Aya Sofya

[Don_P]

Hagia Sophia,
This deserves it's own thread, it is a very cool building.
This was a good description of the mechanics of it from a really full page;

Celestial Domes
[Source: The Australian, October 8, 2005]

Hagia Sophia, or Ayasofya as it is called in Istanbul, is only a few minutes walk from our hotel, so we get up early, see the sun rise over the Golden Horn--the water of which turns a deep, red-flecked gold--then go on to our treasure.

Hagia Sophia--Holy Wisdom--was commissioned by Emperor Justinian I in 532 and when completed five years later was regarded not only as the greatest church in the Eastern Roman Empire--Byzantium--but the greatest church in the world.

In scale and architectural ingenuity it outstripped the Holy Sepulchre in Jerusalem and St. Peter's Basilica in Rome and was heralded as one of the new wonders of the world. Its architects--Anthemius of Tralles and Isidorus of Miletus--seem to have been determined to eclipse the domed and massively constructed Pantheon in Rome, which was completed in about AD128 as a pagan temple to all the gods.

Hagia Sophia achieves its stupendous scale with an elegance, refined minimalism and scientific ingenuity that puts the Pantheon in the shade. Indeed, when first completed, its lofty dome seemed to be an almost supernatural incarnation of God's creation, a celestial hemisphere that hovered--virtually unsupported--between heaven and earth.

It was pioneering; nothing quite like it had been created before. When Justinian saw the completed interior for the first time in 537, he revealed another inspiration for the building: "Solomon," he exclaimed, "I have surpassed thee."

My first view of the Hagia Sophia is shocking; it's a sacred mountain of a building, vast and elemental, rising out of humdrum urban surroundings. It's like seeing the pyramids rising above the banal suburbs of Cairo; giant works of genius, almost not of this world, set among the dross of man's daily life. The violence of the visual juxtaposition is almost like a bodily assault; I blink to take it in. The huge dome, with its dark covering, is framed by much later minarets, added in the late 15th and 16th centuries after the church was converted to a mosque when the Turks seized Constantinople in 1453.


The exterior is complex, but what is clear is that the building is really all to do with the interior space it creates. It's the inside that's important--that is, a simulation of God's creation--and the most important part of the interior is the celestial dome.

I enter the building through a door in its southwest corner that leads below a wonderful early mosaic revealing the source of the Holy Wisdom after which the church is named. In its centre is the Virgin Mary, the new Christian personification of Mother Earth, female power and wisdom that had been represented by great goddesses such as Isis, Ishtar and Minerva.

The Virgin is flanked and being bowed to by Emperor Constantine (AD 285-337), who holds a model of his city of Constantinople, and by Justinian, who holds a model of Hagia Sophia. They are offering--dedicating--their creations to the Virgin, asking for her protection.

Little can prepare you for the experience of the main interior. It's like entering a new, ideal world over which the dome of heaven presides. That, of course, is just the point. It's a magical harmony of square and circle, the symbols of the material and the sacred worlds. I imagine all who have walked here before me, the English Crusaders who came here in the 12th century, men from the fogs and damps of northern Europe where architecture was massive and ponderous.

What on earth would they have made of this? A tall, airy structure, light flooding in, a huge dome--like a flying saucer--high above their heads. It must have been beyond their comprehension.

Although the great central dome dominates, this is far more than just a spectacular domed interior. The space created is complex, in its form and its meaning.

Early churches in Europe generally took the traditional form of the Roman basilica, a rectangular hall with a central nave divided by columns or piers from flanking aisles that, usually, had lower ceiling heights than the nave. This form, with the addition of short transepts to create a cruciform ground plan, suited Christian liturgy--its parades, processions and festivals--and it is this that inspires the plan of Hagia Sophia.

The main body of the building is rectangular, with the nave forming a double square in plan. In the centre of this nave floats, high up, the dome. The way in which the rectilinear basilica transforms as it rises, so that it sustains--in a sense becomes--the curvaceous series of domes and semi-domes, is miraculous.

The four main piers of the basilica sprout four huge semi-circular arches that leap from one pier to the other. These are linked by four concave triangular forms called pendentives that join to form the circular ring on which the base of the drum sits.

This structure, subtly squaring the circle, is doing much to support the weight of the dome. But this is only the obvious part of the support system. Because this structure appears so minimal and elegant, the dome appears to float, especially since its lower portion is pierced by a closely set row of windows to let light pour in, making the junction between dome and supports look transparent, almost nonexistent.


The brilliant and brave science comes with the way in which the outward, lateral thrust of the central dome is handled. Domes are immensely strong structures capable of supporting great weights and spanning wide spaces, but they are difficult to construct and difficult to keep standing.

The curved form, although strong by design, like an eggshell, means that much of its weight exerts a horizontal thrust, so the dome, by its nature, wants to spread, to flatten itself. This outward thrust can be reduced depending on the materials or methods of construction and can be resisted in an ugly or elegant fashion. At Hagia Sophia, the solution is breathtaking. The lateral thrust of the huge central dome is balanced by the opposite and roughly equal counterthrusts exerted by two half-domes opening to the east and west, and by the small domes at the four corners of the nave.

Sturdy buttresses to north and south transfer much of the horizontal thrust of the dome into the rest of the structure and carry it down to the ground. All is in equilibrium, poised, the laws of science, of nature, used to keep the structure standing. This was an unprecedented structure but its designers never lost their nerve.

I have received permission to climb the scaffold that rises below the central dome so, now, up I go. It is a high climb but I can see wonderful things. When Islam first took over the building, the Christian decoration--showing figures such as Mary and Christ, who are venerated in the Koran--was tolerated. But in the 16th century a harder attitude was taken and all images showing living beings were painted over in case God might think them idols.

However, as I climb higher and look down into the galleries, I'm reminded that these 16th-century Muslim fundamentalists were not the first to rob this place of some of its beauty and meaning.

In the 8th century, the Byzantine church resolved to stop the production of icons because it was feared that congregations were worshipping the image rather than the divinity it portrayed; Christians were becoming worshippers of idols. In the galleries, I can see the remains of marvelous mosaics plastered over in the 8th century and revealed relatively recently. I catch a glimpse of the original magnificence and glory of this interior.

Once more in the nave, below the dome, I stand and look up at this epic construction, an elemental work that has withstood the violence of nature and of man. It has been rocked by earthquakes, ransacked by invaders (notably Crusaders who attacked Constantinople in 1204) and repainted by fundamentalist iconoclasts.

But here it is, a mighty prayer in brick and stone rising towards heaven. A vast building that, paradoxically perhaps, achieves spiritual power through the supreme understanding of the material world. Here the forces of nature have been harnessed to realize a structure that makes God's wonder and wisdom manifest.

Good pics and history here;
http://lookuparchitecture.com/historybyzantine.htm

[Dimitri]

A copy of what I mentioned in the other thread:

Stone is over rated. Emperor Justinian thought the same till Isidore of Miletus decided to make the Hagia Sophia more out of brick and mortar then just stone.

The building is still there 1,500 years later, other then the domes, it has survived, several large 7+ earth quakes, a ransacking by the Crusaders of the 4th crusade, and being changed hands a few times.

Reason? The entire outer wall is actually not ridge by more of a flexible composition in nature. The original builders used too much mortar, and had crushed brick into the mortar itself, giving it a strong elastic property, which allowed the outer walls to flex when subjected to lateral loading such as from a earthquake.

They also used a lot of steel in the building to tie everything together. Something that was never done to such a scale before.

Dimitri

[Don_P]

These early masonry arches predate steel or reinforced construction. Some have been reinforced later, but this was incredible old school masonry.

They got it close enough to work, here on the second attempt, the Romans didn't fully understand the forces in a dome, their arches show the same flawed thinking, they conquered and assimmilated knowledge. The earlier Minoans and Myceneans actually had a better understanding. This is getting back around 3,000 bc in stone, large ~parabolic rather than hemispherical roman domes. The Treasury of Atreus and many others;

http://www.minoanatlantis.com/Garlo_Tholos.php

[Don_P]

The Pantheon is another neat ancient, unreinforced, dome, a good description here;
http://www.romanconcrete.com/docs/chapt01/chapt01.htm

Some more background that might help with terms here;
http://theconstructor.org/structures/domes/985/

here's an excellent set of graphics with descriptions including how domes work;
http://site.iugaza.edu.ps/marafa/files/Spherical-dome.pdf