TYPES OF
Construction and Materials - V
STEEL STRUCTURES
Rahman Ali Khan 17arb566 Department of Architecture
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
What are steel structures? Types of steel structures Classification of steel structures Tension members Compression members Truss system Frame system Space frame system Built-up members Shell structures Suspension structures Case study: Home insurance building, Chicago
INTRODUCTION
What are Steel Structures?
S T E E L
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STRUCTURES Composition of Structural Steel
TYPES OF STEEL
ADVANTAGES OF USING
STRUCTURES
STRUCTURAL STEEL
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1. CHARACTERISTICS Structural steel differs from concrete in its attributed compressive strength as well as tensile strength. 2. STRENGTH Having high strength, stiffness, toughness, and ductile properties, structural steel is one of the most commonly used materials in commercial and industrial building construction.[12] 3. CONSTRUCTABILITY Structural steel can be developed into nearly any shape, which are either bolted or welded together in construction. Structural steel can be erected as soon as the materials are delivered on site.
Frame Structures
4. FIRE RESISTANCE Steel is inherently a noncombustible material. When heated to temperatures seen in a fire scenario, the strength and stiffness of the material is significantly reduced.
Shell Structures
5. CORROSION Steel, when in contact with water, can corrode, creating a potentially dangerous structure. Measures must be taken in structural steel construction to prevent any lifetime corrosion.
Trusses
Space Frame
Example of steel truss system
6. MOLD Steel provides a less suitable surface environment for mold to grow than wood.
CLASSIFICATION OF STEEL STRUCTURES FRAMED STRUCTURES
TRUSS STRUCTURE
SHELL STRUCTURES
A space frame or space structure is a truss-like, lightweight rigid structure constructed from interlocking struts in a geometric pattern. Space frames can be used to span large areas with few interior supports.
A truss is an assembly of beams or other elements that creates a rigid structure frame systems consists of linear element like beams & columns. Trusses are used in a broad range of buildings mainly where there is a requirement for very long spans, such as in air port terminals, stadiums etc.
Shell structures are also called plate structures. They are lightweight constructions using steel cast elements. These elements, typically curved, are assembled to make large structures. Typical applications include aircraft fuselages, boat hulls, and the roofs of large buildings.
SUSPENSION STRUCTURES OR CABLE STAYED
COMPRESSION MEMBERS
TENSION MEMBERS
Compression members are basic components that are pushed together or carry a load, more technically they are subjected only to axial compressive powers. Examples are Columns etc.
Tension members are structural elements that are exposed to pure tensile forces. The determination of their cross segment is one of the least complex and most direct issues experienced in steel design
A cable-stayed structures or suspension structure is one where the building elements is stayed by cables attached to towers. It is a very efficient means of achieving a long span and aesthetically pleasing. Examples are Suspension bridges etc.
Compression steel application
Tension Joint
TENSION MEMBERS A tension member is designed as a structural member subjected to tensile force in a direction parallel to its longitudinal axis. A tension member is also called a tie member or simply a tie. Tension members are structural elements that are exposed to pure tensile forces. The determination of their cross segment is one of the least complex and most direct issues experienced in steel design. A structural member is viewed as a pressure part if it is under a compressive load, either alone or with other loadings. Component parts of frames, columns, beam-columns, plates and the compression flange of beams or plate girders could be remembered for this classification. Examples of tension members are supporting structures and extensions, truss members and cables in suspended roof frameworks. TYPES OF TENSION MEMBERS The types of structure and method of end connections determine the type of a tension member in structural steel construction: 1.Wires and cables, 2. Rods and bars 3. Single structural shapes and plates 4. Built up members
STEEL RODS AND PLATES
Wires
COMPRESSION MEMBERS Compression members are basic components that are pushed together or carry a load, more technically they are subjected only to axial compressive powers. That is, the heaps are applied on the longitudinal axis through the centroid of the part cross segment, and the load over the cross sectional area gives the weight on the compressed member. Stability is an important consideration in design and behavior of compression members and area is generally spread out to maximize Radius of Gyration. Compression members are commonly used as columns in building structures, chords or webs in trusses, bridge piers or braces in framed structures. The maximum strength of a steel compression member depends, to a large extent, on the member length and end support conditions. TYPES OF COMPRESSION MEMBERS There are several types of compression members: 1. 2. 3. 4. 5. 6.
Column Strut Post Stanchion Top chords of trusses Diagonal members in end panels of trusses Wires
TRUSS SYSTEM A truss is made up of a web of triangles joined together to enable the even distribution of weight and the handling of changing tension and compression without bending or shearing. Trusses consist of triangular units constructed with straight members. The ends of these members are connected at joints, known as nodes. The trusses are widely used to serve two main functions: ❑ ❑ ❑ ❑ ❑
To carry the roof load To provide horizontal stability Achieve long spans. Minimize the weight of a structure. Reduced deflection.
Trusses are typically made up of three basic elements: • • •
A top chord which is usually in compression. A bottom chord which is usually in tension. Bracing between the top and bottom chords.
ADVANTAGES ▪ Considered to be more expensive, metal roof trusses can span further than wood. ▪ Metal roof trusses can be manufactured to exact standards. ▪ They are much more lightweight and this allows for larger shipments. ▪ Metal roof trusses are fire resistant. ▪ Metal roof trusses are recyclable and therefore environmentally friendly. DISADVANTAGES ▪ ▪
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Skilled labor is required to install metal roof trusses. They are not energy efficient since they allow more heat to escape from the structure. Metal roof trusses allow sound to be more easily transmitted. The metal is cut, drilled, scratched or welded, rust can become a problem.
TYPES OF TRUSS ▪ ▪ ▪ ▪ ▪
PRATT TRUSS FAN TRUSS NORTH LIGHT ROOF TRUSS QUADRANGULAR ROOF TRUSS TUBULAR STEEL TRUSS
FORMS OF TRUSS ▪ ▪ ▪
SIMPLE TRUSS PLANER TRUSS SPACE FRAME TRUSS
Fan Truss
Space Frame Truss
Simple Truss
Tubular truss
Quadrangle truss
North Light roof truss
Planner Truss
SPACE FRAME SYSTEM A space frame or space structure is a truss-like, lightweight rigid structure constructed from interlocking struts in a geometric pattern. Space frames can be used to span large areas with few interior supports. Like the truss, a space frame is strong because of the inherent rigidity of the triangle; flexing loads (bending moments) are transmitted as tension and compression loads along the length of each strut. The simplest form of space frame is a ▪ Horizontal slab of interlocking square ▪ Pyramids tetrahedra built from tubular steel struts.
❑ APPLICATIONS OF SPACE FRAMES Space frame truss can be used for a platform or overhead structure that spans large distances without need for internal load bearing support. Ex. sports arenas, exhibition pavilions, assembly halls, transportation terminals, airplane hangars, workshops, and warehouses
Tetrahedron
❑ SPACE FRAME COMPONENTS ▪
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Members are axial elements with circular or rectangular sections, all members can only resist tension or compression. The space grid is built of relatively long tension members and short compression members. Connecting joints: Both functional and aesthetic. joints have a decisive effect on the strength and stiffness of the structure and compose around 20-30 percent of the total weight.
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ADVANTAGES Lightweight Mass Productivity Stiffness Versatility JOINT
MEMBERS
TYPES OF SPACE FRAME ACCORDING TO CURVATURE
FLAT COVERS
BARREL VAULTS
SPHERICAL DOME
These structures are composed of planar substructures. The plane are channeled through the horizontal bars and the shear forces are supported by the diagonals.
This type of vault has a cross section of a simple arch. Usually this type of space frame does not need to use tetrahedral modules or pyramids as a part of its backing.
These domes usually require the use of tetrahedral modules or pyramids and additional support from a skin.
TYPES OF SPACE FRAME ACCORDING TO THE NUMBER OF GRID LAYERS
SINGLE LAYER
DOUBLE LAYER
TRIPLE LAYER
All elements are located on the surface to be approximated. Generally present in light weight structures.
The elements are organized in two parallel layers with each other at a certain distance apart. The diagonal bars connecting the nodes of both layers in different directions in space.
Elements are placed in three parallel layers, linked by the diagonals. They are almost always flat. This solution is to decrease the diagonal members length.
TYPES OF SPACE FRAME ACCORDING TO THE TYPE OF JOINT
SYSTEM III SPACE FRAME
PYRAMID SPHERE SPACE FRAME
The most versatile and attractive forged steel ball and tube system available. ▪ Easiest ball and tube system to assemble. ▪ Virtually unlimited span capability. ▪ Flexibility of form through freedom of angle
Traditional ball and tube appearance without the cost. This is a great system for simple flat or flat sloping space frame projects. ▪ Variable module designs. ▪ Top junction plate for economical design. ▪ Long span capability
AXENT SPACE FRAME
HEMISPHERICAL NODE Most economical space frame system. Fits most geometric designs. ▪ Easiest, most economical system to assemble. ▪ Variable module sizes. ▪ Ideal solutions for medium spans. ▪ Maximum span 90 feet
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Attractive and cost efficient addition to any display or exhibit. Practical assembly with the aid of a hand wrench only. Contemporary appearance combined with a simple and mobile construction process Examples are Mero Space Frame.
BUILT-UP MEMBERS Built-up members are used in many structures, such as compression members of trusses or supporting columns. They are composed from two rolled U-sections or four rolled angles. The distance between them is fixed by lacing or battening. The built-up members are economic, since the connection between the chords can be realized with elements of less volume than with continuous plates. In the design of built-up compression members the effect of shear deformation of connecting elements should be taken into account, since a shear force is acting from the compressive force during the overall buckling of the member with an initial eccentricity.
TYPES OFBUILT UP MEMBERS
COMBINE SYSTEM OF LACING AND BATTEN BUILT UP MEMBERS
Wires
SHELL STRUCTURES Shell structure, In building construction, a slight, bended plate structure molded to transmit applied forces by compressive, tensile and shear focuses on that demonstration in the plane of the surface. They are normally developed of concrete reinforced with steel work. Shell construction began in the 1920s, the shell emerged as a significant long-range solid structure after World War II. More complex forms of concrete shells have been made, including: ▪ Hyperbolic paraboloids ▪ Seat shapes ▪ Converging explanatory vaults TYPES OFSHELL STRUCTURES • Concrete shell structures, often cast as a monolithic dome or stressed ribbon bridge or saddle roof • Lattice shell structures, also called grid shell structures, often in the form of a geodesic dome or a hyperboloid structure • Membrane structures, which include fabric structures and other tensile structures, cable domes, and pneumatic structures.
Wires
CONCRETE SHELL STRUCTURE MONOLITHIC DOME
STRESSED RIBBON BRIDGE
SADDLE ROOF
A monolithic dome is a structure cast in a one-piece form. The form may be permanent or temporary and may or may not remain part of the finished structure. Monolithic domes are a form of monolithic architecture.
A stressed ribbon is a tension structure. The suspension cables are embedded in the deck which follows a catenary arc between supports. Unlike the simple span, the ribbon is stressed in traction, which adds to the stiffness of the Structure.
A saddle roof is a roof form which follows a convex curve about one axis and a concave curve about the other. The hyperbolic paraboloid form has been used for roofs at various times since it is easily constructed from straight sections of lumber, steel, or other conventional materials.
LATTICE SHELL STRUCTURES GEODESIC DOME A geodesic dome is a hemispherical thinshell structure (lattice-shell) based on a geodesic polyhedron. The triangular elements of the dome are structurally rigid and distribute the structural stress throughout the structure, making geodesic domes able to withstand very heavy loads for their size. GRID SHELL A grid shell is a structure which derives its strength from its double curvature, but is constructed of a grid or lattice. Large span timber grid shells are commonly constructed by initially laying out the main lath members flat in a regular square or rectangular lattice, deforming this into the desired doubly curved form. HYPERBOLOID STRUCTURE Hyperboloid structures are architectural structures designed using a hyperboloid in one sheet. Often these are tall structures such as towers where the hyperboloid geometry's structural strength is used to support an object high off the ground.
MEMBRANE STRUCTURES Membrane structures are spatial structures made out of tensioned membranes. The structural use of membranes can be divided into pneumatic structures, tensile membrane structures, and cable domes. In these three kinds of structure, membranes work together with cables, columns and other construction members to find a form. Membranes are also used as non-structural cladding, as at the Beijing National Stadium where the spaces between the massive steel structural members are infilled with PTFE coated glass fiber fabric and ETFE foil.
SUSPENSION
CASE STUDY
STRUCTURES
HOME INSURANCE BUILDING, CHICAGO
Building structures in which the main elements that support the load (wires, cables, chains, grids, sheet diaphragms, and so on) are subject only to forces of extension. Suspension structures, which exist under conditions of extension, make possible the full use of the mechanical properties of high-strength materials (for example, steel wire) their light weight makes it possible to cover structures that have extremely large spans. The most straightforward type of plane structure is a wire attached to supports and from which are suspended components that take the local stress. Examples Scaffolds, rooftops, ropeways, and bridges for pipelines.
SUSPENSION BRIDGE
The Home Insurance Building, built in 1885 and located on the corner of Adams and LaSalle Streets in Chicago, Illinois, went down in history as the world’s first modern skyscraper. Designed by engineer William LeBaron Jenney. The Home Insurance Building was completed in 1885; it originally had 10 stories and stretched 138 feet in the air. During its construction, city authorities were so worried that the building would topple over that they halted construction for a period of time so that they could ensure its safety. In 1890, two additional floors were added at the top, bringing the total height to 180 feet (55 meters). In addition to being the first of a new generation of steel-framed skyscrapers built in cities across America and the world, the building set the standard for various other building innovations, including rapid, safe elevators, wind bracing and modern plumbing.
THANK YOU
REFERENCES: https://www.designingbuildings.co.uk/wiki/Types_of_structure https://www.researchgate.net/publication/329013553_Overview_on_Space_Frame_Structures https://www.academia.edu/6244542/24_Space_Frame_Structures_24_1_Introduction_to_Space_Frame_Structures http://3dspaceco.com/public/user_data/shokouh/%D9%85%D9%82%D8%A7%D9%84%D8%A7%D8%AA%20%D9%84%D8%A7%D8%AA%DB%8C%D9%86/11-_space_frames_construction.pdf
Department of Architecture, AMU
