Constrained optimal design of seismic base absorbers based on an extended KDamper concept

In this paper, an extended KDamper (EKD) concept is proposed, for implementation as a seismic base absorber. The complexity of the EKD renders the conventional minmax (H infinity) approaches ineffective. For this reason, a dedicated constrained optimization problem is proposed for the selection of the optimal system parameters. The EKD is designed according to seismic design codes and the constraints and limitations of the EKD components are evaluated based on engineering criteria. In order to better observe the efficiency of the proposed configuration, an acceleration filter is placed, as an additional constraint. Therefore, each set of optimized parameters of the EKD refers to the maximum structure acceleration, expressed as a percentage of PGA. A database of artificial accelerograms, compatible with the EC8 response spectra is generated. Sensitivity analysis is performed, and the effect of detuning is observed. Subsequently, the EKD is implemented as a seismic base absorber in a multi-story building. The performance of the proposed control strategy is compared not only to the original structure but also to the cases of conventional and highly damped base isolation systems, as well as to the KDamper. The EKD presents an improved superstructure dynamic behavior, comparable with a base isolated system. At the same time, the base relative displacement is drastically reduced, in the order of a few centimeters, rendering the implementation of the EKD feasible using conventional structural elements, without the need for special types of bearings. In addition, the base shear is reduced, as compared to the original structure, with the implementation of the proposed configuration, and thus, EKD can be considered a possible retrofitting option for seismic protection.

Automated summary

This study introduces a new concept of extended KDamper (EKD) as a seismic base absorber, which aims to reduce base relative displacement and base shear in a multi-story building by optimizing parameters and implementing acceleration filtering.