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Pall Friction-Dampers

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The development of Pall friction-dampers was pioneered in the late
seventies. These dampers have successfully gone through rigorous proof
testing on shake tables at the University of California (1987) and at the
University of British Columbia (1985). Pall friction-dampers have been used
in more than 30 projects of new construction as well as retrofit of existing
buildings in Canada and the U.S.  Several more are under construction or in
the design phase.

Pall friction-dampers are simple and fool proof in construction. Basically,
these consist of a series of specially treated steel plates clamped together
to develop very reliable friction. Their performance is reliable, repeatable
and they possess large rectangular hysteresis loops with negligible fade.
They are not temperature or velocity dependent. For a given force level, a
much greater quantity of energy can be dissipated in friction than any other
method so fewer Pall friction-damping devices are required to dissipate
seismic energy.  These are designed not to slip during wind.  During a major
earthquake, the dampers slip before yielding of structural members.  After
the earthquake, the strain energy of the structure forces the dampers to
near original alignment.  There is nothing to damage or leak, hence they
need no maintenance, repair or replacement after the earthquake.

Patented Pall friction-dampers are available for bracing in framed
buildings: tension cross bracing, tension/compression single diagonal
bracing, and chevron bracing. Pall friction-connectors are also available
for frame cladding, and for use at expansion joint of adjacent buildings to
avoid pounding.

Buildings with friction dampers require the use of nonlinear time history
dynamic analysis. Several computer programs such as DRAIN-2DX, DRAIN-3DX,
DRAIN-TABS, E-TABS (nonlinear), SAP2000 etc. are available.  Modeling of
Pall friction-dampers is very easy.  Since the hysteretic loop of Pall
friction-damper is similar to rectangular loop of an ideal elasto-plastic
material, the dampers are modeled as a plastic element.  Slip load
represents fictitious yield force.  FEMA 273 /274 ?NEHRP Guidelines for the
Seismic Rehabilitation of Buildings? provide guidelines on the analysis of
buildings with friction-dampers.

References:

 Aiken, I.D., Kelly, J.M., Pall, A.S., 1988, "Seismic Response of a
Nine-Story Steel Frame with Friction- Damped Cross-Bracing", Report No. UCB
/ EERC-88/17. Earthquake Engineering Research Centre, the University of
California at Berkeley, PP. 1-7.

Filiatrault, A., Cherry, S., 1986, ?Seismic Tests of Friction-Damped Steel
Frames?, Proceedings Third Conference on Dynamic Response of Structures,
ASCE, Los Angeles.

Hale, T., Tokas, C., Pall, A., 1995, ?Seismic Retrofit of Elevated Water
Tanks at the University of California at Davis?. Proceedings, Seventh
Canadian Conference on Earthquake Engineering,
Montreal, PP. 959-966.

Pall, A.S., Marsh, C., Fazio, P., 1980, ?Friction Joints for Seismic Control
of Large Panel Structures?, Proceedings, Journal of Prestressed Concrete
Institute, Vol.. 25, No. 6, PP. 38-61.

Pall, A.S., Marsh, C., 1981, ?Friction Damped Concrete Shearwalls?, Journal
of American Concrete Institute, No. 3, Proceedings, Vol.. 78, PP. 187-193.

Pall, A.S., Marsh, C., 1982, ?Seismic Response of Friction Damped Braced
Frames?, ASCE, Journal of Structural Division, Vol.. 108, St. 9, June 1982,
PP. 1313-1323.
         (Recipient ?Raymond C. Reese Research Prize1983? ASCE).

Pall, A.S., Verganelakis, V., Marsh, C., 1987, ?Friction-Dampers for Seismic
Control of Concordia University Library Building?, Proceedings Fifth
Canadian Conference on Earthquake Engineering, Ottawa, PP. 191-200.

Pall, A., 1989, ?Friction-Dampers for Economic Seismic Design?, Proceedings,
Structures Congress ?89, San Francisco, PP.159-166.

Pall, A.S., 1989, ?Friction Damped Connections for Precast Concrete
 Cladding?, Proceedings, PCI- Architectural Precast Concrete Cladding - Its
Contribution to Lateral Resistance of Buildings, PP. 300-309.

Pall, A.S., Pall, R., 1993, ?Friction-Dampers Used for Seismic Control of
New and Existing Buildings in Canada?, Proceedings, ATC 17-1, Seminar on
Seismic Base Isolation, Passive Energy Dissipation and Active Control, San
Francisco, Vol.. 2, PP. 675-686.

Pall, A., Vezina, S., Proulx, Pall, R., 1993, ?Friction-Dampers for Seismic
Control of Canadian Space Agency Headquarters?, Journal Earthquake Spectra,
Vol.. 9, Number 3, PP. 547-557.

Pall, A., Pall, R., 1996, ?Friction-Dampers for Seismic Control of
Buildings ? A Canadian Experience?, Eleventh World Conference on Earthquake
Engineering, Mexico, Paper # 497.

Pasquin, C., Pall, A.S., Pall, R., 1994, ?Hi-Tech Seismic Rehabilitation of
Casino de Montreal?, ASCE Structures Congress, Atlanta, PP. 1292-1297.

Savard, G., Lalancette, J.R., Pall, R., Pall, A., 1995, ?High Tech Seismic
Design of Maison 1 McGill, Montreal?, Proceedings, Seventh Canadian
Conference on Earthquake Engineering, Montreal, PP. 935-942.

Vezina, S., Proulx, P., Pall, R., Pall, A., 1992, ?Friction-Dampers for
Aseismic Design of Canadian Space Agency?, Proceedings, Tenth World
Conference on Earthquake Engineering, Madrid, Spain, PP. 4123-4128.

Wagner, P., Vavak, L., Pall, R., Pall, A., 1995, ?Seismic Rehabilitation of
the New Hamilton Court House?, Proceedings, Seventh Canadian Conference on
Earthquake Engineering, Montreal,  PP. 951-958.

Pasquin, C., Charania, H., Steele, R., Pall, A., Pall, R., 1998,
?Friction-Dampers for Seismic Control of Selkirk water Front Offices,
Victoria?, Proceedings, Sixth U.S. National Conference on Earthquake
Engineering, Seattle.

Elliot, J., McCaffrey, G., Guruswamy, G., Pall, R., Pall, A., 1998,
?High-Tech Seismic Rehabilitation of Justice Headquarters Building, Ottawa?,
Proceedings, Structural Engineers World Congress, San Francisco, Paper No.
T189-3.

For more information, please contact:
Avtar Pall, Ph. D., P.Eng.
Pall Dynamics Limited
100 Montevista, D.D.O.
Montreal, Quebec
Canada H9B 2Z9
Tel: (514) 412-2605
Fax: (514) 684-8185
Email: PallDynamics(--nospam--at)msn.com