Spectral analysis and design approach for high force‐to‐volume extrusion damper‐based structural energy dissipation

Abstract

High force‐to‐volume extrusion damping devices can offer significant energy dissipation directly in structural connections and significantly reduce seismic response. Realistic force levels up to 400 kN have been obtained experimentally validating this overall concept. This paper develops spectral‐based design equations for their application. Response spectra analysis for multiple, probabilistically scaled earthquake suites are used to delineate the response reductions due to added extrusion damping. Representative statistics and damping reduction factors are utilized to characterize the modified response in a form suitable for current performance‐based design methods. Multiple equation regression analysis is used to characterize reduction factors in the constant acceleration, constant velocity, and constant displacement regions of the response spectra.With peak device forces of 10% of structural weight, peak damping reduction factors in the constant displacement region of the spectra are approximately 6.5 ×, 4.0 ×, and 2.8 × for the low, medium, and high suites, respectively. At T = 1 s, these values are approximately 3.6 ×, 1.8 ×, and 1.4 ×, respectively. The maximum systematic bias introduced by using empirical equations to approximate damping reduction factors in design analyses is within the range of +10 to −20%. The seismic demand spectrum approach is shown to be conservative across a majority of the spectrum, except for large added damping between T = 0.8 and 3.5 s, where it slightly underestimates the demand up to a maximum of approximately 10%. Overall, the analysis shows that these devices have significant potential to reduce seismic response and damage at validated prototype device force levels. Copyright © 2007 John Wiley & Sons, Ltd.

Performance of a damage‐protected beam–column subassembly utilizing external HF2V energy dissipation devices

“…In response to these objectives, a high force-to-volume (HF2V) lead-extrusion damper was developed [13,14]. The HF2V damper is a relatively simple device, as illustrated in Figure 1.…”

“…When the shaft moves, the bulge displaces the lead from one side of the bulge to the other and is capable of sustaining a constant force upon 43 yielding, similar to the behaviour of the mild steel energy dissipation devices. These devices have been shown to be relatively insensitive to velocity [14], with a relationship between damper force and velocity defined: 1…”

“…where F is the damper force; C a constant dependent on device architecture; v the velocity of 3 the shaft; and the velocity component, which can be taken as 0.12 [13,14]. The compact HF2V devices are based on the original lead-extrusion dampers developed by 5…”

“…These early devices were quite large (1-2 m long for 100+ kN capacity), limiting their use to specific applications such as base isolation [16]. In contrast, the 7 unique aspect of the HF2V devices is their ability to fit into tight volumetrically constrained applications, such as directly into beam-column joints [13,14]. More specifically, 100-350 kN 9 devices have been built that are 120 mm long, with a 100 mm outside diameter of the confining cylinder, considerably smaller than other devices of similar capacity [13].…”

“…The experimental testing is intended to confirm the 13 benefits of such devices when incorporated into ductile-jointed connections. In addition, results can be compared with the spectral analyses and design guideline predictions developed for these 15 devices [13,14].…”