Twickenham Bridge

Structure Information

Figure 1. Twickenham Bridge

The Twickenham Bridge was designed by Alfred Dryland, head engineer, and Maxwell Ayrton, architect, in 1931. Aubrey Watson Ltd built the bridge for £217,300 to connect the Old Deer Park in Richmond with the district of St. Margaret’s on the north bank. A crossing at the Thames River at this location was brought to discussion as early as 1909 (22 years earlier) but the bridge was known locally as ‘The Bridge that Nobody Wants’ [1]. With a title like that, I would also wait 22 years before acting… There were disagreements about the exact route and the financing of the bridge, but finally in 1926, the Ministry of Transport agreed to go ahead and finance the bridge. The Twickenham Bridge was part of a three-bridge road scheme, known as the Great Chertsey arterial road scheme, in order to relieve Hammersmith Bridge and alleviate congestion in Richmond [2].

Alfred Dryland was considered “the greatest expert in Britain of his day” and “a pioneer in the planning and construction of motorways.” The architectural ornamentation of the bridge was done by Maxwell Aryton. He apparently was a very famous architect and was an advocate for concrete stating concrete is “a material worthy of architectural recognition” [1]. Basically, the Twickenham Bridge had some successful people working on it.

Historical Significance

Twickenham Bridge was an innovative structural engineering design because it was the first large-hinged concrete arch bridge to be built in the UK. It is hinged at the crown and at the springing points of the arch, thus the arches overcame many of the defects are inherent in fixed arch bridges, particularly the difficulty in calculating abutment reactions. This is just good news for me because it makes my analysis easier.  Although the three-hinged arch was developed by many engineers in the mid-19th century for arched metal roofs and bridges, the concept was only applied to reinforced concrete structures in the early 20th century [1].

Cultural Significance

As I was researching the history of this bridge, I came across a ‘Transport for London’ journal that was written in 2008 and stated “Twickenham Bridge remains as important today, as it was seventy-five years ago.” The article was celebrating the bridges 75th anniversary and described how it greatly improved London’s traffic flow [2]. I can’t think of too many things that remain good with age (other than wine and cheese) so the fact that the bridge that was designed for traffic in the early 1900s is still relevant now is impressive.

Once the bridge design was finalized, there were mixed reactions towards the bridge. About 200 men were hired to construct the bridge which was a big deal because it was during a time of high unemployment. However, in order to construct the new traffic route, over 300 families had to relocate as houses and shops that were in the way were demolished. Also, the initial designed featured four 70-foot towers at the river banks and retaining walls that were 20 feet above the road level. The Daily Telegraph organized a local petition against the design claiming this was “inappropriate to the setting in Richmond.” Luckily, the engineers and architects were very responsive and changed the design. About 56,000 vehicles cross the bridge every day, which is significant. While the bridge was originally built to relieve traffic, it remains just as important today [2]. Fun fact: the bridge was declared a Grade II listed structure in 2008, providing protection to preserve its special character from unsympathetic development [3].

The Twickenham Bridge is supposed to represent a unity between architecture and structural engineering, but honestly after taking Historical Structures, I don’t know if I can look at an architect the same way ever again. The Art Deco theme is continued in the use of ornamental tiles that are embedded in horizontal seams and in the bronze cover plates over the expansion joints at the abutments [1].

Structural Art

Figure 2. Stairs leading up to the deck.

Scientifically, the arch does show the loads. All the loads are brought from the top deck to through the arch to the columns and to the footings. Socially, for the towns of Richmond and St. Margaret’s and the surrounding areas, this bridge was a big deal. It allowed for the towns to easily be connected and helped relieve the traffic congestion around the surrounding areas. Symbolically, this bridge is the first three hinged arch concrete large bridge in the UK. The architect wanted to make sure it was known to be a big technical feat and portrayed that through the design. From these statements alone, it would seem as though the bridge qualifies as structural art. However, this structure is heavily ornamented by an architect. Even though the architect’s main purpose was to accentuate the structure and loads, I think the ornamentation goes against what Billington defines as structural art; the structure should speak for itself without the need for additional design. Because of this, I would say this bridge is not structural art.

Structural Analysis

The Twickenham Bridge is a 145.5m long and 21.3m wide bridge that has 5 arches. The central span is 31.4m while the two arches next to that are 29.9m. The two arches on land each measure 17.1m. The bridge is made of reinforced concrete arches on top of very narrow piers. When looking closely at the bridge, you will notice some striations. This is purely architectural and textured by a bush hammer. One of the most distinctive features of this bridge are the decorative bronze cover plates. These are an Art Deco style (just like the Bank of America Plaza, my first blog post!) and help accentuate the three structural hinges at the crowns and springings of each arch. The architect, Maxwell Aryton, wanted to make sure the hinges stood out and “gave prominence to the bridge’s technical virtuosity” because it was the first large three-hinged concrete arch bridge to be built in the United Kingdom [1].

As mentioned in the cultural significance section, the construction of this bridge was a big deal. Many people who were unskilled were hired so the construction had to be simple. Although the form was a newer one for the UK, constructing bridges had been done before and this one was no different. Many parts were assembled at factories and then taken to the construction site. The footings were sunk into the water and the construction proceeded from there. Because the bridge was over water, many of the parts were floated to the site by boat.

The loads on the bridge travel from the deck to the arches and down to each of the springings/ footings. The arches are all in compression due to the reactions from the footings acting upwards.

In order to calculate all the reactions in the bridge, I idealized the bridge as a typical three-hinge arch bridge and only focused on the central span. I chose a live load of 952.4 kg/m as that is the average live load for a vehicular arch bridge of this size.

Consider the equilibrium of the entire structure:

∑Fy = 0

(952.4 kg/m)(31.4m) + RAV + RBV = 0

From symmetry: RAV = RBV

RAV = RBV = 14952.68 kg

Break into parts and only consider left side:

P1 = ()(952.4kg/m)= 14952.68 kg

∑MC= 0

(RAV) () – (P1)() – RAH (HMAX) = 0

(14952.68 kg) () – (14952.68 kg)() – RAH (6.1m) = 0

RAH = 19242.38 kg

∑FX = 0

RAH = RBH  = 19242.38 kg

Explaining this design to the stakeholders was important as it took about 17 years for the bridge to actually start construction from which the idea was brought up for the bridge. What finally persuaded the stakeholders to commit to the design was the *surprise surprise* finances and path of the new roadway. The design drawings were most likely used to explain how efficient the three-hinge arch design is and how an efficient design can save money because of less material and less need for restoration.

Personal Response

To be honest, one of the reasons I chose to analyze this bridge because it was located far from our hostel, so I knew that no one else would choose it. But once I actually looked into the history of the bridge, I didn’t realize how important it was to the surrounding communities and the city of London. This bridge has been alleviating traffic for over 75 years and was the first large concrete three hinged bridge in the UK. That’s actually pretty impressive! I guess I chose well.

 

  1. https://historicengland.org.uk/listing/the-list/list-entry/1253011
  2. https://tfl.gov.uk/info-for/media/press-releases/2008/july/twickenham-bridge-at-75
  3. http://london.wikia.com/wiki/Twickenham_Bridge
  4. http://thames.me.uk/s00300.htm

The Mobile Walkway of Geneva

Last week I had the opportunity to travel to Switzerland. My days were filled with beautiful scenery, decadent chocolate, and too much cheese for my own good. While walking around the city of Geneva, a bridge caught my eye. Located right in the city center, this pedestrian bridge connected the esplanade to the main area, directly in front of the Jet d’Eau. When I got home that night, I knew I had to look it up and see what this bridge was all about.

Structure Information

Figure 1. Mobile Walkway located in Geneva in its upright position for boats to pass through [1]

The pedestrian bridge at the esplanade is located south of the Pier Eaux-Vives and officially called The Mobile Walkway of Geneva. The project was completed on June 25th, 2016 and serves as a symbol of inclusiveness to the Swiss. The project cost 4.5 million francs ($4,536,225) and was funded by the State of Geneva, the GIS, and a private foundation that wishes to remain anonymous.  Previously, the pier could only be reached by walking up a set of narrow stairs, making it not accessible to everyone. Designed by the structural firm Ingeni, this new walkway is a flat path, making it accessible to wheelchairs and strollers. Also, the unique design folds up into a set of stairs when a boat needs to pass underneath. Barbara Tirone, the vice president of the associated Handicap Architecture Urbanism (HAU) stated “It is symbolically very strong to allow everyone to finally reach this emblematic site of Geneva” [2].

Historical Significance

This new pedestrian bridge is the definition of innovative.

Figure 2. Jet d’Eau in Geneva [3]

The engineers, Etienne Bouleau and Gabriele Guscetti at Ingeni, even patented their invention of a mobile walkway. This pathway is typically a flat pathway allowing access to all pedestrians, but when a boat needs to pass below, it compresses together to form an arch bridge and allows the boat to pass. This project proposed the “widening and extension of the existing pontoon by a generous wooden esplanade” [4]. The bridge uses a scissor mechanism in order to change from an arch bridge to a cantilever bridge.

From my research, this seems to be the first bridge of it’s kind, hence the engineer’s patent on their design. The only previous example I could find is a trial run for scissor-like bridge to be used during emergencies. But that model was for transportable bridge, not ones that are meant to be permanent [5]. Because of this innovative design, I am sure that we will be seeing this style of pedestrian bridge popping up around the world within the next 5-10 years. The concept of allowing boats underneath the bridge while allowing accessibility for everyone to cross is a tremendous deal.

Cultural Significance

Figure 3. The mobile walkway lays flat to provide accessibility to the jetty for everyone [1]

The area around the Jet d’Eau is known as the Mecca of Geneva. The Jet d’Eau was built in 1886 to “control and release the excess pressure of a hydraulic plant at La Coulouvrenière” [6]. Soon afterwards, the fountain became a symbol of the city, so the pressure was amplified, and it was relocated to the center of the lake. To the people of Switzerland, the fountain became “the symbol of strength, ambition, and vitality” [7].

Before this new foot bridge, the only way to get to the jetty was by crossing a narrow wooden bridge with steep steps. This made it nearly impossible for people with walking difficulties, or even strollers, to get to the other side. By constructing this new walkway, it enabled all people to cross over to the pier and see in Jet d’Eau in its full glory. The people of Geneva loved this new installation. They felt like their pride of the city was finally able to represent their feelings towards being welcoming to all. The bridge normally lays flat and raises into an arch when a boat needs to pass. Unfortunately, I found no details on the mechanism used to control the bridge’s movement; I assume it is a hydraulic system given its location.

Structural Art

Figure 4. Front view of the Geneva Walkway in arch form [1]

In my opinion, this structure is a great example of structural art. In regards to Billington’s first structural art criteria, the bridge checks the box for being scientific. This was the first of its kind in terms of engineering. The engineers worked hard to be able to please everyone, and certainly succeeded, justifying their decision to get a warrant for their design. Socially, this new bridge brought the people of Geneva together at their city center. It made everyone who visited the city feel welcome because they are now able to see such a big attraction. Symbolically, this bridge represents the kind and inclusive people of Geneva and how important the Jet d’Eau is to them. They spent 4.5 million Francs on this bridge in order to make it accessible to everyone. This certainly was not a requirement for the city,as you can see the Jet d’Eau from farther away (I saw it from the airplane when we were landing!), but the city decided to spend their money to truly showcase this symbol of the city.

Structural Analysis

The first thing you notice about the structure is the groundbreaking scissor mechanism that allows it to move up and down. The scissor mechanisms were cut using a water jet from a 20-60mm steel plate and are about 1.2 meters high and weigh 400kg. The pairs of the scissors are linked by a 12cm diameter metal aces that includes porous bronze rings in order to reduce friction and to be able to adjust the pairs of scissors easily. Duplex 1.4462 grade of steel was chosen because of it’s great resistance to wear, good corrosion resistance, and it has an elastic limit of about 500MPa [1].

Because of the design of the deck and how it extends, a standard bracing system couldn’t be used. Instead, horizontal stability is provided by the cross members in the load-bearing scissor mechanisms at both ends of the walkway [1].

I chose to analyze this structure when it is in it’s cantilever form because the entire time I was in the area, I only saw it lay flat.

Figure 5 illustrates the load path of the distributed load of pedestrians. I chose to use a distributive load because while the Jet d’Eau has light shows and during holidays, the entire lakeside it packed full of people. The load first goes to the deck where it then transfers to the pin supports. From the pin supports, the load travels to the trusses and works it way outwards to the column supports at the two ends.

 

Figure 5. The load path on the bridge due to pedestrians

Figure 6. Stress forces on the truss (plate) members

Figure 6 demonstrates where the stresses are the largest when the bridge is in cantilever form. Note, the stresses are almost the same throughout the whole bridge, except for the ends which have a slightly higher stress. This is due to the bridge being symmetrical and evenly distributing the weight of the live load.

I wanted to calculate the stress in the individual truss members. To do so, I first calculated the tributary area. Figure 7 shows how the forces are divided among the pins; there are 16 pins (represented by white circles) along each side. The red lines show how the tributary area is divided. I also added the green dashed line to show how the tributary area aligns with the elevation view. Figure 9 shows all the calculations.

Figure 7. Tributary area of the pin joints

Figure 8. Idealized truss system of the center 9 joints

I used a live load of 85 psf because that is an average pedestrian live load. I found the width of the bridge to be 12.5 ft. Figure 7 illustrates all the forces acting on it [8]. I calculated the dead load of the steel and assumed a width of .5 ft for the steel plates and found it to have a thickness of .2 ft. For the deck, I assumed it to be made of redwood because that is a popular wood for decks. I also assumed a thickness of .67 ft because that is the minimum standard according to codes for wood jetties. I started by calculating the tributary areas, then applying the area to the density of my materials to find all the loads on the connections. Next, I used method of joints to calculate the internal forces in the truss.

Tributary Area

Deck: (12.5 ft/2)(892 ft/ 16) = 348.44 ft2

Steel plates:

(sqrt(2.52+42))= 4.7 ft

(4.7 ft)(.5 ft)(.2 ft) = .47 ft3

Load on each pin

Live load: (85 lb/ft2 )( 348.44 ft2) = 29,617 lb

Dead load (steel): (490 lb/ft3)( .47 ft3) = 230.3 lb

Dead load (redwood deck): (32 lb/ ft3)( 348.44 ft2 )(.67 ft) = 7470.56 lb

Figure 9. Method of joints

Calculating internal forces

∑Fy = FAC(2/2.36) + FAB(2/2.36) – (29617+230.3+7470.56) = 0

∑Fx = FAC(1.25/2.36) – FAB(1.25/2.36) = 0

FAC  =  FAB

∑Fy = FAC(2/2.36) + FAC(2/2.36) – (29617+230.3+7470.56) = 0

FAC  =  FAB = 22,017.53 lbs or 22 K

Because the bridge is symmetrical, all the members of the truss have the same force of 22 K. Due to all the assumptions, my calculations were quite off from the stress values shown in Figure 6, however I verified the idea that the stress should be consistent throughout the structure.

Figure 10. Construction of the mobile walkway.

The construction of the walkway was unique because of the mechanisms. The entire walkway was pre-assembled in workshop shown in Figure 10. This way, the engineers were able to run a series of test on the structure before it was available to the public. The structure was mounted on a metallic frame that was used for constructing, transporting, and eventually hoisting the assembly.  Once on the wharf, a crane was used to place the walkway on the supports [1].

I think it was quite simple to show this design to the stakeholders considering it was built indoors first. Because it was the first design of it’s kind, many different tests were run on it and I am sure that the city of Geneva was involved throughout the process because they were funding it. The other known company that helped fund the project was GIS, who is actually a lifting solution company. I am sure that when a crane was needed GIS was the company that was selected. Sounds like a conflict of interest to me, but if it gets the job done I guess it’s alright?

Personal Response

From visiting this bridge, it was nice to see how many people were just sitting outside enjoying the view. From tourists to natives, there were many people outside just taking in the sunshine, laughing, and appreciating their time together. I understand how this place can be viewed as the “Mecca” because of the energy that is felt when you are there. I’m glad the city of Geneva wanted to make everyone feel welcome and made sure this bridge was a priority.

References

[1] https://ingeni.divisare.pro/projects/338960-the-new-mobile-walkway-of-geneva-s-jet-d-eau
[2] https://www.tdg.ch/geneve/actu-genevoise/jet-eau-presente-nouveaux-atours/story/22163401
[3] http://www.geneva.info/jet-d-eau-fountain/
[4] (http://www.ge.sia.ch/node/182
[5] http://www.engineersjournal.ie/2015/07/28/novel-scissor-like-bridge-structure-use-emergencies/
[6] (http://www.geneva.info/jet-d-eau-fountain/
[7] http://www.geneva.info/jet-d-eau-fountain/
[8] http://www.conteches.com/DesktopModules/Bring2mind/DMX/Download.aspx?Command=Core_Download&EntryId=9850&language=en-US&PortalId=0&TabId=144

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.

References

  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