向剪力,实现完全抗剪连接件.用本文理论模型计算的极限承载力与试验结果吻合良好,误差小于5%.

The penetration rate of prefabricated building industry is constantly improving.Given the demand for prefabrication industrialization,a novel type of prefabricated double-channel composite beam with web openings(DCCP)is proposed,which is formed by bolting together two modules.The dry connections and web openings of this composite beam accommodate pipelines and ducts,reducing floor heights and structural steel in buildings.To investigate the influence of web openings on the performance of composite beams,static bending tests were conducted on a DCCP with circular web openings and four DCCP beams with varying elongated web opening lengths.The failure modes,load-deflection curve,strain distribution,out-of-plane displacement,and end slip were analyzed.A theoretical model was proposed for calculating the ultimate bearing capacity.The results indicated that the web openings had a substantial effect on the mechanical behavior of DCCPs.The composite beam with circular web openings failed because of the yielding of the C-channel flanges and the crushing of the concrete slab at midspan,presenting flexural failure.Beams with elongated web openings failed because of the appearance of plastic hinges at the corners of openings and the crushing of concrete slabs at the high moment end of the opening,presenting Vierendeel mechanism failure.As the length of web openings increased from 150 mm to 900 mm,the ultimate capacity and ductility decreased by 20% and 23%,respectively.The average ductile coefficient value of DCCPs with web openings was 8.The separation between modules constrained by high-strength bolts was minimal,and the overall integration performance was satisfactory.The maximum end slip was 0.34 mm,indicating that the channel steel plate shear connectors effectively transferred the longitudinal shear forces between the steel beam and the concrete slab,achieving a complete shear connection.Moreover,the ultimate capacity of DCCPs predicted by the proposed theoretical model was consistent with experimental results,with an error of less than 5%.