A novel type of prefabricated steeltruss waffle slab has been proposed in this article, and compared with traditional waffle slab, there are several typical characteristics of this floor system. It consists of a perimeter footing the edge beam and a series of narrow internal beams the strip footings at one metre nominal centres running each way. Working from one corner, lay out the waffle pods and spacer in a grid pattern within the formwork, as specified in the footing design. Slab onground is the most common and has two variants. This will stop any absorption of moisture into your slab. It is used where vibration is an issue and where large span slabs are to be constructed i. Ribbing beams reinforcement, slab top wire mesh, waffles dimensioning, voids width and depth, slab thickness. It didnt include the thermal performance of floor slab systems with polystyrene pods, but recent modelling means this data is now available. Still no winner in the raft slab vs waffle slab shoot out. A the slab thickness on both a waffle pod and a conventional slab is 85110mm. Residential footing design policy for all of its residential footing designs. In this paper, the optimum design of reinforced concrete waffle slabs is so ught using the simple genetic algorithm. Analysis of steel concrete composite waffle slab with opening.
There are two common ways to build a slab for a house. A waffle slab can be made in different ways but generic forms are needed to give the waffle shape to the slab. There simply isnt enough weight in the slab and footings to resist the high forces. Developed in south australia in the late 1980s and also known as a waffle pod, it consists of a stiffened raft with closely spaced ribs constructed on the ground with a slab. Analysis and design of the slab similar to design of simply supported beam as indicate in the previous chapter. Think of a waffle pod as a raft lying flat above your soil. Twoway joist waffle slab design approach and methodology twoway joist slab often called twoway ribbed slab or waffle slab is an economical floor system when the spans are long andor loads are high. The h class slab shown below uses 300 mm high pods the pods are 1090x1090 mm in area. This makes the matrix approx 20% concrete and 80% polystyrene.
The wafflemat system uses forms to create a waffle slab with a set geometry, with ribs typically spaced at 38 on center. Architectural floor plan, engineer plan and slab detail or soil test report. The waffle pod slab system is a better way of building concrete slabs for new homes, extensions or commercial industrial buildings. The solution involved residential house slab technology waffle pods, and we believe this was the first. The design of waffle slab is done in such manner so as to achieve better load distribution. Feasibility of structural design of members has been ensured under the provision of is.
Slabs that have span greater than 16m can make use of a waffle slab design. The house was constructed on a waffle pod raft slab designed by mcfarlane and partners pty ltd mcfarlane. The ribs are reinforced with steel to resist flexural tensile stresses. A waffle slab is a type of reinforced concrete footing and slab system usually constructed at ground level. Waffle pod slabs vs raft slabs simon anderson consultants. Waffle slab purpose, uses, advantages and disadvantages.
A twoway floor system consisting of a reinforced concrete slab poured with integral ribs in two directions beneath it. Waffle pod raft from the time of first european settlement in 1836 until about 1950, house footings. Waffle raft slabs are suited to lightly and moderately reactive clay sites in particular, because. The waffle slab has been considered as monolithically connected to band beams. Furthermore, waffle pod engineers try to design the waffle pod slab without considering the uplift loads from the roof framing. Can the concrete crack on a waffle pod slab and show cracking in the garage.
Depending on theen gineers design criteria unfortunately, with either one you can expect there to sometimes be. Pti recommendations for ribbed slab design include spacing limitations for. 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. Calculations showed that the wafflemat system is equivalent to a. This waffled feature in slabs will help to take up heavy loads. With an interesting name, it can make you think that the slab floats like a raft. The lateral loads are independently resisted by shear walls. The pods are the formwork for the waffle ribs and as such are not structural in the long term.
In fact, a lot of builders refer to this type of slab as a floating 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. Waffle slabs home builders in melbourne supa group. Pdf analysis and design of waffle slab with different. Actually the introduction of support hoists made waffle slab very stiff. Drop reinforcement bars into position on the spacers in between the waffle pods. This technical note offers several views of posttensioned. The waffle pod slab systems allows more accurate specification of concrete quantities, reduces waste and provides a substantial boost to building site efficiency. Drainage under a slab shall be avoided where practicable. Lay top mesh, following design specifications and fasten where.
Calculations for waffle pod slab requirements for plan take off and estimating. The waffle holes are formed by square shaped polystyrene pods. Optimum design of reinforced concrete waffle slabs alaa c. Ribraft floors foundations concrete flooring nz firth. How waffle pod slabs offer better cost and time efficiencies over traditional concrete slabs. Foamex diamond pods are a strong yet lightweight polystyrene waffle pod void former system for concrete slabs. Twoway joist concrete slab floor waffle slab system. To compare the results obtained for a waffle slab with altered span of i beams with the validation or base model and find out the percentage variation in the strength of the slab. Twoway joist waffle slab design approach and methodology. Fiberglass waffles slab forms mfg construction and water. Slab cracking waffle slab vs conventional raft slab. We can provide pricing for single house slabs, to multiple residential dwellings with accessories for a detailed pricing takeoff, please s end through your information, drawings and requirements for a 100%. The popularity of waffle rafts persuaded the australian.
Causeway repair, waffle pod slabs, rural road culverts. Eps pods and waffle raft slabs blog expanded polystyrene. This paper deals with the problem of optimum design of reinforced concrete twoway ribbed waffle slabs using genetic algorithms. A waffle raft uses polystyrene void formers or waffle pods to form up the edge beams and internal beams and give the slab the required stiffness, without using excessive amounts of concrete. Depending on theen gineers design criteria unfortunately, with either one you can expect there to sometimes be small surface cracks less than 3mm. Furthermore, waffle pod engineers try to design the waffle pod slab without. Waffle slabs are most suitable for construction of slabs with long span. Pdf optimum design of reinforced concrete waffle slabs. They are designed to be a raft foundation type system, prepared with minimal. Defination according to engineer florentino regalado1, the waffle slab belongs to the family of reinforced concrete slabs that are nonhomogeneous, lightened, and reinforced in two orthogonal directions, forming a ribbed plate. So, to answer your calls, we have established this waffle raft blog, which will be updated in weekly instalments. Reinforced concrete waffle slabs have become a common option for designers due to a need. Thermally, a normal slab with double glazing should be better, particularly if the slab. Beware waffle slabs structural engineers cornell engineers.
The system has a waffle like pattern when viewed from below. Waffle pod slab construction has a number of benefits including speed of production and huge cost savings. Note that the polystyrene is not structural, it is simply a void former. Keep in mind that the waffle pod diagram must be inverted when entering data. Waffle slabs are a reinforced concrete footing and slab system. These cracks dont follow the mesh and sometimes start in internal corners. This paper outlines the journey of the greater taree city council design team in dealing with a small concrete causeway on belbora creek road, in rural nsw. Waffle slab or ribbed slab is a structural component which is plain on its top and contains grid like system on its bottom. One major concern of their utilization in cleanroom design is whether the dynamic performance of the slabs would meet the desired vibration criteria. Waffle slab or ribbed slab construction procedure and advantages.
Pdf numerical and experimental study of a waffle slab designed. The material properties as well as the dimensions of the slab and i beams were taken from the journal11. The building and site drainage design and height of the floor level above finished ground. Waffle slab or ribbed slab construction procedure and. Welcome to epsas blog about eps pods and waffle raft slabs. Floor slabs with polystyrene pods the branz house insulation guide details the expected thermal performance for common construction options. 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 7 c 9 c 10 c 11 c 12 32 8 11 b 1210 bb c c 14 c 15 c 16 16. Waffle slab laid out and ready for the concrete to be poured.
Promotors of waffle slabs put forward a case that this type of slab is cheaper, there are less site works required, hence less labour and contracting costs, and that there is better insulative properties through the ground to the floor of the house. Manual for the design of reinforced concrete building structures. By ian coxsmith, branz building physicist design right t. The only type of cracking that might be different between waffle. The drop panel depth for twoway joist waffle slab is set equal to the rib depth.
Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need. Comparative study of waffle slabs with flat slabs and. I think generally waffle pod slabs are likely to be cheaper than a conventional slab, however there have been some instances where waffle pod slabs have had subsidence problems which you should probably check out. Comparing with traditional castinplace waffle slabs, precast waffle slabs have the intrinsic merits of better quality control, shorter construction time, and thus a reduced construction cost. We know many people, be it home owners, builders or doityourselfers are interested in keeping uptodate with innovative materials and methods. Eps waffle pod prices are calculated per pod and quantity required. Dynamic features of precast waffle slabs in cleanroom.
Because of the ribs and double reinforcement, it is more stable and recommended for larger span slabs or foundations. Waffle pod slabs are less affected by rain delay than conventional slabs waffle pod slabs provide better insulation from. A costly case of slab heave doyles construction lawyers. Design the concrete floor slab system shown below for an. Waffle pod slabs are even stronger than conventional slabs, as the slab is poured as one piece. Foundation types waffle pod waffle pod foundation system is the most common foundation used for residential structures. A limit state methodology for ultimate strength design of residential slabs is recommended as a costeffective way to mitigate the slab heave problem with waffle rafts. This innovative method of concrete floor construction sits on the ground not in the ground making it seismically strong. Designed specifically for residential, commercial and industrial markets, foamex diamond pods provide under slab insulation and support, while reducing the effects of soil movement, and lowering the amount of concrete required for a build.
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