Holy S…!

Holy structure! Yeah, structure. Don’t let your mind suggest something else!


Figure 1: The Basilica of The Sacred Heart of Jesus[1]

Structure Information

During one of my rare errands on Peachtree Street in Atlanta, I’ve came across this beauty and convinced myself that it might be a good time to be religious. Formerly known as Saints Peter and Paul, the Basilica of the Sacred Heart of Jesus is a church founded in 1880 that

Figure 2: Location[2]

was initially located a few blocks away westward. The needs for relocation occurred in response to the congregation’s increasing number and the commercialization of the area. A new denomination “The sacred Heart of Jesus” came along with the French Romanesque design of the architect W.T. Downing in 1897. The impressive creation won a place in the National Register of Historic Places in 1976 and was later consecrated as The Basilica of the Sacred Heart of Jesus by His Holiness Pope Benedict XVI himself! Funding came from diverse unrevealed sources. During my short tour guide, I came to understand that the facility is projecting important repairs and only fifty percent of the $1.25M needed is met. I’m not preaching here…your donation…lol!


Historical Significance

Figure 3 : Inside toward the tabernacle

Figure 4: Inside, toward main exit/entrance














The engineering design for this structure was not entirely new. As expressed earlier, the Architectural style was inspired from the Roman French with a final product that demonstrated a particular touch from Downing and his engineering team. Both the exterior and interior are predominantly consisted of arches and decorative columns which are literally Roman’s footprints/signature . The idea of improving pre-existing designs in order to obtain enhanced products could not be condemned, is it? The humanity has been long relying on old patterns to define new ones.


Cultural Significance

While it was still Sacred Heart, Mother Theresa of Calcutta, an important figure of the Roman Catholic church, was there for a Mass in June 1995.  She came at the Basilica for the blessing of the Sisters of Charity AIDS hospice. The renowned Father Michael A. (Tony) Morris led the congregation during its growth and revitalization. The “artistically significant architecture” is said to have influenced the recognition to the National Register of Historic Places. All sort of religious education are provided on the premises in both English and Spanish.


Structural Art

The walls of the First Catholic Church of Atlanta are essentially made of masonry, pressed brick and terra cotta. Two twin towers with octagonal shape along with arches of various span were heavily represented. Columns are symmetrically placed, creating an aesthetic touch that follows the “function follows form” of David P. Billington [3]. Architect Downing used eyebrow windows to enhance the building’s aesthetic expression. The conic element on the top of the one-hundred and thirty-seven feet towers is visibly made from lighter material but stiff enough to resist wind loads; revealing the combination of what qualify, in my opinion, the building as a structure art.


Structural Analysis

The design principles were those associated with resistance to wind loads, dead weight. From the interior pictures -little dark by the way- we could perceive how the high ceiling in the shape of a dome -above the tabernacle, specifically- transmits its load to the symmetrically and strategically positioned columns. Considering the relatively small section of the columns and the thickness of the outside walls, I’m tempted to say that most of them were bearing-walls. However, the columns were collecting loads from the tributary areas of the roof and of the beams between the spans of the high-rise building. The base of the towers consists of cubic blocks containing tall, round-headed windows incorporated in recessed walls framed by strip buttresses. Depending on the cases, the arches were submitted to a triangularly distributed load which, in return are transmitted to the columns. For example, the Triple-arched doorway at the entrance displayed at the right present how the loads are applied. The reaction at the base of each column should withstand the weight of the associated tributary area. In this case, it’s clearly predictable that the pair of columns in the middle would more likely have the same design and a more consistent load compared to the others two.

Figure 4: Load below the beam on arches

Figure 5: Tributary area, load distribution

Figure 6: Collection of tributary load into the column









Due to symmetry, there’s a high likelihood to have multiples structural elements with the same sections; making the engineering duty less complex unless geotechnical conditions differ.

It was recorded that the building was built for $28,000 on a land initially acquired for $12,000[4]. I was not able to collect any technical information. I’ve resolute to focus on the design of the high ceiling with the following assumptions:

Figure 7: Load on arches

-Dead load for concrete = 145 lbs/ft3  [5]

-Live Load (snow) = 5 lbs/ft2 [6]

-Hmax = 25 ft (pure estimation)

-Slab thickness = 8 in (previous experiences input)

-Tributary Area A = 180 ft2 (pure estimation)

-Span L = 150 ft (pure estimation)


Figure 8: Determination of loads


With these information, I was able to compute the reactions on the buttresses and the load on the columns as displayed in the following figure.

The next step was to evaluate the bearing stress on the columns. With the diameter of the column estimated to be around 18 feet, the area of the column is estimated to be in the order of 36,643.54 in2. The bearing stress being equal to the force over the area, the bearing stress of the columns is evaluated at 80.41 psi. With a supposed Factor of safety of 11, I was able to conclude that the allowable stress should be 884.5 psi in order to prevent any eventual buckling. Furthermore, it’s imperative to appreciate the responsiveness of the columns to stress and since the maximum occurs at the center, that would be the center of our focus.


Personal Response

The physical presence inside an historic building of this type is more than insightful. Anyone else could have also suspected the building for being a little old but just not as much as a century. Its powerful in some ways to get so close of one of the oldest structures built in Atlanta which is still functional. Now I understand, how incertitude has influenced a relatively greater factor of safety for ancient structures; leading for massive sections not necessarily cost-efficient. Especially, in this case of a religious building, I just hope for my visit to have occasioned my sins to be washed away!



[1] http://www.sacredheartatlanta.org/directionsparking.html

[2] https://screenshots.firefox.com/UKHW08xvzEaflSA7/www.google.com

[3] David P. Billington  The Tower and the Bridge: The New Art of Structural Engineering


[5] https://www.atlantaga.gov/government/departments/city-planning/office-of-design/urban-design-commission/church-of-the-sacred-heart-of-jesus

[6] https://www.atlantaga.gov/home/showdocument?id=33495



The Lincoln Memorial

Lincoln Memorial

As I was watching Elle Woods (in the movie Legally Blonde) fiercely climb the stairs of the Lincoln Memorial and find the courage to pursue her dreams while gazing into the strong stare of Lincoln on his throne, I knew at that moment that I too wanted to live out a dramatic scene on those stairs and experience the majestic strength that emanated from that structure.

The statue itself is magnificent but what really grabs attention and allows the structure to truly shine is the house where the structure sites. Its high columns give Lincoln a regal, majestic almost celestial feel. The large scale of the memorial, the height, the thickness of the columns and the stark white of the marble give me the impression that it is almost sitting on clouds. It is, in my opinion, a piece of architectural art; but is it structural art? Keep reading to find the answer. 

I did not grow up in the United States and all I ever knew about Lincoln was from the embarrassing amount of television dramas that my mom (me really) watches. Through this blog post, I had the opportunity to learn more about this great man as well as the structure used to remember him. Lincoln was a man of honor who served his country like no other and died in a most tragic way. It only seemed right that he may be remembered in a structure as grand as he was.

Related image

Figure 1: The Lincoln Memorial looking as though it sits on clouds [2]

Structure Information

Ever since Lincoln’s death in 1865, Congress had been toying with the idea of having built a monument in his honor. It was not until 1911 though that Congress gathered enough funds to commission the memorial. They approved, $2 million dollars (3) bill (in today’s money) and created a commission that was headed by President Taft to oversee the project. Construction started on February 12th, 1914, (Lincoln’s birthday) and the memorial was dedicated on May 30th, 1922. It is located at West Potomac Park at the western end on the national mall in Washington DC The Lincoln memorial is actually across from the Washington Monument for those who have never been (shame on you!).

The memorial ended costing $2,957,000 and the statue $88,400 for a total cost of $3,045,400. The structure includes 3 chambers with the statue resting in the central one. The purpose of this building is to commemorate the 16th president of the united states, Abraham Lincoln who was tragically assassinated in 1865. It is a historical site and a tourist attraction.

Three people contributed to the design, each acting in different part. The architect of the memorial was famous French architect of the time Henry Bacon (3). The murals feature intricate artwork done by Jules Guerin and the statue itself was carved by artist, Daniel Chester French.

Image result for lincoln memorial structure

Figure 2: Lincoln Memorial [4]

  1. Historical Significance 

Nothing about the Lincoln memorial ‘s structural design is particularly innovative. It was built to be reminiscent of old Greek temples, but with a modern twist. I doubt that this will be a model for future buildings due to its symbolic nature and its use of old structural themes.


Image result for greek parthenon

Figure 3: Ruins of Parthenon in Acropolis, Athens, Greece [6]

  1. Cultural Significance 

The Lincoln memorial today stands as an iconic symbol of America. Its representation can be found on the back of 5-dollar bill (I have provided a picture for those who forgot what money looks like). It was also found at the back of pennies. As Lincoln abolished slavery, his memorial played an important role in the civil rights movement. It served as a place of protest, it was a part of the March on Washington in 1963 and the place that Martin Luther King Jr. gave his famous “I have a dream” speech. It hosted the Easter Sunday Concert (9) a major event for the civil rights movement too.

Figure 4: penny [11]


Figure 5: 5 dollar bill showing memorial [12]

As stated previously, the design was based on Greek Parthenian temple. You might wonder what Greece has to do with the United States.  Don’t worry you are not the first to ask such a question. When the design was first released it received great criticism for architects all over the United States. Many detested the designed and the fact that it was based on old Greek architecture. A certain architect, Lewis Mumford, went as far as to say it reminded him of the “mortuary air of archeology” (5). Bacon justified his choice saying he saw Greece as a symbol of democracy, which is what Lincoln embodied to him (3).

  1. Structural Art 

When first looking at this building and seeing the strong columns one may confuse certain elements with structural art. Though the load path on the columns may seem clear, there are many more columns then needed to support the weight of the roof- the number was a purely aesthetic choice. This structure was not designed by an engineer but by an architect, its sole purpose was to carry its own weight and the weight of its statue. Although it has a beautiful historic significance in most of its design features, none of the elements designed for the memorial were chosen based on economy or efficiency, two key components to structural art.  Throughout the construction process, reinforcements were added as needed, almost on a trail error basis. There is very little correlation between design and efficiency or even economy.  There are too many decorations and superfluous elements for this to be considered structural art.

For the structural analysis I will only be analyzing the outside structure which houses the statue and not the statue.

The materials used were to emulate the unity of the country. The chose materials from all over the 36 states: granite from Massachusetts for the terrace, marble form Colorado for the upper steps and outside facade, pink marble from Tennessee for the floor of the chambers, limestone form Indiana on interior walls and columns of the chamber, marble from Alabama for ceiling tiles and the statue itself was carved from Georgia marble (1). The structure also has 36 columns to represent the 36 existing states of the time.


Most of the load of the system is carried through its foundation. The foundation is very deep and constitutes about 40% of the structure. The foundation is made of concrete and is 44 to 66 (1) feet deep. The foundation needed to be very deep to support the weight of the memorial and that of the marble structure. It is enclosed by granite retaining walls.

For this analysis we will assume that the entirety of the weight of the exterior roof is supported by all 36 columns and the walls. In reality, most of the columns support zero to few loads. The columns are in compression and transfer 36 point loads to the foundations.  For the interior structure, the weight is supported by the 5 walls. The interior structures transfer a uniform surface load onto the foundation. The foundation receives the 36 points loads as well as the uniformly distributed surface loads. It is important to note that the foundation bears the entirety of the load.



Figure 6: Wall Load Paths

Figure 7: Column Load Paths


Given information(1)

Foundation of building: 44 to 65 feet from original grade to bedrock.

Total width of building north to south: 201 feet 10 inches at widest point.

Total depth of building east to west: 132 feet at widest point.

Memorial weight: 76,000,000 pounds.

Given that the total weight of the memorial is known, we will treat it as a surface load onto the foundation.

Given a height of 44’, a length of 201’10” and width of 132’, the dead weight load is 64.8lb/ft^3.

Figure 9: Simplified drawing of foundation


Figure 9: Tributary area and load


Solving for R1 and R2

W = 64.8lb/ft^3 * 132ft * 44ft =376.42k/ft

Sum of Forces in Y:

R1+ R2 = 376.42k/lb * 201ft 10in = 76 000 k

Sum of Moment about A

R2 (201’10”)-76000k(201’10”/2)=0

R2= 38 000k

R1 = 38 000k


Figure 8: Shear and Bending Moment Diagrams

The max shear is 38 000k

The max moment is  15,344,400k ft.


Now that we have analyzed the system let us look at why congress found thiss design appealing.

One of the reasons this design was kept is because it aligned with the aesthetic conservatism (3) ideas of congress. President  Taft was largely conservative. Congress wanted to commemorate Lincoln but did not want an overly complicated design. The design by Bacon displayed a Greek like structure  with large central court and flanking sanctuaries that would contain “ a statue of heroic size expressing Lincoln’s humane personally and memorials of his two speeches” (7). One of the rejected designs had taken inspiration from the pyramids and was seen as overly complicated. Initially there was more interest in the statue, the building was actually built with a plaster model of the statue in it to make sure it would fit. Upon realizing the unusually large scale of the memorial, a larger statue had to be ordered.


Figure 9: One of the originals plans of the Lincoln Memorial [10]

Figure 10: Floor Plan [10]


6. Personal Response

In April 2016, I finally had the honor to visit this structure and experience its magic with my two eyes. My first impression that there was a whole lot of people! In fact, there were so many people that I could not see Lincoln properly. All my pictures were photo bombed by random people, I got hit, pushed, yelled at and tousled like a bag of potatoes. The structure itself was much bigger than I had imagined and as impressive.





[3] https://traveldigg.com/lincoln-memorial/



[6] https://www.pinterest.com/pin/166422148706667374/








Connecting Railway, Schuylkill River Bridge

Structure Information

The Connecting Railway, Schuylkill River Bridge is in Philadelphia, PA, and it crosses the Schuylkill River. Construction began in 1866 and was completed in 1867. The bridge has seen modifications, which took place in 1873, 1897, and 1912-1915. The main purpose of the bridge was to help create a more direct route in the railroad system from Philadelphia to New York City. It was designed by the Chief Engineer of the project, John A. Wilson. The Pennsylvania Railroad (PRR) helped fund the Connecting Railway. The bridge in Figure 1 came from reconstruction in 1912, which was designed by Alexander C. Shand at the discretion of PRR. [3]

Figure 1. View of the bridge across the Schuylkill. [1]

Historical Significance

Initially, the bridge had a cast and wrought iron, double-intersection Whipple truss in the center of stone arches. When this type of truss couldn’t carry the increasing railway loads, the Whipple truss was replaced by a Pratt truss. They switched the trusses in under two and a half minutes, which paved the way for fast construction techniques. When traffic began to pick up in the twentieth century, the PRR wanted to widen the bridge. This new bridge did not use any innovative structural engineering designs because it was made of stone. Some marked how unusual it was because reinforced concrete was already available. During this time, city authorities like the Fairmount Park Commission most likely influenced the use of stone. It made the bridge quicker to construct and less expensive. Even though the construction techniques weren’t new, it was the first bridge to eliminate the detour between West Philadelphia and the waterfront across from New York City. [3]


Cultural Significance

What was interesting about the initial construction of the bridge was that Wilson wasn’t in charge during construction. He took a job with the Philadelphia & Reading Railroad, so George B. Roberts oversaw construction. In both major construction periods, the designer didn’t do much. Roberts oversaw construction in the first bridge and the builders made decisions about how to construct the 1912 bridge. Many appreciated this bridge when it was first built because it made the commute time by rail between Philadelphia and New York City less. This bridge was used as inspiration for many artists, including Thomas Eakins and Edmund Darch Lewis. This part of the Schuylkill River is also used by many rowing teams. I found the bridge when I was at the Dad Vail Regatta recently. Many people row under the arches of it and can see the design. In Figure 2, you can see a painting by Eakins that portrays a man in a single, rowing. Today, Amtrak and Pennsylvania Transportation Authority’s passenger trains use the bridge. [3] Even through all of the reconstruction phases, the bridge is still used for the reason it was created.

Figure 2. Max Schmitt in a single scull. [2]

Structural Art

By using the stone, the PRR was able to save money, which fulfills the economic portion of structural art. However, even though the old bridge had a truss, the new one has stone arches. The truss would have been lighter and more open, but you can’t see through the stone arch. This makes the bridge not aesthetically appealing. Also, the new bridge wasn’t trying to conserve material. They built it out of stone instead of concrete even though concrete or another material would have been stronger. Since large span stone bridges can’t support trains, multiple arch spans had to be used for this bridge. The builders for reconstruction were more focused on making the new bridge look like the old bridge instead of trying to create structural art.


Structural Analysis

At first design, stone arches were placed on both sides of a cast and wrought iron, double-intersection Whipple truss. The arch spans were 60’ stone-faced brick, and they were separated by 7’ piers to support the arches. In the 1873 reconstruction, builders increased the thickness of the stone piers at both ends. Then, a Pratt truss replaced the Whipple truss in 1897 to support increased railway loads. When the Pennsylvania Railroad wanted to increase the number of tracks going across, Shand initially designed two 103’ spans and a pier in the middle of the river which would go underneath the existing truss. Eyre Shoemaker, Inc., the construction company, was not able to build on the old arches because they were damaged. Instead, Shoemaker tore down the arches and rebuilt it trying to resemble the preexisting bridge as much as possible. Today you can see what Shoemaker built. There is a 22’ pier in the center of the river that supports the two main arch spans of 103’. On the outside of these arches are two more piers that are slightly larger resembling the 1873 reconstruction. Next to these two piers lay more stone arches that have only a 60’ span. [3] The arches were slightly corbeled so that the bridge could take more load as well. The bridge involves a dead load from the stone, which can be very heavy, and a live load from the trains. As seen in Figure 4, the load is transferred down the arch and to the pier.

Figure 4. Load distribution of the arch.

Next, I analyzed the different parts of the arch. As seen in Figure 2, I assumed that the depth of the bridge was about 90 feet since there are five train tracks, that the height of the load was 10 feet, and the weight of sandstone is 150 lb/ft^3.

Figure 5. Calculation of weight of sandstone.

Once I got a number for the load distribution, I decided to calculate the live load at different parts of the main span since the train is a live load. I assumed the train load as a uniform load, and I also assumed the passenger train weighs 1.08 million pounds and with 6 cars and a locomotive, is around 600 feet in length. This came to a uniform load of about 1800 lb/ft existing on top of the dead load of the sandstone. Using this information, I was able to calculate the vertical reaction forces, as seen in Figure 6.

Figure 6. Finding vertical reaction forces.

Once I did this, I made a cut in the middle of the arch. I was then able to solve for the horizontal reaction force and the maximum force at point A, as seen in Figure 7.

Figure 7. Calculation of the maximum force.

Since the train is moving, I decided to treat the train as a uniform load only in the first quarter of the arch, which can be seen in Figure 8.

Figure 8. Live load on part of the arch.

Using the entire beam, I was able to calculate the reaction forces at A and then the maximum force at A. All the calculations can be found in Figure 9.

Figure 9. Calculations to find the reaction and maximum forces.

Since these calculations were for the main span, I also included one analysis of a bridge with the smaller, 60-foot span. Again, I made all of the assumptions I previously made for the 103-foot span arch. As shown in Figure 10, the span is 60 feet, but everything else is the same.

Figure 10. Loads on the 60′ span arch.

I was then able to calculate all of the forces, which can be seen in Figure 11.

Figure 11. Calculations for 60′ span arch.

Engineers like Shand and others would have made calculations like I did (and more complicated ones since I only know so much structural engineering) to figure out how much load a pier could take through combining the maximum loads of two arches. It was especially important for this bridge that the engineer make the piers large enough to support the weight of the stone and of the trains moving across. When Shand’s design didn’t work initially, Shoemaker took his own initiative to make sure that the bridge was stable and would hold the railway load.


Personal Response

You see old railway bridges in books and movies from the past, but you never realize how different a stone arch bridge across the Schuylkill is from the surrounding area. Philadelphia houses many types of bridges, and surrounding this bridge are many up-to-date bridges that make this bridge seem out of place. I really enjoy looking at historic structures, but it is a little odd to see this kind of bridge still used among all the newer bridges. I’m sure it sticks out like a sore thumb to many who see it visiting Philadelphia.



[1] https://en.wikipedia.org/wiki/Pennsylvania_Railroad,_Connecting_Railway_Bridge

[2] https://www.metmuseum.org/toah/works-of-art/34.92/

[3] http://cdn.loc.gov/master/pnp/habshaer/pa/pa1600/pa1646/data/pa1646data.pdf

Bank of America Plaza

Structure Information

Bank of America Plaza, originally named NationsBank Plaza, was built in 1992 in Atlanta, GA.

Figure 1. Bank of America Plaza [1]

The building was built as a headquarters for NationsBank. Once NationsBank was bought out by Bank of America, the building’s name was changed to Bank of America Plaza and became an office space for Bank of America and other tenants. As Atlanta’s tallest building, Bank of America Plaza was also designed as an “anchor between Midtown and Downtown” [2]. Bank of America Plaza has become a symbol of Atlanta.

Bank of America Plaza was designed by Kevin Roche, John Dinkeloo and Associates (KRJDA) [1]. CBM Engineers were the structural engineers [1]. Beers Construction Company was the main contractor [1]. NationsBank, in coordination with Cousins Properties, funded the project [3].

Historical Significance

At 1023 feet tall, Bank of America Plaza is the tallest building in Atlanta and the Southeast [3]. It is also the 13th tallest building in the United States, and the tallest in the country outside of New York and Chicago.

The architectural vision for the building was a mix between the art deco and postmodern architectural styles. This causes the building to have an appearance resembling more traditional skyscrapers, like the Empire State Building [4]. The building is accented with a 23-karat gold pyramid that is illuminated at night, as shown in Figure 2. When the building was constructed, Atlanta was preparing to host the 1996 Olympic Games. Bank of America Plaza symbolized Atlanta’s hope to emerge from hosting the Olympics as an internationally known city.

Figure 2. Illuminated Spire [1]

A unique feature of the building is its 45-degree angle with its bordering streets [1]. This means that the primary sides of the building form a square in plan, but at a 45-degree angle to the adjacent streets, as shown in Figure 3. This design choice was made in an attempt to provide “undisturbed views in all directions” [1]. The placement of the curtain wall was also chosen to help provide stellar views to the building’s tenants.

Figure 3. View from bordering street

In addition to being constructed on-budget and on-time, the Bank of America Plaza was constructed in 14 months, one of the fastest constructions of a building with a height of over 1000 feet. [5] The building was also awarded Atlantic Business Chronicle’s Best Community Impact and Architectural Deal of the Year awards [1]. While the building was modeled after existing skyscrapers, Bank of America Plaza’s features and statistics show that it is a remarkably unique structure.

Cultural Significance

The building was originally proposed as a new headquarters for Citizen and Southern Bank (C&S). Before construction was completed, C&S was bought out by NationsBank, and the building was named NationsBank Plaza. In 1999, after NationsBank was bought out by Bank of America, the building’s name was changed to Bank of America Plaza [6].

The building came to life when Atlanta and real estate were booming. In 2006, Bentley Forbes bought the building for $436 million [6]. When the U.S. economy fell into a recession, more and more vacancies began to fill the iconic tower [6]. In 2012, the building faced foreclosure. Even today, the 55-story building is only half-filled [7]. The history of Bank of America Plaza demonstrated that economy can have a dramatic impact on even iconic buildings.

The new symbol of Atlanta was not loved by all. Critics called it “conventional” and said it looks like a pencil [7]. When I first visited Atlanta after getting accepted into Georgia Tech, I loved everything about Atlanta. Except for this building. Something about the skeletal pyramid on top bothered me. The vast number of members confused me and made me feel like they left it unfinished, rather than intended it as art.

Flash forward to my first weeks at Georgia Tech. I learned that students fondly refer to Bank of America Plaza as the “Pencil Building”. I also learned that the clarinet section of the Georgia Tech Marching Band loved the building so much that they would sacrifice pencils to the Pencil Building ahead of a Georgia Tech home football game for good luck. The building grew on me as I saw its effect on Tech students. As the tallest building in Atlanta, it gives students a sense of direction when exploring the city and provides a feeling of home when returning to Atlanta after time away. While there are mixed opinions on its appearance, Bank of America Plaza is an important symbol in Atlanta.

Structural Art

A building demonstrates structural art if it is efficient, economic, and elegant. Bank of America Plaza features a column-free interior [1]. Its external columns and central core carry both gravity loads and wind loads, making the structural system efficient [1]. In addition to benefitting the building’s efficiency, a column-free interior lowers cost [1]. However, the building features a decorative 23-karat gold spire above the building’s usable space. While this addition seems excessive, the spire “encloses the cooling tower, elevator penthouses and other mechanical equipment.” [1] The space beneath the spire has a use in addition to being an aesthetic highlight. However, the argument can be made that the spire’s “closely-spaces horizontal tubes” reduce the efficiency of the spire and increase cost. 23-karat gold itself unnecessarily raises the cost. The horizontal tubes also reduce the transparency of the structure, making it harder to determine how the spire carries load.  As mentioned earlier, there is debate over whether the building has an aesthetic appearance. Based on my initial reaction to the building, I would say that the building is not elegant. While Bank of America Plaza contains some noteworthy features, the gaudy nature of the golden spire demonstrates excess economy, reduced efficiency, and questionable elegance. Therefore, Bank of America Plaza is not structural art.

Structural Analysis

According to KRJDA, the building was designed to be a “modern interpretation of art deco with an enduring iconic stature.”[2] This is achieved with a red granite and glass façade that is accented with a golden spire [5]. Columns are used to emphasize the vast vertical height of the building. The building’s core is made of reinforced concrete and 4 concrete encased steel columns [3]. The building features 4 towers, each of which has 2 large concrete encased steel columns [1]. Steel is used as the floor spanning [3]. Figure 4 shows the building during its construction.

Figure 4. Bank of America Plaza Construction [8]

The structural system utilized the “super column” system by using large columns to both carry gravity loads and wind loads [1]. Each floor load is supported by beams, which are supported by the super columns.

Figure 5. Loads on whole structure


Figure 6. Spire Load Path

The tip of the building acts as a point load on the spire’s truss-like system. The spire is made up of diagonal, vertical, and horizontal members. The diagonal, vertical, and large horizontal members carry load similar to a truss. The smaller horizontal members and crossbars provide bracing. The bottom beams of the spire then act as line loads over the columns. Each floor’s slab is supported by steel beams that acts as point loads to the columns. The columns transfer load into the foundations.

Figure 7. Simplified Model of Building

Figure 5 shows the loads in relation to the super structure. The loads acting on the building are wind loads, dead loads, and live loads. The red lines demonstrate the load path due to gravity loads, while the green lines represent the wind load. The wind load increases as the height of the building increases. In contrast, the gravity loads are higher at the bottom of the structure, compared to the top of the structure. As seen in Figure 5, additional columns appear at lower elevations to add additional support to the super columns. Each of the columns are buried into the foundation which provides a horizontal force, vertical force, and moment. This means that the structure has one fixed end and one free end, like a cantilever beam.

Figure 7 is a simplified model of the forces on the building. Again, the green arrows show the wind load and the red arrow shows the gravity loads. The blue arrows show the support reactions. By examination, the horizontal reaction force is equal to the distributed wind load multiplied by the height of the building, or wH. The vertical reaction force is equal to the weight of the building and the live loads. Since moment requires a force acting over a perpendicular direction, the moment at the fixed end is caused only the distributed wind load. This moment is equal to w*H*H/2, with w being the distributed wind load and H being the height of the building.

The live load of the building comes from 3 components, the offices, the lobby, and the roof. For a standard office building, the live load from offices is 50 psf and the live load from the lobby is 100 psf [9]. The typical live roof load is 12 psf, but since the roof houses mechanical equipment, I assumed a live load of 25 psf [9]. Each floor plate is between 20,000 and 25,000 square feet throughout the building’s 55 floors [2]. Using the average of 22,250 sf, the office live load is calculated at 60,750 kips as a result of multiplying 50 psf by 22500 sf by 54 floors. Using the same method with an area of 25,000 sf, the lobby live load is 2500 kips. The roof live load, using an area of 20,000 psf, is 500 kips. The addition of these live loads results in a total live load of 63,750 kips.

The dead load on the building is a result of the floor slabs, mechanical equipment on the roof, and the spire. The weight of the mechanical equipment was assumed to be 20 kips. From counting the number of members in the spire at approximately 300, the weight of the spire was calculated to be 2883 kips, using steel with a weight of 0.283 pounds per cubic inch. The cross section of each member was assumed to be 6 inches by 12 inches with a hollow interior of 4 inches by 10 inches. The average length, based on the floor area, was assumed to be 70.75 feet. Assuming the steel floor spanning is 10 inches thick with a weight of 408 pounds per square foot, the dead load of the slabs is 495,720 kips. The total weight due to dead loads is 498,623 kips.

Combining the dead loads and live loads, the vertical reaction is 562,373 kips. Dividing this by the 8 columns, the force in each column due to vertical forces is 70,297 kips. The stress for each column under uniaxial loading is the force over its area. Given that the area of each column is 8 square feet, the stress felt by each column can be calculated as 61.0 ksi [1].

Personal Response

What started as my least favorite building in Atlanta, slowly grew on me as it became a symbol of Atlanta in my life. I chose to write this blog because of my changing opinions. After visiting the building for this project, my opinion changed again. As the tallest building in Atlanta, Bank of America Plaza can be seen all over the Atlanta area. From afar, the building appears as if it consists of really long columns of shiny, red metal. As I approached the building, I saw the evolution from one massive structure into its individual red granite stones. Once in front of the building, I was greeted by greenery and a long staircase leading to the grand entrance. While seeing the building in person was cool, its size and grandeur was intimidating. The plaza around the building sets the building back from the street making it seem exclusive and hard to reach. While I did read articles that mentioned the building’s poor connection with its surrounding area, it wasn’t until going there myself that I understood the uneasy feeling the building could bring to a person.

Figure 8. Building entrance [1]


  1. http://www.krjda.com/Sites/BankAmericaInfo1.html
  2. http://www.bankofamericaplaza.com/our-building
  3. http://www.skyscrapercenter.com/building/bank-of-america-plaza/429
  4. http://artsatl.com/rediscovering-atlantas-architecture-bank-america-plaza/
  5. https://www.emporis.com/buildings/121137/bank-of-america-plaza-atlanta-ga-usa
  6. https://www.ajc.com/business/bank-america-plaza-becomes-atlanta-priciest-repo/yKEFrl8ElBb2oAiPguIjfJ/
  7. http://www.atlantamagazine.com/90s/nationsbank-plaza-now-bank-of-america-plaza-rises-up/
  8. https://www.reddit.com/r/Atlanta/comments/29p2f6/bank_of_america_plaza_under_construction_1991/
  9. https://www2.iccsafe.org/states/Florida2001/FL_Building1/PDFs/Chapter%2016_Structural%20Loads.pdf

Millennium Arch

Millennium Gate museum

Structure Information

The millennium gate bridge is located on 17th street in Atlantic station which is a popular mixed-use development in midtown Atlanta.  Construction began in 2005 and was opened to the public on July 4th 2008.Image result for millennium arch atlanta

Figure 1: Millennium Arch

This structure was funded by the National Monuments Foundation because they wanted to honor the rich history of Atlanta. Back in the mid-1800s Atlanta was known as the gate city because the rail system that ran through the city was the first to connect the east coast to the western United States. The National Monuments Foundation thought it was fitting to build an actual gate in the heart of Atlanta to honor fast growing city. The design of the arch came to be through an international competition which was judged by some of the most respected architects of the time.  [1]

Historical Significance

This structure was not an innovative structural engineering design. The arch was perfected by the ancient Greeks back in 470 BC. There has been plenty of Arch monuments that have been built around the United States and around the world like the Titus Arch in Rome and the Washington Square Arch, in New York’s Washington Square. [1]

Cultural Significance

Atlantic Station today is a highly populated area in Atlanta which is known for is retail, high density apartments and tall office buildings. It was not always like this. Back in the early 1900s the Atlanta Hoop factory was founded here where they made cotton bale ties and barrel hoops. With the advancement of technology steel was in high demand and the factory switched its focus to steel and became known as the Atlantic Steel Mill. It finally closed in the 90s and was abandoned.  The steel mill created a lot of hazardous waste and because it was abandoned no one ever cleaned up the waste properly. This became a huge road block for developers whose hopes were to transform this area into a huge retail area to try to improve and grow Atlanta. The EPA determined that this area was too harmful to build here where families would live. Experts came up with a plan to remove and also burry most of the waste along with other methods.

This development became a huge success by accelerating the growth of Atlanta which is now one of the fastest growing cities of it size. People from Atlanta have enjoyed this monument as it sits in a park where people can sit and reflect in such a beautiful place

Structural Art

Billington would definitely not consider the Millennium Arch as structural art. One could say that the load path is clear and is a very elegant looking structure but that is about it. There was no new technology developed in the design of this monument, the arch outdates the ancient Greeks. Also, the economy and politics didn’t really add any constraints to this project to effect its final design.

Structural Analysis

I had a difficult time finding the exact dimensions of this arch so I had to make a few assumptions. I do know that the total height of the arch is 100 ft tall. Based on this I assumed the length of the arch is 35 ft long and 20 feet 12 feet high. The structure is made of lime stone which ways 150lb/ft3 so I made an assumption that the distributed load along the top of the arch is 184 kip/ft.  Please see Figure below.


Figure 2: Loads Applied

To calculate the reaction of this arc, I first summed the forces in the y direction of the entire structure. I did this because there is a symmetric load across the arch so the two reactions will equal each other. I got both of the y reactions to equal 3220 kips. Then to find the x reactions I cut the arch in half where the arch is at its tallest height which is 12 ft. At that maximum point there is no internal force in the y direction.  I took the Moment about C and got the x value to equal 2348 kips. IF you look at the entire arch again and sum forces in the x, you will notice that the x values on both side of the arch will equal the same value.

The reason this structure works well is that the top of this arch corbeled. This allows the weight from the top of the structure to get evenly distributed across the arch without collapsing. The forces flow from the arch to the columns it sits on and into the the ground.

Personal Response. 

This arch has always stood out to me but I never had the chance to actually go and visit before. Getting to see it up cloase and person I got see how much detail went into this monument. I really does show how rich Atlanta’s history is and and just how important this area really sparked the immense growth in the A.T.L





  1. http://thegatemuseum.org/history/
  2. http://www.atlanticstation.com/history

Boston Custom House

Structure Information         

The Historic Structure I chose was the Boston Custom House, which is located downtown Boston.  I had a layover in Boson before coming to London, so I decided to explore Boston. The building was designed by architect Ammi B. Young, and the lot for the building was purchased in 1837 and construction was authorized by President Andrew Jackson. The building was complete in 1847 during James K Polk administration. The Custom House was funded by the federal government, and was the most expensive building built in America, with a price tag of $1.2 million [2] .


Boston Custom House Before 1913

Boston Custom House Tower

Historical Significance

The beginning construction process was interesting to me; 3,000 large logs were used was the building’s support [2]. The logs were ugly I am assuming, because they covered the logs with layers of granite, brick and cement to create the sturdy foundation. The twenty-six-floor tower hat was added in 1913 caught my eye at first, because I could see it from the train station [1]. The columns made me think of the ancient Caesar’s Palace, which I learned about in history class. The Custom House has an original design of a Greek temple, with Doric columns on all four sides, and a large domed roof. The style is a Greek Revival-style hence the Caesar similarity.



Cultural Significance

The Custom House was the center of the communications commission, and the center for Boston’s customs officials. Before Federal income tax were introduced to the United States, the government relied on the duties and taxes collected by the Customs Service at Boston’s wharfs.  The Custom House played an important role in the United Stated in the early 1800’s, they accounted for 1/5 of the money collected for the federal government [2]. The reason I gravitated to this building is because, I asked a restaurant host “what was ha building?” and she replied “the Marriott hotel”. I immediately thought that was a cool looking hotel, and wanted to explore the inside.

The Custom House was completely renovated in the 1990s, and now is a timeshare owned by Marriott Vacations. The concierge in the inside was very knowledgeable about the building, nice, and gave me a fact sheet about the history. When I was leaving, he made the remark “That was easy”, so I am guessing he gives out facts to tourist all the time and is now considered a pro at doing it.


Inside Marriott Hotel

Structural Art

Based on the three principles efficiency, economy, and elegance I can determine if the Custom House is structural art. Since, this building played a major role in the federal government finances, I feel that it benefited the economy. It was pricy, but the materials such as granite, brick, cement, and logs made balanced the cost and was efficient. The load for the tower was not transparent, but from the dome down to the columns the load paths can be traced. The Custom House has a Greek elegance about it, and because of its historic look It is structural art. This building screams structural art when looking at the columns. Out of the 36 columns, only half are supporting the structure. The rest are free- standing, so I am guessing the other half are just for looks.

Structural Analysis

After the building was constructed, the exterior of the building consists of 6 columns on each side on a high flight of steps, an order of engaged columns around the walls 20 in number, all on a high basement. The columns are 5 feet 4 inches in diameter and 32 feet high, the shaft being in one place, each weighing about 42 tons. The square footage of the building is 886 sf. The assumption was made that he building is made from stone, so the weight of stone is 133 per cubic feet [3].

Load path

Self Weight Load Path

Self Weight & Force in y-Direction Calculation

Personal Response

By visiting Boston, I now understand why this historical building is well seen verses other historical buildings. I learned that Boston’s pre-1928 building code limited commercial buildings to 125 feet high or approximately 11 stories. Since this was a prominent federal building, the codes did not apply. To somewhat apply to the code, the developers compensated for this restrictive zoning by using innovative massing techniques and by expanding the floor plate [2].  This was my first time in Boston, and I enjoyed exploring and learning about the Historic Structures. When I think of Boston, I think of the Boston Celtics and the New England Patriots. Now I have the knowledge of how federal money was collected before federal income taxes.

Me at Boston Custom House



[1] http://www.iboston.org/mcp.php?pid=customHouse

[2] http://www.celebrateboston.com/architecture/custom-house.htm



Bankhead Highway Bridge

I saw this dilapidated bridge from Tech Parkway, and walked by later along Northside Drive to get a closer look. Although somewhat nondescript, it caught my attention because I was surprised to see an abandoned structure of its size in the middle of the city. The simplicity and eccentricity of the bridge led me to delve further into its history and decide that it would make for an excellent blog post.

Figure 1 – Bridge Against Atlanta Skyline

Structure Information

The Bankhead Highway Bridge was built in 1912 to carry Bankhead Highway (roughly modern day US 29) over the Norfolk Southern and CSX railroads. It was most likely funded by GDOT and designed by a contractor they hired [1]. At the time of its construction, both the railroad and the highway saw very heavy usage, but eventually highway reroutes caused the bridge to become extraneous. Along with high maintenance costs this led to its abandonment and ultimately the destruction of one of the approach ramps. [2]

Figure 2 – Bridge Location

Historical Significance

This bridge is not at all innovative in either construction or design, but is an excellent example of a trussed steel bridge from the time period. It can be viewed as the typical quick and easy solution for land based spans that needed to carry only the load of cars during the early 1900s [1].

Cultural Significance

During active usage, the bridge provided a major causeway for access to the center of Atlanta which otherwise would have been obstructed by the railway. This railway was not for passengers, but instead long commodity filled trains ran along it. In the early 1900s these lines were an important artery for goods transportation to and from Atlanta [3]. Today the bridge is banned from public access (both vehicle and foot traffic) due to extreme structural integrity problems, and the deck, superstructure, and substructure have all been rated “Imminent Failure” in inspections since 1991 [2]. There is also a missing approach ramp and the bridge terminates abruptly at that side with no guard railing or warnings to keep people from falling. However this does not stop graffiti artists and homeless people from climbing onto it, and these are the only people who currently utilize the structure for anything other than the background of grungy Instagram pics.

Structural Art

The three ideals of Structural Art are efficiency, economy, and elegance, and I would argue that the Bankhead Highway Bridge accomplishes the first two, and closely approaches the third. The steel truss structure itself is composed of smaller trusses, creating a light but very strong superstructure and using a minimum of materials. The trusses support a span made of concrete that rests on reinforced concrete pillars, both span and pillars using a reasonable amount of materials. The bridge is therefore quite efficient, and uses materials that were cheap and commonly produced during the time period. It was also built using fairly quick and easy construction processes, as the land based nature of the span eliminates many of the challenges seen in bridges over bodies of water. Both of these factors lead to the conclusion that the bridge also fills out the economic ideal. When it comes to elegance however the bridge is weakest, and I’m sure Billington would hate it, but I personally appreciate its appearance. The bridge is skewed, meaning that the side trusses are the same length, but displaced a single truss length so that from above the bridge is parallelogram shaped. This is an interesting aspect and drew my eye initially as it can create a subtle optical illusion. I also believe that the truss structure connects solidly with the concrete base and together look simple, but strong. Along with the clearly visible load paths from truss to concrete span to pillars (and laterally through the top truss) I believe that the Bankhead Highway Bridge is Structural Art, although Billington may have disagreed based upon its lack of innovation and heavy looking form.

Figure 3 – View of Bridge from Below Missing Approach Ramp

Structural Analysis

The bridge approaches were simply supported cast in place concrete slabs on concrete pillars, and the truss structure is made of steel and supports the concrete middle span of 99.7 feet. This concrete span is 47.9 feet wide and approximately 2 feet thick and the trusses have a vertical clearance of 13.1 feet [2]. The truss structure is a Warren Truss (equilateral triangles) with added verticals and the trusses themselves are also smaller Warren Trusses but without verticals. The top chords and non vertical horizontal trusses have a hollow rectangular cross section with two sides consisting of trusses and all the other members are just single trussed beams. The trusses are riveted together and it is a through truss, so motor vehicles would pass between the upper and lower chords [1]. The truss is skewed as it crosses the railroad at diagonal angle, and from an elevation view looks like a long parallelogram. The top cord is also trussed in the same manner to provide lateral stability, although due to the small span, stiff base, and minimal footprint from an elevation view, the lateral stiffening is somewhat redundant. There is also a concrete sidewalk cantilevered off both sides of the bridge deck. The building techniques of the time were pretty similar to current bridge building techniques (other than the new automatic bridge building machines), and involved wooden form and scaffolding to pour the concrete and the steel was Bessemer mass produced [1].

As the bridge is not currently in use, the only important load is dead load from the self weight of the concrete span. This load is carried by the truss structure which supports the weight of the large concrete slab through members in both compression and members in tension. The weight is ultimately carried by two thick concrete pillars on either side of the span. In the single remaining approach span, there is no truss structure, so its entirely supported by large columns. Below is a simplified truss structure that represents the sides of the bridge to show in a basic way which members take compressive or tensile forces. The green members are experiencing compressive force and the red members are taking tensile force, while the white member has forces that balance out to zero. When the self weight (simplified in the picture [4]) is applied across the bottom chord,  the max stress in any member is in the outside diagonals and is approximately 0.75x the total force. The total force on the bridge due to the self weight of the concrete using a density of 145 lbs/ft^3 and previously stated measurements is 1,384,932.7 lbs which means that the max force in a member is 1,038,699.5 lbs (the total multiplied by 0.75). The compressive strength of old steel is about 36,000 psi (from an internet database), and the end diagonals on the bridge are the only non-trussed members, I had to assume a cross sectional area of about 50 in^2 from the photos. Using these values and the formula (F/A) the normal compressive stress on the outside diagonals is 27,698.7 lbs/in^2 which is less than the compressive strength of steel but only barely. If any live loads from vehicles were added to the bridge failure would rapidly occur, making it abundantly clear that closing the bridge was the correct choice.

Figure 4 – Simplified Warren Truss with Verticals

Another area of possible failure is in the concrete support columns, which could buckle or crumble from compressive bearing stress as shown in the photo below as green arrows. The four columns each have a symmetrical tributary area of 1/4 of the bridge and so must each support 346,233.2 lbs (total weight/4), and are 20 ft tall (previously stated). The columns are slightly tapered squares, and from pictures I will assume that the area at the top of the beam is 3×3 ft and is about 3.5×3.5 ft at the middle. Using these values (and F/A) the bearing stress on each column is 267.2 lbs/in^2, and the compressive strength of concrete is higher than that by at least a factor of ten, so there is no danger of failure from crumbling at the supports. The critical buckling load would be at the red line halfway down the column in the picture below. Using a modulus of elasticity of 2.9 x 10^6 psi (from internet database) and an estimated moment of inertia of 139,968 in^4 (I=b(h^3)/12 using 3×3 ft approximation) comes out to be 6,9551,102.2 lbs (Pcr = (pi^2)EI/(L^2)), a simply massive number that the bridge would never reach. The Bankhead Highway Bridge therefore is in no danger of failure due to its columns, but instead its trussed superstructure and concrete span.

Figure 5 – Compressive Bearing Stress and Hypothetical Buckling Location

Personal Response

It’s somewhat difficult to see from the pictures, but when I was actually walking around the bridge I was fascinated by the skewed truss. It hadn’t occurred to me that such a design was an option, maybe I had seen some in the past but never really took notice, but it was an exciting departure from the normal truss bridge I’ve always seen. I’ve always had some difficulties with trusses (ever since statics) and it was very interesting to try and trace the load paths in person, and then check my answers through equations during the analysis, and my understanding of the joint and section methods has definitely improved. I would love to go up on the bridge, but it’s kind of hard to get to, probably dangerous, and had some homeless people camped out on it, so I may not actually go for it.


  1. http://historicbridges.org/bridges/browser/?bridgebrowser=georgia/bankhead/
  2. https://bridgereports.com/1096608
  3. https://bridgehunter.com/ga/fulton/12151210/
  4. http://ivanmarkov.com/truss-simulator.html

Mercedes-Benz Stadium

Structure Information

Mercedes-Benz Stadium is an 80,000+ capacity stadium in downtown Atlanta, used for football and soccer games and other large events. The design team was led by HOK on the architecture side and BuroHappold on the structural engineering side. HOK won the design for the unprecedented pinwheel-style retractable roof, which is the defining feature of the stadium. The building is owned by the Georgia World Congress Center and the Atlanta Falcons.

Figure 1 – Mercedes-Benz Stadium

Historical Significance

The stadium has all of the expected features for an NFL venue—a large reinforced concrete shell, huge overhanging seating areas, towering columns, a Chick-fil-a even though games are on Sundays—but what sets Mercedes Benz stadium apart is its roof. Its “Ocular Roof” uses eight “petals” that slide past each other simultaneously on steel trusses. These petals retract in the same way a flower or camera aperture would. The roof can open or close in around ten minutes, and roof’s lightweight ETFE membrane allows natural light to inside. Also, under the roof is the first ever 360° display screen. The other important features include the building’s ‘Window to the City’, a floor-to-ceiling glass curtain wall that allows views of Downtown Atlanta, and eight triangular steel and glass sections whose angular sides make up the building’s façade. The roof is the most important and impactful engineering challenge of the stadium, as its design is literally the first of its kind. Owner’s did not want another “vanilla” stadium—they wanted to be “game-changers” in the world of stadiums. Mercedes-Benz Stadium is an unprecedented stadium design, and its influence on other stadiums is difficult to measure since it’s brand-new. My feeling is that its design elements will be used in future building for years to come, as the example set by the stadium will challenge other stadium architects and engineers to push the limits of structures.


Figure 2 – The Stadium from the Inside

Cultural Significance

The stadium is arguably the coolest stadium in the world, and it’s a huge source of pride for Atlanta natives. Some did believe that it was wasteful to build a $1.6 billion stadium when the former stadium, the Georgia Dome, was fully functional. Though there was some pushback, most see the stadium as a welcome addition to the city, with its attractive appearance and ground-breaking features allowing Atlanta sports fans to actually have some self-respect for once. It’s also worth mentioning that we would have never had the joy of seeing a Marta bus block the live stream of the Georgia Dome implosion if the Dome would have been kept. In a city that basically worships sports, this new stadium, primarily used for professional football and soccer, is basically a monument to its beloved sports teams. For the time being, Atlanta has the most impressive stadium in the country, and those who live in the city are pleased to be the best at something in the world of sports and have an amazing addition to the skyline. Besides within the city itself, the stadium has even larger impacts. The SEC football championships will be held there every year, and it will be the venue for the Super Bowl in 2019. Additionally, Wallpaper named it one of the top buildings that shaped the world’s culture in 2017.

Structural Art

Even though many of the design choices made for the stadium were architectural, many aspects of the stadium are great examples of structural art. This is an example of a structure where the architectural pursuits governed the engineering side, but the ingenuity required to solve these engineering challenges allowed for elements of structural art to shine through. For the purposes of analyzing the structure as structural art, I will focus on the steel roof system, as this feature of the stadium informed the design more than any other component and is the first of its kind in the world.

The first ideal of structural art, efficiency, is definitely accomplished by this structure. The system has to carry the typical wind and gravity loads of a roof in addition to eight 500-ton petal-shaped retractable roof pieces. Oh, by the way—the 500-ton steel flower petals move! Not only does this design succeed in carrying these (seemingly) impossible loads, but it was actually the first design to ever attempt to carry this type of load. The second ideal of economy is when things become a little less definitive. The project went $600 million over budget, winding up at about $1.6 billion—largely due to the roof features. Although this is true, this type of roof had never been attempted before, and it could be argued that the costs were difficult to predict. Perhaps the cost was actually the lowest possible to achieve the structure’s lofty goals, but there is no definitive evidence. Lastly, the ideal of elegance is certainly achieved by the structure. The structure was able to provide a complex roof opening system that is amazing to view, and even the components that support the moving parts are aesthetically elegant. The mosaic of interlocking trusses is impressive in its complex shapes, incredible in its size and scope, and it creates a sense of confidence in the structure without appearing too bulky. Overall, the roof system demonstrates structural elegance and efficiency, but it is difficult to argue that it succeeds in terms of economy.

Structural Analysis

On the most basic level, the stadium can be divided into two main structural systems—the massive reinforced concrete shell (Figure 3) and the steel roof (Figure 4) made up of a vast truss system. The reinforced concrete shell, which supports and includes all of the spaces occupied by people and also supports the roof system, was constructed first. Most of the smaller members of concrete were precast and brought to the site, but the larger pieces (such as the “mega-columns” that support the roof) were cast in place. The roof system, which was designed to support the intricate retractable roof portion, was constructed on top of the concrete shell.

The closing roof is supported by a massive cambered steel roof underneath it. Giant steel trusses make up most of the roof, and the world’s largest movable crane was used to put it all together.

Figure 3 – Concrete Shell

Figure 4 – Roof Structure

The roof required over 21,000 tons of steel. Each of the four main trusses (which support the petals above it and are depicted in figure 4) are 72 feet above the floor and are about 720 feet long. Each of the eight petals (Figure 5) on the roof weigh 500 tons, and they must move in sync—cantilevering over the field 200 feet when closed. The petals are 128′ wide.

Figure 5 – Retractable Petal

Figure 6 – Petal Cantilever Calculations

These massive cantilevers use a fixed reaction system, and, based on my calculations (shown above), the reaction has to supply 1,000 k in the vertical direction. Additionally, the reaction must supply a counter-clockwise moment of 6.66×107 ft*lb. Since the petal is fixed to the support across a line instead of a point, these reactions will be distributed as a line load across the 128′ width of the petal.

Moving on to the concrete shell, a very typical stadium approach was used. Deep foundations were used for the cast in place concrete bowl, while shallow foundations were used for the precast inner dome. After the foundations, the main bowl structure was built, with three separate seating areas. Where the concrete shell becomes atypical is with the 19 “mega-columns” that dominate the structure. These columns were built to support the concrete structure and are also the 19 connection points for the roof system.


Figure 7 – Mega-Column Connection To Roof

Figure 8 – Mega-Column Calculations

The load of the roof system is transferred through the mega-columns, and (simplifying the loads as point loads) I calculated that the average load carried by these columns 2,210.5 k. The combination of this large amount of load from the roof system and the loads from the concrete shell structure led to these columns being designed to be so large. These columns look extremely big in person, and when I visited the stadium I thought that they might have been the largest columns I had ever seen.

The overall design for the stadium was selected by the owners, with HOK winning the design mainly due to the retractable roof. After this design was selected, HOK and BurroHappold continued to communicate their design ideas through presentations, sketches, models, and especially through detailed computer models.

Personal Response

I first visited the stadium for Georgia Tech Football’s opening 2017 game against the Tennessee Volunteers (maybe the most scarring sporting event I have ever had to endure). While I don’t have the emotional strength to describe how badly that game went, the experience of the stadium itself was incredible. Years of hype about the stadium had my expectations through the (retractable) roof, but I have to say the stadium went even beyond what I expected. Being inside the building justifies the structural backbends that the design team had to go through to complete this stadium, as the massiveness of the space, the jaw-dropping roof design, and the 360° screen are well worth the construction and design pains. Before I visited I suspected that the complex design and construction process was all overkill, but standing inside the stadium convinced me that the entire process was justified.


[1] https://www.burohappold.com/projects/mercedes-benz-stadium/

[2] https://www.designboom.com/wp-content/uploads/2017/08/mercedes-benz-stadium-atlanta-falcons-hok-designboom-1800.jpg

[3] https://www.stadiumsofprofootball.com/wp-content/uploads/2016/08/mbs17950.jpg

[4] http://mercedesbenzstadium.com/the-stadium/

[5] http://www.seaog.org/Presentations/MBS/MBS%20Presentation_SEAOG.pdf






Bank of America Plaza

Bank of America Plaza

There’s no way you could have been to Atlanta and not have seen this building. The Bank of America Plaza, or more popularly known as “The Pencil Building” is a prominent feature of Atlanta’s skyline. It boasts not only being the tallest building in Atlanta, but also in the entire southeast region!

When I came to Georgia Tech’s freshman orientation almost three years ago, I remember a student proclaiming, “If you are ever lost, look for ‘The Pencil Building’ and that’s where home is.” As I began adventuring off campus during my freshman year, I always kept that statement in mind; I looked for the pencil building wherever I was and I always found it’s glowing point. When I was returning to Georgia Tech for my sophomore year after a summer at my house in New York, I vividly remembering driving to Georgia Tech from the airport and seeing The Pencil Building in sight. I may have shed a tear… for me The Pencil Building symbolized my return to my new home in Atlanta, Georgia.

Structure Information

Pencil Building in Atlanta, GA [1]

The Bank of America Plaza was built in 1992 and is located on North Avenue in Atlanta; it stands between Midtown and Downtown, representing the dividing line. The building currently serves as office space and has a few restaurants, geared towards the tenants. The architecture firm of Kevin Roche, John Dinkeloo and Associates had designed it, Beers Construction built it, and Shorenstein Properties LLC was funded the construction[2].

Historical Significance

Left to Right: Bank of America Plaza [3], Messeturm [4], Empire State Building [5], Chrysler Building [6]

Designed in the 1990s, the building architecturally demonstrates an Art Deco style. Similar styles to this include the Empire State building and the Chrysler Building, both in New York City and the Messeturm in Frankfurt, Germany shown in the above images. Structurally, the long columns are exaggerated, fabricating a visual effect of leanness. Additionally, all the columns are on the outside perimeter,  creating an open floor plan throughout the offices. The entire tower was built in only 14 months, which is one of the fastest construction schedules for any 1,000 ft building. While there are no specifics on how they constructed the building so quickly, from experience working in the field, I can say this is impressive.

Cultural Significance

During the time when the Bank of America Plaza was built, Atlanta was undergoing a huge transformation. The city was booming, unemployment was low, businesses were prospering, and the 1996 Olympic Games were coming to town. The Olympics gave Atlanta the chance for world recognition and many companies took this as their chance to “tap into Atlanta’s latest potential.” The owners wanted to build a structure to symbolize the new reputation of Atlanta: the city of growth.

While the building was supposed to serve as a symbol of affluence, there were some critics. Urban planners dubbed the name “tower in a park” because they felt that it separates itself from the already built surroundings. There are no street level pedestrian entrance ways and all the retail space can only be entered from the inside, leaving the tenants to be isolated from the outside. One critic called the building’s shaft “unconventional,” while noting that its apex “looks peculiarly like a pencil” [7]. While this critic deemed that the building looking like a pencil was a negative remark, here at Georgia Tech, I think that it is the building’s most notable quality, thus explaining the nickname “The Pencil Building.”

Structural Art

Pencil Building in Atlanta, GA

In order to decide if this building embodies structural art, I first need to define exactly what qualifies as structural art. According to Professor Billington of Princeton University, structural art should be interpreted in terms of the ‘Three S’s’; the scientific, social, and symbolic meaning [8].

The scientific detail will be explained in more detail below, but the Bank of America has eight super columns at each corner of the building. The columns get all the loads from the slabs and from the truss system on top and carry the load down to the foundation. The building is composite meaning it has a mixture of both concrete and steel like many other buildings in Atlanta.

The social role this building plays into society is a limited one. This building was designated as an office space, and with that role it doesn’t separate itself from many of the other downtown buildings in Atlanta. However, it was built during a prosperous time in Atlanta during the 1990s right before the Olympic Games when Atlanta wanted to look good as the whole world would be watching the city. Unfortunately, the building is currently only half occupied which clearly shows that this structure plays a minimal role in the functioning of society.

In a symbolic sense, to me and many others at Georgia Tech, the Bank of America Building symbolizes “home.” Only two blocks away from campus, the building is a literal thumbtack into the map for where Georgia Tech is. Because you can see it from anywhere in Atlanta due to it being the tallest building in Atlanta, it’s a sure way to locate where home is.  Although many people don’t like the design of the building (which I will blame on the architect, not the civil engineer), it is clearly a symbol as in every movie/ TV show that is located in Atlanta always has a scene panning around this building.

As to Billington’s criteria, the structure is not “transparent.” This means that the it isn’t apparent how the loads are being transferred. Starting from the top of the structure, the trusses that create the obelisk shape are very crowded and thin, clearly meant to be an architectural detail. There are so many bars that it was even hard when I was looking at a picture to try and trace how the load was being carried. Side note: the spire at the top is mostly covered in 24 karat gold leaf!! [9] Talk about ornamentation… Once the load reaches the building, it seems as though the load is carried straight down due to the eight super columns. While this is mostly true, I do not think this represents structural art because it seems that the purpose of this façade was to make the building appear taller and slimmer, not to depict it’s function. Due to the fact that the Bank of America Plaza was not built to serve a specific function, but mostly for architectural components, I determined that the Bank of America Plaza is not structural art.

Structural Analysis

The Bank of America building is consistently referred to defeating an extraordinary construction feat as it was only built in 14 months, making this one of the fastest construction schedules for any building over 1,000 feet. To my surprise, despite this feat, neither the structural engineer, CBM Engineers Inc., nor the main contractor, Beers Construction, have any information on this project. The structural material is composite: the core is reinforced concrete, the columns are concrete encased steel, and the floor spans are steel [10]. The Bank of America Plaza was constructed with a composite frame. It was also an early example of the use of super columns, which are actually quite super because the 2 large eight foot square columns at each of the edges of the tower are the only columns that take loads, creating a completely structural column free interior. The super columns are set into the facades of the tower, adding an exterior texture through 8 granite clad points that extend from the base to the crown.


Shows how as the height increases, the load decreases.

Loads shown on Bank of America Plaza.

From the figure to the left, it can be assumed that the gold part of the building puts its load onto the rest of the building through the corners. Additionally, from the figure, you can see how the forces flow. Keep in mind the horizontal lines represent the concrete floor slabs and the drawing is not to scale; there are 55 floor slabs in the Bank of America Plaza. From the corners of the structure, the forces flow down through the columns all the way to the bottom concrete footings. Each of the concrete slabs also has their own load. These forces travel to the closest column and join in on the way down to the footings. The Bank of America Plaza was designed with all the load bearing columns to be on the perimeter of the building to provide for open floor plans for office, hence the picture’s two distinct columns in the cross section shown. Shown in the figure on the left, as you go down the building (get closer to the ground) the loads increase. This is because all the columns on the bottom are carrying the self-weight and the weight of everything above it, but at the top, there is less weight to carry.

In addition to acting as a column, the Bank of America building also works as a cantilever. Due to the building being a tall structure (over 1000 feet), wind loads play a role in how the forces affect the structure. Illustrated in the picture below are the forces that are applied to the Bank of America Plaza due to the wind.


Illustration showing how the winds loads transfer to the building and can be converted into a cantilever beam.


The force of the wind was found in the Georgia State International Building Code and I chose to design for a Risk Category III Hurricane and EF2 Tornado due to the building’s location in Atlanta. Under these conditions, the minimum wind speed to design for is 145 mph [11]. From there I used a wind velocity chart to determine that the pressure is 52.5 psf [12]. Since this pressure was in pounds per square foot, I found the width of the building to be 252.5 feet. Then, by multiplying the width of the building with the pressure per square foot, I found the pressure of the distributed load, 13,258 lbs/ foot. In order to move from the first figure to the second, the building was turned 90 degrees to be symbolized as a cantilevered beam. I then expressed the distributed load as a point load in order to calculate the reactions and moment at the base of the tower.

∑Fy = AY – 13606k = 0

AY = 13606K

∑MA = MA + 136060k (511.5 ft) = 0

MA = -6,959,469 kips∙foot

After making these calculations, I checked my theories on Mastan2. Shown below is the moment diagram and deflected shape of my “beam” aka The Bank of America Plaza. The structural program proves my calculations are accurate and helps illustrate how the largest moment is at the bottom of the tower while the largest deflection is at the top due to wind load.

Mastan2 illustrating the moment diagram of the load.


Mastan2 illustrating the deflection of the load.

By stating that the moment at A is a negative moment, it describes that the bean has developed tension in the upper portion because it gets elongated and compression in the lower portion because it gets shortened. This makes sense if we think it through; if there is a giant force of wind on the left side of the building, the deflection will be shown the building bending to the right, describing the scenario above perfectly. Of course, this is all in theory because wind comes from all sides. Also, there are numerous factors to consider including how close the other buildings are to the Bank of America building. If the buildings are close together then there are other buildings that take an extent of the wind load on their own structure.

Strangely enough, I had found no references to this building from the architect, structural engineers, or contractors. It seems as though none of them wanted credit for it. The closest thing I got to a description was from the structural engineer’s project page that states it was built in Atlanta, California…someone needs to fire their intern [13].

Since none of this information was readily available online, I do not think this information was used to communicate the design to the stakeholders. In current times, most stakeholders are only concerned with their cost revenue and the ratio between the cost of building and the cost earned from tenants; their only concern about the structure would then be the cost and to make sure the building doesn’t collapse.

Personal Response

After visiting the Bank of America Plaza, I understand how isolating it could be. There were no doors for me to get inside from the street and the exterior was just a plain brick façade. The main door was through the parking garage, but I felt uncomfortable entering the building since I did not work there. For being my symbol of Atlanta, it did not feel very “homey” in person.

I also never realized how controversial the Bank of America Plaza was until I start researching it. The building was foreclosed in 2012 due to it’s vacancy demonstrating how unwanted it was for an office space. Many people also think that the glowing obelisk at the top is destructive to the skyline and sticks out like a sore thumb. Also, numerous people thought that the building represented either an ugly pencil or a cigarette (yes, cigarette. I never thought of that one! It gets worse at night when the top starts to smoke too…).

Despite all this, I will maintain my positive image of The Pencil Building because whenever I spot the building, it reminds me that Atlanta is home.


  1. https://www.atlantadowntown.com/go/bank-of-america-plaza
  2. http://www.skyscrapercenter.com/building/bank-of-america-plaza/429
  3. https://www.tripadvisor.com/Attraction_Review-g60898-d527262-Reviews-Bank_of_America_Plaza-Atlanta_Georgia.html
  4. https://commons.wikimedia.org/wiki/File:01-01-2014_-_Messeturm_-_trade_fair_tower_-_Frankfurt-_Germany_-_05.jpg
  5. https://www.embusyliving.com/2016/06/empirestatebuilding-topoftherock.html
  6. https://www.askideas.com/27-very-amazing-night-view-pictures-of-chrysler-building-manhattan
  7. http://www.atlantamagazine.com/90s/nationsbank-plaza-now-bank-of-america-plaza-rises-up/
  8. http://www.curee.org/CASCE-5/Lectures/L0009.html
  9. https://www.ajc.com/business/bank-america-plaza-becomes-atlanta-priciest-repo/yKEFrl8ElBb2oAiPguIjfJ/
  10. http://www.skyscrapercenter.com/building/bank-of-america-plaza/429
  11. https://dca.ga.gov/sites/default/files/2013_drbc_ibc_appendixn.pdf
  12. http://www.nctlinc.com/velocity-chart/
  13. http://www.cbmengineers.com/project_bank_of_america_plaza.html

Park Drive Bridge

I found this bridge while walking in Piedmont Park this weekend to break in my hiking boots and immediately thought of how great it would be to write a blog post about. I took some pictures (shown below) and explained to my friend how we could see the load paths (which went right over his head).

Figure 1: Park Drive Bridge

Structure Information

Figure 2: Location of Park Drive Bridge [2]

Upon further research (pulling up Google Maps), I figured out the bridge was on Park Drive. The bridge is called the Park Drive Bridge, previously known as the Piedmont Park Boulevard Bridge. The structure was built in 1916 and designed by O.F. Kauffman, who was a city engineer working at the Department of Bridges and Estimates. The purpose of building this bridge was to connect neighborhoods to the park without having to walk over the railroad tracks that ran along the park, which is now the Atlanta Beltline (see map to the left). The bridge was funded by four sources: City of Atlanta, Fulton County, Southern Railway, and Northern Boulevard Park Corporation. [1]


Historical Significance

Since the bridge was built long after the invention of reinforced concrete and the arch bridge, there was nothing significant about the Park Drive Bridge’s design or how it was built. In fact, since the bridge is over land rather than water, it was easier to build than many of the bridges we have learned about in class so far.

Cultural Significance

Figure 3: Mural under the Park Drive Bridge [2]

This bridge previously served as a connection from the developing Druid Hills neighborhoods into the park over the railroad [1]. After the Piedmont Park parking lot was build, the bridge was used for parking lot access until the parking area for the park was moved. Now, the bridge is not open to the public for vehicles, but is still open for pedestrians and bicyclists, although there is no railroad to worry about crossing over anymore. Additionally, the Park Drive Bridge has been incorporated into the Art of the Atlanta Beltline project and features a mural.

Figure 4: Close-Up View of the Middle of Park Drive Bridge

Structural Art


From far away, this bridge can very well show structural art. The load paths seem clear, there doesn’t seem to be any extra beams or columns, and you can see through the bridge, as Billington commonly uses as a requirement.

Once closer to the bridge, however, you notice the tiles for decoration on the entire bridge and the heavy-looking deck with thick, ornamental bricks as a railing. You can also see small beams connecting the spandrels, which do not seem to be load-bearing given the large girders underneath the deck. These beams are most likely for decorative purposes or because the engineer was worried that the girders could not hold the entire load. This extra material and the cost to add these decorations go against the values of economy and efficiency needed for a structure to be structural art.



Structural Analysis

This bridge was built as an arch bridge in the middle and simply supported sections on the sides out of reinforced concrete. The construction was contracted to Case & Cothran and cost $28,904.75. The brick section at the top was laid and plastered after the completion of the bridge and the 7 foot deep slab. [1]

In the middle section, the longer span, an arch is in compression against two abutments. The spandrels above the arch are also in compression. There are beams connecting both arches across the bridge as well as beams running between the spandrels in line with the arches. The girders lie perpendicular to the arches and connect to the spandrels that are above the arch. These components can be seen in Figure 4.

Figure 5: Load Path on Park Drive Bridge

The load goes from the slab to the girders. These loads are then transferred to the spandrels down to the arches. The arches transfer the load to the large abutments, which finally take the load to the ground.

The load comes from both the dead load of the railings and the very small live load from the pedestrians walking across the bridge; however, there used to be a larger live load when vehicles were allowed on the bridge.

The braces connecting the arches are there for stability to make sure they do not start leaning. The beams between the spandrels are either for decoration or to provide extra support for the variable side of the girders at the edges of the deck of the bridge.

Figure 6: Full Arch Diagram


If the span of the bridge between the abutments is 500 ft, and the load

Figure 7: Free Body Diagram of the Left Side of the Arch

on the deck is 1000 lb/ft, the reaction forces on the abutments can be calculated, neglecting the self-weight of the structure, seen in figure 6.  The reactions in the y-directions can be found to be 250 kips.



Figure 8: Free Body Diagram of Left-Most Point of Arch

To find the reaction in the x-direction, you must split the arch in half, and find the sum of the moments about L/2 (see figure 7).

The reactions in the x-direction are towards the arch and equal 625 kips if the maximum height of the arch is assumed to be 50 ft.

To find the maximum stress of the arch, the maximum force must first be found. This is done by finding the internal compressive force at the end of the arch. A free body diagram of the edge of the arch can be seen in Figure 8. The maximum force is equal to 673.15 kips. Assuming an area of 8 square feet, the maximum stress in the arch is 84.14 kips/square foot.

Personal Response

I have walked by this bridge many times and never thought it was anything special. I think that the ornamental tiles and brick wall on top make it look like it belongs in another time period. If the bridge were cleaned up and these parts were removed, I think I would like it a lot more. Overall, I think it was very cool to see a bridge that looks similar to the sort of designs we’ve been learning about in class. Seeing this in-person, and realizing on-the-spot that I could follow the load paths, was very cool.