The Behavior of a Steel Connection Equipped with the Lead Extrusion Damper

Abstract

The seismic behavior of the steel connection equipped with the lead extrusion damper (LED) is examined through the experimental and analytical studies. The LED implemented has spherical type bulge and does not consist any lubricant layer. The experimental study is performed in Structural and Earthquake Engineering Laboratory of Istanbul Technical University (STEELAB). In the experimental part, force-displacement relations of the connections with and without LED are achieved for the reversal displacement cycles. The measures of the dissipated energy, the equivalent damping ratio and the effective stiffness are obtained from the experimental study and compared for the connections. The total energy dissipated by the connection with the LED is approximately 175% greater than the total energy dissipated by the bare connection. In the analytical part of the study, nonlinear dynamic time history analyses are performed for the selected earthquakes and mass condition using the analytical models for the connections with and without LED. The maximum top displacement decreases approximately 50% for the connection equipped with the LED respect to the bare connection for the considered earthquakes. The maximum value of restoring force for the connection equipped with LED is approximately 25% greater than the bare connection for the accomplished analyses. Finally, the LED responses obtained in the nonlinear time history analyses are compared with the isolated LED test results.

Design and Experimental Assessment of a Prestressed Lead Damper with Straight Shaft for Seismic Protection of Structures

“…The HF2V technology was practically employed in the Kilmore Street Medical Center in New Zealand, where the HF2V devices were used to develop a hybrid system, called the "Advanced-Flag Shape" system, to allow controlled rocking of the structure [27]. Further research on this technology was carried out by Soydan [14][15][16][17], Patel [36,37], Yang [37,38] and Quaglini [10,11]. The application of HF2V devices in structural connections of both precast structures and steel structures was studied in [29,33,35].…”

“…The damper dissipates the input energy through the friction activated between a lead core and a steel shaft and achieves high specific dissipation capability through prestressing the working material. Differently from lead dampers proposed in the past [13][14][15][16][17][18], the operation of the novel device, which is called the prestressed lead damper with straight shaft (or PS-LED), is based on friction solely and does not exploit the extrusion of lead through an orifice, which mitigates the cyclic degradation of the response, eases the design and the construction and reduces production costs. The performance of the damper is assessed experimentally to evaluate the damping capability and the robustness during repeated cycles and to verify the compliance with the requirements of the European standard EN 15129 for displacementdependent devices [19].…”

Development of Finite Element Model for a Special Lead Extrusion Damper

“…Hence, it was also utilized in some base isolation systems [10][11][12]. Lead extrusion damper (LED) which is a passive EDD also benefits from the metallurgical properties of lead [13][14][15][16][17][18][19]. LED dissipates the energy by extrusion of lead through a hole or an orifice.…”

“…The LED comprises lead, a tube, a cap, and a bulged shaft, Figure 1. Even though the behavior of LED was determined experimentally in the literature [13][14][15], the finite element model of the damper is crucial for the prediction of behavior, especially for LEDs with distinct geometric dimensions. LED is difficult to model by finite elements since lead rapidly gains back its original characteristics, [20].…”

“…The rationale of the study is the development of a three-dimensional detailed finite element model of LEDs that were tested (T-LED), [13][14][15][16][17][18][19], and studied in the literature (L-LED), [21][22]. To this extent, numerically obtained force-displacement hysteresis of T-LED and the maximum force of L-LED were compared with the related experimental results.…”