Thornton Tomasetti

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Thornton Tomasetti (formerly the Thornton-Tomasetti Group, Thornton Tomasetti Engineers, Lev Zetlin & Associates and LZA Technology) is a 1,500-plus person engineering consulting firm headquartered in New York City. The company operates more than 50 offices, serving clients worldwide.


The company has expertise in structural engineering, façade engineering, forensics, renewal, construction engineering, property loss consulting, sustainability, applied science, protective design and transportation. The engineering firm provided the structural design for several of the world's tallest building structures, including the Petronas Towers in Kuala Lumpur, Malaysia; and Taipei 101 in Taiwan. Other structures designed by the firm include Soldier Field in Chicago, Petco Park in San Diego, and the Minneapolis Public Library in Minneapolis. Among other architects of note, Thornton Tomasetti has collaborated with Cesar Pelli, Santiago Calatrava, Renzo Piano, and Rafael Vinoly.

Thornton Tomasetti works to advance sustainable design and construction practices. About one-fifth of its staff are LEED accredited professionals (LEED AP). Thornton Tomasetti was the first structural engineering company to sign the AIA 2030 Commitment. [1]


The company began using the name Thornton Tomasetti in 1975 when Charlie Thornton and Richard Tomasetti purchased Lev Zetlin & Associates (LZA) from Gable Industries, to which Lev Zetlin had sold LZA in 1971. Thornton Tomasetti immediately began to branch out and enter the highrise market with several innovative designs. [2]

New York City office

The New York City office essentially began in 1956 as Lev Zetlin & Associates (LZA), founded by Lev Zetlin upon the completion of his PhD at Cornell University. Zetlin pioneered the use of the double layer bicycle wheel roof system used in the Utica Civic Auditorium (also known as the Utica Memorial Auditorium), as well as the hyperbolic (hypar) roofs used in American Airlines 747 super-hangars at airports in Los Angeles and San Francisco. Lev Zetlin also embraced the creative use of materials, most notably demonstrated in a bridge design made entirely of paper products for an International Paper ad. [3] [4]

Chicago office

Eli Cohen EliCohenSE.jpg
Eli Cohen

In 1993, Thornton Tomasetti acquired Cohen-Barreto-Marchertas (CBM) and created a Chicago office. Founded in 1965 by Eli Cohen, CBM pioneered the use of the now-common composite steel structural system, which combines a reinforced concrete core wall (to resist lateral loads) with a light steel floor framing. The development of 50- to 60-story buildings became more feasible and efficient because the lighter framing reduced construction time and expense, and allowed for large, column-free spans, giving architects greater freedom in exterior expression. In the early 1960s, Cohen's adaptation of the concrete cooling tower design to high-rise offices required a change in the way the unions worked. Until that time, ironworker contracts forbid members of other trades to work at higher elevations at job sites. But the proposed system was reviewed with them and they agreed to let concrete workers work above them. [5] [6] [7] [8] [9]

Merger with Weidlinger Associates

On September 8, 2015, Thornton Tomasetti announced that it had merged with structural engineering firm Weidlinger Associates. "The combined firm will have 1,200 employees operating in 34 cities internationally", and will operate under the Thornton Tomasetti name. [10]


Taipei 101 101.portrait.altonthompson.jpg
Taipei 101
Petronas Towers KLCC-01.jpg
Petronas Towers
The New York Times Building Ny-times-tower.jpg
The New York Times Building

Skyscrapers, buildings and structures

Stadiums and convention centers

The New Minneapolis Central Library, designed by Cesar Pelli, completed in 2006 MinneapolisCentralLibrary.jpg
The New Minneapolis Central Library, designed by César Pelli, completed in 2006
Ford Field Ford-Field-September-10-2006.jpg
Ford Field
U.S. Bank Stadium US Bank Stadium - West Facade.jpg
U.S. Bank Stadium
Banc of California Stadium LAFC East Side Stadium interior.jpg
Banc of California Stadium

Renewal and rehabilitation

Forensics, investigation and property loss consulting

Under construction

Community projects

In addition to founding Thornton Tomasetti, Charlie Thornton founded The ACE Mentor Program, which is a not-for-profit organization, formed to enlighten and motivate students toward architecture, construction, engineering, and related careers by providing mentoring opportunities for future designers and constructors. [12] In 2008 Thornton was awarded the Henry C. Turner Prize for Innovation in Construction Technology from the National Building Museum for his work with this program. [13]


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    2. Thornton Tomasetti, Thornton Tomasetti Corporate Website , retrieved 2007-09-30
    3. Forrest Wilson (1975), merging Form in Architecture: Conversations with Lev Zetlin, Boston, Massachusetts: Cahners Books
    5. Trevor Jensen, Eli W. Cohen: 1927–2007 (– Scholar search ), retrieved 2007-09-30[ dead link ]
    6. Clyde N. Baker Jr., Thoughts on Eli Cohen, archived from the original (– Scholar search ) on 2007-06-11, retrieved 2007-09-30
    7. Lynn Becker, Thoughts on Eli Cohen , retrieved 2007-09-30
    8. ZweigWhite Information Services, Eli W. Cohen, structural engineering pioneer , retrieved 2007-09-30
    9., Thornton Tomasetti , retrieved 2007-09-30
    11. "Indiana State Fair Commission August 13, 2011 Collapse Incident Investigative Report" (PDF). Indiana State Fair Commission August 13, 2011 Collapse Incident Investigative Report. ThorntonTomasetti BS. Retrieved 25 November 2013.
    12. ACE Mentor Program Archived 2007-11-09 at the Wayback Machine
    13. "Archived copy". Archived from the original on 2011-03-05. Retrieved 2011-03-15.CS1 maint: archived copy as title (link)