Dynamic Analysis of Staggered Truss Framing System

A procedure for evaluating the lateral response of staggered truss framing system subjected to a prescribed base motion is developed for use on a digital computer. Actual trusses of the system are represented by equivalent trusses, having the same lateral stiffness and strength as the actual trusses but fewer members. The inelastic activity is restricted to the chord members in the central panel of the trusses. The moment-rotation behavior at the ends of these chord members is assumed to be of a bilinear hysteretic type with the stiffness in the yield region taken as 5% of the elastic stiffness. A 20-story structure designed by current code procedure and subjected to 1.5 times the El Centro earthquake of 1940 is analyzed. The results indicate that the columns in the system are primarily axial force carrying members with very small end moments and there is substantial inelastic activity in the trusses.