Damage avoidance design of special truss moment frames with energy dissipating devices

An innovative concept using energy dissipating devices, such as buckling restrained braces (ORB), is proposed for special truss moment frames (STMF). The configuration of the proposed system consists of pins introduced at the ends of the top and bottom chord elements of the special segments. Subsequently, energy dissipating devices are used in the form of diagonal braces inside the special segments. An energy-based design methodology is adopted such that the BRBs are designed to provide sufficient energy dissipation capacity with respect to seismic input energy demand on the structure. This energy-based methodology is demonstrated to be accurate by means of a series of nonlinear time-history analyses. The overall seismic response of the proposed system is contrasted with the conventional STMF in terms of story displacements, interstory drifts, story shears and overturning moments, as well as observed damage to structural elements. The proposed system leads to more predictable seismic response and would potentially allow lighter construction and significant cost savings, due to significantly reduced member forces (up to 50% compared with conventional design). Furthermore, damage to structural elements is largely mitigated, hence allowing damage avoidance design of STMFs. (C) 2008 Elsevier Ltd. All rights reserved.