中美规范扩展基础冲切与剪切计算差异

Differences between Calculations of Punching and Shearing of Spread Foundation Based on Chinese and American Codes

中国《建筑地基基础设计规范》和美国《Building Code Requirements for Structural Concrete(ACl318M-11)and Commentary》对扩展基础的冲切与剪切计算方法存在较大差异,其对基础冲切和剪切模式的划分、公式表达等方面均有不同,对计算结果也产生较大影响。本文对冲切和剪切进行了辨析,对中国规范和美国规范影响扩展基础冲切和剪切计算的因素进行对比分析,对基础冲切和剪切破坏机理认识上存在不同,导致在抗剪强度取值、计算条件、计算截面位置、荷载图形和位置等方面的规定存在一定差异,从而使得计算所得到的基础底板厚度有所不同。从算例计算结果看,基础高度由冲切控制,且美国规范冲切高度比中国规范冲切高度大。

There is a big difference in calculation methods for punching and shearing of spread foundation in Chinese'Code of Foundation Design for Buildings' and American 'Building Code Requirements for Structural Concrete( ACl318M- 11) and Commentary '. There are many differences in the two codes in terms of the demarcation of foundation punching and shearing modes and formula expression etc. which have a greater impact on calculation results. In this paper, punching and shearing are analyzed,and the factors affecting punching and shearing calculations of spread foundation based on Chinese code and American code are compared and analyzed. Different understanding of damage mechanisms of punching and shearing of foundation results in different stipulations for value selection of shear strength parameters,calculation conditions,calculation of section area location,load graphics and location and other aspects,so that the thickness of the foundation base plate by calculation is different. Looking at the results from the calculation example,the foundation height is controlled by punching, and the punching height of American code is larger than the punching height of Chinese code.