NEHRP Clearinghouse

Optimal Design of Localized Nonlinear Systems with Dual Performance Criteria Under Earthquake Excitations.
Bhatti, M. A.
National Science Foundation, Washington, DC., July 1979, 110 p.
Identifying Number(s)
This report presents a formulation for earthquake-resistant design of localized nonlinear systems. Based upon the current design criteria, two levels of performance constraints are imposed as follows. For small earthquakes which occur frequently, the structure is constrained to remain elastic with no structural damage. For a large earthquake, the structure can undergo inelastic deformations at known locations of nonlinearities, with limited damage. The problem is formulated as a min-max problem, and a general strategy to transcribe it to the canonical form of a nonlinear programming problem is given. An algorithm of the feasible directions type is given to solve the resulting nonlinear programming problem. The general techniques are applied to the design of nonlinear energy-absorbing devices, which are part of an earthquake isolation system for many types of buildings. Several design problems with different performance criteria are considered and the results compared to see the effect of these different criteria. Comparison is also made with results reported earlier with only one level of constraints. The results clearly show the effectiveness of the present approach with dual performance criteria over the conventional single criterion approach.
Dynamic response; Computer programming; Ground motion; Nonlinear programming; Earthquake engineering; Earthquake resistant structures; Seismic design; Algorithms; Nonlinear systems; Minimax technique; Computer aided design; Dynamic structural analysis