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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.

 

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 W36x393 Bm and W14x550 Col

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.

Click here for : Slotted Web Connection Forces