扩展基础冲剪破坏特征试验研究

通过10个基础模型试验，研究了钢筋混凝土扩展基础的冲剪破坏特征和破坏规律。试验结果表明，当基础宽度大于柱宽加两倍基础有效高度时，将发生冲切破坏；当基础宽度小于或等于柱宽加两倍基础有效高度时，若基础底板只配置抗弯钢筋时，基础将发生剪切破坏；当基础板按梁式配筋时，基础将发生弯曲破坏，在基础尺寸、底面纵筋相同时，柱下条形基础按基础梁配筋与按板式配筋相比，基础的延性性能和承载力都将有较大提高。建议在柱下条形基础设计时按基础梁的形式进行配筋，以避免基础发生脆性的剪切破坏。

Experimental study of shear failure characteristics of spread foundations

The shear failure characteristics and failure law of spread foundations are researched by tests on ten model foundations. The results show that punching shear failure of foundations will occur when the width of foundation is greater than the width of column plus double effective height h0 of the foundation. When the width of foundation is less or equal to the width of column plus double h0, shear failure will occur if only arranging bending reinforcement; and bending failure will occur if arranging reinforcement according to beam. The ductility and bearing capacity of strip footing under column will increase considerably comparing with raft foundations when the size of foundation and longitudinal reinforcements are identical. The arrangement of reinforcement of strip footing under column should design according to that of beams are suggested, so as to avoid brittle shear failure of foundations.