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Presentation On RCC Slabs

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Published in: Engineering
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Types of RCC Slabs Applications Advantages Disadvantages

Vamsi P / Dubai

6 years of teaching experience

Qualification: Civil Engineering

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  1. TYPES OF REINFORCED CEMENT CONCRETE SLABS Vamsi Putta 3rd year Bachelors in Civil engineering AMITY UNIVERSITY OueAi
  2. What is RCC? RCC is the combination of ordinary concrete with the reinforcement(steel, fiber, etc.,) to increase its compressive and tensile strength to a great extent. Purpose of RCC? LT.-I Concrete has very high compressive strength, but has low tensile strength. But where tensile forces are also involved, as in, beams and slabs, there is a very high risk of its failure when plain concrete is used. Steel has very high tensile strength, so then steel and concrete are added together, resulting in a material that 's capable of withstanding both tensile and compressive forces acting upon the structure.
  3. Types of RCC uOne way system slab OJoist slab (Ribbed) uFIat slab aFlat plates UTwo way system slab aWaffIe slab LIHollow core slab uHardy slab •Bubble deck slab 2Precast slab •Composite slab
  4. One way slab One way slab is supported by beams on the two opposite sides to carry the load along one direction. Longer span Shorter span span Deflection usually governs the design, and steel content is usually increased to reduce service stress and increase capacity These slabs bend in the direction along its shorter span. Main reinforcement is provided in shorter span and distribution reinforcement is provided in longer span.
  5. One way slab Applications Cantilever slabs Office buildings (low rise) Shopping malls Warehouses, Verandahs. Economic span range. 4 - 7m Economic slab thickness range: 150 - 250mm Live loads: 3 - 5KN/m2 Advantages Simple construction Penetrations in the slabs are easily manageable Disadvantages Associated down stand beams may require greater story height Deter fast formwork cycles. Compromise flexibility of partition location and horizontal service distribution
  6. Joist slab (Ribbed) It consists of a floor slab supported by reinforced concrete ribs. The ribs are supported on girders that rest on columns. Introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section. A slightly deeper section is required, but these stiffer floors facilitate longer spans and provision of holes.
  7. Joist slab (Ribbed) Applications Parking structures Office buildings (low rise) Warehouses Economic span range: 8- 12m Economic slab thickness range: 50 - 100mm Live loads: 4 - 6KN/m2 Advantages Medium to long spans Lightweight Holes in topping easily accommodated Large holes can be accommodated Profile may be expressed architecturally Disadvantages Higher formwork costs than for other slab systems Slightly greater floor thicknesses Slower floor to floor cycle
  8. Flat plate Flat plates can be constructed as one-way or two-way slabs and it is directly supported by columns or walls. The main feature of the flat plate floor is a uniform thickness with a flat soffit which requires only simple formwork and is easy to construct. The floor allows great flexibility for locating horizontal services above a suspended ceiling or in a bulkhead.
  9. Flat plate Applications Residential & Office buildings (high rise, low rise) Parking, Hotels Economic span range. 5 - 8m (Conventional) 6 - 10m (Post-tensioned) Economic slab thickness range: 230 - 350mm Live loads: 3 - 5KN/m2 Advantages Typically has the lowest floor to floor cycle time of the cast in-situ options. No beams - simplifying under-floor services. Minimum structural depth and reduced floor-to-floor height. Disadvantages Long-term deflection ma be a controlling factYor. May not be suitable for heavy loads. High concentration of reinforcement around the columns in order to ensure the slab has adequate punching shear capacity.
  10. Flat slab This is typically a reinforced slab supported directly by columns or caps, without the use of beams. Drop panels, formed by thickening the bottom of the slab around columns, increase shear capacity and the stiffness of the slab, allowing thinner slabs to be used. A flat slab with prestressing tendons (PT) results in longer spans and thinner slabs.
  11. Flat slab Applications Residential & Office buildings (high rise, low rise) Parking, Hotels Economic span range. 6 - 9m (Conventional) 7 - 11m (Post-tensioned) Economic slab thickness range: 210 - 330mm Live loads: 4 - 7KN/m2 Advantages More efficient than flat plate, typically with lower stress concentration at column locations. Slabs are generally thinner than flat plates. Absence of beams allows lower storey heights. Flexibility of partition location and horizontal service distribution. Disadvantages More complicated formwork which can increase floor to floor cycle time. Drop panels require a higher level of coordination with the services in the ceiling space than flat plates and may not be architecturally acceptable for areas where suspended ceiling is not envisaged.
  12. Two way slab Two-way slabs are supported on all sides. More stiffness of the slabs, producing low deflection. Economical flooring system, costs less than flat plates or flat slabs. In other words, when the loads or spans or both become quite large, the slab thickness and column sizes required for flat plates or flat slabs are of large magnitude that it is more economical to use two-way slabs with beams, despite the higher form work costs.
  13. Two way slab Applications Super markets Residential & Office buildings (high rise, low rise) Warehouses, Parking Economic span range. 9 - 12m Economic slab thickness range: 210 - 300mm Live loads: 3 - 6KN/m2 Advantages Economical for longer spans and high loads Less column sizes Disadvantages Presence of beams may require greater storey height. Requires a regular column layout Slow floor cycle Flexibility of partition location and horizontal service distribution
  14. Waffle Slab It is a type of RCC slab that contains square grids with deep Voids and thus reducing the deadweight. Slab thickness is governed by deflection, punching shear around columns and shear in ribs. Waffle slab construction process includes fixing forms, placement of pods on shuttering, installation of reinforcement between pods, installation of steel mesh on top of pods, and pouring of concrete.
  15. Waffle slab Applications Roofing, Carparks Office buildings Economic span range: 8- 14m Economic slab thickness range: 85 - 100mm Overa// depth: 300 - 600mm Live loads: 4 - 7KN/m2 Advantages Slab soffit profile may be expressed architecturally. Longer spans possible. Lightweight in nature. Disadvantages Higher formwork costs than for other slab systems. Slightly greater floor thicknesses. Slower floor-to-floor cycle. Requires square or rectangular column/grid arrangements.
  16. Hollow core slab It is a type of precast slab through which cores are run. Not only do these cores decline slab self-weight and increase structural efficiency but also act as service ducts. Pre-cast floor systems will typically consist of factory pre- tensioned pre-cast planks, tied together with a structural topping to provide a robust and efficient floor system to resist the imposed vertical and horizontal loading. The most commonly used pre-cast slabs in the UAE market are the pre-stressed, pre-cast hollow core planks.
  17. Hollow core slab Applications Residential, Office buildings (Low rise) Educational Parking structures Warehouses Economic span range: 6 - 16m Typical plank thickness range: 150 - 400mm Live loads: 2.5 KN/m2 for 16m span Advantages Heavy load carrying capacity. Exceptional fire resistance. Lower self-weight. Superior acoustic insulation and thermal properties. Rapid speed of erection. Factory made with highest quality control. Disadvantages Irregular shaped hollow cores are difficult to cast and expensive. The segments cannot be cut on site, must be carefully designed.
  18. Hardy slab It is constructed using hardy bricks (hollow concrete blocks) which significantly decline the amount of concrete and eventually the slab's self-weight. The construction of hardy slab involves formwork installation, hardy block placement, placement of reinforcement into gaps between blocks, placement of steel mesh on the blocks, and finally pouring of concrete. Dimensions of Hardy brick is 40cm x 20cm x 20cm.
  19. Hardy slab Applications Constructed at locations with high temperatures, generally seen in Dubai and China. Hospitals, office and residential buildings. Economic span range. more than 5m Economic slab thickness range: around 270mm Live loads: moderate Advantages Improved insulation for sound and heat. Reducing slab weight by reducing the amount of concrete below neutral axis. Ease of construction, especially when all beams are hidden beams. Disadvantages If not properly handled, the hollow core ribbed brick units may be damaged during transport. Not economic for small spans. Difficult to repair and strengthen
  20. Bubble deck slab kg of recycled plastic replaces zoo kg of concrete, low cost and sustainable
  21. Bubble deck slab It is constructed by placing plastic bubbles which are prefabricated and the reinforcement is then placed between and over plastic bubbles and finally, fresh concrete is poured Consequently, not only does it decline the total cost of construction but is also environmentally friendly since it reduces amount of concrete. The plastic bubbles replace the ineffective concrete at the center of the slab.
  22. Bubble deck slab Applications Residential, office buildings Utility and industrial buildings Schools, parking, hospitals, laboratories factories. Economic span range. 5 - 24m Economic slab thickness range: 230 - 700mm Advantages Less weight, more strength. Larger spans can be provided, fewer columns needed. No beams or ribs under the ceiling are required. Disadvantages Skilled labor required. Thickness of slab is limited. Punching shear capacity is low. Conventional slab is less deflect than bubble deck slab. Load carrying capacity less than conventional slab.
  23. Precast slab Precast concrete slabs are casted and cured in manufacturing plants, and then delivered to the construction site to be erected. Double-T's are most commonly used precast slabs for long spans. They are relatively lightweight with a high load capacity. The units are pre-stressed and can be left exposed. Units are intended for up to two hours fire resistance.
  24. Precast slab Applications Carparks. Office buildings. Warehouses, roofing, bridges and industrial buildings. Economic span range. 8 - 20m Typical double-T depth range : 500-1200mm Advantages Speed of construction. Longer spans. Elimination of formwork or propping. Preparation of slabs in manufacturing plants increases efficiency and higher quality control. Disadvantages Crane may prove critical.
  25. Composite slab Composite slabs consists of profiled steel decking with an in-situ RC topping. The steel decking acts as a permanent formwork and also provides sufficient shear bond with the concrete. The decking acts as working area during the construction phase, and it also acts as external reinforcement during service life of the slab.
  26. Composite slab Applications Residential, Office, Educational buildings (Low, high rise) Hospitals, Cinemas & Theatres, Hotels. Economic span range. 2.5 - 4m Stee/ decking of thickness: 50-60mm Advantages Speed of construction. Elimination of formwork. Safe method of construction. Saving in weight. Shallower depth. Sustainability. Highly efficient, lightweight design. Disadvantages Limited spans and capacities. Propping may be required. Fire proofing.
  27. References https://civiIread.com/16-different-types-sIabs-construction/#2_Two_Way_SIab https://civilshastra.com/2019/04/12/types-of-sIabs/ https://bsbg roup.com/blog/one-way-concrete-flooring-system https://bsbg roup.com/blog/guidelines-for-two-way-concrete-flooring-system https://theconstructor.org/practical-guide/concrete-slab-construction-cost/28153/
  28. THANKYOU Vamsi Putta AMITY UNIVERSITY OueAi