Prefabricated structures

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Prefabricated structures

  1. 1. 1 PRE FABRICATED MODULAR STRUCTURES GUIDED BY: SOUMYA MISS ASST PROFFESSOR, UKFCET, KOLLAM PRESENTED BY: FAIZAL.A.M 7TH SEMESTER CIVIL ENGINEERING UKFCET, KOLLAM
  2. 2. Contents  Introduction  Features  Comparison  Design concept  Components  Types of precast system  Design consideration  Equipments  Assembling  scheduling  Advantages  Limitations  Conclusion  references 2
  3. 3. Introduction  The concept of precast structures also known as prefabricated/ modular structures.  The structural components are standardized and produced in plants in a location away from the building site.  Then transported to the site for assembly.  The components are manufactured by industrial methods based on mass production in order to build a large number of buildings in a short time at low cost. 3
  4. 4. Features  The division and specialization of the human workforce.  The use of tools, machinery, and other equipment, usually automated, in the production of standard, interchangeable parts and products.  Compared to site-cast concrete, precast concrete erection is faster and less affected by adverse weather conditions.  Plant casting allows increased efficiency, high quality control and greater control on finishes. 4
  5. 5. Comparison Site-cast  no transportation  the size limitation is depending on the elevation capacity only  lower quality because directly affected by weather  proper, large free space required Precast at plant  transportation and elevation capacity limits the size-  higher, industrialized quality – less affected by weather  no space requirement on the site for fabrication  unlimited opportunities of architectural appearance  option of standardized components 5
  6. 6. Design concept for precast concrete buildings  The design concept of the precast buildings is based on  1.build ability.  2.economy 3.standardiz ation of precast components. 6
  7. 7. Precast concrete structural elements 7 Precast slabs Precast Beam & Girders
  8. 8. 8 Precast Columns Precast Walls
  9. 9. 9 Precast stairs Precast concrete Stairs Steel plates supported on 2 steel beams
  10. 10. Design considerations  final position and loads  transportation requirements – self load and position during transportation  storing requirements – self load and position during storing – (avoid or store in the same position as it transported / built in)  lifting loads – distribution of lifting points – optimal way of lifting (selection of lifting and rigging tools)  vulnerable points (e.g. edges) – reduction of risk (e.g. rounded edges) 10
  11. 11. Types of pre cast system 1. Large-panel systems 2. Frame systems 3. Slab-column systems with walls 4. Mixed systems 11
  12. 12.  box-like structure.  both vertical and horizontal elements are load-bearing.  one-story high wall panels (cross-wall system / longitudinal wall system / two way system).  one-way or two way slabs. 12 1. Large-panel systems
  13. 13. 2. Frame systems  Components are usually linear elements.  The beams are seated on corbels of the pillars usually with hinged- joints (rigid connection is also an option).  Joints are filled with concrete at the site. 13
  14. 14. 3.Lift-slab systems  - partially precast in plant (pillars) / partially precast on- site (slabs).  - one or more storey high pillars (max 5).  - up to 30 storey high constructions.  - special designed joints and temporary joints.  -slabs are casted on the ground (one on top of the other) – then lifted with crane or special elevators. 14
  15. 15. Lift-slab procedure 15 1. pillars and the first package (e.g. 5 pieces) of slabs prepared at ground level 2. lifting boxes are mounted on the pillars + a single slab lifted to the first floor level 3-8. boxes are sequentially raised to higher positions to enable the slabs to be lifted to their required final position - slabs are held in a relative (temporary) positions by a pinning system
  16. 16. Planning traffic route  How long transporter vehicle is required?  What is the required load capacity of the transporter vehicle?  What is the maximum vertical extension of the shipment  Routs on the site 16 • Is route permission required?
  17. 17. Equipments cranes:  mobile crane  tower crane (above 3stories) lifting tools:  spreader beams  wire rope slings rigging tools:  eye bolt  shakles  hooks 17
  18. 18. Assembling…. 18 Column to column connection
  19. 19. Beam to column connection 19
  20. 20. Beam-slab joints 20
  21. 21. 21 Precast concrete structure consisting of solid wall panels and hollow core slabs. Wall to slab connection
  22. 22. Advantages  Quick erection times  Possibility of conversion, disassembling and moving to another site  Possibility of erection in areas where a traditional construction practice is not possible or difficult  Low labor intensivity  Reduce wastage of materials  Easier management of construction sites  Better overall construction quality  Ideal fit for simple and complex structures 22
  23. 23. Limitations  size of the units.  location of window openings has a limited variety.  joint details are predefined.  site access and storage capacity.  require high quality control.  enable interaction between design phase and production planning.  difficult to handling & transporting. 23
  24. 24. Scheduling some approximate data for installation  emplacement of hollow core floor slabs - 300 m2/day  erection of pillars/columns - 8 pieces/day  emplacement of beams - 15 pieces/day  emplacement of double tee slabs - 25 pieces/day  emplacement of walls - 15 pieces/day  construction of stair and elevator shafts - 2 floors/day 24
  25. 25. Examples…. 25 The hospital will feature multi-trade prefabricated racks in the corridors, an approach that is still new in the U.S.
  26. 26. 26 Miami Valley Hospital Dayton,OH
  27. 27. Conclusion 27 oThe use of prefabrication and preassembly is estimated to have almost doubled in the last 15 years, increasing by 86%. oThe use of precast concrete construction can significantly reduce the amount of construction waste generated on construction sites. o Reduce adverse environmental impact on sites. o Enhance quality control of concreting work. o Reduce the amount of site labour. o Increase worker safety . o Other impediments to prefabrication and preassembly are increased transportation difficulties, greater inflexibility, and more advanced procurement requirements.
  28. 28. References  [1] Szőnyi L.: Construction of prefabricated reinforced concrete buildings, 2011  [2] Benett, D.: Concrete Elegance 2004. Concrete Centre, 2005  [3] Precast Concrete Structures. www.paradigm.in 2012.10.10  [4] S. Brzev, T. Guevara-Perez: Precast Concrete Construction. http://business.management6.com/PRECAST-CONCRETE- CONSTRUCTION-pdfe13174.  [5] Sonjoy Deb: Precast Concrete for Building Systemshttp://masterbuilder.co.in/Archives/Building%20Material s/Concrete/Precast%20 Concrete%20for%20Building%20Systems.pdf 2012.10.10  [6] Lift slab systemhttp://webs.demasiado.com/forjados/patologia/lift_slab/as pect/index.htm2012.10.23  [7] http://www.liftplanner.net/steamdrum.html 2012.10.23 28
  29. 29. 29 Questions ?.....
  30. 30. 30 Thank you

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