Optimal Viscous Damper Placement for Elastic-Plastic MDOF Structures Under Critical Double Impulse

Hiroki Akehashi,Izuru Takewaki

doi:10.3389/fbuil.2019.00020

Hiroki Akehashi, Izuru Takewaki

Open Access

https://doi.org/10.3389/fbuil.2019.00020

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Abstract

A new method for optimal viscous damper placement is proposed for elastic-plastic multi-degree-of-freedom (MDOF) structures subjected to the critical double impulse as a representative of near-fault ground motions. The double impulse consists of two impulses with different directions and the critical interval between those two impulses is characterized by the criterion on the maximum input energy that is expected to lead to the maximum deformation. The critical timing of the second impulse is the timing at which the sum of the restoring force and the damping force in the first story attains zero. The objective function and constraint in terms of the maximum interstory drift along the building height or the sum of the maximum interstory drifts in all stories are selected and the corresponding optimization algorithm based on time-history response analysis and sensitivity analysis is investigated. Since the objective function in terms of the sum of the maximum interstory drifts in all stories is superior to the objective function in terms of the maximum interstory drift along the building height, it is employed in this paper. A new concept of double impulse pushover (DIP) is proposed for determining the input velocity level of the critical double impulse. It is demonstrated that the combination of two algorithms, one for effective reduction of the overflowed maximum interstory drift via the concentrated allocation of dampers and the other for effective allocation of dampers via the use of stable objective function, is effective for finding a stable optimal damper placement.

Highlights

Viscous dampers such as oil dampers are passive dampers effective for broader amplitude ranges under the condition that the stiffness is not added
A new method for optimal viscous damper placement is proposed for elastic-plastic MDOF shear building structures subjected to the critical double impulse as a representative of near-fault ground motions
It can be observed that, while the analysis in the elastic range is not easy by Algorithm 1 for Problem 1 owing to the inability to set the total damper quantity and the maximum interstory drift distribution of the final model obtained by Algorithm 2 for Problem 2 is unstable depending on the model, a stable damper allocation is possible by Algorithm 3 for Problem 3 regardless of the input velocity level of the critical double impulse and the final maximum interstory drift distributions are apt to become uniform

Summary

Introduction

Viscous dampers such as oil dampers are passive dampers effective for broader amplitude ranges under the condition that the stiffness is not added. Shiomi et al (2018) investigated a problem of optimal hysteretic damper placement for elastic-plastic multi-degreeof-freedom (MDOF) shear building models under the double impulse as a representative of near-fault ground motions and proposed a sensitivity-based method.

Results

Conclusion