Torsion effect evaluation of the staggered truss steel framing

According to the composition characteristics of staggered truss steel framing under lateral loads, the calculating formula of the torsional effect coefficient is derived, and investigate whether the clause 3. 2. 2 of the Chinese Technical specification for steel structure of tall buildings JGJ 99-98 is applicable to the staggered truss steel framing or not. The calculating result indicates that the staggered truss steel framing system is a plane irregular structure essentially, the clause 3. 2. 2 is not applicable to the staggered truss steel framing, and the torsional influence should be considered, especially when the building length-width ratio is smaller than 5.