Domes built in the 20th century benefited from more efficient techniques for iron production and steel production, as well as advances in structural analysis. In the 20th century, planetarium domes spurred the invention by Walther Bauersfeld of both thin shells of reinforced concrete and geodesic domes. The use of steel, computers, and finite element analysis enabled yet larger spans. Tension membrane structure became popular for domed sports stadiums, which also innovated with rigid retractable domed roofs.
Developments Graphical equilibrium analysis was used in America at the beginning of the 20th century to check the designs of domed structures, such as St. Paul's Chapel at Columbia University and the vaults of Spanish architect Guastavino.
American state capitol domes built in the twentieth century include those of Arizona, Mississippi, Pennsylvania, Wisconsin, Idaho, Kentucky, Utah, Washington, Missouri, and West Virginia. The West Virginia capitol building has been called the last American Renaissance capitol.
Early Modernist architecture, characterized by "geometrization of architectural detail", includes the domed Greek Catholic parish churches of Čemerné (1905–1907) and Jakubany (1911) in Slovakia. The monumental domes of the Greek Catholic (1901–1906), in Jarosław, Poland, (1902–1907), and the in Surochów, Poland, (1912–1914) also have simplified geometry that attempt to blend traditional and modern styles, an effort interrupted by World War I and the breakup of the Habsburg monarchy.
Wooden domes in thin-wall shells on ribs were made until the 1930s. After World War II, steel and wooden laminate structural members made with waterproof resorcinol glues were used to create domes with grid-patterned wooden support structures, such as the Skydome in Flagstaff, Arizona. Glued laminated wooden structures were also used in 1983 to create the Tacoma Dome, in 1990 to create the Superior Dome, and in 1997 to create the Nipro Hachiko Dome.
Stand-alone dome structures were used to house public utility facilities in the 20th century. The "Fitzpatrick dome", designed by John Fitzpatrick as an inexpensive structure to store winter road service sand and salt, has been used in countries around the world. The first was built in 1968. The domes have twenty sides and are normally in diameter and a little more than tall. The conical shape is meant to conform to the 45 degree slope of a pile of wet sand. They are built on concrete footings and covered with asphalt shingles.
In the second half of the twentieth century, study of domes increased with the application of limit analysis and elastic analysis to models. Beginning in 1967, Professor applied limit analysis to the traditional technique of analyzing domes along the arches created by cutting the structure with meridian planes. He published studies analyzing dome collapse and cracking patterns. Limit analysis, which models domes in a simplified manner as a kinematic chain of rigid blocks, was often used to study the collapse of masonry domes under various conditions of load, shape, and structural features. The analysis assumed "infinite compressive strength, infinite sliding strength and tensile strength equal to zero" for masonry domes. Elastic analysis uses more refined models to perform three-dimensional membrane analysis of the distribution of stresses in domes with various shapes, loads, and boundary conditions. It models masonry as composed of either isotropic or orthotropic materials and takes block arrangement and mortar joints into account.
Guastavino tile The Guastavino family, a father and son team who worked on the eastern seaboard of the United States, built vaults using layers of tiles in hundreds of buildings in the late 19th and early 20th centuries, including the domes of the Basilica of St. Lawrence in Asheville, North Carolina, and St. Francis de Sales Roman Catholic Church in Philadelphia, Pennsylvania. The dome over the crossing of the Cathedral of St. John the Divine in New York City was built by the son in 1909. A part-spherical dome, it measures 30 meters in diameter from the top of its merging pendentives, where steel rods embedded in concrete act as a restraining ring. With an average thickness 1/250th of its span, and steel rods also embedded within the pendentives, the dome "looked forward to modern shell construction in reinforced concrete."
Reinforced concrete Domes built with steel and concrete were able to achieve very large spans. The 1911 dome of the Melbourne Public Library reading room, presumably inspired by the British Museum, had a diameter of 31.5 meters and was briefly the widest reinforced concrete dome in the world until the completion of the Centennial Hall. The Centennial Hall was built with reinforced concrete in Breslau, Germany (today Poland), from 1911–13 to commemorate the 100-year anniversary of the uprising against Napoleon. With a central dome surrounded by stepped rings of vertical windows, it was the largest building of its kind in the world. Other examples of ribbed domes made entirely of reinforced concrete include the Methodist Hall in Westminster, London, the Augsburg Synagogue, and the Orpheum Theater in Bochum. The 1928 Leipzig Market Hall by Deschinger and Ritter featured two domes.
The thin domical shell was further developed with the construction of two domes in Jena, Germany in the early 1920s. To build a rigid planetarium dome, Walther Bauersfeld constructed a triangulated frame of light steel bars and mesh with a domed formwork suspended below it. By spraying a thin layer of concrete onto both the formwork and the frame, he created a dome that was just 30 millimeters thick. The second dome was still thinner at 40 meters wide and 60 millimeters thick. These are generally taken to be the first modern architectural thin shells. These are also considered the first geodesic domes. Beginning with one for the Deutsches Museum in Munich, 15 domed projection planetariums using concrete shells up to 30 meters wide had been built in Europe by 1930, and that year the Adler Planetarium in Chicago became the first planetarium to open in the Western Hemisphere. Planetarium domes required a hemispherical surface for their projections, but most 20th century shell domes were shallow to reduce the material costs, simplify construction, and reduce the volume of air needing to be heated.
In India, the Viceroy's House in New Delhi was designed in 1912–1913 by Edwin Lutyens with a dome.
Although an equation for the bending theory of a thick spherical shell had been published in 1912, based on general equations from 1888, it was too complex for practical design work. A simplified and more approximate theory for domes was published in 1926 in Berlin. The theory was tested using sheet metal models with the conclusion that the membrane stresses in domes are small with little reinforcement required, especially at the top, where openings could be cut for light. Only the concentrated stresses at point supports required heavy reinforcement. Early examples used a relatively thick bordering girder to stabilize exposed edges. Alternative stabilization techniques include adding a bend at these edges to stiffen them or increasing the thickness of the shell itself at the edges and near the supports. In 1933–34, Spanish engineer-architect Eduardo Torroja, with Manuel Sanchez, designed the Market Hall in Algeciras, Spain, with a thin shell concrete dome. The shallow dome is 48 meters wide, 9 centimeters thick, and supported at points around its perimeter. The indoor stadium for the 1936 Olympic Games in Berlin used an oval dome of concrete shell 35 meters wide and 45 meters long.
The use of metal structures in Italy was reduced in the first half of the 20th century by autarchy and the demands of the world wars. Steel became broadly used in building construction in the 1930s. A shortage of steel following World War II and the demonstrated vulnerability of exposed steel to damage from intense fires during the war may have contributed to the popularity of concrete architectural shells beginning in the late 1940s. In the 1960s, improvements in welding and bolting techniques and higher labor costs made steel frames more economical.
In 1940, California architect Wallace Neff built a dome using an inflated balloon of sailcloth as formwork. The balloon was made airtight by wetting, inflated, then supported steel reinforcement as concrete was sprayed onto it in layers. This technique was used to build "bubble houses" in Florida.
After World War II, reinforced concrete was used in dome reconstruction in Palermo, Sicily, because it was quick, strong, economical, and readily available. Examples include Church of the Gesù, Sant'Ignazio all'Olivella, and Santissimo Salvatore.
Popularized by a 1955 article on the work of Félix Candela in Mexico, architectural shells had their heyday in the 1950s and 1960s, peaking in popularity shortly before the widespread adoption of computers and the finite element method of structural analysis. Notable examples of domes include the Kresge Auditorium at MIT, which has a spherical shell 49 meters wide and 89 millimeters thick, and the Palazzetto dello Sport, with a dome designed by Pier Luigi Nervi.
Built from 1955 to 1957, the prestressed concrete dome of the main exhibition hall of the Belgrade Fair has a span of 106 meters. It was designed by Branko Žeželj, using a pre-stressing system developed by him, and was the largest dome in the world until 1965. It remains the largest dome in Europe.
In the 1960s, Italian architect Dante Bini developed an inflatable formwork system using a nylon-reinforced neoprene spherical balloon. First, a concrete floor slab and ring beam was poured. The ring beam included voids for air inlets and outlets and an inflatable tube that held the balloon membrane in place. The balloon was laid out uninflated over the floor slab and secured at the ring beam, reinforcement bars spaced with springs were laid on top, the concrete was applied, an outer membrane of PVC was laid over the concrete, then the balloon was inflated and lifted the material into the dome shape. After inflation, the concrete was vibrated using rolling carts attached to cables. After drying, the balloon could be removed and openings for door or windows could be cut out of the dome. This "Binishell" system was used to build over 1,500 elliptical-section domes in countries around the world between 1970 and 1990, with diameters between 12 and 36 meters. Examples include the Edinburgh Sports Dome in Malvern (1977) and a project at Sydney's Ashbury School.
The dome of the Church of the Holy Sepulchre in Jerusalem experienced an earthquake in 1927, a fire in 1934, and a fire in 1949, which partially destroyed its lead roof. In 1977 it was decided to renovate the dome to better resist earthquakes and fire. A British team of contractors used steel connectors to attach a 115 millimeter thick reinforced concrete dome shell to the outside of the 1870 wrought iron arches. They reduced the dome's total weight by 100 tons, so that either the shell or the arches could each support the total weight of the dome independently of the other. No flammable materials were used. The exterior was covered in traditional hand-finished lead sheeting. The interior was covered with a 25 millimeter thick layer of plaster attached to the wrought iron arches with a metal mesh.
Reticular and geodesic domes The West Baden Springs Hotel in Indiana was built in 1903 with the largest span dome in the world at . Its metal and glass skin was supported by steel trusses resting on metal rollers to allow for expansion and contraction from temperature changes. It was surpassed in span by the Centennial Hall of Max Berg.