Design firm successfully upholds its patent for structural steel seismic connections

LOS ANGELES—Successfully resolving its first patent infringement suit, construction engineering firm Seismic Structural Design Associates, Inc. (SSDA), has upheld the patents protecting its SlottedWeb structural steel seismic connection against unlicensed use.

The settlement includes confirmation by Defendants Loren Carpenter, Ph.D., and WHL Consulting Engineers that the extended weld access hole is covered by the SSDA SlottedWeb patents, by virtue of their purchase of a license to utilize this SSDA technology.

The award-nominated SlottedWeb connection is a structurally important and cost-effective design that has become the standard for earthquake-resistant construction. More than 400 buildings nationally, including commercial office buildings, hospitals, schools, hotels, and residential structures, already license SSDA’s SlottedWeb connection to secure the integrity of their structures.

The Washington, D.C.-based law firm Venable LLP represented SSDA in the litigation. Venable partners James Burdett and Peter Curtin were among the attorneys working on behalf of SSDA.

"We are very satisfied with this settlement, especially since it follows the first time we had to take legal action to support the patent for our slotted web design," said SSDA President Jay Allen.

"We believe this case demonstrated the strength of our intellectual property and reflects the merit of our design, as well as the importance of the SlottedWeb connection to builders throughout the construction and engineering industries," said James Partridge, a co-inventor of the patented connections along with Jay Allen and Ralph M. Richard, Ph.D.

The settlement comes out of a suit filed in Los Angeles federal district court in 2005, charging that WHL engaged in various infringements of SSDA patented designs. The infringement occurred at Constellation Place, a 35-story high-rise property designed by architect Johnson Fain Partners, developed by JMB Realty Investment Partners, and built by Hathaway-Dinwiddie Construction with steel subcontractor Herrick Corporation.

The SlottedWeb connection, which was nominated for a 2002 NOVA Award for innovation in the construction industry, works to improve a previous method of field-welded, beam-to-column frame connection that was in widespread use prior to the famous Northridge earthquake of 1994. Despite its widespread use, that field-welded connection was later considered by most structural engineers to be fundamentally flawed.

In SSDA’s patented design for the SlottedWeb, longitudinal slots are cut to separate beam flanges from the beam web in the region of the connection, and the beam web is welded to the column flange. These changes dramatically alter the force, stress, and strain distributions and greatly extend the connection’s seismic cyclic life.

There are two other designs that also fix the pre-Northridge flaw, but both are significantly more expensive than the SlottedWeb. The SlottedWeb connection has been approved for general use as a pre-qualified connection in Special Moment Frames (SMF) by the International Code Council (ICC). It also satisfies the April 15, 1997 Seismic Provisions for Structural Steel Buildings of the American Institute for Steel Construction (https://www.aisc.org), as well as its Supplements No. 1 dated Feb. 15, 1999 and No. 2 dated Nov. 10, 2000.