Optimal vertical configuration of combined energy dissipation outriggers

Abstract

The damped outrigger system emerged as an improvement of the conventional outriggers with the aim to provide supplemental damping and to contribute to the vibration control in super tall buildings where this system is usually applied. In addition to viscous dampers (VDs), buckling-restrained braces (BRBs) have also been employed as energy dissipating members in outriggers. Nevertheless, the combined use of outriggers with VDs and BRBs in the same structure has not yet been studied. Such combination can contribute to achieve an effective multiperformance design of super tall buildings. This paper presents a study whose main objective was to determine the optimal vertical combination of two types of energy dissipation outriggers to control the seismic responses of a 9-zone super tall model structure. Outriggers with VDs (OVDs) and outriggers with BRBs (OBRBs) were placed at the different zones of the structure considering all the possible combinations and in configurations of up to four outriggers. The effects of these combinations on the seismic performance of the structure were studied through parametric analysis and optimization methods. This form of the outrigger system is defined in this paper as combined energy dissipation outrigger system. The results indicate that when two energy dissipation outriggers are used, the combination of OBRB plus OVD shows superior seismic performance compared with other double-outrigger configurations. In addition, the results show that the locations of OVDs and OBRBs play an important role in the structure behavior; it was found that it is more beneficial to place OBRBs above OVDs.

Frequency domain-based analytical framework for seismic performance of viscously damped outrigger systems based on continuous Timoshenko beam theory

“…28 A more elaborated case study can be found in Lu et al 29 Subsequently, the 3D finite element analysis of such system equipped with viscous dampers or/and BRB were examined in Refs. 30–32. These studies further paved the way for applying damped outriggers in engineering practice.…”

Shaking table test of a damped‐outrigger system incorporating friction dampers

“…An 8.1‐m‐tall, reduced‐scale damped‐outrigger specimen utilizing BRB and viscous dampers was tested by shaking table experiments. [ 20 ] The test results suggested that when the specimen is equally divided into nine segments, the damped‐outriggers with BRB and viscous damper can be located at the seventh and the fifth segments from the ground, which is the optimal damped‐outrigger configuration to minimize the seismic response. The test results have also been verified by finite element analysis results.…”

Seismic Behavior of Virtual Outrigger System

“…R. J. Smith and Willford [7] proposed the concept of the damped-outrigger by inserting dampers between the outrigger truss end and the perimeter column to increase the damping, instead of increasing the stiffness. [8], [9], [10], [11], [12] investigated The efficiency of damped outrigger systems, [13], [14], [15] investigated damped-outrigger system incorporating buckling restrained braces. Virtual outriggers was proposed by R. Shankar Nair [16] and also called belt-truss system.…”