Column base structure

Abstract

In a column base structure provided with a column base portion in which a joint metal fitting arranged above a base concrete is fixed to an anchor bolt protruding upward from the base concrete, and a column member which is joined its lower end portion to an upper surface of the joint metal fitting, a design basis strength F 1 ′ of the joint metal fitting is smaller than a design basis strength F 2 of the column member, a bending bearing force of the column base portion is smaller than an index bending bearing force of the column member which is calculated by multiplying a bending bearing force of the column member by a value obtained by dividing the design basis strength F 1 ′ by the design basis strength F 2 , and the column base portion yields before the column member according to an increase of the load applied to the column base structure.

What is claimed is: 
     
         1 . A column base structure comprising:
 a column base portion in which a joint metal fitting arranged above a base concrete is fixed to an anchor bolt protruding upward from said base concrete; and   a column member which is joined its lower end portion to an upper surface of said joint metal fitting,   wherein a design basis strength of said joint metal fitting is smaller than a design basis strength of said column member,   wherein a bending bearing force of said column base portion is smaller than an index bending bearing force of said column member which is calculated by multiplying a bending bearing force of said column member by a value obtained by dividing the design basis strength of said joint metal fitting by the design basis strength of said column member, and   wherein said column base portion yields before said column member according to an increase of the load applied to said column base structure.   
     
     
         2 . The column base structure according to  claim 1 , wherein said joint metal fitting is formed into a plate shape which has both front and back surfaces and a uniform thickness. 
     
     
         3 . The column base structure according to  claim 1 , wherein said joint metal fitting has a bottom plate portion which has both front and back surfaces and a uniform thickness, and is formed into a plate shape, and a support table portion which has a height toward an upward direction in an inner side of a peripheral edge portion of an upper surface of the bottom plate portion, and a lower end portion of said column member is joined to an upper surface of the support table portion.