SOM Awarded Two Additional Patents for Seismic Structural Inventions

July 23, 2010 (San Francisco, California) – The U.S. Patent and Trademark Office has issued patents for two new seismic structural devices, the Link-Fuse JointTM and the Pin-Fuse FrameTM invented by the Structural Engineering Studio in the San Francisco office of Skidmore, Owings & Merrill LLP (SOM). Both the Link-Fuse JointTM and the Pin-Fuse FrameTM are part of a series of three high-performance seismic structural mechanisms developed by SOM and designed to protect buildings in areas of high seismicity. SOM already holds two patents and a trademark for the first device in the series, the Pin-Fuse Joint®.

These three devices that compose the Pin-Fuse Seismic SystemsTM are designed to operate mechanically during a seismic event, allowing the building structure to respond flexibly when subjected to extreme ground movement to thereby maintain structural elasticity. During moderate earthquakes they remain fixed, but during a severe earthquake, they slide or rotate to dissipate energy and reduce potential damage. Following an earthquake, the devices return to their original positions. These innovative new structural mechanisms provide a safer and more cost-effective solution than conventional assemblies as they minimize permanent structural deformation during a seismic event, thereby reducing subsequent repairs to the building structure as well as the associated cost and carbon emissions of repairs.

The Link-Fuse JointTM and the Pin-Fuse FrameTM supplement the original concept, the Pin-Fuse Joint®, which received patents in 2004 and 2006. Inspired by structures that occur in nature that provide organic mechanical movement, such as shoulder or hip joints, the Pin-Fuse Joint® allows beams in frames to rotate during a strong earthquake. The joint remains fixed during the majority of its service life and rotate only after friction in clamped joints is overcome by load due to seismic activity.

These three devices represent a watershed for structural engineering design in areas of high seismicity. The full-scale testing program of all three mechanisms has commenced with results expected by Fall of 2010. Following successful completion of the testing program, these devices may be manufactured and installed in both new and existing occupied structures.

Link Fuse JointTM
US Patent No: 7,647,734 B2
Date of Patent: January 19, 2010

The Link-Fuse JointTM is composed of two plate assemblies, each featuring a diagonal slot at the center. The slots of each plate are arranged diagonally perpendicular to each other and are positioned to allow at least a portion of one slot to align with a portion of the other. A pin is inserted through these openings such that the joint connection accommodates the movement of at least one of the plate assemblies relative to the other when the joint is subjected to a high seismic load.

The Link-Fuse JointTM is generally utilized in a link beam assembly, connecting interior walls within a structure. The joint may be incorporated into the reinforced concrete shear walls or steel braced frames of a structure subject to seismic activity and improves the structure’s dynamic characteristics by allowing the joint to slip under extreme loads. This slippage allows the structure to exhibit elastic properties during seismic events.

While conventional link beam structures may be able to withstand a seismic event, the damage to these structures caused by the seismic activity permanently deforms the beams and therefore requires that they be replaced. In contrast, the Link-Fuse JointTM is designed to withstand a seismic event without experiencing significant beam or joint failure, so that the integrity of the structure remains relatively undisturbed even after seismic activity.

Pin-Fuse FrameTM
US Patent No: 7,712,266 B2
Date of Patent: May 11, 2010

The Pin-Fuse FrameTM incorporates joints that “fuse,” or slide, during earthquakes in order ot protect the structure from damage. By sliding, these joints protect frame members from buckling and yielding, thereby protecting the integrity of the entire structure and minimizing costly post-earthquake repair.

The system comprises a pre-fabricated structural steel beam-column frame assembly with diagonal braces within frame bays. Diagonal braces are divided into two halves connected across a middle gap that allows each half to slip toward or away from the other during a seismic event. Rotational joints at each end of the horizontal beam elements in the frame are also designed to slip when subjected to a high rotational load.

The friction joints developed use arrays of pre-tensioned bolts that either clamp two halves of a brace together or clamp a beam and column together until a seismic event causes the force in the joint to exceed the resistance threshold created by friction. At this threshold, the two connected members are allowed to slip relative to one another within carefully designed slots. If the lateral load imposed on the structure continues to increase representing a rare seismic event, the bolts pass through the full length of the slots and re-engage with the connected members. At this point only do the elements continue to attract additional force and eventually create inelastic behavior of the frame members.

About SOM
Skidmore, Owings & Merrill LLP (SOM) is one of the leading architecture, urban planning, interior design, and engineering firms in the world, with a 75-year reputation for design excellence and a portfolio that includes some of the most important architectural accomplishments of the 20th and 21st centuries. Since its inception, SOM has been a leader in the research and development of specialized technologies, new processes and innovative ideas, many of which have had a palpable and lasting impact on the design profession and the physical environment. The firm’s longstanding leadership in design and building technology has been honored with more than 1,400 awards for quality, innovation, and management. The American Institute of Architects has twice recognized SOM with its highest honor, the Architecture Firm Award—in 1962 and again in 1996. The firm maintains offices in New York, Chicago, San Francisco,  Washington, D.C., London, Hong Kong, Shanghai, Dubai, and Brussels.