在钢筋砼平屋顶与砖砌体承重的混合结构中,内横墙顶部出现八字形裂缝较为普遍。为了探讨这类裂缝形成的机理笔者进行定性分析。一、裂缝的特征 1.正八字裂缝部位一般靠近外墙,在第一块预制板与檐口板一起现浇的部分顶板之间形成一条纵向通长的裂缝,该裂缝与内横墙两端正八字形裂缝相连通(见图一)。裂缝宽度一般约0.3～4mm,最大的可达到20mm左右,个别工程出现内横墙与顶板之间的水 In the reinforced concrete flat roof and brick load-bearing structure, the top of the horizontal cross-wall crack appears more common. In order to explore the mechanism of the formation of such cracks I conduct qualitative analysis. First, the characteristics of cracks 1. Positive eight-character crack site is generally close to the outer wall, the first prefabricated panels and cornices together with the cast-in-part of the roof to form a long vertical cracks, the cracks and both ends of the crossbar eight Glyph cracks connected (see Figure I). Crack width is generally about 0.3 ~ 4mm, the maximum can reach 20mm or so, some works appear between the horizontal wall and the roof of the water