外包式钢柱脚的设计方法

Design method of wrapped steel column base

钢柱脚是钢结构中的重要节点,其作用为将柱下端的剪力、轴力以及弯矩(刚接柱脚)传递给基础,使钢柱与基础有效地连接在一起,进而保证上部结构能够承受各种外力作用。抗震设计时,在有地下室的高层民用建筑中常采用外包式钢柱脚。与外露式钢柱脚不同的是,外包式钢柱脚的柱脚弯矩是由外包层混凝土和钢柱脚共同承担,且该节点用于抗震设防7~9度地区时,除应按地震组合内力进行弹性设计验算外,还应进行极限承载力验算。本文结合一工程实例,具体说明外包式钢柱脚节点的受压、受弯、受剪承载力计算及相关构造要求。

Column base is an important node in the structure.Its function is to transfer the axial force,shear force and bending moment(rigid column base)at the lower end of the column to the foundation,so as to effectively connect the steel column with the foundation and ensure that the superstructure bears various external forces.In seismic design,outsourcing steel column base is often used in high-rise civil buildings with basement.Different from the exposed steel column base,the column base bending moment of the wrapped steel column base is jointly borne by the concrete of the outer layer and the steel column base.When the joint is used in the area with seismic fortification of 7~9 degrees,in addition to the elastic design checking calculation according to the seismic combined internal force,the ultimate bearing capacity checking calculation shall also be carried out.Combined with an example,this paper explains the calculation of compression,bending and shear bearing capacity of wrapped steel column base joints and relevant structural requirements.