ABSTRACT
Test results of composite lattice girders of RHS and I-section members with concrete slabs and their companion steel girders under cyclic anti-symmetrical bending loads are summarized. Beneficial restraining effects of concrete slabs include: the upper chord is prevented from buckling; although one end of the lower chord buckles laterally, the effective length factor is reduced; and the other end of the lower chord is forced to yield in tension. Thus, composite lattice girders show stabler hysteretic behavior over steel girders. Simple design formulas for evaluating the elastic stiffness, ultimate flexural and plastic deformation capacities are proposed.
