Effect of the Stick-Slip Phenomenon on the Sliding Response of Objects Subjected to Pulse Excitation

Nikfar, Farzad; Konstantinidis, Dimitrios

doi:10.1061/(asce)em.1943-7889.0001183

Cited by 24 publications

(16 citation statements)

References 56 publications

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“…However, this is not always the case. The amplification in displacement due to addition of resistance is highly correlated to the characteristics of the input excitation . For instance, if the floor acceleration cannot overcome the resistance, there will be no relative displacement/velocity whatsoever.…”

Section: Shake Table Testsmentioning

confidence: 82%

Shake table investigation on the seismic performance of hospital equipment supported on wheels/casters

Nikfar

Konstantinidis

2016

Earthq Engng Struct Dyn

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Summary This paper presents an experimental investigation on the seismic response of medical equipment supported on wheels and/or casters. Two pieces of equipment were tested: a large ultrasound machine and a cart carrying smaller medical equipment. In the first phase, the resistance of the wheels and casters of the equipment was characterized through a controlled‐displacement procedure on the shake table. In the second phase, an extensive shake table test program was carried out to investigate the seismic response of the equipment. The input signals for the shake table tests included floor motions of a four‐story steel braced‐frame hospital designed to satisfy seismic requirements of a site in the Los Angeles area. The results of 96 shake table tests reported in this study include the seismic performance of the equipment under both unlocked and locked conditions, located on various floor levels of the building. It was observed that engaging the casters' locking mechanism does not necessarily decrease the relative displacement. The displacement response was sensitive to the excitation intensity and the orientation of the equipment with respect to the input excitation. Based on the experimental observations, appropriate structural engineering demand parameters associated with the relative displacement and relative velocity demands of the equipment are proposed and used to develop conditional probability curves. Finally, in an effort to extend the results of this experimental study to similar equipment on wheels/casters, the performance of a simple numerical model in predicting the peak seismic demands is evaluated. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Shake Table Testsmentioning

confidence: 82%

Shake table investigation on the seismic performance of hospital equipment supported on wheels/casters

Nikfar

Konstantinidis

2016

Earthq Engng Struct Dyn

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“…In deriving Equation (38), since Ð F xi dt = 0, Equation (30), which involves the coefficient of restitution of the wall, is not applicable here according to the definition of impact. This, however, cannot ensure Equation (33) is automatically satisfied.…”

Section: There Is Sufficient Friction To Prevent Sliding During Impactmentioning

confidence: 99%

“…This, however, cannot ensure Equation (33) is automatically satisfied. Therefore, when the postimpact velocities computed from Equation (38) violate Equation (33), it is assumed that _ x 2 = RC + _ θ 2 to ensure compatibility. This leads to an indeterminate case since there are four conditions (ie, Equation (29), (31), (35), and _ x 2 = RC + _ θ 2 ) and only three unknowns (ie, _ x 2 , _ y 2 , _ θ 2 ), making it impossible to get a solution that satisfies all the conditions.…”

Section: There Is Sufficient Friction To Prevent Sliding During Impactmentioning

confidence: 99%

“…The sliding response of a rigid block, which represented building content, subjected to ground and floor excitation has been studied analytically at various levels by Choi and Tung, Lopez Garcia and Soong, Chaudhuri and Hutchinson, Konstantinidis and Makris, Voyagaki et al, Konstantinidis and Nikfar, Lin et al, Nikfar and Konstantinidis, and references therein. Nikfar and Konstantinidis investigated the effect of the stick‐slip phenomenon on the sliding response of rigid blocks using a Stribeck friction model.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of a sliding‐rocking block considering impact with an adjacent wall

Bao

Konstantinidis

2020

Earthq Engng Struct Dyn

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Summary A freestanding rigid block subjected to base excitation can exhibit complicated motion described by five response modes: rest, pure rocking, pure sliding, combined sliding‐rocking, and free flight. Previous studies on the dynamics of a rocking block have assumed that the block does not interact with neighboring objects. However, there are many applications in which the block may start or come in contact with an adjacent boundary during its motion, for example, a bookcase or cabinet colliding with a partition wall in an earthquake. This paper investigates the dynamics of a sliding‐rocking block considering impact with an adjacent wall. A model is developed in which the base and wall are assumed rigid, and impact is treated using the classical impulse and momentum principle. The model is verified by comparing its predictions in numerical simulations against those of an existing general‐purpose rigid‐body model in which impact is treated using a viscoelastic impact model. The developed model is used to investigate the effects of different parameters on the stability of a block subjected to analytical pulse excitations. It is found that wall placement (left or right) has a dominant effect on the shape of the overturning acceleration spectra for pulse excitations. In general, decreasing the gap distance, base friction coefficient, and wall coefficient of restitution enhance the stability of the block. Similar observations are made when evaluating the overturning probability of a block using earthquake floor motions.

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“…Sliding of such NSEs can result in economic loss and injury. The literature on these types of NSEs ranges from the closed-form and numerical solutions describing the sliding displacement of NSEs under base excitations *Corresponding Author Email: noroozinejad@kgut.ac.ir (E. Noroozinejad Farsangi) [4][5][6]. Sliding of heavy NSEs may affect the structural response of the structure, and hence their interaction must be considered [7].…”

Section: Introductionmentioning

confidence: 99%

Seismic Response of Building Structures with Sliding Non-structural Elements

Challagulla

Parimi

Mohan

et al. 2020

IJE

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Interaction between a structure under base excitation and heavy non-structural elements that it supports is significant in the seismic analysis and design of the structure. Heavy non-structural elements may slide/rock under base excitation, and this dynamic action affects the seismic behavior of the supporting structure. Hence, in this study, a numerical model was presented to describe the seismic behavior of a primary structure (PS) supporting non-structural elements referred to as secondary bodies (SBs). The governing equations of motion for PS and SBs were developed considering Coulomb's friction model. Seismic hazard levels corresponding to Indian seismic zone III (medium hazard level) and V (highest hazard level) were considered. A parameter called displacement ratio (DR) was defined to quantify the sliding effect of SBs on the displacement response of the PS. A parametric study has been conducted to understand the variation in the DR due to varied time period of the structure, live loads to structure mass ratios and coefficients of friction between PS and SBs. From the analysis of results, it was concluded that the DR varies significantly with the time period, mass ratios, and coefficient of friction values. It can also be found from the study that the energy dissipation due to sliding of SBs was more in the highest hazard level than medium hazard level. Finally, the conditions for which the full mass of sliding secondary bodies should be considered in the seismic design of the structure are also presented.

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Effect of the Stick-Slip Phenomenon on the Sliding Response of Objects Subjected to Pulse Excitation

Cited by 24 publications

References 56 publications

Shake table investigation on the seismic performance of hospital equipment supported on wheels/casters

Shake table investigation on the seismic performance of hospital equipment supported on wheels/casters

Dynamics of a sliding‐rocking block considering impact with an adjacent wall

Seismic Response of Building Structures with Sliding Non-structural Elements

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