开矩形孔的钢筋混凝土梁的试验研究

采用钢筋混凝土开孔梁是降低建筑层高的有效途径，但迄今仍缺乏对开孔梁系统的、多参数的试验研究。本研究进行了20个腹部开设矩形孔的钢筋混凝土简支梁试件在集中荷载下的试验。试验结果表明，梁开设孔洞后，其抗剪承载力下降，其挠曲变形特点也不同于一般的实腹梁；孔侧配置加强箍筋和加强斜筋都可以提高开孔梁的抗剪承载力，当孔侧加强腹筋和弦杆的配箍足够大时，可避免梁发生剪压破坏；孔洞上方混凝土可视为偏心受压杆件，孔洞下方混凝土可视为偏心受拉杆件，两种杆件的杆中均存在反弯点。文献6]的计算方法可以较好地评估开设矩形孔的钢筋混凝土梁的承载力。

Experimental Study on Reinforced Concrete Beam with Rectangular Opening

One of the most effective methods to reduce the story height is to use reinforced concrete beam with opening. But up to now, it is still lack of systematic and multi-parameters experimental study of such kind of beam. 20 simply supported reinforced beams with rectangular opening were tested under concentrated load in order to examine its load-carry mechanic and provide experimental proof for design methods. The experimental results show that its shear capacity is reduced and its deflection deformation characteristic is different from common beams. However, the shear capacity can be strengthened if sound measures are taken, such as adopting strengthen stirrups and bent-up steel bars at the sides of the opening. It also shows that the shear-compression failure mode can be avoided if the transverse reinforcements and the stirrups of the chords are large enough. The concrete above the opening can be considered as eccentric compressive component and the concrete below can be regarded as eccentric tensile component. Both of theses two kinds of component exist anti bending point. The shear capacity of reinforced beams with rectangular opening can be estimated by suggested method.