Seismic Design of Tall Steel Buildings

Earthquake-resistant design of buildings is very complex and is perhaps the most challenging and awesome problem in structural engineering. The magnitude of a major earthquake at a given site at best can only be roughly approximated. The dynamic nature of the problem, including soil-structure interaction effects, adds to the complexity of the problem. Moreover, for reasons of economy, building frames cannot be overly conservatively designed. The strength limit state at presumed extreme loading conditions during the intended life of the structure is the dominant criterion. In this strength limit state some damage to the structure can be tolerated. However, “the overriding considerations of public safety for life, limb and property of human beings” (AISC, 1984) must be strictly adhered to. For these reasons, the steel frames, as designed, do not respond in an elastic manner during a massive earthquake and are expected to develop inelastic action in many of the members and connections. Only very recently our analytical capabilities reached a stage of development where such behavior can be corroborated reasonably well by test results and as yet has not received any significant use in practice.