Kopuły w architekturze

2010

Nr 2(28)

Introduction

structural landmark. In Eastern and Western civilizations,

domes were built in order to emphasize the prestige of

the structure and develop representative interiors of rep-

resentative buildings. The construction designs of domes

reect the technical knowledge and culture of specic

epochs.

Barbara Misztal*

Domes in architecture

Architecture structures are a form of presentation of

signicant message of the period when they were built.

Architecture of centers of power, religious cults or cul-

ture is the synthesis of knowledge about communities

that built them. Ecclesiastical and prestigious structures

were often crowned with domes to develop a prominent

Selected elements of the history of construction of domes

Depending on geographic location, in different propor-

tions, the rst materials which were used to build domes

included stone, clay, and wood. Due to its availability in

the Mediterranean region and its greater durability, stone

was applied in construction of monumental structures in

Egypt, Greece, and Rome.

Ancient Greece contributed to building its innovations

which made the most of the best properties of stone and

wood. In Greek temples, the walls were built of stones

whose thickness was 1/20 of the distance between the

walls. Such proportions were achieved for instance in the

temple of Aeschylus in Epidauros, designed by Theod-

oros from Samos which was built around 370 B.C. The

small thickness of stone masonry walls indicates that they

supported light timber roofs. The distances between walls

and piers show that they could not have been simple beam

Fig. 1. Reconstruction variants of the roof on the Aeschylus’ Temple in Greece according to [2]

Wrocław University of Technology, Faculty of Architecture, Depart-

ment of Building Design and General Construction.

290 Barbara Misztal

roofs. The distances between piers indicate a system of

trusses or arches. Figure 1 shows two variants of the roof

on the Aeschylus by A. Kuźniecow [2]. The construction

design of the temple’s walls and roof can indicate that the

Greeks possessed knowledge of the polygon of forces and

knew how to apply it in building designs.

The development of stone domes in ancient Rome

is connected with the increasing demand for prestigious

structures with large representative interiors. Romans

could adjust the shape of domes to pressure lines. With

greater dimensions of representative rooms, the applica-

tion of fully stone domes was connected with the use of

a lot of materials. That is why the thickness of the walls in

the prestigious structures in Rome topped with domes was

1/6 to 1/7 of their diameters [2]. However, due to their

durability, the domes were built concrete and stone so

they would survive wars and barbarian raids. It resulted in

strengthening the patterns and facilitated their repetitions.

It also contributed to the development of many masonry

domes in the south of Europe.

In ancient Rome in 125, the largest axially symmetrical

dome – Pantheon was built under supervision of Apollo-

doros [1]. The construction of the dome was made of Ro-

man concrete, and the mass of the shell calculated for 1 m

of the section was about 6000.0 kg [3]. Figure 2a shows

the section of the Pantheon dome and its dimensions.

The search for lighter solutions of sail masonry roofs

and sufciently strong timber scaffold needed for their

construction lasted for thirteen centuries. In 1412, the con-

struction of the double-shelled dome of the Santa Maria del

Fiore Cathedral in Florence (Fig. 2b) [1] began; its outer

75.0 cm thick masonry shell was placed on octagonal drum

with its 17.0 m long sides, 55.0 m above the oor level.

Attempts at erecting a scaffold under a double-shelled

masonry dome demonstrated how difcult it is to build

a sufciently strong scaffold made of wood – which was

Fig. 2. Largest domes of the Mediterranean civilization:

a) section of the Pantheon dome in Rome from 125 AD acc. to [2],

b) section of the dome on the Santa Marie del Fiore Cathedral,

in Florence acc. to [1]

Fig. 3a, b. Dome of the Rock in Jerusalem, built in 687–691 AD acc. to [6]

Domes in architecture 291

the only known technology then – to hold the massive

masonry dome shells.

In 1542, the double-shelled dome of St. Peter’s Ca-

thedral in Rome (42.52 m in diameter and 52.0 m high)

dome is about 6800.0 kg per 1m

of the section [3].

In the 7

and 8

centuries, double and triple-shelled

domes appeared in Arabian architecture. In the years

687–691, [6] in Jerusalem a dome was built from Leba-

non cedar wood as a double-shelled semicircular dome

20.4 m in diameter (Fig. 3).

The unknown constructor of the dome deliberately ap-

plied knowledge of possible separation of external and in-

ternal loads in order to build a double-shelled dome. The

builder of the dome 745 years before the construction of the

Santa Maria del Fiore Cathedral in Florence, designed and

built a double-shelled dome. Probably this is the very rst

rod construction where the outer wooden construction bears

the weather loads, and the inner one bears its own dead load

and interior decoration. The dome’s double-shelled construc-

tion consists of the outer shell, king-post truss construction,

and the inner brick dome braced at the keystone to the outer

dome. It is unknown whether this building technology was

introduced in this area by the builders from the areas full of

forests or these are examples conrming high development

of civilization and technical of Arab craftsmanship in the

Middle Ages in comparison to medieval w Europe.

As a result of the prestige requirements in Europe and

increasing dimensions of masonry domes, their weight ex-

ceeded technological capabilities. In order to satisfy the

ambitions of wealthy investors it was necessary to apply

lighter solutions of dome construction. What appeared was

double-shelled masonry domes combined with wooden

scaffold needed in the dome construction stage. On the

basis of preserved accounts, it was found that the inven-

tion of a lighter double-shelled masonry dome with the

shells connected with the use of inner wooden construc-

tion was known in Europe in the Middle Ages. Examples

include the domes from the years 1063–1031, described in

[1] (1996), built in St. Mark’s church in Venice. Figure 4a

and b show the view and section of the dome, the biggest

of which in the middle has the 13.0 m long span between

the walls. Lighter than the masonry single- and double-

shelled, the triple-shelled dome enables the separation of

loads. The lower masonry shell bears its own dead load

and interior decoration. The upper one, strengthened by

the inner wooden construction bears the weather loads.

Figure 5 shows another example of application of

wooden scaffold creating the third shell of the dome. This

Fig. 4. Venice - Saint Mark’s Cathedral, 1063–1031 according to [1]:

a) view of the roof, b) cross section of the three domes acc. to [1]

a b

Fig. 5. London – Saint Paul’s Cathedral, 1710 acc. to [1]

292 Barbara Misztal

is the triple-shelled dome built on the tower of Saint Paul’s

Cathedral in London [1]. After the earlier tower roof was

destroyed by re, the rebuilders were afraid to erect a tradi-

tional masonry dome on the building whose structure was

weakened. Designed by the astronomer Christopher Wren,

the new dome of Saint Paul’s Cathedral in London was

built in about 1710. Two slender masonry domes braced to

the third outer dome on post and beam scaffold were built.

After the construction was completed the outer scaffold

was left as a shell protecting the two inner domes against

wind. The masonry domes of Saint Paul’s Cathedral: the

semicircular one and the conical one (Fig. 5) jointly trans-

fer the vertical loads. The conical dome bears the load of

the lantern, transferring the vertical forces to the ring beam

which is the same for both inner shells. The lower dome

transfers its dead load and rich architectural detail demon-

strating the structure’s prestige and function.

External scaffolds protecting double-shelled masonry

domes were built in many multi-shelled domes in Ba-

roque and later.

In the rst half of the 19

century, the German ar-

chitect Stüler A.F. replaced the post and beam construc-

tion protecting masonry domes with a system of trusses.

Figure 6 shows such a solution applied in construction of

the wooden outer dome of the church designed by Stüler

A.F. in Berlin. The transformation of the external scaffold

into a system of meridian trusses with parallel braces was

a breakthrough.

The principle of construction of domes introduced by

Stüler A.F. was also applied by other architects (Wein-

brener F.), which popularized in Western Europe build-

ing of dome structures based on scaffolds used to build

masonry vaults which, however, already featured separate

load bearing meridian and parallel elements, typical of

domes. Instead of posts and beams, the scaffolds often

used meridian trusses with parallel braces, with the cur-

vature formed by centerings adjusted to the radius of the

domes. The timber centering, which was used for centu-

ries in wooden scaffolds, was the element which was most

developed in this construction technology.

The system of meridian and parallel ribs, which was

gradually improved in timber protecting domes, resulted

in the development of simple and economical construc-

tions of ribs built from timber centerings.

Figure 7 shows one of the rst such domes – dome de-

signed by G. Möller with the diameter of 33.5 m which was

built in the middle of the 19

century for a catholic church

in Darmstadt, Germany. The dome by Möller G. is the rst

wooden dome described in [6] (1900) with minimalistic

ribbed construction. This is the result of the evolution of

timber scaffolds used to build vaults and masonry domes

which lasted for two thousand years. The timber centering

which is the external element of the scaffold supporting the

masonry dome became an independent load-bearing rib

of the dome. Its supporting scaffold was eliminated. The

division of the construction into meridians and parallels

resulted in a clear distribution of forces in the dome and

facilitated static calculations of load-bearing elements.

Möller’s idea was improved in the following designs

of structures topped with domes.

Fig. 6. Stüler’s Dome in Berlin acc. to [6]

Fig. 7. View of the dome construction by Möller G. acc. to [6]

Conclusions

Domes are the works of architecture which present the

technical culture of the times when they were constructed.

The form of domes developed over centuries along with

the structure best suited for them. Depending on the build-

ing material which was used, dome constructions were

different. The paper presented one of the directions of

Domes in architecture 293

evolution of timber dome structures. It evolved from the

transformation of timber scaffold used to build heavy ma-

sonry vaults into a dome load-bearing system. The trans-

formation of the protecting post and purlin scaffold into

a system of meridian and parallel load-bearing elements

was a breakthrough. At rst it was a system of wooden

meridian trusses with parallel braces, protecting sensitive

masonry domes. As a result of experience gained over the

years, the external members of trusses made of centerings

were transformed into a load-bearing system of ribs typi-

cal of a spherical form of the dome.

The minimalistic ribbed construction made of timber

centerings developed over time into various load-bearing

systems of domes made of solid wood.

References

[1] Heinle E., Schlaich I., Kuppeln aller Zeiten aller Kulturen, Stuttgart,

Deutsche Verlags Anstalt, 1996.

[2] Kuzniecow A.W., Tektonika i konstrukcja cientriczeskich zdani,j

Moscow 1951.

[3] Lisowski A., Projektowanie dome obrotowych, Biuro Studiów i Pro-

jektów Wzorcowych Budownictwa Miejskiego, Warszawa 1955.

[4] Murray P., Architektura włoskiego renesansu, Wydawnictwo VIA

1999.

[5] Stierlin H., Skarby Orientu. Architektura i sztuka islamu od Isfahanu

po Tadż Mahal, Arkady, Warszawa 2002.

[6] Warth O., Die Konstructionen in Holz, Gedruct von A. Th. Engelhardt,

Lipsk 1900.

Kopuły w architekturze

Architektura obiektów w kulturze Wschodu i Zachodu obejmowała

dachy zwieńczone kopułami. Kiedy masa kopuł murowanych prze-

kroczyła możliwości techniczne konstruowania podpierających drew-

nianych rusztowań, rozpoczęło się poszukiwanie lżejszych rozwiązań

konstrukcyjnych. Ewolucja rusztowania stosowanego do wznoszenia

ciężkich powłok betonowych i murowanych była jednym z kierunków

powstawania konstrukcji kopuł z drewna jednolitego. W toku trwających

kilkaset lat doświadczeń przekształcono tradycyjne rusztowanie w kon-

strukcję z kratownic o układzie południkowym, stężonych równoleżni-

kowo. Podział konstrukcji na elementy południkowe i równoleżnikowe

wpłynął na rozwój statyki i konstrukcji kopuł żebrowych z drewna

jednolitego.

Key words: domes, architecture Słowa kluczowe: kopuły, architektura

Kopuły w architekturze

Barbara Misztal

Streszczenie