VFPI: an isolation device for aseismic design

Pranesh, M.; Sinha, Ravi

doi:10.1002/(sici)1096-9845(200005)29:5<603::aid-eqe927>3.3.co;2-n

Cited by 25 publications

(50 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The uncoupled equations are solved by step-by-step integration procedures. The close-form final expressions for the evaluation of modal response in both non-sliding and sliding phase are analogous to those for SDOF systems presented in Pranesh and Sinha (2000a).…”

Section: Solution Proceduresmentioning

confidence: 91%

“…To eliminate these disadvantages the geometry of sliding surface in case of VFPI has been modified. Its geometry has been derived from the basic equation of an ellipse, with its semi-major axis being a linear function of sliding displacement (Pranesh and Sinha, 2000a). The geometry of sliding surface of VFPI can be represented as…”

Section: Vfpi Geometrymentioning

confidence: 99%

“…The typical time-history for recoverable energy of equipment (kinetic energy + strain energy) (Pranesh, 2000) is shown in Fig. 3b.…”

Section: Time-history Responsementioning

confidence: 99%

“…The spherical shape of the sliding surface results in a fairly constant isolator time period (for small displacements relative to radius of the spherical sliding surface) and re-centring mechanism through gravity. The FPS isolators have many advantages over pure friction system; however, severe practical difficulties of aseismic design using FPS isolator due to its fixed time-period have also been observed (Pranesh, 2000). Gravity has been effectively used as a restoring force mechanism in other isolation systems such as antifriction and multi-step base isolation unit (AF&MSBI) and ball-n-cone (BNC) isolator (Shustov, 1992;Tekton, 1994).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Aseismic design of structure–equipment systems using variable frequency pendulum isolator

Murnal¹,

Sinha

2004

Nuclear Engineering and Design

Self Cite

View full text Add to dashboard Cite

Sliding isolation systems have emerged as very useful vibration control technique that incorporate isolation, energy dissipation and restoring mechanism in one unit. However, most currently available systems such as friction pendulum system (FPS) and pure friction (PF) system have practical limitations and are of limited effectiveness when input excitation level is significantly different from its design level. To overcome these limitations while preserving the advantages, a new system called the variable frequency pendulum isolator (VFPI) has been developed by the authors. The isolation period of VFPI continuously decreases with increase in horizontal sliding displacement which results in a more robust isolation system. The VFPI also limits the maximum force transmitted to the structure by providing a restoring force-softening mechanism. In this paper, it has been shown that isolating a structure using VFPI is very effective for vibration control of structure-equipment and other primary-secondary systems. An example five-storey structure with equipment mounted at its top has been analysed to demonstrate the effectiveness of VFPI. It is shown that VFPI provides better vibration control properties compared to other friction isolation systems, and excellent response reduction is observed for a wide range of equipment properties and excitation characteristics. The performance of the example structure with VFPI has been compared with the other frictional systems such as FPS and PF system.

show abstract

Section: Solution Proceduresmentioning

confidence: 91%

Section: Vfpi Geometrymentioning

confidence: 99%

“…The typical time-history for recoverable energy of equipment (kinetic energy + strain energy) (Pranesh, 2000) is shown in Fig. 3b.…”

Section: Time-history Responsementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Aseismic design of structure–equipment systems using variable frequency pendulum isolator

Murnal¹,

Sinha

2004

Nuclear Engineering and Design

Self Cite

View full text Add to dashboard Cite

show abstract

“…A new type of isolator called the VFPI (Pranesh and Sinha, 2000) incorporates the advantages of both the friction pendulum system (FPS) and Pure-Friction (P-F) isolators (see Figures 2 (a) and (b)). In this isolator, the shape of the sliding surface is non-spherical.…”

Section: Description Of Vfpimentioning

confidence: 99%

Seismic behavior of variable frequency pendulum isolator

Panchal

Jangid

2008

Earthq. Eng. Eng. Vib.

View full text Add to dashboard Cite

Earthquake performance of a fl exible one-story building isolated with a variable frequency pendulum isolator (VFPI) under near-fault and far-fi eld ground motions is investigated. The frictional forces mobilized at the interface of the VFPI are assumed to be velocity dependent. The interaction between frictional forces of the VFPI in two horizontal directions is duly considered and coupled differential equations of motion of the isolated system in the incremental form are solved iteratively. The response of the system with bi-directional interaction is compared with those without interaction. In addition, the effects of velocity dependence on the response of the isolated system are also investigated. Moreover, a parametric study is carried out to critically examine the infl uence of important parameters on bi-directional interaction effects of the frictional forces of the VFPI. These parameters are: the superstructure time period, frequency variation factor (FVF) and friction coeffi cient of the VFPI. From the above investigations, it is observed that the dependence of the friction coeffi cient on relative velocity of the system does not have a noticeable effect on the peak response of the system isolated with VFPI, and that the bi-directional interaction of frictional forces of the VFPI is important and if neglected, isolator displacements will be underestimated and the superstructure acceleration and base shear will be overestimated.

show abstract

VFPI: an isolation device for aseismic design

Pranesh

Sinha

2000

Earthquake Engng. Struct. Dyn.

Self Cite

104

View full text Add to dashboard Cite

Sliding isolators with curved surface are e!ective base isolation systems incorporating isolation, energy dissipation and restoring mechanism in one unit. However, practical utility of these systems, such as friction pendulum system (FPS) has limitations due to constant isolator period and restoring force characteristics. A new isolator called the variable frequency pendulum isolator (VFPI) that overcomes these limitations while retaining all the advantages has been described in this paper. VFPI has oscillation frequency decreasing with sliding displacement, and the restoring force has an upper bound so that the force transmitted to the structure is limited. The mathematical formulations for the response of a SDOF structure and energy balance are also described. Parametric studies have been carried out to critically examine the behaviour of structures isolated with VFPI, FPS and PF system. From these investigations, it is concluded that the VFPI combines the advantages of both FPS and PF system, without their undesirable properties. The VFPI performance is also found to be stable during low-intensity excitations, and fail-safe during highintensity excitations. VFPI is found to exhibit robust performance for a wide range of structure, isolator and ground motion characteristics clearly demonstrating its advantages.

show abstract

VFPI: an isolation device for aseismic design

Cited by 25 publications

References 0 publications

Aseismic design of structure–equipment systems using variable frequency pendulum isolator

Aseismic design of structure–equipment systems using variable frequency pendulum isolator

Seismic behavior of variable frequency pendulum isolator

VFPI: an isolation device for aseismic design

Contact Info

Product

Resources

About