Life-cycle cost optimization of tuned mass dampers for tall buildings subjected to winds and earthquakes

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.