STRUCTURAL SYSTEMS LAMELLA DOMES

LAMELLA DOMES INTRODUCTION: Lamella dome is made of intersecting arches hinged together at their midpoints to form an interlocking network in a diamond pattern. arches hinged midpoints DIAMOND PATTERN STRUCTURAL SYSTEMS

LAMELLA DOMES ARE CHARACTERIZED BY only a few of the ribs running from the rim to the crown of the dome as meridional spherical sector dividers all other ribs running as intra—sector parallel lines, curvilinear or straight, and a diamond grid being thus formed. VARIATIONS IN LAMELLA FRAMES. STRUCTURAL SYSTEMS

dispensing with the necessity of introducing a LAMELLA DOMES THIS TYPE OF STRUCTURE HAS THE ADVANTAGES OF eliminating the crowding effect of meridional ribs at the crown of the dome dispensing with the necessity of introducing a compression ring around the crown having all panel loads at rib intersections almost equal in magnitude requiring only short, light struts for all rib segments (straight or curved), and uniform stress distribution. STRUCTURAL SYSTEMS

LAMELLA DOMES EXAMPLE : Many lamella domes have been built in France. Germany, Italy and Russia. In the United States many domes of this type have been built by the Roof Structures Inc. of St. Louis, Missouri. The WICHITA UNIVERSITY FIELD HOUSE, 75 m in diameter was the first large steel dome to be constructed in 1956, using the lamella system. STRUCTURAL SYSTEMS

Curvilinear lamella domes TYPES Main types of lamella domes Two types:- Curvilinear lamella domes Parallel lamella domes STRUCTURAL SYSTEMS

CURVILINEAR LAMELLA DOMES: In these domes the short struts are connected at the junction of several diamonds. Each diamond may be subdivided in to triangles. Individual struts can be straight or curved, of steel or aluminum tubing, or of laminated wood, steel or aluminum when welded at the intersections provides a rigid frame assembly not requiring mw provision at the base of the dome for thrust. Laminated wood members, however, require a tension ring at the base. The base of a lamella dome is a many sided figure that closely approximates to a circle (The uses of curved decking would result in a circular base) STRUUCTURAL SYSTEMS

LAMELLA DOMES By retaining the features of having compression rings at the crown, incorporating intermediate rings at the crown, incorporating intermediate rings of concentric circles, and running ribs from lower rim to the top centre compression ring, as in solid rib domes, but locating these ribs intersecting each other on a curved plan so as to form diamond-shaped panels, results in the curvilinear lamella dome. This system has increased interlocking stiffness, offers the simplicity of having only two different triangles between any two rings (which differ only in their base lengths)- Thus it provides duplicate lengths and connections between latitupes , but still has the disadvantage of having all curved ribs focusing on the top centre. STRUUCTURAL SYSTEMS

This dome has a diameter of 95 m. LAMELLA DOMES EXAMPLES OF CURVILINEAR LAMELLA DOMES: The ENGINEERING EXHIBITS PAVILION built in 1959 for the Brno, Czechoslovakia, international Trade Fair is an example of the curvilinear lamella dome. This dome has a diameter of 95 m. STRUUCTURAL SYSTEMS

LAMELLA DOMES EXAMPLES OF CURVILINEAR LAMELLA DOMES: The curvilinear lamella dome for a conservatory on top of little MOUNTAIN IN QUEEN ELIZABETH Park in Vancouver, Canada. This dome has a base diameter of 42.67m and a rise of 10.3m. It is built out of Triode tic components (minimum tube size 10 cm, maximum tube size l2 cm. All the tubes have a thickness of 0.375 cm). STRUUCTURAL SYSTEMS

LAMELLA DOMES All the structural components of this dome were fabricated in Ottawa and shipped to Vancouver site. The erection was completed in 775 man hours. The dome was covered with a series of shaped triangular Plexiglas panels fitted to an aluminum glazing system connected to the nodal points. Ventilation to this dome is provided by means of a mechanical fan which is situated at the apex of the dome. STRUCTURAL SYSTEMS

PARALLEL LAMELLA DOMES: Parallel Lamella system is a system in which the dome is divided into a number of cyclically symmetrical sectors braced by two sets of lamella members, each parallel to one of the main radial ribs. This arrangement of bracing, though developed in connection with the construction of steel lamella domes, differs so basically in layout from those previously described, that it is usually referred to as Kiewitt Dome, after the name of its inventor. STRUCTURAL SYSTEMS

LAMELLA DOMES EXAMPLES OF PARALLEL LAMELLA DOMES: 1. KIEWIT DOME The world's largest indoor desert exhibit, located within the world's LARGEST GLAZED DOME, opened at Omaha's Henry Dourly Zoo in March 2002. Major items of work included drilling 159 30-ft.-deep belled piers; placing nearly 900 ft. of buried reinforced concrete pipe; pouring two 41,000-sq.-ft. base floor slabs; constructing a 32-ft.-tall concrete ring wall; and erecting and anchoring the 137-ft.-tall glazed dome, which is composed of 1,760 quarter-in.-thick acrylic, triangular-shaped panels. STRUCTURAL SYSTEMS

LAMELLA DOMES During construction of the slabs and ring wall, crews placed 10,000 tons of concrete and 250 tons of reinforcing steel. Inside the dome, more than 2,000-ft. of masonry walls enclose animal exhibits, keeper rooms and holding areas. Another 60,000 masonry blocks were used for irregular walls that form the exhibit rockwork's main support. KIEWIT DOME STRUCTURAL SYSTEMS

LAMELLA DOMES 2. HARRIS COUNTRY SPORTS STADIUM IN HOUSTON One of the biggest steel domes in the world has a clear span of about 200 m and covers the Harris Country Sports Stadium in Houston, Texas. This dome is 63 m high at centre and covers an area of 3 ha. It is an excellent example of the parallel lamella form of construction. Its surface is divided into 12 sectors, each sector being divided again into six peripheral joints along the tension ring and six joints along the meridian ribs. STRUCTURAL SYSTEMS

LAMELLA DOMES The dome provides 46,000 seats for baseball or up to 66,000 seats for conventions and boxing matches. This dome is stiffened by a tension ring and supported on its perimeter lines by 72 columns. The unit weight of steelwork for this dome is70kg/m2 SECTION STRUCTURAL SYSTEMS

OTHER ASPECTS OF LAMELLA DOMES Lamella domes are structurally indeterminate. Usually these types of domes are analysedusing matrix methods of structural analysis. The calculation of the coordinates of the junction points of the diamonds and the lengths of the individual struts is tedious and time consuming unless they are mathematically programmed for machine computations. The erection of lamella dome can be performed by the use of a gin pole with the top-most struts fastened together first, the structure lifted, and additional struts then attached, until the entire dome is completed. The most common form of sub—roofing for lamella domes is curved wooden decking, progressively applied. Precast concrete units can also be fastened to individual triangles. STRUCTURAL SYSTEMS

I Prefabricated lamella domes can be constructed using wooden members. DETAILS OF TIMBER LAMELLA DOMES LAMELLA DOMES I Prefabricated lamella domes can be constructed using wooden members. Many domes of this type have been built in India, Africa and other countries. The details of these timber domes have been developed at the Forest Research Institute. Dehra Dun. STRUCTURAL SYSTEMS

THANK YOU… Submitted by, Rashmi Bhatt 060129 8th sem