预弯复合梁在反复荷载作用下正截面强度的试验研究

本文根据跨度为１２．０ｍ的预弯复合梁（即预应力劲性砼梁）足尺试验结果，观察梁在反复荷载作用下裂缝发生、发展及闭合规律，测定梁的挠度、截面应变与作用荷载的关系，得出了预弯复合梁开裂后刚度随作用荷载的衰减规律，有效截面的几何形心随作用荷载的移动规律，从而得出预弯复合梁开裂后刚度及强度的实用计算式。它与国外现行规范相比，物理概念明确，计算结果更接近梁开裂后的实际工作状态。

Experimental Study on Flexural Strength of Preflexed Composite Beams under Repeated Load

In this paper, according to the lost results of a full-scale preflexed composite beam with a span of 12m, the regularity of crack occurrence,its development and closing up as well as the strain distribution of the beam under repeated load have been obtained. The regularity of attenuation of beam stiffness along with the load after the cracking of the preflexed composite beam and the variation regularity of the cross-sectional geometrical center along with the load are then obtained as well. Lastly, the practical stiffness and strength calculation formulas for preflexed composite beam after cracking are established. These formulas have a wide range of application and a clear physical concept. The calculation result bears a better approach to the actual working state of beam than that obtained by the method given in foreign specification.