About the author  ⁄ Lachezar Handzhiyski, S.E.

Lachezar V. Handzhiyski is a Senior Project Manager with Simpson Gumpertz & Heger (SGH). (lvhandzhiyski@sgh.com)

Located at 301 Mission Street, the 650-foot-tall Millennium Tower was designed to be San Francisco’s premier residential address. The project geotechnical report predicted 4 to 6 inches of settlement over the project’s life; however, as construction neared completion in 2009, the settlement had already reached 10 inches. As development occurred on adjacent parcels, accompanied by continuous dewatering of the surrounding soils, settlement continued. By 2014, instrumentation installed to monitor the effect of adjacent construction recorded that the mat had dished, settled nearly 14 inches and that the roof had tilted to the northwest a similar amount. As the City of San Francisco threatened to red tag the building, counsel for the developer, Mission Street Development (MSD), retained Simpson Gumpertz & Heger (SGH) to determine if the settlement had damaged the structure and created a safety issue. Although SGH found that settlement had not appreciably affected the structure’s adequacy, in 2015, with settlement exceeding 16 inches, litigation ensued between the homeowners’ association, MSD, the City of San Francisco, and the development teams for adjacent projects. Under the terms of a negotiated settlement, SGH designed a foundation stabilization upgrade that formed the basis for dispute resolution and is currently under construction. This article focuses on the structural aspects of the problem and the upgrade.

Read More →
111 Main’s reinforced concrete core wall system provides vertical and lateral support for an innovative 25-story office tower suspended over adjacent performing arts center.

Located in a region of high seismicity in close proximity to the active Salt Lake Segment of the Wasatch Fault Zone, the new 111 Main office tower in Salt Lake City, Utah, comprises 501,455 square feet of Class A office space. The 25-story building rises 387 feet above grade and contains a penthouse roof-level steel hat-truss system with all perimeter columns suspended to allow for air-rights overhang at adjacent performing arts center.

Read More →
111 Main’s innovative “balanced” structural system supports the 25-story high-rise above an adjacent performing arts center.

In Salt Lake City, Utah, at 387 feet above grade, 111 Main has become the newest and one of the tallest additions to the skyline. Currently under construction in the heart of the downtown City Center neighborhood, the roof hat-truss structure of the 25-story, 501,455 square foot Class A office tower was topped off this past January, with its loads successfully transferred from a temporary shoring support system to the permanent structural system during a one-day 12-hour period.

Read More →
STRUCTURE magazine