Sustaining a Historic High-Rise Structure
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ctbuh.org/papers Title: Sustaining a Historic High-Rise Structure Authors: Nina Mahjoub, Project Engineer, Holmes Culley Megan Stringer, Project Engineer, Holmes Culley Bill Tremayne, Principal, Holmes Culley Subjects: Retrofit Seismic Keywords: Life Cycle Analysis Retrofit Seismic Structure Sustainability Publication Date: 2015 Original Publication: CTBUH Journal, 2015 Issue I Paper Type: 1. Book chapter/Part chapter 2. Journal paper 3. Conference proceeding 4. Unpublished conference paper 5. Magazine article 6. Unpublished © Council on Tall Buildings and Urban Habitat / Nina Mahjoub; Megan Stringer; Bill Tremayne Retrofit / Seismic Sustaining a Historic High-Rise Structure One of the tallest seismic retrofits in North America was undertaken in the heart of San Francisco. The Pacific Telephone & Telegraph Company headquar- ters was an achievement of architecture of its day when completed in 1925, and it remains an emblem of the Art Deco movement. The building’s current owner decided to embark on the challenging endeavor of reviving the historic structure. This meant preserving the historic fabric, creating an open, flexible Nina A. Mahjoub Megan Stringer workspace, and infusing state-of-the-art technology and sustainability into all its aspects, including a voluntary full seismic structural upgrade. Introduction capacity of the existing building system. Moreover, this approach allows the engineer Situated in the heart of downtown San to better understand how the new and Francisco, the Pacific Telephone & Telegraph existing systems behave together during a (PT&T) Company headquarters opened in seismic event, and therefore provides a Bill Tremayne 1925, reaching 132.7 meters and becoming smart, more sustainable, and less obstructive the tallest building in the city upon solution while maintaining the historic fabric Authors completion (see Figure 1). The building, now of the building. Nina A. Mahjoub, Project Engineer known as 140 New Montgomery (140NM), Megan Stringer, Project Engineer Bill Tremayne, Principal still stands as an icon of design and a Lastly, the paper discusses the environmental Holmes Culley San Francisco reminiscence of the power of the latest benefits of retrofitting versus rebuilding, and 235 Montgomery Street, Suite 235 San Francisco, CA 94104, United States technology of the time. how the sustainability objectives of the t: +1 415 693 1600 project shaped the design. f: +1 415 693 1760 e: [email protected]; The building’s current owner since 2008, [email protected]; Wilson Meany, a real estate developer, [email protected] http://www.holmesculley.com decided to embark on a challenging The Historic Building endeavor of reviving the historic structure. Nina A. Mahjoub While it will continue to host offices, the 140NM consists of a 26-story base, with a Nina Mahjoub is a project engineer at Holmes Culley, building will now introduce state-of-the-art four-story tower above Level 27 and two and was involved in the 140 New Montgomery project from schematic design phase to construction technology in all aspects, including a basement levels, designed by Timothy completion. She holds a Bachelor’s Degree in Civil voluntary structural system upgrade, while Pflueger and Frank Miller. When completed, Engineering from UCLA and a Master of Engineering in High-performance Structures from MIT. She has maintaining the architect’s original intent. In 140NM became the tallest building in the more than five years of experience in New York City addition to preserving the building’s historic city, until its height was matched by the and California. Her projects have been focused on renovation, adaptive reuse, and seismic retrofits of features, the project team wanted to create a neighboring Russ Building two years later. existing and historic buildings. healthy, sustainable space for its tenants and targeted LEED Gold for the project. The building provided space for PT&T’s 2,000 Megan Stringer Megan Stringer is a project engineer at Holmes employees. The PT&T building was known Culley. She holds a Master’s degree in Structural This paper outlines the design goals of this nationally and internationally in the business Engineering from the University of Texas at Austin. An active member in the sustainable design community, upgrade: from the preservation of the and design communities, and was visited by she chairs the Structural Engineers Association of historic fabric to the creation of open flexible VIPs such as Winston Churchill, who in 1929 California’s Sustainable Design Committee and is a member of ASCE’s SEI Sustainability Committee. She office space, all while providing a safe and made one of the first Transatlantic phone has presented at various conferences on sustainability sustainable structure in San Francisco’s calls from the building. and the role engineers play in shaping the built environment. unforgiving seismic environment. It also discusses the strengthening scheme The building is classified by the City of San Bill Tremayne evaluated and challenges faced during the Francisco as a Category I Historic Building Bill Tremayne is a principal and technical director at Holmes Culley. With more than 13 years of experience, design. It presents details on the analysis and is eligible to register for the National he leads the firm’s practice of performance-based method of the seismic retrofit, which utilized Register of Historic Places. Some of its engineering, which has been successfully applied to numerous seismic evaluation, retrofit, and new a performance-based design. This method historic features include 2.4 hectares of building projects in the United States and New presents the engineer with the capability to terracotta façade constructed by the Zealand. Bill is an ongoing contributor to the development of the masonry and analysis provisions look past conservative building codes and Gladding McBean Company, and eight of ASCE 41. determine in a more precise way the terracotta eagles perched atop the tower 34 | Retrofit / Seismic CTBUH Journal | 2015 Issue I Some of the building’s historic features “include 2.4 hectares of terracotta façade constructed by the Gladding McBean Company, and eight terracotta eagles perched atop the tower. The entrance houses an ornate and dramatic lobby with detailed bronze doors, marble walls, and a hand- painted plaster ceiling by Mark Goodman.” now, one can quickly notice that the historic companies in the tech sector, by providing Figure 1. 140 New Montgomery, San Francisco. fabric of the structure has stayed intact them with state-of-the-art technology © Nathaniel Lindsey throughout the decades. infrastructure and flexible workspace within (see Figures 2 and 3). The entrance houses an a historic high-rise. To achieve that vision, the ornate and dramatic lobby with detailed After housing one company for over 80 developer engaged a design team in 2011 bronze doors, marble walls, and a hand- years, the building was sold in 2008 to a real that would spend the next few years painted plaster ceiling by Mark Goodman estate developer. It was the refined character following the guiding principles that would (see Figure 4). The entrance also leads to a of the historic building that would set the restore and reinvigorate this iconic structure. marble staircase. tone for the project and the vision of its new and proud owner. Some of the major work undertaken in this Since completion, the building has remained renovation includes the historic lobby relatively untouched, with a façade rehabilitation, elevator modernization (to renovation in the 1980s and parapet bracing Project Vision and Goals support destination control), and entirely installed just prior to the 1989 Loma Prieta new mechanical, electrical, and plumbing earthquake. Comparing the building then to An article in San Francisco Newsweek from systems designed with tenant controllability. 1925 described 140NM as “the new building generation, a monument to western progress, and foresight.” Eight decades later, a new developer was determined to continue this vision and honor its original inception as a modern communication hub and a center of innovation. 140NM was going to continue housing the technology of tomorrow by attracting creative entrepreneurs and Figure 2. Terracotta façade along New Montgomery Figure 3. Eight terracotta eagles perched atop the 140 Figure 4. Historic Lobby Entrance. © Stephen Schafer Street. © Stephen Schafer NM. © Nathaniel Lindsey CTBUH Journal | 2015 Issue I Retrofit / Seismic | 35 Figure 5. Typical interior floor after soft demolition. © Blake Marvin Figure 6. Typical existing wind brace moment-resisting connections. The majority of the windows were replaced at Level 19, 23, and roof. The existing founda- finite element model of the building was with high-performance glazing and will tion consists of perimeter concrete walls and developed. The analysis simulated how the remain operable to promote natural ventila- concrete spread footings at each column. building would perform during a large tion. Some exterior restoration of the historic earthquake, and how a seismic strengthening terracotta and historic glazed brick façade was The existing lateral structural system consists scheme could be most effectively designed to undertaken, which included repointing of of steel beams and columns, classified as reduce damage and mitigate collapse hazards. joints and patching/repainting individual units “partially restrained moment frames.” The This provided the developer with a better