Effective Lengths Of Compressed Members In Multi-planar Tubular Truss With Simple Joints

The tubular truss with multi-planar simple joints is used more and more popularly. In order to ensure the stability of this type of structure, buckling of single compressed member must be analyzed, which is represented by the concept of member's effective length. Therefore, reasonable effective lengths of compressed chords and braces are necessary and important to make sure the structure's security and to make full use of the material's mechanical property.In the design code of steel structure in our country, there are only specifications about effective lengths of compressed members in plane truss with common sections, the proposals of members in tubular truss are not specified.Simple joints in multi-planar tubular truss usually act as constraints to the compressed members, which decrease the members' effective lengths. This paper researched the compressed chords and braces in multi-planar triangle tubular truss(including circular hollow sections and rectangular hollow sections), analyzed many factors influencing the effective lengths and compared the values in multi-planar truss with them in plane truss. At last, the suggestion values of effective lengths were presented.