波形钢腹板组合梁无黏结预应力筋应力增量研究

Research on prestressing tendons stress increment of prestressed composite beams with corrugated webs

预应力波形钢腹板组合梁翼板内的无黏结预应力筋应力变化与梁上荷载之间存在显著的相关关系,因而无黏结预应力筋的应力增量可以通过截面配筋指标等相关参数建立回归公式。参数分析表明:对于受弯破坏的预应力波形钢腹板组合梁,影响翼板内无黏结预应力筋应力增量的主要参数为受拉翼板的钢筋屈服强度及配筋率、钢翼缘板屈服强度及面积、翼板混凝土强度以及混凝土翼板厚度与梁截面高度之比,而波形钢腹板的厚度及其屈服强度、预应力筋的初应力及预应力筋配筋面积、梁跨高比等参数影响很小。通过大量计算分析,建立了翼板内无黏结预应力筋应力增量与受拉翼板的钢筋屈服强度及钢翼缘板屈服强度的关系,并提出了预应力波形钢腹板组合梁屈服时预应力筋应力增量计算方法,计算结果精度较好。

It has been shown that there is a significant relevant relationship between the stress increment of unbonded prestressing tendons and beam load of prestressed composite beams with corrugated webs,that is to say,a regression formula of the stress increment of unbonded prestressing tendons can be established by sectional parameters such as reinforcement index. Parametric analysis reveals that for prestressed composite beams with corrugated webs having flexural failure mode,the major parameters which influence the ratio of stress increment of unbonded prestressing tendons to that of bonded non-prestressing reinforcement include: the rebars yield strength and reinforcement ratio of concrete flange in tension,the yield strength and area of steel flange plate,the strength of concrete,and the ratio of concrete flange thickness to beam depth,whereas the strength and thickness of corrugated webs,the initial stress and area of prestressing tendons,and span-to-depth ratio have little influence. By massive computational analysis,the ratio of stress increment of unbonded prestressing tendons to that of bonded non-prestressing reinforcement was established,and the calculation method of stress increment of unbonded prestressing tendons when prestressed concrete beams with corrugated webs yields was also presented. The calculation results have good precision.