Flat slab suitable span 20 to 30 ft with ll 80 150 psf advantages low cost formwork exposed flat ceilings fast disadvantages need more formwork for capital and panels waffle slab suitable span 30 to 48 ft with ll 80 150 psf advantages carries heavy loads attractive exposed ceilings fast disadvantages formwork with panels is expensive. Waffle slab purpose, uses, advantages and disadvantages. The cost function represents the cost of concrete, steel, and formwork for the slab. Cost optimization of a composite floor system, oneway waffle slab. Traditional construction technique of waffle slab system includes the storage of materials, establishment of supports and formwork assembly in situ for worker convenience. Ribbed slabs are made up of wide band beams running between columns with narrow ribs spanning the. This form of construction is not very common because of the formwork costs and the low fire rating.
Pa location 814 4383959 ks location 814 4381147 custom quote. Ribbed or waffle slab is a slab system which consists of series of parallel reinforced concrete t beams framing into reinforced concrete girders. Ribbed and waffle slabs types, advantages, disadvantages. The waffle slab is also sometimes termed as ribbed slab system but you would find it interesting to know that ribbed and waffle slab are somehow two different things. Waffle slab construction allows a considerable reduction in dead load as compared to conventional flat slab construction since the slab thickness can be minimized due to the short span between the joists.
Manual for the design of concrete and reinforced concrete structures of heavy. Whereas, table 2 shows the results of the slab provided with 5 ribs along each of the two spans, table 3 gives results for slab with 7 ribs. A simplified drawing of a flat slab plate or waffle slab structure adapted from. Waffle slab foundation features and construction details. The system was designed to decrease the weight of traditional fullconcrete. Waffle slab or ribbed slab construction procedure and advantages. Direct design method is used for the structural analysi s and design of slabs. This is achieved by placing clay pots or other shapes on the formwork before casting of the concrete. A wide variety of used slab shoring formwork in concrete for sale options are available to you. The speed of construction for such slab is faster compared to conventional slab. In this 3d animation, youll see six simple steps to build a wafflemat foundation, from clearing the pad to setting the individual waffleboxes, to.
Jan 10, 2016 what is flat grid slab waffle slab system. The cost function represents the cost of concrete, steel reinforcement and formwork. Www waffle slab formwork records square circle formwork, wtf formwork, variant factory ltd, saligny construct, etc. The waffle slab foundation area is marked and leveled on the ground. Waffle slabs provide stiffer and lighter slabs than an equivalent flat slab. Twoway joist concrete slab floor waffle slab system. Results for slab with 9 ribs in each direction are given in table 4. Feb 15, 2012 in this 3d animation, youll see six simple steps to build a wafflemat foundation, from clearing the pad to setting the individual waffleboxes, to pouring the concrete and removing the form boards. Cost optimization of a composite floor system, oneway waffle. This type of reinforcement is common on concrete, wood and metal construction.
The first is awaffle slab with solid heads, and the second is a waffle slab with band beams along columncenterlines. Skydome modular formwork system for reinforced concrete slabs. Recub horizontal formwork enables twodirectional grid slabs with rib alignment. This lesson explain design considerations for horizontal concrete formwork. Waffle slab or ribbed slab is a structural component which is plain on its top and contains grid like system on its bottom surface. Numerical and experimental study of a waffle slab designed to serve. For design purpose, waffle slabs are considered as flat slabs with solid head acting asdrop. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. The construction of waffle slabs can be done by three ways as follows. Manufactured from filcor with an external polypropylene skin, each waffle mould is made to suit the individual requirements of the project and can.
A slab formwork to build biaxial waffle slabs in residential and commercial buildings, the system was designed to decrease the weight of traditional fullconcrete slabs the domeshaped forms create a matrix of voids surrounded by orthogonal ribbed slabs structure, creating a twoway configuration very suitable for largespanning slabs the selfweight of concrete slab formed with skydome is. This paper deals with the problem of optimum design of reinforced concrete twoway ribbed waffle slabs using genetic algorithms. Waffle moulds are a reusable formwork system for constructing twoway spanning ribbed concrete floors, which can achieve greater spans and use less concrete when compared to traditional flat slabs. The formwork was built with plastic formwork developed for waffle slabs by ulma formas e escoramentos ltda. Thecost function represented the cost of concrete, steel, and formwork for the slab. This modular formwork is mainly oriented towards nonresidential construction and is ideal for car park construction. Because there are joists in both directions, this floor system is the strongest and will have the least deflection. Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. When one says ribbed slab it is actually a one way spanning system with ribs where as in waffle slab the joists form a two way system.
Consequently, reinforcement is cut and tied followed by the insertion of opening steel cylinder into the reinforcement. According to tradeline, waffle slab construction is defined as a building system using concrete waffle slab floors supported by columns. The steps involved in the construction of the waffle slab foundation are. Waffle pod slabs are even stronger than conventional slabs, as the slab is poured as one piece a conventional slab has the footings and slab poured separately they are equivalent in terms of stiffness and flexibility both waffle pod slabs and conventional slabs are 85 mm to 110 mm thick concrete, as specified by the engineer. The waffle slab is a monolithicpoured concrete slab with a flat top surface and an undersurface made of a rectangular grid of deep concrete beams running at right angles. Direct design method is used for the structural analysis and design of slabs. About 72% of these are formwork, 2% are scaffoldings. Waffle slab is good against shrinkage and it is lower than stiffened rafts and footing slabs. Coffered slabs as a perspective type of the reinforced concrete. Calculations for waffle pod slab requirements for plan take off and estimating.
Along the line, formwork is set up to employ waffle arrangement which is then followed by the concreting process. Online index of waffle slab formwork companies that are active in the commercial construction industry. Edge formwork makes the sides of the slab and polystyrene pods create the formed voids between the strip footings. Slab formwork modular and beam formwork, waffle and aluminium forms for concrete slab construction. A waffle pod slab is constructed entirely above the ground by pouring concrete over a grid of polystyrene blocks known as void forms. Waffle formwork for grid slabs recub ulma construction. Features of the grid slab they are used on flat sites. Formwork tools required in the construction of waffle slab are. Dome slab is a system of reusable formwork for the construction of bidirectional waffle slabs directly onsite. Waffle form is a special type of formwork particularly for the casting of floor slab with beam ribs running through it in close grid. A slab formwork to build biaxial waffle slabs in residential and commercial buildings, the system was designed to decrease the weight of traditional fullconcrete slabs the domeshaped forms create a matrix of voids surrounded by orthogonal ribbed slabs structure, creating a twoway configuration very suitable for largespanning slabs. Traditional technique since hightech plants occupy a very large area, each floor has a large span and the lengthwidth of the waffle slab may reach 100 m. Composite floor system oneway waffle slab concrete slab formwork. Charleson, seismic design for architects, architectural press 2008, p.
The design variables are taken as the effective depth of the slab. The critical sections shall be located with respect to. Architectural floor plan, engineer plan and slab detail or soil test report. Waffle slab twoway pan joist twoway joist slab, also called a waffle slab. The speed of construction for such slab is faster compared to. Optimum dimension of posttension concrete waffle slabs.
Dec 01, 2016 features of the grid slab they are used on flat sites. Sheathings are in the form of sheets of plywood, and joists, stringers and. Recub is a horizontal formwork for the construction of bidirectional reticular slabs with reusable box moulds waffles with the same standard items, slabs with different rib widths can be built, according to the fire protection standard 12, 16 and 20 cm. Waffle slab or ribbed slab construction procedure and. The top of ribbed slab is normally thin and the bottom grid lines are generally ribs which are laid perpendicular to each other with equal depth. Reusable formwork for reinforced slabs skydome from geoplast. Waffle pod slab a waffle pod slab is constructed entirely above the ground by pouring concrete over a grid of polystyrene blocks known as void forms. Dome slab concrete forms systems leaders in formwork. Abstract in this paper, the optimum design of some floor systems, including composite. They are either oneway spanning systems known as ribbed slab or a twoway ribbed system known as a waffle slab. Pdf optimum design of reinforced concrete waffle slabs. A waffle slab usually is the most economical type for long spans, although formwork may be more expensive than for a solid slab. They provide a very good form of construction where slab vibration is an issue, such as laboratories and hospitals. Waffle pod slabs are generally suitable for sites with less reactive soil and use about 30% less concrete and 20% less steel than a raft or ground level slab waffle pod slabs are only suitable for very flat.
The lateral loads are independently resisted by shear walls. The spacing between the ribs should be in general 2030 inch. Ccl posttensioned slab systems can be integrated into any type of slab, including flat, ribbed or waffle slabs, which may include drop caps, drop panels or band beams to produce optimal configurations. Skydome by geoplast is a modular formwork system in abs plastic created to build biaxial waffle slabs completely onsite.
Reinforced concrete waffle slabs have become a common option for. Preliminary twoway joist slab waffle slab for slabs with changes in thickness and subjected to bending in two directions, it is necessary to check shear at multiple sections as defined in the aci 31814. Coffered slab is a ribbed structure with reinforced ribs in the lower zone which have. In this paper, the optimum design of some floor systems, including composite slab, one way waffle slab, and the formwork of a concrete slab, is performed via recently developed metaheuristic algorithms, namely, the charged system search css and the enhanced charged system search ecss. The formwork of concrete slabs typically includes sheathings, joists, stringers and shores. Formwork for ribbed concrete floors waffle moulds two way. Optimum design of reinforced concrete waffle slabs alaa c. Design of waffle slab without beams by direct design method 32 32 32 c 1 c 2 c 3 c 4 2 c 5 c 6 c 7 c 8 32 s ss 22 3. Twoway joist concrete slab floor waffle slab system analysis and design design the concrete floor slab system shown below for an intermediate floor with partition weight of 50 psf, and unfactored live load of 100 psf.
Diagram showing examples of flat plate and flat slabs. A waffle slab is a type of building material that has twodirectional reinforcement on the outside of the material, giving it the shape of the pockets on a waffle. Its typically used when stiffness is important or if there are abnormally heavy loads. Waffle slab requires only 70% of concrete and 80 % of steel from the concrete and steel used for stiffened raft. Waffle pod slabs are generally suitable for sites with less reactive soil and use about 30% less concrete and 20% less steel than a raft or ground level slab waffle pod slabs are only suitable. A waffle slab can be made in different ways but generic forms are needed to give the waffle shape to the slab. Skydome modular formwork system for reinforced concrete. In the traditional technique, the materials are stored onsite first and supports are established for worker convenience. The slab is the flange of the beam and the extended part is the web. Waffle slab or ribbed slab is a structural component which is plain on its top and contains grid like system on its.
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