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A necessary ingredient for achieving this skyscraper’s bold and unconventional architectural vision was CH2M’s extraordinary skill in structural design and creative problem solving.

Project Overview

This project is a model for the successful combination of iconic architecture and functionality, demonstrating that owners can have both when project teams share a motivation to achieve an extraordinary outcome.

The winner of the 2014 Structural Steel Design Award, this new addition to the London skyline provides benefits to both businesses and the community with its Sky Garden. As a popular destination for both locals and tourists, the top level of the building is a state-of-the-art environment in which to take in the city's historic landscape.  

Key facts

50%

increase in leasable capacity for the upper floors

 

4D

building information modeling minimized onsite construction problems

Testimonial

Being involved in interesting and innovative projects, with interesting and innovative people [is gratifying].

Paul Walters
20 Fenchurch Street Project Director
  • 20 Fenchurch Street building in downtown London.
  • 20 Fenchurch Street building in downtown London.
  • 20 Fenchurch Street building in downtown London.
  • 20 Fenchurch Street building in downtown London.
  • 20 Fenchurch Street building in downtown London.
  • 20 Fenchurch Street building in downtown London.
  • The 20 Fenchurch Street building’s top-floor Sky Garden offers gardens, restaurants, and stunning views.
  • The 20 Fenchurch Street building’s top-floor Sky Garden offers gardens, restaurants, and stunning views.
  • The 20 Fenchurch Street building’s top-floor Sky Garden offers gardens, restaurants, and stunning views.

What was involved?

Our services included structural design, façade engineering, resident engineering and construction materials factory review and performance test modeling.

Fenchurch skygarden

Façade engineering to provide continuous guidance to the project’s other team members to support proper installation of the building’s unusual flared façade

Resident engineering to protect the client’s interest by seeing that construction was performed in accordance with design

Construction materials factory review and performance test modeling to see that construction materials were in accordance with client specifications

Structural design innovations determined where to place this unusual building’s structural core, maintain the clear spans between the core and column and design individually-sized floor plates for each story

Community impact

The aesthetic aspect of this project’s community impact is expressed in comments from judges who awarded this project a 2014 Structural Steel Design Award, describing it as “one of the latest prestigious additions to the City of London’s skyline.” The building’s top-floor Sky Garden, with gardens, restaurants and stunning views, is now a popular destination for Londoners as well as tourists. A positive sustainability impact is the building’s delivery of 50 percent more space in its upper floors than its ground floor, allowing greater urban density and leasable space to the client. 

The 20 Fenchurch Street building’s top-floor Sky Garden offers gardens, restaurants, and stunning views.
In Detail
20 Fenchurch Steet in London, England

Adding to London's iconic skyline

Structural engineering was critical to achieving this building’s creative design

A central challenge was where to place the building’s structural core, which is typically located in the center where the center of mass resides in a conventional office building. However, the off-center mass of the design required spans of varying lengths between the core and perimeter columns. We used prefabricated steel cellular beam I-sections of varying thicknesses to maintain clear spans between the core and column, and to limit the depth of the beams.

Another design challenge was accommodating the building’s increasing spans higher up the building. At the second floor the beams span 11 meters (36 feet) between the core and the perimeter columns, but as the building flares out the perimeter of the building increases up to 22 meters (72 feet) from the core.

Four-dimensional modelling (3D building information modelling [BIM] with time added as a fourth dimension) was used to demonstrate the anticipated build, as well as to predict the challenges that needed to be overcome to achieve the highest levels of safety and quality.

The Structural Steel Design Awards are sponsored by the British Constructional Steelwork Association and Tata Steel. The judges’ comments noted “The flared shape of this iconic building, in its tight City environment, results in geometric changes at each floor. This presented huge challenges to the design and construction team. By using advanced 4D-BIM modelling, the onsite construction problems were minimised.”