Acor/Al <1.35和Ab扩展到边梁侧面时混凝土局压试验

完成了11个Acor/Al为0～1.316的配置螺旋式间接钢筋的试件和12个模拟预应力梁在边梁侧面锚固的试件的局部受压试验.获得了Acor/Al1.35时的混凝土局部受压承载力计算方法.这个方法的思路是将现行规范局压承载力计算公式中间接钢筋贡献项乘以间接钢筋强度折减系数λ,而且当Acor/Al1时将公式中配置间接钢筋的局部受压承载力提高系数βcor取为1,将间接钢筋对局压承载力贡献项中的局部受压净面积Aln以净核心面积Acor,n代替.λ与Ab/Al、Acor/Al两个比值有关,且随着两比值乘积的增大而增大.指出了当局部受压计算底面积探出预应力梁侧以外的尺寸与边梁宽度的比值≤2、边梁宽度不小于局压面积短边尺寸时,边梁侧面可按现行规范作为局部受压计算底面积的一部分,并可按照相应公式进行局压承载力计算.

Experiment and analyses on local compression bearing capacity of concrete in the case of Acor /Al <1.35 and Ab extending to side face of boundary beam

Experiments on local compression bearing capacity of 11 specimens were reinforced with the spiral indirect reinforcements with A cor /Al ranging from 0 to 1.316 and 12 specimens simulating prestressed concrete beams were anchored in the side face of boundary beam.The calculation method for local compression bearing capacity of concrete with A cor /Al < 1.35 was obtained.The contribution of indirect reinforcements to local compression bearing capacity in current code was multiplied by the reduction factor of strength of indirect reinforcements (λ).When A cor /Al < 1,the enhancement coefficient of local compression bearing capacity due to indirect reinforcements (β cor) equals to 1,and the net local compression area(Aln) in the indirect reinforcements contribution is replaced by the net concrete core area (A cor,n).λ relates to A b /Al and A cor /Al,and increases with the increase of the product of two ratios.It is presented that the side face of boundary beam can be taken as a part of local compression calculated bottom area according to current code,and the local compression bearing capacity can be calculated according to corresponding formulas,when the ratio of length of calculated bottom area outside the section of prestressed concrete beam to width of boundary beam is less than 2 and the width of boundary beam is larger than the shorter length of local compression area.