Within the general field of architecture is the essential need for structural engineers regardless of the size of the structure. The field of structural engineering is focused on analyzing and creating designs for structures that will either support or resist a load. As nearly every structure created by man falls within this broad category, this field can offer a great deal of opportunity for the specialty as well as variety.
While most people tend to think structural engineers can only find work in areas such as civil engineering, building bridges and dams for instance, or in large scale buildings such as corporate skyscrapers, structural engineers can also be involved in other projects such as designing machinery, specialized medical equipment or vehicles or any other construction with issues of load. In the performance of their jobs, structural engineers are generally responsible for ensuring that the design achieves the goals of the project, guarantees a standard level of safety and that the project will creatively and efficiently make use of the funds available (Heyman, 1999).
To guarantee safety, structural engineers must ensure that the project is using appropriate materials and including necessary structural elements to provide the needed safety levels and appropriate warning systems. While this may not sound like a very exciting position in its general description, consider that all of the amazing buildings of the world have relied upon a structural engineer to make them happen. Beginning with the introduction of new materials into the architectural scene with the Chicago school, structural engineering has made some amazing structures possible including St. Louis Arch and has some astounding work going into the future with a new focus on ‘green architecture’ such as that found at the Brighton Jubilee Library.
Architecture was changed forever in the 19th century as changes in technology and the need for larger structures introduced the need for structural engineers to begin discovering new materials to use to effectively and efficiently meet the needs of the industrialized world. Of course, buildings throughout time have had to overcome these challenges – the Parthenon, St. Peter’s Dome to name a few – but with the new needs came new access to building materials such as steel and cement that drove architects of the Chicago School to begin discovering what they could do to quickly and affordably reach the sky. The Chicago School was a group of architects who were united by two major characteristics.
The first characteristic was “highly utilitarian, marked by a strict adherence to function and structure, and was in great part derived from certain forms of urban vernacular building in Europe and the eastern United States” (Condit 1998: 1). These architects and engineers also shared a dedication to the malleable elements of plastic justified as introducing “a new theoretical spirit and the conscious determination to create rich symbolic forms – to create, in short, a new style expressive of contemporary American culture” (Condit, 1998: 1).
It was through the representative works produced by these architects and made possible through the process of structural engineering that the idea of the steel-frame building came forward, paving the way for the larger constructions of future skyscrapers to emerge. The incorporation of steel frames made it possible to lighten the overall building load by including large blocks of glass windows in the development of their buildings, while still maintaining structural integrity.
As the concept of the skyscraper developed, the structure type also gained a relatively standardized set of uses. Public elements of the building’s use such as gathering areas and vendor stations were most often located on the first floor providing the greatest space for ornamentation and conveying an impression of solidity and widespread functionality. From the first few floors to the floors just under the upper levels was considered the ‘business end of the building, is primarily devoted to workrooms, offices and the necessary amenities stations such as restrooms and break rooms necessary for the occupation.
The top floors and upper space of the building came to represent the capital element of the classic Greek column which was intended not only to serve as the balancing element of support but also provide the building’s ornament and character (Billington, 1985). Some of the important architects who contributed to these concepts were Henry Hobson Richardson, Daniel Burnham, William LeBaron Jenney, Dankmar Adler, Martin Roche, William Holabird, John Root, Louis Sullivan, Solon S. Beman, and the very popular Frank Lloyd Wright before he branched out into more residential developing.
Adopting the perspective of requiring a form to follow function rather than the other way around, architects including Frank Lloyd Wright and CFA Voysey incorporated the ideals of the two major art movements of the period – the Chicago School representing the Modern and the Arts and Crafts Movement insisting upon the importance of the human touch as a means of achieving true artistry. They did this by demonstrating how the new materials available made it possible to achieve machine-made functionality that retained a strong element of artistic form. Wright, for example, the most important aspect of architecture is in providing a humanly comfortable space, a sense of being sheltered and protected.
This aspect was as much a principle of emotion as it is a question of form and led him to develop his concept of the prairie houses for which he became famous (Cronon, 1994). The designs featured several common characteristics with these ideals in mind including low pitched roofs that offered deep overhangs and an emphasis on the horizontal. His famous design Falling Water uses cantilevered cement horizontals that extend over a running river.
Although the structure is suffering some instability now, it is suggested that had Wright’s original structural plans been followed, the house would still be stable today (Cronon, 1994). Whether working on the residential or corporate level, Wright’s designs consistently introduced innovations and emerging technologies to design structures that were well-engineered as well as communicative and artful in their form.
How these ideas were transferred to the concepts of modern structural engineering can be seen in the design of the Gateway Arch of St. Louis. This structure is one of the nation’s most identifiable landmarks around the world. The arch was designed in 1947 by the Finnish-American architect Eero Saarinen, one of the most celebrated and controversial architects of his time (Barbano, 2006). However, the 630 foot tall by 630-foot wide arch wasn’t built until the 1960s (Escherich, 2006).
Unfortunately, Saarinen died at age 51 in 1961, two years before the actual work on the Arch began, but the project was carried forward by German structural engineer Hannskarl Bandel who had worked closely with Saarinen on the design. “When Saarinen tried to demonstrate his desired shape with a chain suspended in his hands, he couldn’t achieve the slightly elongated, ‘soaring’ effect he wanted; Bandel asked for the chain, came back in a few days, and delighted the architect by producing Saarinen’s curve, as if by magic” (Encyclopedia, 2009). Bandel’s innovative problem-solving skills were challenged in the construction of this complicated structure.
The Gateway Arch stands out because of its innovative use of solid material and clean faces. The structure is exactly what its name implies as it is simply and beautifully an inverting sweeping arch rising from near the banks of the Mississippi River. A cross-section taken of the legs, cutting them in half across the longest side, each side would produce a triangle with equal lengths and equal angles, making it an equilateral triangle (Leland, 2006).
This particular shape is considered to be the most geometrically stable shape and tends to give the structure a stronger sense of stability on an intuitive level. The legs have a perimeter of approximately 51 feet at the base and taper gradually as they rise to span only 17 feet at the top. This, plus perspective illusions, gives the arch its delicate tapered appearance as it strains ever upward. There is a special name for the type of curve that was used for the structure of the arch which is important from a structural engineering standpoint. It is called a centenary curve. “This is the curve that would result by hanging a chain upside down from two points” (Leland, 2006).
This particular curve is considered to be the most stable curve found in nature. It has proven its worth in its use for this structure. Although the Gateway Arch has been through numerous strong storms that have been significant enough to damage the grounds on which the arch stands, the structure itself has sustained no damage (Escherich, 2006). Although the arch is cased with stainless steel to give it a sleek, modern appearance, this exterior façade is reinforced with a combination of carbon steel walls, concrete, and rebar. The concrete extends upward within the columns to an elevation of approximately 300 feet and rebar is used to reinforce from this point to the curve and back down (Escherich, 2006).
The arch’s interior is designed to be mostly hollow to encourage tourists. Within the structure, a specialized tram system was constructed that had its structural requirements and challenges. This system must transport passengers up from the ground and then somewhat diagonal before coming to a stop at the curve at the top of the arch, all while maintaining proper gravitational orientation for the riders. At the apex of the arch, an enclosed observation deck gives passengers a spectacular view of the surrounding countryside (Leland, 2006). Although this tram system has been in place nearly since the arch opened, it has rarely experienced any serious problems.
However, to ensure visitor safety, a set of stairwells has also been built into each leg that will enable passengers to exit the arch should any kind of break-down occur at any point along the route. The interior structure also provides space for special displays at either leg of the arch. On the north side, displays educate visitors about the construction of the arch such as how engineers brought the mismatched two legs of the arch together in the middle by having the fire department come out and spray them with cold water. The metal had heated up during the day, causing it to shift and the cold water cooled the metal which brought the halves in line enough for the necessary connections to be made. The south side display gives a history lesson about what life was like in the 1800s.
Moving into the new century, there is a new challenge cresting on the structural engineering horizon promising entirely new challenges – ‘green building’. Concerns about global warming and increased efforts to help the environment have encouraged architects and engineers to rethink future design approaches to include ideas such as protecting the environment, working with non-harmful resources and materials, and designing with sustainability in mind. Green building technology considers the health of the humans who will utilize the interior space as well as attempts to improve or at least not harm the exterior environment (California Integrated Waste Management Board, 2007).
Thanks to the increasingly improved capabilities of computer modeling, the effort to comply with emerging green building guidelines is becoming easier, but there are still many challenges to overcome. These programs enable developers to optimize building designs including the electrical and mechanical systems by allowing the entire building to be designed as a unified, integrated system that functions to support itself as much as possible (California Integrated Waste Management Board, 2007).
Buildings can now be designed from the computer screen that, when built, will have the capability of producing at least a portion of their own energy needs through solar panels, collecting some of their water resources for non-potable use through specially designed rainspouts combined with installed, sometimes even concealed collecting basins and that otherwise utilize as many of the available natural resources of the physical environment in non-impactful ways. These efforts can be further improved as a result of integrated structural systems such as insulating concrete walls that serve a dual purpose of cooling the building at the same time that it serves as a collection point for condensed water purposefully and productively.
The Brighton Jubilee Library is a good example of a green engineering framework in a completely usable, functional, and aesthetic design. Based upon the ideas of Viollet, the building represents form following function in both its interior and exterior design (Hale, 2000). Several of the main characteristics of architecture as engineering are apparent in this structure, including permitting many of the foundational building materials to remain exposed to view, honoring an honest expression of structure at the same time that the design provides easy access to servant areas which often require frequent replacement or maintenance.
The four-story building has an outer façade of glass, beams, and blue tiles all made of local building material. The blue tiles were selected as an economical alternative to the more common in and the glass is designed to work in precise mathematical angles about the tiles to maximize the use or disuse of natural sunlight. “Heating bills during winter months are further reduced by the library’s magnificent south-facing glass facade, with louvers specially angled to allow in winter sun but deflect it in the summer” (“Jubilee Library”, 2006).
Three large wind towers stand on the roof of the building. “These are an integral part of the passive cooling system, drawing warmed air up and out of the structure. … High-efficiency heat recovery units capture heat from lighting, PCs, and people, recycling it back through the system” (“Jubilee Library”, 2006). This process works because of the internal structural elements that also contribute to the green function of the design.
According to one of the designers, Nick Lomax, the rooftop towers are designed to “add to the flamboyance of the city skyline” as well as to “use the breeze to draw excess heat, especially in summer, up from the spaces below” (Glancey, 2006), suggesting a strong integrated approach to design and development. Inside the structure, tall concrete columns accentuate the height of the building and maximize the open space in the center while supporting the high soffit ceiling on the fluted crowns.
The exposed concrete of these columns works with the specially designed hollow-core concrete internal floors and the rooftop turbines to circulate and collect hot and cold air. Warm air rises through the columns is sucked out of the building as a natural process during warm weather while cooler air is filtered down into the building during the evening hours through the same process. This is due to the properties of the materials used and how they are linked. By allowing the concrete to remain exposed, the building naturally draws heat during the day and passes it to the outside while also filtering cooler air into the interior rooms thus keeping the building at an even temperature year-round.
This circulation process is naturally reversed in the winter as the concrete collects heat from the sun during the day and releases it into the interior rooms in the evenings. The heavy use of exterior and interior glass allows uninterrupted natural light throughout the building which reduces the need for artificial light in the daytime at the same time that it gives users of the structure a pleasing, open sensation.
The field of structural engineering provides a wide variety of potential areas for specialization and exploration. This has been proven throughout time but has only become more dynamic in the last few centuries as new materials and new approaches have been quick in coming. This is revealed in the new theories that emerged out of and in response to the Chicago School and the amazing structures that were conceived as a part of the resulting Modernist movement.
Although there are many fine examples of this, the Gateway Arch of St. Louis is a great example of how structural engineers play a vital role in the execution of any load-bearing design as well as the need for designs that involve something other than buildings in the presence of the tram system. In recent years, increasing concerns and emphasis regarding environmental protection have opened the field again to new and exciting possibilities as are expressed in the economical and sustainable development of structures such as the Jubilee Library in Brighton, England. With new technologies, materials, and processes available every day, the future is full of possibilities in this field.
References
Barbano, Michael. (2006). “Eero Saarinen: Shaping the Future.” Finnish Cultural Institute. New York. Web.
Billington, David P. (1985). The Tower and the Bridge: The New Art of Structural Engineering. Princeton University Press.
California Integrated Waste Management Board (CIWMB). (2007). Green Building Basics. Web.
Condit, Carl W. (1998). The Chicago School of Architecture. University of Chicago Press.
Cronon, William. (1994). Inconstant Unity: The Passion of Frank Lloyd Wright. New York: The Museum of Modern Art.
“Encyclopedia: Hannskarl Bandel.” (2009). NationMaster. Web.
Escherich, Susan. (2006). “Gateway Arch.” National Historic Landmarks. Web.
Glancey, Jonathan. (2006). “Sweet and Low Down.” Guardian Unlimited. Web.
Hale, Jonathon A. (2000). Building Ideas: An Introduction to Architectural History. West Sussex: John Wiley & Sons.
Heyman, Jacques. (1999). The Science of Structural Engineering. London: Imperial College Press.
“Jubilee Library, Brighton.” (2006). The Concrete Centre. Web.
Leland, J. Michael. (2006). “St. Louis Arch.” Michael’s Architecture Page. Web.