RC开孔梁承载力试验研究与理论分析

Experimental Study and Theoretical Analysis on Bearing Capacity of RC Beams with Openings

基于孔洞位置、数量、直径、间距以及是否配置加强筋等因素,进行了集中荷载作用下开孔RC梁承载力的试验研究。研究结果表明,在梁的纯弯段和剪弯段开孔对梁的承载力性能影响不同。在纯弯段开孔梁的开裂荷载显著减小;而在剪弯段开孔会使梁的极限承载力明显减小;双孔梁较单孔梁承载力损失更大,剪弯段开双孔除了能进一步减小梁开裂荷载及极限承载力外,能使梁出现明显的脆性破坏;随着梁开孔直径的增加,梁的极限承载力逐渐减小;梁开双孔时,增加两孔间的距离能使开双孔对梁所造成的承载力损伤显著降低;在孔洞周围布置加强筋后能够有效降低因开孔造成的极限承载力的损失,且其极限承载能力的降低值在10%以内。在试验研究的基础上,给出了开孔梁抗剪承载力的计算公式,可为开孔梁的设计及应用提供参考。

Based on the numbers of holes,position,diameter,spacing,with strengthen reinforced or not,and other factors,the bearing capacity of RC beams with openings under concentrated load is tested. The results show that the position of the hole has different effects on the bearing capacity of the beams. Cracking load significantly reduces when the hole locates at pure bending section of the beam; ultimate bearing capacity significantly reduces when the hole locates at shear bending section of the beam; the bearing capacity of beams with double holes decreases more than those with single hole,in addition to further reduce the cracking load and ultimate bearing capacity of the beam,having double holes at shear bending section can make the beams to appear obvious brittle failure; with the diameter of the hole increas,the ultimate bearing capacity of the beam decreases; increasing the distance between the two holes can significantly reduce the damage on the bearing capacity; reinforcement rebar can effectively reduce the loss of the bearing capacity of beams with openings,and limit the loss of ultimate bearing capacity in 10%. On the basis of studies,calculation formulas of shearing capacity are given for the design and application of the beam with opening.