Sloped multi‐roller isolation devices for seismic protection of equipment and facilities

Wang, Shiang‐Jung; Hwang, Jennie S.; Chang, Kuo‐Chun; Shiau, Chia-Yi; Lin, Wan-Wan; Tsai, Ming-Rung; Hong, Jia-Xiang; Yang, Yin-Han

doi:10.1002/eqe.2404

Cited by 43 publications

(42 citation statements)

References 17 publications

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“…The typical hysteretic behavior of sloped rolling‐type seismic isolators is shown in Figure . This important characteristic as well as the self‐centering and energy dissipation capabilities, have already been numerically and experimentally demonstrated in several past researches …”

Section: Introductionmentioning

confidence: 64%

“…The normal force required for built‐in sliding friction is produced by compression of linear spring modules installed in the side plates. This mechanism has been experimentally demonstrated in the researches of Wang et al Note that to prevent the undesired pounding between the rollers and inclined surfaces, an arc rolling range with a fixed curvature radius is designed at the intersection of two inclines of V‐shaped surfaces of bearing plates.…”

Section: Introductionmentioning

confidence: 99%

“…In the researches of Wang et al, on the basis of a simplified model shown in Figure , in which a cylindrical roller is sandwiched between two V‐shaped surfaces designed with different sloping angles under biaxial excitation, the exact generalized equation of motion for the horizontal dynamic behavior of sloped rolling‐type seismic isolators has been derived as given by

\begin{matrix} centertrue \\ (M + m_{1}) [1 + cos (θ_{1} - θ_{2})] {\overset{x}{true}}_{1} + \frac{(cos θ_{1} + cos θ_{2})}{2} [2 F_{D} sgn ({\dot{x}}_{1}) + (M + m_{1}) g (sin θ_{1} + sin θ_{2}) sgn (x_{1})] = \\ - \frac{(M + m_{1}) (cos θ_{1} + cos θ_{2})}{2} [{\overset{x}{true}}_{g} (cos θ_{1} + cos θ_{2}) + {\overset{z}{true}}_{g} (sin θ_{1} + sin θ_{2}) sgn (x_{1})], \end{matrix}

where M , m 1 , and m 2 are the seismic reactive masses of the protected object, superior bearing plate, and roller, respectively; r is the radius of the roller; θ 1 and θ 2 are the sloping angles of the superior and inferior bearing plates, respectively;

{\ddot{x}}_{g} ((), {\overset{z}{true}}_{g})

is the horizontal (vertical) acceleration excitation; x 1 ( z 1 ),

{\dot{x}}_{1} ((), {\overset{z}{true}}_{1})

, and

{\ddot{x}}_{1} ((), {\overset{z}{true}}_{1})

are the h...…”

Section: Introductionmentioning

confidence: 99%

“…A simplified model for sloped rolling‐type seismic isolators: (a) static condition; (b) free body diagrams when sgn( x 1 ) = sgn ( x 2 ) = 1 and

sgn ((), {\overset{x}{true}}_{1}) = sgn ((), {\overset{x}{true}}_{2}) = 1

…”

Section: Introductionmentioning

confidence: 99%

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Effects of design and seismic parameters on horizontal displacement responses of sloped rolling‐type seismic isolators

Wang

Cho

et al. 2019

Struct Control Health Monit

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Summary The influences of design parameters, including sloping angles of bearing plates and friction damping forces, together with seismic parameters, including corner periods and effective peak accelerations that are usually used for characterizing a design response spectrum, on the maximum horizontal displacement responses of sloped rolling‐type seismic isolators are numerically discussed in this study. Because the seismic isolators feature the constant acceleration control (or zero postelastic stiffness) performance, the equivalent linear model conventionally adopted in the equivalent lateral force procedure might not be adequate for predicting their maximum horizontal displacement response under a given seismic demand. Therefore, considering a small number to a large number of coefficients, several statistics‐based empirical formulas that are able to approximate their maximum horizontal displacement response are proposed. Not only the accuracy but also the conservative property of the proposed empirical formulas are discussed by comparing their predictions with the nonlinear response history analysis results. To efficiently determine the horizontal displacement capacity of sloped rolling‐type seismic isolators during the preliminary design stage, the statistics‐based empirical formula considering a reasonable number of coefficients is recommended.

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Section: Introductionmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

\begin{matrix} centertrue \\ (M + m_{1}) [1 + cos (θ_{1} - θ_{2})] {\overset{x}{true}}_{1} + \frac{(cos θ_{1} + cos θ_{2})}{2} [2 F_{D} sgn ({\dot{x}}_{1}) + (M + m_{1}) g (sin θ_{1} + sin θ_{2}) sgn (x_{1})] = \\ - \frac{(M + m_{1}) (cos θ_{1} + cos θ_{2})}{2} [{\overset{x}{true}}_{g} (cos θ_{1} + cos θ_{2}) + {\overset{z}{true}}_{g} (sin θ_{1} + sin θ_{2}) sgn (x_{1})], \end{matrix}

{\ddot{x}}_{g} ((), {\overset{z}{true}}_{g})

is the horizontal (vertical) acceleration excitation; x 1 ( z 1 ),

{\dot{x}}_{1} ((), {\overset{z}{true}}_{1})

, and

{\ddot{x}}_{1} ((), {\overset{z}{true}}_{1})

are the h...…”

Section: Introductionmentioning

confidence: 99%

“…A simplified model for sloped rolling‐type seismic isolators: (a) static condition; (b) free body diagrams when sgn( x 1 ) = sgn ( x 2 ) = 1 and

sgn ((), {\overset{x}{true}}_{1}) = sgn ((), {\overset{x}{true}}_{2}) = 1

…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of design and seismic parameters on horizontal displacement responses of sloped rolling‐type seismic isolators

Wang

Cho

et al. 2019

Struct Control Health Monit

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“…Base isolation has been recognized as a solution for enhanced functionality of important structures, and applications have grown significantly in the past three decades [2][3][4][5][6][7][8][9]. In Japan, the construction of base-isolated building structures increased rapidly after the 1995 Kobe earthquake, and by 2010, there were more than 2500 such buildings.…”

Section: Introductionmentioning

confidence: 99%

Disorder and damage of base‐isolated medical facilities when subjected to near‐fault and long‐period ground motions

Shi

Kurata

Nakashima

2014

Earthq Engng Struct Dyn

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SUMMARY A series of full‐scale shaking table tests were conducted at E‐Defense for a four‐story base‐isolated hospital. The operation room in the specimen was chosen for detailed examination of its disorder and damage during large ground motions. It was arranged with various medical appliances in as a realistic manner as possible, and the appliances were characterized by casters installed at the bottom to ensure mobility. Two types of ground motion, the near‐fault ground motion and long‐period ground motion, were adopted, and the responses of the appliances were recorded using the motion capture technique. Thanks to the base isolation, the floor response was greatly reduced, and no disorder or damage was observed in the operation room except for the case when subjected to a long‐period ground motion. In this case, the unlocked appliances moved seriously (by more than 3 m), and collisions occurred between the appliances and between appliances and the surrounding wall. The force of collision reached 36 kN, which is sufficient to injure a person. The acceleration due to collision was as high as 10 g, which is far beyond what can be tolerated by acceleration‐sensitive appliances. It is notable that such large motion was not observed once the appliances were locked. The test was also carried out for the corresponding fixed‐base structure. Among all cases in the experiment, by far the most serious damage occurred in the fixed‐base structure when subjected to the near‐fault ground motion, clearly because the floor response was significantly amplified from the ground motion. Copyright © 2014 John Wiley & Sons, Ltd.

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An isolation system for limited seismic gaps in near‐fault zones

Ismail

2014

Earthq Engng Struct Dyn

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SUMMARYThe ability of a recently proposed seismic isolation system, with inherent self-stopping mechanism, to mitigate or even eliminate seismic pounding of adjacent structures is investigated under severe nearfault earthquakes. The isolation system is referred to as roll-in-cage (RNC) isolator. It is a rolling-based isolator that provides in one unit the necessary functions of vertical rigid support, horizontal flexibility with enhanced stability, hysteretic energy dissipation, and resistance to minor vibration loads. In addition, the RNC isolator is distinguished by a self-stopping (buffer) mechanism to limit the bearing displacement under excitations stronger than a design earthquake or at limited seismic gaps, and a linear gravity-based self-recentering mechanism to prevent permanent bearing displacement without causing vertical fluctuation of the isolated structure. A previously developed multifeature SAP2000 model of the RNC isolator is improved in this paper to account for the inherent buffer mechanism's damping. Then, the effectiveness of the isolator's buffer mechanism in limiting peak bearing displacements is studied together with its possibly arising negative influence on the isolation efficiency. After that, the study investigates how to alleviate or even eliminate those possibly arising drawbacks, due to the developed RNC isolator's inner pounding as a result of its buffer activation, to achieve efficient seismic isolation with no direct structure-to-structure pounding, considering limited seismic gaps with adjacent structures and near-fault earthquakes. The results show that the RNC isolator could be an efficient solution for aseismic design in near-fault zones considering limited seismic gaps. Earthquake Engineering and Structural Dynamics.

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Sloped multi‐roller isolation devices for seismic protection of equipment and facilities

Cited by 43 publications

References 17 publications

Effects of design and seismic parameters on horizontal displacement responses of sloped rolling‐type seismic isolators

Effects of design and seismic parameters on horizontal displacement responses of sloped rolling‐type seismic isolators

Disorder and damage of base‐isolated medical facilities when subjected to near‐fault and long‐period ground motions

An isolation system for limited seismic gaps in near‐fault zones

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