前言采用薄腹板以尽力减小恒载的预应力I字梁和箱型梁在结构中已被广泛地使用。由于承受剪力而在薄腹板中导致很大的斜向压应力,极可能使这种梁产生以腹板压碎方式的剪切破坏。当这样的梁以位于腹板中的钢束予以后张时,腹板混凝土的一个相当的宽度被预应力管道所取代了。因而,腹板的抗压强度可能成为控制梁的抗剪能力的关键。早已认识到,预应力管道的存在降低了 Pre-stressed prestressed I-beams and box beams with thin webs to minimize dead load are widely used in structures. Due to the shearing forces which cause a large diagonal compressive stress in the thin web, it is very likely that this beam will have shear failure by web crushing. When such a beam is tensioned by the steel beam in the web, a considerable width of web concrete is replaced by the prestressed pipe. Thus, the compressive strength of the web may be the key to controlling the shear capacity of the beam. It has long been recognized that the presence of prestressed pipes is reduced