Domes

QUESTION: Describe the technology of dome building in chronological order of the Roman Pantheon, the Hagia Sophia and Brunelleschi’s dome on the church of Santa Maria de la Fiore. How did the time period, geographic location and available technology affect these masterpieces of architecture? Describe what other factors they all have in common.

PART 1

Summary
There was a lot of research that needed to be done for this essay. I found that videos were the best resource, as they used graphics to explain architectural concepts I didn't really understand initially.

Reason
I remember covering Brunelleschi's dome in my previous Art History course. Sometimes, artists in the 2D tradition forget how magnificent a statement architecture can make. I believe this question was asked to get me more involved in how architecture was a tool of the times just as much as sculpture and painting could be.

Purpose
I believe this question wanted me to focus on how technology and geography could effect construction of as difficult a structure as the dome, using these three examples.

Direction
Like I said above, I'd learned about Brunelleschi's dome before, which was why I wanted to answer this question. I remember being intrigued by his solution, but learning more about these other domes really helped me understand how troublesome domes really are. The research involved in this essay has supplemented my appreciation for architecture, to put it mildly.

Impressions
I was interested to learn that the oculus actually helps support the structure! I thought it would rather do the opposite, but it's quite literally the same in function to a keystone, which I found interesting.

PART 2

Most political buildings today have this big architectural similarity: domes. Domed roofs appear in places of power and importance, making a statement about the inhabitants as well as the society around it. Nowadays, they impress an elegance as well as being imposing. Take the Rhode Island Statehouse in Providence for a nearby example. It's lofty, beautiful, and intimidating all at once. Construction for the Statehouse was finished in 1904, but this building's design inspiration, as with many other political buildings, can be found long ago in these prominent domed ceilings: The Pantheon in Rome, the Hagia Sophia in Istanbul, and Brunelleschi;s dome on the Church of Santa Maria de la Fiore in Florence.

The Pantheon, in my opinion, is the clearest origin story for the popularity of the dome. We look to Roman culture as the birthplace for much of the western mentality and style, though I consider them as more of a surrogate mother to Grecian culture personally. But one thing the Romans had in spades was ingenuity and innovation. The use of concrete as a major construction tool is a perfect example of their technological savvy.

"The Romans were pragmatic, and their practicality extended from recognizing and exploiting undeveloped potential in construction methods and physical materials to organizing large-scale building works. Their exploitation of the arch and vault is typical of their adapt-and-improve approach. Their innovative use of concrete, beginning in the first century BCE, was a technological breakthrough of the greatest importance. In contrast to stone--which was expensive and difficult to quarry and transport-- the components of concrete were cheap, relatively light, and easily transported. Building stone structures required highly skilled masons, but a large, semi-skilled workforce directed by a few experienced supervisors could construct brick faced concrete buildings...Concrete's one weakness was that it absorbed moisture, so builders covered exposed surfaces with a veneer, or facing, of finer materials, such as marble..." (Text, pg 182-83)

Emperor Hadrian was responsible for the Pantheon. He was greatly influenced by Greek culture and so named it (pan= all, theon= gods in Greek). It is understood as a embodiment of the heavens and of the roman ideal of the cosmos. It was constructed out of varying grades of concrete and external marble veneer. The interior, as shown in the image gallery below, shows that the Pantheon's dome is a hemisphere with an oculus (circular opening) at it's highest point, with a large rectangular entryway attached. Square coffers (inlets) circle in rings the inside of the dome, stopping with a wide space before the oculus. The walls are painted, and there are inlets with statues along the walls. It makes for an incredible sight, but above that, it's a technological feat of great importance. Much of the design comes directly out of the need for physical support.

Domes are not in any way easy to make, but it's even harder to keep them stable. The dome was preceded by the arch, something we all associate with Rome because of the aqueducts. When rotated in a circle, you get the dome's form. The aqueducts arches were made stable with the use of a keystone, without which they would surely collapse. That in itself was a breakthrough. The dome had many more issues. Initially they were implemented in everyday structures like the bathhouse, but in much smaller scale. In the Pantheon's case, the large size gives the open space the dome was valued for, but shows us the numerous problems. For one thing, the downwards push of gravity versus the upwards push of the masonry on the curve usually provides strength through compression. It's the reason the oculus is possible at the top. However, the material used was incredibly heavy, and the downwards push of gravity causes a stretching called tension, which would expand the base and cause cracks. To prevent this from happening, the designers implemented steprings, which from the outside look like a ring of stairs around the dome. These, coupled with the thick walls of the Pantheon, are what allow the wonder of the dome to remain even today. The designers also had to find a way to lighten the weight of the dome, and their solution was the square coffers inside the Pantheon. They literally serve to subtract the amount of concrete as well as adding an artistic interest to the building. The density of concrete near the top also was intentionally lower so as to optimize the weight. (http://www.teachersdomain.org/resource/phy03.sci.phys.mfw.bbdome/ [video]) It is the Roman's understanding of their material and of architectural rules that outlive them in the form of the Pantheon. It is probably the most famous of any domed building in the western world, deservedly, and served to inspire many other architects, including Thomas Jefferson and his Monticello and even Brunelleschi, who studied the Pantheon in his efforts to solve the problem of the dome of the Florence cathedral.

The Hagia Sophia in Istanbul is presented a similar challenge to it's architects. Hagia Sophia-- meaning “holy wisdom”-- is as much a symbol of power as place. It's one of the largest domes even today, 56 meters high and 31 across. “It replaced a fourth-century church destroyed when crowds, spurred on by Justinian's foes, set the old church on fire. The empress Theodora, a brilliant, politically shrewd woman, is said to have goaded Justinian to resist the rioters by saying "Purple makes a fine shroud"--meaning that she would rather die an empress (purple was the royal color) than flee for her life. Taking up her words as a battle cry, imperial forces crushed the rebels and restored order in 532. To design a church that embodied imperial power and Christian glory, Justinian chose two scholar-theoreticians, Anthemius of Tralles and Isidorus of Miletus... They developed a daring and magnificent design." (text, pg 255)

First things first, it's pretty challenging to build a dome in an area notorious for earthquakes (then, Constantinople). Therefore, the structure would need to be as stable as possible. Imagine if this symbol of Justinian's power collapsed when the ground shook? That would surely be a shame to the entire imperial world! So, this church has to be large and imposing, but cant have any indication of instability. The architects had a big problem to solve. The placement of the dome, for one thing. It was to be suspended above four pillars, arranged in a square. The pillars were connected by arches, and the dome was to sit on top of them. However, the dome would only be supported upon the topmost curve of the arches, and that is not sufficient, as without more support it would crack and collapse inwards. Unlike the Pantheon, this Eastern Roman building utilized stone ashlar masonry and bricks, and thus is incredibly heavy. Anthemius and Isidorus implemented pendentives, and it is their use of these curved forms that is considered the crowning achievement of the pendentive today. It was the first time they had been used as support for a dome. They successfully serve to channel the weight of the dome into the piers which channel it into the ground, and look good while doing it. Yet as with the Pantheon, the horizontal thrust and tension that the dome's shape creates remains a problem. In the Pantheon, the steprings serve to counteract the issue. Anthemius and Isidorus come up with a different solution. Coupled with Justinian's desire for a tremendous dome, they devise a design that extends the dome further down the nave without compromising structural integrity. They do this by adding semi-dome (half-dome) to each end. This reinforces the arches as well as extending the open roof, and at the end of the semi-domes they add additional smaller semi-domes to further this positive effect. Like buttressing for arches, the weight and thrust have to travel down each additional semi-dome and gets dispersed along the way (http://natgeotv.com/ca/ancient-megastructures/videos/hagia-sofia-dome-secrets [video]). It was an ingenuous solution that is highly praised : "The new Hagia Sofia was not constructed by the miraculous intervention of angels, as was rumored, but by the mortal builders in only five years (532-37). The architects, engineers, and masons who built it benefited from the accumulated experience of a long tradition of great architecture. Procopius of Caesarea, who chronicled Justinian's reign, claimed poetically that Hagia Sophia's gigantic dome seemed to hang suspended on a "golden chain from heaven." Legend has it that Justinian himself, aware that architecture can be a potent symbol of earthly power, compared his accomplishment with that of the legendary builder of the first temple in Jerusalem, saying "Soloman, I have outdone you."" (text, pg 255)

Unlike the Pantheon and the Hagia Sophia, Brunelleschi's dome of the church of Santa Maria de la Fiore in Florence was not supposed to be perfectly spherical in shape. That is to say, if you looked at a cut out of the Pantheon or of the central dome in the Hagia Sophia, the dome itself would serve as the top portion of a large-scale circle. Brunelleschi's dome, designed to follow original plans from over forty years prior to his involvement, was a taller, stretched octagonal shape. “When the cathedral was begun in 1296, Arnolfo di Cambio, the original architect, built a scale model to illustrate his design, which included a huge dome on an octagonal drum. The design was audacious, in that no one at that time had any idea how to build such a structure without it collapsing under its own weight. Nonetheless, the patrons of the cathedral clung to that bold vision, and when the nave was completed in 1380, they would wait for 40 more years with a huge hole in the ceiling of their cathedral until an architectural genius arrived on the scene with a solution.” (http://upword.blogspot.com/2011/05/climbing-brunelleschis-dome.html)

That genius was Fillipo Brunelleschi. “When interest in completing the cathedral revived around 1407, the technical solution was proposed by a young sculptor-turned-architect, Filippo Brunelleschi... Brunelleschi (1377-1446), whose father had been involved in the original plans for the cathedral dome in 1367, achieved was many considered impossible: he solved the problem of the dome." (text volume II, 4^th edition, pg 595) And there were many problems. Unlike the other two, this dome's shape didn't include positive aspect of uniformity-- a classic dome's shape allowed diffusion of weight as well as that issue of thrust, but for which there were documented solutions. Brunelleschi had to find another way. He resolved the issue in a creative and unparalleled way: two domes. Brunelleschi designed an inner dome which would be more spherical and uniform and thus weight bearing, and the outer dome with it's atypical proportions would rest on the inner dome as a support. This was an incredible idea, and even today visitors can marvel at his solution by climbing the steps between the two domes. Yet the process of building had issues as well. The cathedral was already 170 feet tall when he began, and 150 feet wide. How can you build a huge dome on top of that? There was no way that scaffolding could be used on something that large. Brunelleschi in turn devised numerous tricks in brickwork laying, transport of materials, and a scaffold-free system to construct his famous architectural wonder. (http://upword.blogspot.com/2011/05/climbing-brunelleschis-dome.html) It remains a stand-out example of the renaissance mindset and forwards-thinking.

Each of these domes had technical problems to overcome, and ingenious architects. The designs were lofty and almost unachievable if not for the clever use of available technology and understanding the creators of these marvelous structures had. Spanning close to 1500 years, these three domes remain incredible symbols of the eras they originated in, as well as architecture in the whole.

GALLERY

 

PANTHEON

source
The Pantheon
mainly concrete, marble veneer, etc.
Unknown/rebuilt by Hadrian
126 CE

source

source
Pantheon Dome
video
WGBH/ Teacher's Domain
accessed November 2012

source

HAGIA SOPHIA

source
Hagia Sophia
ashlar and brick
Isidorus of Miletus & Anthemius of Tralles
532 BCE

source
Hagia Sophia: Dome Secrets
video
National Geographic Channel
accessed November 2012

 BRUNELLESCHI'S DUOMO

source
Dome of the Church of Santa Maria de la Fiore
stone masonry
Fillipo Brunelleschi
completed 1436 CE

source
Climbing Brunelleschi's Dome
photo
Tom Chatt
May 2011

source
Unequaled Courage + Genius
blog
George Lafferty
May--August 2011