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Current research on tall buildings design has shown the need for multi‐hazard approaches in numerous practical cases. To improve the performance under hazard‐related horizontal loads, supplemental damping devices emerge as an efficient solution. For example, passive tuned massive dampers (TMDs) have been used in tall buildings for decades. However, since earthquakes and winds mobilize the structures in different ways, the multi‐hazard design of TMDs remains a difficult task. Thus, adaptive devices are an encouraging solution for this purpose. This research proposes an efficient use of existing semi‐active TMDs that were proposed for other purposes through tuning them exclusively to two sets of frequency and damping ratio: a set for seismic loads and a set for wind loads. These bi‐tuned STMDs would behave as passive dampers during any hazard event, but with an appropriate tuning. Because mechanical properties switch only at the beginning and at the end of seismic events, the control system required would be simple and reliable. An optimization‐based methodology is proposed to design multiple BSTMDs. The total added mass is minimized, while the building life‐cycle cost (LCC) is selected as a performance constraint. An efficient gradient‐based algorithm, originally developed for passive TMDs, is adapted for BSTMDs. Two problem formulations are proposed, to allow distinct design alternatives. The devices design is illustrated by four case studies. The examples show that BSTMDs may provide the same performance of their passive counterparts, using less than half of their total added mass.

In the last decades, much research has been dedicated to developing methodologies to optimize dampers for wind or seismic control. However, little investigation has been performed to deal with multi-hazard demands. Nevertheless, previous works have shown that from a life-cycle loss perspective winds and earthquakes may be equally relevant to many tall buildings. Thus, methodologies for multi-hazard loss optimization of tall buildings with dampers are of much need. To join these hazards in a sole optimization procedure, we adopt the life-cycle cost (LCC) resultant from wind and earthquakes as a unified design criterion. This work presents a multihazard optimization methodology of Tuned Mass Dampers (TMDs) in tall buildings. The methodology is applied to a 76-story building, employing the LCC as objective function. A Multiple TMDs system composed of four TMDs is considered on the top floor, assigned to dampen the first four modes. The TMDs mass, damping ratio and frequency are taken as design variables, and different constraints are imposed on the total added mass and individual TMDs frequencies. The linear dynamic analysis results are used to calculate the LCC through a platform based on the PEER equation. An efficient genetic algorithm combined with a pattern search algorithm permits to achieve the optimal solutions. A purely intuitive MTMDs design based on modal analysis would suggest largest masses should be assigned to the dominant modes. However, the results reveal this rationale could be misleading, demonstrating the need for optimization techniques to obtain adequate dampers designs. This innovative design procedure can improve long-time performance and deliver an optimal design from economic standpoint.

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