Thornton Tomasetti

Last updated
Thornton Tomasetti
Company type Private
Founded1949;75 years ago (1949)
Number of locations
50+ offices
Area served
Key people
Mike Squarzini (Co-CEO)
Peter DiMaggio (Co-CEO)
Wayne Stocks President
Gary Panariello Director
Tom Scarangello Executive Chairman
Number of employees

Thornton Tomasetti (formerly the Thornton-Tomasetti Group, Thornton Tomasetti Engineers, Lev Zetlin & Associates,LZA Technologyand Weidlinger Associates ) is a global, 1,500-plus person scientific and engineering consulting firm.



Thornton Tomasetti has expertise in structural engineering, facade engineering, forensic engineering, structural renovations, construction engineering, Resilience (engineering and construction), sustainable design, applied science, protective design and security, civil engineering and bridge design and rehabilitation. The firm's services are supported by its internal research and development CORE teams, which provides technology-focused expertise, computational simulation and software development as well as artificial intelligence and machine learning. [1]

The firm provides consulting expertise to clients in a variety of industries, including architecture/engineering/construction, insurance and law firms, real estate developers, building owners/operators, defense, life sciences, manufacturing, natural resources and space systems. [2]


1949—Paul Weidlinger opens consultancy: Weidlinger Associates dates back to 1949 with the launch of Paul Weidlinger Consulting Engineers in Washington, D.C. A native of Budapest, Hungary, Paul earned a master's degree from the ETH Zurich in Zurich. He apprenticed with Le Corbusier in Paris and László Moholy-Nagy in London before coming to the United States in the late 1940s.

1950s—Applied Science division launched: Paul Weidlinger, Dr. Mario Salvadori and Dr. Melvin Baron shared an interest in the dynamic response of structures, which led the firm to create an Applied Science division. The group developed analysis and design procedures to protect structures from the effects of blast loadings. Their methods led to early and continuing use of computers in advanced analysis and design.

1956—Lev Zetlin starts Lev Zetlin Associates: After earning a doctoral degree from New York’s Cornell University, Lev Zetlin decided to start his own company, Lev Zetlin Associates (LZA).

1960—Charlie Thornton joins LZA: Charlie Thornton, who earned master’s and doctoral degrees from New York University and authored a thesis on cable nets, joined Lev Zetlin Associates in 1960. Serving as co-chairman of the firm until 2004, he was involved in the analysis, design and construction of projects worldwide.

1964 -- 1964 New York World’s Fair (Flushing Meadows, New York): Early in his career, Lev Zetlin devised a “double-layer bicycle wheel” roof system. The system combines upper and lower cables with varying tensions that are jacked apart and connected by rigid vertical struts. Connecting cables that have differing natural frequencies minimizes wind-induced fluttering. First developed for the Utica Memorial Auditorium, which was completed in 1960, Lev Zetlin's bicycle wheel system has helped to shape the design of other tensile structures, among them the New York State Pavilion, Madison Square Garden, the Seoul Olympic Gymnastics Arena, Tropicana Field, and the Georgia Dome.

1968—Richard Tomasetti joins LZA: Richard Tomasetti joined Lev Zetlin Associates after working in the aerospace and submarine industries. Tomasetti created Environspace Research and Development, the firm’s first research and development group.

1977—Charlie Thornton and Richard Tomasetti buy LZA from Gable Industries: Charlie Thornton and Richard Tomasetti purchased Lev Zetlin Associates while it was a subsidiary of Gable Industries. It was at this time that the firm began performing some work as Thornton Tomasetti. The firm's name changed officially from the TTG Group to Thornton Tomasetti in 1999.

1980s-1990s—FLEX code introduced: The FLEX code was first developed by Weidlinger in the early 1980s to support Nuclear Test Ban Treaty monitoring. Its name is derived from its primary focus, performing ”fast large explicit’ time-domain dynamic simulations, and from its versatility and speed in modeling unusually large structures. In the early 1990s, the FLEX code was diversified into a family: NLFlex (blast), EMFlex (electromagnetic waves), and PZFlex (sonar and ultrasound). In 1999, SpectralFlex was developed to serve the growing field of medical therapeutics, and in 2002, Weidlinger created the FLEX Template System, for modeling and simulation of structural components of civilian structures subjected to bomb blasts.

2001—World Trade Center collapse (New York, New York): In the 10 months after the September 11 attacks, crews removed more than 1.6 million tons of debris. Thornton Tomasetti staff were the first engineers on the site on September 11,[ citation needed ] and started work that afternoon. [3] The firm supervised 20 member firms of the Structural Engineers Association of New York and arranged for 24/7 coverage of the site for nine months. The firm assisted in rescue, demolition and clean-up, advising on structural issues that required resolution as part of the recovery effort.

2004—Taipei 101 (Taipei, Taiwan) Completed: The first 21st-century building to become the world’s tallest upon completion, Taipei 101 is, as its name implies, a 101-story tower. Working with engineer of record Evergreen Consulting, Thornton Tomasetti established an efficient steel-based dual structural system and solved wind behavior problems with distinctive double stair-step corners. By 2020, Thornton Tomasetti had designed five of the 20 tallest complete buildings in the world. [4]

2011 – CORE studio founded: CORE studio is the firm's internal research and development group that specializes in application development, computational modeling and artificial intelligence to create efficiencies in the structural design and construction process.

2012—Response to Hurricane Sandy: On October 29, 2012, Hurricane Sandy made landfall near Atlantic City, New Jersey. In response, the firm conducted damage assessment in three states related to structural and architectural integrity, HVAC, electrical, plumbing and fire protection equipment and systems. Included in the investigations were high-rise office and residential facilities, and other retail, rail, aviation and government facilities. [5]

2015—Thornton Tomasetti and Weidlinger merge: Thornton Tomasetti and Weidlinger Associates announced a merger. Weidlinger Associates was a U.S.-based structural engineering firm that designed and rehabilitated buildings, bridges, and infrastructure and provided special services in applied science, forensics, and physical security. The merger created two new entities: CORE Lab - a sister internal group to CORE studio - that focuses on the long-term development of internal methods, capabilities and products to evaluate new business opportunities; and TTWiiN, a technology accelerator and product commercialization platform. [6]


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

Affiliated organizations

Notable alumni

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  2. "Thornton Tomasetti Website" . Retrieved 9 December 2020.
  3. "World Trade Center Disaster Response - Thornton Tomasetti" . Retrieved 9 December 2020.
  4. "" . Retrieved 9 December 2020.
  5. "Superstorm Sandy Project - Thornton Tomasetti" . Retrieved 9 December 2020.
  6. "Weidlinger Associates and Thornton Tomasetti Merge, Solidifying Leadership in Engineering Innovation" . Retrieved 9 December 2020.
  7. "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.