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Acm Space Frames

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Acm Space Frames

  1. 1. ADVANCE CONSTRUCTION AND MANAGEMENT S P A C E F R A M E S S U S P E N D E D R O O F S M E M B R A N E S T R U C T U R E S C A B L E S T R U C T U R E S
  2. 2. SPACE FRAMES AND THEIR CONSTRUCTION TECHNIQUES OF ERECTION
  3. 3. WHAT IS SPACE FRAME AND WHY SHOULD WE USE IT .?
  4. 4. A three-dimensional structural framework which is designed to behave as an integral unit and to withstand loads applied at any point  SPACE FRAMES PROVIDE A LIGHTWEIGHT SOLUTION TO THE PROBLEM OF CREATING LARGE SPAN ENCLOSURES.
  5. 5. SPACE FRAME APPLICATIONS: Space Frames are typically used for Roofing of Large Span Structures without center columns which are extremely useful in projects like: Sports Stadiums, Airports, Shopping Malls, Coal, Cement & Sugar Storage Domes, Skywalks, Pedestrian Bridges, Metro Railway Stations, Large Warehouses, Swimming Pools, Toll Gates, Border Security Gates, Petrol/ Gas Stations.
  6. 6. Cable structures 1. INTRODUCTION 2. LOAD TRANSMISSION 3. CLASSIFICATIONS 4. CABLE 5. TYPES OF CABLE STRUCTURES 6. DIFFERENCE BETWEEN CABLE STAYED BRIDGE AND CABLE SUSPENSION BRIDGE Aaqib Iqbal 13131AA001
  7. 7. Cable structures Cable structure, Form of long-span structure that is subject to tension and uses suspension cables for support. Highly efficient, cable structures includes the suspension bridge, the cable-stayed roof, and the bicycle-wheel roof. A cable structure is a type of structure that utilizes tensioned cables to support or transmit the major loads of the structure. In conventional structures concrete columns are usually used to support the self-weight of the structure as well as the downward loads but there are cases where this system is undesirable. Take for instance a soccer stadium. A major column to take the dead load of the roof of the stadium cannot be place in the middle of the structure because it would land in the middle of the field. An exoskeleton could be used, but it would probably mean the structure would have to be very large to be able to support such a large heavy roof
  8. 8. From ancient Roman canopies and rope bridges, to modern day tents and suspension bridges cable structures, also known as tensile structures, are applications of "tension-only" members. It was not known that steel cables, which first appeared during the industrial revolution, could effectively be used in structures until the late nineteenth century, when Vladimir Shukhov of Nizhny Novgorod, Russia constructed the first tensile steel shell The world's first diagrid hyperboloid structure by Shukhov, Nizhny Novgorod, 1896
  9. 9. 19 Load transmission slab Cables pylons Pile cap piles soil Tension Compression Classifications Based on arrangements of the cables • Radiating • Harp • Fan • star Based on the shape of pylon • A-type • H-type • Y-type
  10. 10. PILE CAP A pile cap is a thick concrete mat that rests on concrete or timber piles that have been driven into soft or unstable ground to provide a suitable stable foundation. It usually forms part of the foundation of a building, typically a multi-story building, structure or support base for heavy equipment. The cast concrete pile cap distributes the load of the building into the piles. PILE It is a long slender foundation member made either of timber, structural steel or concrete to transfer the load of the structure in deep foundation. ADVANTAGE OF PILING To take the structure deep into the ground and hence preventing over turning. To provide a strong bedrock soil (i.e. higher bearing capacity) for the structure and transfer the total load of the structure. To distribute the weight of the structure over a large area. To prevent unequal settlement.
  11. 11. CLASSIFICATIONS radial : cables connect evenly throughout the deck, but all converge on the top of the pier harp : cables are parallel, and evenly spaced along the deck and the pier fan : a combination of radial and harp types star-shaped : cables are connected to two opposite points on the pier
  12. 12. 22 CABLE A cable may be composed of one or more structural ropes, structural strands, locked coil strands or parallel wire strands. A strand is an assembly of wires formed helically around centre wire in one or more symmetrical layers.  A strand can be used either as an individual load-carrying member, where radius or curvature is not a major requirement, or as a component in the manufacture of the structural rope. A rope is composed of a plurality of strands helically laid around a core. In contrast to the strand, a rope provides increased curvature capability and is used where curvature of the cable becomes an important consideration.
  13. 13. 23 SELECTION OF CABLE CONFIGURATION Cables are made of high-strength steel, usually encased in a plastic or steel covering that is filled with grout , a fine grained form of concrete, for protection against corrosion. The selection of cable configuration and number of cables is dependent mainly on length of the span, type of loadings, number of roadway lanes, height of towers, and the designer’s individual sense of proportion and aesthetics. Cost also plays important role in deciding the selection. Using less number of cables increases concentrated load at a single point thereby requiring additional reinforcement for the deck slab as well as pylon . Positions of the cables in space Two plane system  Two Vertical Planes System  Two Inclined Planes System The Single Plane System
  14. 14. Types of Cable Structures Suspension bridges: the earliest method of crossing large gaps. • Early bridges realized from a walkway suspended from hanging ropes of vines. • To walk a lighter bridge of this type at a reasonable pace requires a particular gliding step, as the more normal walking step will induce travelling waves that can cause the traveler to pitch (uncomfortably) up and down or side-to-side. • Suspension bridge realized following the simple design of early bridges: cables (catenaries) / light deck hangers & suspending the deck on catenaries • Lack of stability in high winds
  15. 15. • Very flexible under concentrated loads, as the form of the cable will adapt to loading form • Improved behavior under traffic and wind loads: stiffening trusses at the level of the deck, that distributes concentrated loads over greater lengths • Alternatively: restrain vertical movement of the catenaries by inclined cables attached to the top of the towers or inclined struts below the deck
  16. 16. Cable-stayed bridges - A bridge which consists of a superstructure of steel or reinforced concrete members that is supported at one or more points by cables extending from one or more towers. The cables transfer their tensile load to the towers .This load is then transferred to the main column on which the tower is constructed • A cable-stayed bridge consists of one or more piers, with cables supporting the bridge deck. • Few of the main reasons for the development of these types of bridges was their low cost of construction, the speed of erection and the fact that they had the potential to cover a relatively longer spans.
  17. 17. • Basic idea: reduce the span of the beam (deck) several times compared to the clear span between the piers • Steel cable-stayed bridges are regarded as the most economical bridge design for spans ranging between 200 and 400 m • Reducing the span of a beam greatly improves the maximum stress and deflection
  18. 18. 1. Cable-stayed bridges can be either concrete or steel though a combination of both materials is often chosen. 2. For concrete cable stayed bridges free cantilever construction is considered economical. With this method the deck segments can be either precast or cast-in-situ by travelling shutter arrangement. 3. In a cable stayed bridge, depending on its design, the cables carry the bridge deck from one or both sides of the supporting tower. The stay cables carry the deck and transfer all bridge loads to the foundations. This is done by transmitting the cable stay forces, through its extremities, at it anchorage points. Stay cables are firmly attached to the anchorages which are designed to resist the buckling forces of the loads. Fig: Stay cable anchorages on a concrete deck
  19. 19. DIFFERENCE BETWEEN CABLE STAYED BRIDGE AND CABLE SUSPENSION BRIDGE A multiple-tower cable-stayed bridge may appear similar to a suspension bridge, but in fact is very different in principle and in the method of construction.  In the suspension bridge, a large cable hangs between two towers, and is fastened at each end to anchorages in the ground or to a massive structure. These cables form the primary load-bearing structure for the bridge deck. Before the deck is installed, the cables are under tension from only their own weight.  Smaller cables or rods are then suspended from the main cable, and used to support the load of the bridge deck, which is lifted in sections and attached to the suspender cables. The tension on the cables must be transferred to the earth by the anchorages, which are sometimes difficult to construct owing to poor soil conditions.
  20. 20. Advantages of cable stayed bridges much greater stiffness than the suspension bridge, so that deformations of the deck under live loads are reduced can be constructed by cantilevering out from the tower - the cables act both as temporary and permanent supports to the bridge deck for a symmetrical bridge (i.e. spans on either side of the tower are the same), the horizontal forces balance and large ground anchorages are not required.
  21. 21. BENEFITS 1. One benefit of cable structures is that the tension forces in the cables can be used as points of references in the analysis of structures. For example, Figure 1 involves a weight (w) which causes tension in the cable. This weight pushes the cable down. The cable is now in tension. 2. Stability is another benefit of tensile structures. The tension in the cables cause the resulting structure to be stable. This is commonly demonstrated in tents. As tents, or any structure of that nature, are held by guy wires, which are connected to a grounded point located at the center of the structure, loads are free to act anywhere on the structure. This is because the guy wires are initially in tension.
  22. 22. 1. One of the major benefits of cable structures is that they allow you to displace loads from one part of a structure to another part of the structure. In the previous example the roof load of a soccer stadium which was located at the center of the structure was displaced to the extremities of the structure. In contrast the loads from a structure can be displaced from its extremities to a central pillar. 2. Another benefit of cables structures is that compared to reinforced concrete, cables weigh significantly less and they can generally hold materials such as Kevlar vinyl and other 'soft materials'. These soft materials act like a sheet or blanket being pulled out at each corner, tension in the material opens it up and gives it structure. Cables supply the required tension to keep these ‘soft materials’ open and rigid.
  23. 23. THANK YOU

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