As one of the most advanced ancient civilizations, the engineering accomplishments of the ancient Romans are typically recognized as extremely practical and purpose based. The engineers were always searching for structural solutions that would provide more open and usable spaces or more successful means of accomplishing their vision for a design. The concrete dome in particular is one of the most important structures that the Romans perfected through logical engineering and improvements and has had a profound impact on many western civilization structures since.
Practicality of the Dome
The reason that the Romans began using the dome is because they recognized the benefit of large spaces that were uninterrupted by columns, walls or any other roof supporting structure. With their technology of unreinforced concrete, flat roofs and columns, this vision was not possible because the unreinforced concrete or stone roof could not span large distances without cracking and failure. Stone and concrete both perform incredibly well in compression but poorly in tension. The difficulty in spanning long distances with flat forms of such materials is that the form will experience bending which creates compression stresses on the top and tensile stresses on the bottom of the form as seen below in Figure 1. These bending stresses cause cracking on the tension side and the stone or concrete form will collapse.
|Figure 1: flat form bending and stresses (“Bending Stress”, n.d.)|
Perhaps the Romans had attempted such designs and seen that they needed to develop a more suitable method of obtaining large open rooms. By building on established knowledge of arches, the dome seems like a logical progression as it is merely an arch spun 360 degrees to create a semicircular three dimensional form. The engineers of the Roman time had already realized the potential of the concrete or stone arch and its use in spanning large distances under heavy loads by compression forces, so it is likely they realized that a well-engineered dome would be similarly effective for large spans when applied to a three dimensional space.
Influence from Other Civilizations
Considering that the Romans had intelligent engineers, it is possible that they developed the idea of a dome on their own. However, evidence of dome structures dated prior to the Roman Empire have been found throughout the middle east and surrounding regions although many are corbelled domes and not true domes. A corbel dome is unlike a true dome in that it does not rely purely on the compressive forces between the stone or concrete components to maintain it’s shape and structural integrity and therefore has a very limited span (Chant & Goodman, 1999). Some archaeological investigations have revealed other ancient civilizations that were building true domes and several have been uncovered in the ruins of the Sumerian city state of Ur (Chant et al., 1999). Chant and Goodman (1999) report that true domes and evidence of their wooden centering have been found in the cemeteries for royalty of ancient Ur and dated to 2500 BC. This would place knowledge of the stone true dome long before the rise of the Roman Empire. Also, although not true domes, evidence of timber domes has been found in the ancient Etruscan area of Italy that date back to the beginning of the rise of Rome (Keinbauer, 1971). Since Rome began with heavy Etruscan influence it is easy to see how the timber dome would naturally become a part of the early engineering ideas in the city and it is likely many were constructed that we have no evidence of. As the city of Rome grew in power and began to expand it is unknown whether or not stone domes were encountered in nearby regions because no conclusive evidence for such structures has been found in these areas. It seems just as likely that the domes of ancient Ur were known to the Romans through expeditions or that the Romans developed the technology on their own from progression of the stone arch. Either way, the dome was not a Roman invention but they were the first civilization to perfect it.
One of the greatest difficulties associated with building a large self supporting curved shape out of stone or concrete is the formwork necessary to support it during construction. This difficulty is increased by the double curvature of a dome because it requires more support and smaller pieces of wood in order to approximate the rounded shape. For arches and domes this formwork is termed “centering” and enabled the Romans to construct the desired shape without danger of the unfinished structure collapsing in on itself before compressive forces are established by inserting the keystone and achieving equilibrium. The Romans eventually developed a method of centering for arches that was accurate, stable and provided a firm support to build the arch on as seen in Figure 2 below.
|Figure 2: Roman arch centering (Lancaster, 2005)|
When concrete dome construction began, the centering system used for arches was a good two dimensional starting point. The engineers needed to develop a new system and the error and progression of their method can be seen in the earlier domes. Two different ways were developed to construct the dome centering, radial and horizontal formwork as seen in Figure 3 below (Lancaster, 2005). With horizontal formwork, the planks had to be relatively short in order to approximate a smooth curvature. The ends of each plank typically would line up with a single meridional line so that they could all be supported with evenly spaced radial frames. In a radial formwork system, the planks could be longer and each plank would typically end on a common circumferential line. This method allowed less radial frames to be used but it required the circumferential line framing to be supported in a curved shape which was difficult. It is difficult to tell which system the Romans used more often because many of the domes constructed did not leave evidence of formwork on the interior (Lancaster, 2005).
|Figure 3: Horizontal and Radial formwork for centering of Roman domes (Lancaster, 2005)|
The way that the arches and domes of the Roman civilization were designed often provided ledges at the base of the curvature to place the centering in order to minimize the amount of ground support that was needed. For arches, often times long timber columns could be avoided through these designs and completely self supported centering was achieved (Lancaster, 2005). This avoided the problem of flimsy and unstable wood columns under heavy loads from the stones that would deflect and result in a sagging arch. Domes typically still required some columns for support of the centering because the three dimensional shape and large spans made it difficult to achieve the same stability of centering without added support from the ground but the Romans also had the technology to build self supporting centering for double curvature (Lancaster, 2005). It took the engineers some time before designing a reliable method of centering for domes that yielded a high accuracy completed shape but by the 2nd century A.D. they had succeeded.
Once the problem of formwork was solved, the stiffness of these large domes came into question. If a dome was too flexible, when the centering was removed the dome apex may have sagged down significantly and this deflection could result in extensive cracking at certain areas. This could have been discovered through observed deflections and failed designs or perhaps it was something that the Roman engineers intuitively knew would happen. They developed different methods of building domes with stiffening elements placed throughout the curved shape in order to avoid such large deflections. One method developed used ribs that were visible on the interior of the structure as those on the vault in Figure 4 below. The Romans used this same technique in many of the domes that they constructed. These ribs not only served to strengthen the structure but also provided a strong visual texture to the otherwise plain interior of a curved shape through the indentations called coffers. The structure could not have been built with a uniform thickness matching that at the deepest point of the coffer but it was also unnecessary to use a uniform thickness matching that of the ribs. By employing this ribbed technique, the dome was able to be stiffened and decorated through one method and, although increasing the difficulty of formwork, was used extensively. Another system of stiffening that is evident in domes is placed within the dome and is not visible from the interior or exterior. This system began being used during the 4th century and employs a type of brick lattice that is then filled in with concrete to create a closed dome as in Figure 5 below (Lancaster, 2005). The vertical lines of bricks essentially form a series of arches that are connected at the top of the dome by a common keystone. These arches would transfer loads through pure axial forces down to the base of the dome and in many domes it can be seen that the Romans placed these brick lattices so that they landed on a main support (Lancaster, 2005). In this manner, they could avoid placing unnecessary stresses on openings and thinner areas of supporting walls.
|Figure 4: Vault in Roman Forum with interior coffers forming stiffening ribs (self)|
|Figure 5: Brick lattice ribbing at the Baths of Agrippa (Lancaster, 2005)|
Additional purposes have been proposed for the use of the brick lattices in domes and they were likely also intended by the Roman engineers. During construction of a dome, the lattices likely served to divide the dome up into manageable sections of construction and also aid in placing formwork for the general shape of the dome. Many domes have horizontal courses of bipedalis bricks at vertical intervals between the brick lattices and these could have been stood on by carpenters so they could place the formwork just ahead of the construction. In this way the formwork for the entire dome would not have to be built before any concrete placement began (Lancaster, 2005). The lattices could also keep the dome stiff while curing of the concrete took place (Lancaster, 2005). With the weight of the concrete, the wooden frames used to hold the formwork during curing would have slightly deflected and the brick lattices could help mitigate this problem and increase quality control. After developing a solution to this challenge of dome flexibility, the Romans had all the necessary technology to confidently build these structures on a large scale.
Next Page: Roman Dome Progression
Back to Article Overview: Evolution of the Roman Dome
How was the Roman dome developed? ›
Around 100 A.D., Roman builders rotated an arch in a circle and discovered that it created a strong three-dimensional shape -- the monolithic dome. In time, they were capping churches and mosques with this new and brilliant design. The earliest domes were made of stone.What did Romans use to improve the dome? ›
They developed different methods of building domes with stiffening elements placed throughout the curved shape in order to avoid such large deflections.What did the Romans invent in engineering? ›
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In 1546, at age 71, Michelangelo received the greatest and final commission of his life. Pope Paul III appointed him chief architect of the sprawling St. Peter's Basilica, the opulent centerpiece of the Vatican where popes are laid to rest, and home of the tallest dome in the world.Why was the dome developed? ›
Dome structure acted as shelter from prehistoric times when humans used local materials to build it. The local material varied from place to place and thus the shelter structure varied and also the methods of construction. In Mezhirich, Ukraine, 4 huts and 139 mammoth bones were found which dated 19,280 – 11,700 BC.Did Romans develop the dome? ›
While the ancient Romans did not invent domes, they refined the techniques with which to build them, developed an extensive repertoire of shapes, expanded their potential sizes and ascribed a rich variety of functions and meanings to the domes they built.What material made it easier for Romans to build domes? ›
The use of concrete, combined with the employment of true arches allowed for vaults and domes to be built, creating expansive and breathtaking interior spaces.How did the Romans improve architecture? ›
Roman architecture developed the use arches and vaults in architecture. While Roman architecture may not have invented the arch or the vault, they certainly perfected them. These architectural forms allowed Roman architects to create large roofed structures without a reliance on pillars.Why was Roman engineering so advanced? ›
The Romans achieved high levels of technology in large part because they borrowed technologies from the Greeks, Etruscans, Celts, and others. With limited sources of power, the Romans managed to build impressive structures, some of which survive to this day.
What was the greatest Roman engineering accomplishment? ›
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The “rotunda” (Italian for “round”) is the name for the main central structure of the Pantheon and it refers to the Pantheon's distinctive cylindrical shape. This was the first element of the building to be constructed, using the Roman concrete (opus caementicium) technique.Why is the Pantheon significant in engineering? ›
In fact, one of the main reasons it's so important is that it still has a roof, which is a rarity in itself! Its huge hemispherical dome and open occulus are a marvel of engineering and evidence of the Roman mastery of concrete building techniques.How did the Romans build such large structures? ›
The Romans developed brick making techniques that became the main building material in the 1st century AD for the walls of houses, Roman baths, and monuments. Opus latericium (Latin for "brickwork") is a form of construction in which bricks of thick structure are used to face a core of opus caementicium.Did Roman architecture use domes? ›
The Romans were the first builders in the history of architecture to realize the potential of domes for the creation of large and well-defined interior spaces. Domes were introduced in a number of Roman building types such as temples, thermae, palaces, mausolea and later also churches.Who helped with the architectural design of this dome? ›
|Born||Filippo di ser Brunellesco di Lippo Lapi 1377 Florence, Republic of Florence|
|Died||15 April 1446 (aged 68–69) Florence, Republic of Florence|
|Known for||Architecture, sculpture, mechanical engineering|
|Notable work||Dome of Santa Maria del Fiore|
dome, in architecture, hemispherical structure evolved from the arch, usually forming a ceiling or roof. Domes first appeared as solid mounds and in techniques adaptable only to the smallest buildings, such as round huts and tombs in the ancient Middle East, India, and the Mediterranean.What was the purpose of a Roman dome? ›
Roman domes were used in baths, villas, palaces, and tombs. Oculi were common features. They were customarily hemispherical in shape and partially or totally concealed on the exterior.How did ancient people build domes? ›
The earliest domes were likely domed huts made from saplings, reeds, or timbers and covered with thatch, turf, or skins. Materials may have transitioned to rammed earth, mud-brick, or more durable stone as a result of local conditions.
What was innovative about The Dome? ›
After studying the first large-scale domes built by the Romans, architects in recent centuries have been innovating the dome design by adding components like height, support rings for stronger roofs, and even optical illusions to make a dome feel taller than it really is.What is the famous Roman dome architecture? ›
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Along with vaults, they gradually replaced the traditional post and lintel construction which makes use of the column and architrave. The construction of domes was greatly facilitated by the invention of concrete, a process which has been termed the Roman architectural revolution.What were the 3 major building techniques used by the Romans? ›
Building Techniques: Arch, Vault, Dome
This included the arch and the vault, which were destined to carry Roman engineering into a development directly away from that of ancient Greece, who preferred "post-and-lintel" building methods to arches and domes.
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Art and Architecture
For example, they continued the use of columns, but the form became more decorative and less structural in Roman buildings. Ancient Romans created curved roofs and large-scale arches, which were able to support more weight than the post-and-beam construction the Greeks used.
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Roman engineering had a large influence on Roman architecture. Arches were used a lot due to their strength. The Romans also used domes as they enabled them to build large ceilings with wide open spaces. The Romans built over 400,000 km of roads including 29 highways that lead to the city of Rome.
What was a Roman engineer called? ›
The Roman legionary fortified camp
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It's not the Pantheon's facade facing the Italian piazza that makes this architecture iconic. It is the early experimentation with dome construction that has made Rome's Pantheon important in architectural history. The portico and dome combination has influenced Western architectural design for centuries.What construction method made the construction of Roman amphitheaters possible? ›
Ancient Roman buildings utilized arches because they allowed for large blocks of stone to be placed in a way that supports the structure and carries weight. This is arguably the most important architectural feature of the arena, surrounding the entire facade.Why was Roman engineering so good? ›
Roman engineers improved upon older ideas and inventions to introduce a great number of innovations. They developed materials and techniques that revolutionized bridge and aqueducts' construction, perfected ancient weapons and developed new ones, while inventing machines that harnessed the power of water.How did the developments in Roman engineering allow for the Pantheon to be constructed? ›
The structure itself is an important example of advanced Roman engineering. Its walls are made from brick-faced concrete—an innovation widely used in Rome's major buildings and infrastructure, such as aqueducts—and are lightened with relieving arches and vaults built into the wall mass.
How was engineering important to the solution of the dome design? ›
When concrete dome construction began, the centering system used for arches was a good two dimensional starting point. The engineers needed to develop a new system and the error and progression of their method can be seen in the earlier domes.What did Romans use to build strong structures? ›
The development of concrete to form the structural core of buildings was one of the most important innovations in Roman architecture. Concrete is easier and quicker to use than cut stone, and its raw materials are cheap and easy to transport.Why is Roman architecture so strong? ›
Old Roman arches were created with a very durable type of concrete that was made from a mixture of volcanic sand and lime. This ancient concrete was able to support large amounts of weight, and as a result, it enabled people to build larger and more variable types of buildings, like the aqueducts we discussed above.How was the dome built in architecture? ›
dome, in architecture, hemispherical structure evolved from the arch, usually forming a ceiling or roof. Domes first appeared as solid mounds and in techniques adaptable only to the smallest buildings, such as round huts and tombs in the ancient Middle East, India, and the Mediterranean.How was Roman architecture developed? ›
Republican Period. Republican Roman architecture was influenced by the Etruscans who were the early kings of Rome; the Etruscans were in turn influenced by Greek architecture. The Temple of Jupiter on the Capitoline Hill in Rome, begun in the late 6th century B.C.E., bears all the hallmarks of Etruscan architecture.What was the purpose of domes in Rome? ›
Roman domes were used in baths, villas, palaces, and tombs. Oculi were common features. They were customarily hemispherical in shape and partially or totally concealed on the exterior.What is the structural design of domes? ›
Domes have synclastic shell surfaces with positive Gaussian curvature. They are strong and structurally stable. Dome roofs can be constructed from steel, various fiber reinforced composites, and reinforced concrete materials. Precast shells made of these materials have also been constructed successfully.What makes domes so strong? ›
Why are domes so strong? Domes are so strong because of their shape. The dome shape distributes the weight/pressure/force evenly over the entire dome shape, which reduces the load on a single point. We normally think of eggshells as brittle or that they tend to break easily.What is the architectural advantage of the Dome? ›
The dome structure allows for a wide variety of floor plan designs because it needs no interior support. This allows you to take advantage of the wide open space of your building. Because of the structure's tightness, they conserve vast amounts of energy, making them more cost effective to run and heat.What are the 3 most important architectural features developed by the Romans? ›
With concrete, the Romans were able to span much larger areas by the use of the arch, the vault, and the dome. The vault and the dome had already been employed by the Mycenaeans in the 13th century BC, but there'd been a break in the architectural tradition.
What was one of the major developments in Roman architecture? ›
Roman architecture developed the use arches and vaults in architecture. While Roman architecture may not have invented the arch or the vault, they certainly perfected them. These architectural forms allowed Roman architects to create large roofed structures without a reliance on pillars.How was the dome of the Rock designed? ›
The overall form of the architectural dome follows the Byzantine model of churches and martyriums (structures designed to house relics); and the mosaics decorating its interior draw extensively on Byzantine mosaic techniques and aesthetics in their execution of vegetal motifs (while combining them with Sasanian ...