The SlottedWebTM connection design rationale
that sizes the beam/web separation length, shear plate and connection weldments, is based
upon ATC-24 protocol test results and extensive inelastic finite element analyses of the
stress and strain distributions and buckling modes. Incorporated in this rationale are the
UBC and AISC Load and Resistance Factor Design (LRFD) Specifications and the 1997 AISC
Seismic Design Provisions for Steel Buildings and its supplements.
SSDA
has successfully completed ATC-24 protocol tests with beams ranging from W27x94 to W36x300
with columns ranging from W14x176 to W14x550. Additionally, successful tests have been
completed using W24x94 and W36x170 beams with deep W30 columns. None of these assemblies
experienced the lateral-torsional mode of buckling of the beams or columns that is typical
of non-slotted beam and column assemblies.
Shown
in Figures 2, 3, 4, 5 and 6 are the total plastic rotation hysteresis curves for each of
the following ATC-24 assemblies: a W24x94 beam and a W30x132 column, a W36x170 beam and a
W30x235 column, a W27x94 beam and a W14x176 column, a W33x141 beam and a W14x283 column,
and a W36x300 beam and a W14x500 column. Two of each of these assemblies using current
SSDA design rationale were successfully tested and reported in accordance with the current
AISC Seismic Provisions for Structural Steel Buildings.
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Figure 2.
Moment
- Plastic Rotation Curve for a W24x94 Bm and W30x132 Col |
Figure 3.
Moment
- Plastic Rotation Curve for a W36x170 Bm and W30x235 Col |
Figure 4.
Moment -
Plastic Rotation Curve for a W27x94 Bm and W14x176 Col |
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Figure 5.
Moment -
Plastic Rotation Curve for a W33x141 Bm and W14x283 Col |
Figure 6.
Moment -
Plastic Rotation Curve for a W36x300 Bm and W14x500 Col |
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SSDA Tests 23, 24, 25, and 26, (refer to
Figs. 2 and 3 above) were made specifically to demonstrate slotted web connection ATC-24
test performance when used with deep columns. These columns were laterally braced only at
the top beam flange level to simulate restraint of a concrete filled metal deck. Neither
column twisting nor lateral torsional beam buckling occurred during these four successful
tests.
Both analytical studies and ATC-24 protocol
tests have demonstrated that the SSDA SlottedWebTM connection designs develop
the full plastic moment capacity of the beam and do not reduce the elastic stiffness of
the beam. All of the above attributes of this proprietary connection enhance its strength
and ductility, which makes it applicable for use in both new construction and the
retrofitting of existing connections in seismic moment frames.
Currently SSDA has completed or contracted
for the design of the SlottedWebTM connections in over 150 new buildings in
California, Utah, Arizona and Nevada. Included in these are a 40 story building in San
Francisco, a 32 story building in San Diego, and a 20 story building in Salt Lake City.
Six buildings have been retrofitted including a 10-story office building in Burbank and a
three story medical office building in Granada Hills. The Office of Statewide Health
Planning and Development (OSHPD) has approved the SlottedWebTM connection designs for use
in three hospitals in California.
Additional specific qualification and design
information for the SlottedWebTM connection including low cycle fatigue studies
and ATC-24 test reports, the rationale for designing the slots, shear plate, weldments,
and the construction details may be obtained from the licensor directly or through their
website www.ssda.net.
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