Re-shaping hysteretic behaviour using semi-active resettable device dampers

The seismic performance of a test structure fitted with semi‐active resetable devices is experimentally investigated. Shaking table tests are conducted on a ⅕th scale four‐storey building using 27 earthquake records at different intensity scalings. Different resetable device control laws result in unique hysteretic responses from the devices and thus the structure. This device adaptability enables manipulation or sculpting of the overall hysteresis response of the structure to address specific structural cases and types. The response metrics are presented as maximum 3rd floor acceleration and displacement, and the total base shear. The devices reduce all the response metrics compared with the uncontrolled case and a fail‐safe surrogate. Cumulative probability functions allow comparison between different control laws and additionally allow tradeoffs in design to be rapidly assessed. Ease of changing the control law in real‐time during an earthquake record further improves the adaptability of the system to obtain the optimum device response for the input motion and structural type. The findings are an important step to realizing full‐scale structural control with customized semi‐active hysteretic behaviour using these novel resetable device designs. Copyright © 2008 John Wiley & Sons, Ltd.

Section: Introductionmentioning

confidence: 56%

Section: Resetable Devicesmentioning

confidence: 99%

Section: Resetable Device Control Law Definitionmentioning

confidence: 99%

Section: Resetable Devicesmentioning

confidence: 99%

Section: Resetable Devicesmentioning

confidence: 99%

See 3 more Smart Citations

Experimental validation of semi‐active resetable actuators in a ⅕th scale test structure

Mulligan¹,

Chase²,

Mander³

et al. 2008

Spectral analysis for a semi‐active–passive net‐zero base‐shear design concept

Rodgers

Chase

Roland

et al. 2011

Passive high force-to-volume (HF2V) dampers offer significant displacement reduction and energy dissipation, but cannot customise overall response. Semi-active resettable devices offer adaptive, custom hysteresis loops that reduce displacement and base shear, but have limited dissipation. This paper presents a new, combined concept to maximise displacement reduction without increasing base sheara net-zero base-shear concept.HF2V devices, up to a maximum of 10% structural weight, are combined with fixed stiffness resettable devices. Spectral analyses are run for the three SAC ground motion suites that iteratively size the HF2V device at each structural period to achieve maximum displacement reductions without increasing median base shear. HF2V velocity dependence and the need to scale HF2V capacity to spectral velocity are examined in terms of their impact on the results of these analyses.The net-zero approach reduces base shear by up to 50% and displacements by 30-70% over all ground motions, exceeding reductions obtained by either device separately by 30-50% (relative). The net-zero condition is not reached within the device limits defined, except at relatively long periods (>3.5 s) because of a virtuous circle of reduced displacement from the resettable and HF2V devices outweighing the increased base shear from the HF2V devices alone. These results are independent of HF2V device scaling, design and velocity dependence. The overall net-zero concept offers a significant advantage in a combination that cannot be achieved by passive or semi-active solutions alone.primarily to present the net-zero base-shear concept and the unique approach of specifically managing the base-shear demands of the structure. This investigation presents an initial framework for assessing the efficacy of the concept and presents some overall indicative results suitable for use in design and specification.

Damping reduction factors and code‐based design equation for structures using semi‐active viscous dampers

Hazaveh

Rodgers

Pampanin

et al. 2016

Self Cite

Summary This study uses a semi‐active viscous damper with three different control laws to reshape the structural hysteresis loop and mitigate structural response, referred to as 1–4, 1–3 and 2–4 devices, respectively. The 1–4 control law provides damping in all four quadrants of the force‐displacement graph (it behaves like a standard viscous damper), the 1–3 control law provides resisting forces only in the first and third quadrants, and the 2–4 control law provides damping in the second and fourth quadrants. This paper first outlines the linear single degree of freedom structural performance when the three types of semi‐active viscous dampers are applied. The results show that simultaneous reduction in both displacement and base‐shear demand is only available with the semi‐active 2–4 device. To enable guidelines for adding a 2–4 device into the design procedure, damping reduction factors (RFξs) are developed, as they play an important role and provide a means of linking devices to design procedures. Three methods are presented to obtain RFξ and equivalent viscous damping of a structure with a 2–4 semi‐active viscous damper. In the first method, the relationship between RFξ and the damping of a semi‐active structure can be obtained by calculating the area under the force‐deformation diagram. The second and third method modified the Eurocode8 formula of RFξ and smoothed results from analysis, respectively. Finally, a simple method is proposed to incorporate the design or retrofit of structures with simple, robust and reliable 2–4 semi‐active viscous dampers using standard design approaches. Copyright © 2016 John Wiley & Sons, Ltd.