Towards understanding, estimating and mitigating higher-mode effects for more resilient tall buildings

Rapid urbanization has resulted in increased demand for tall buildings in many large and medium-sized cities around the world. Current code-based standards for seismic design are primarily aimed at minimizing life-safety risks under major earthquakes. While reinforced concrete (RC) high-rise buildings designed following current code requirements are expected to achieve collapse-prevention, the contribution of higher modes of vibrations to the dynamic response of these structures can produce seismic demands significantly larger than those obtained from prescriptive code-based procedures, causing unexpectedly higher structural and non-structural damage to these buildings. These imply considerable costs associated with the loss of residences and business operations as well as the post-earthquake recovery of cities. This paper presents a concise review of the current state-of-the-art and state of research pertaining to the understanding, estimation and mitigation of higher-mode effects on the seismic response of tall and slender RC structures. The paper is organized into four main foci: (1) analytical studies on understanding and quantifying higher-mode effects, (2) available experimental work on this topic, (3) advances in code practices in accounting for higher-mode effects in seismic design of RC tall buildings, and (4) recent developments in innovative systems intended to mitigate higher-mode effects in RC tall buildings. The paper concludes by briefly summarizing future challenges facing the construction of earthquake-resilient RC tall buildings that are essential in building resilient cities of the future.