The waffle pod slab system is a better way of building concrete slabs for new homes, extensions or commercial industrial buildings. Numerical and experimental study of a real scale waffle slab. Pdf analysis of two way ribbed and waffle slabs with hidden beams. A waffle slab foundation, also called a ribbed slab foundation, is an aboveground type of foundation used to provide loadbearing capacity in expansive, rocky or hydro collapsible soils. Powered by the equivalent frame method of analysis and design per latest american aci 31814 and canadian csa a23.
There are many methods that are used to analyze twoway slabs and the precision of these methods vary depending. Twoway joist concrete slab floor waffle slab system. For most conventional slabongrade design, the steel does not have to be discontinuous at the. Concrete expands and shrinks with changes in moisture and temperature. The stem wall supports the building loads and in turn is supported directly by the soil or a footing. Each was examined through different slab aspect rations r of 1, 1. The comparison is done on the basis of flexural parameters such as bending moments and shear forces obtained from various methods. The foundation is created by placing a series of singleuse plastic forms set directly on grade to create a grid of ribs, and then monolithically pouring a post tensioned, rebar or fiber reinforced concrete. This paper presents an historical and analytical evaluation of the ribbed floor slab systems developed by. For slabongrade construction in sdcs d1 and d2, when the conditions described above require an interior braced wall line to have a foundation, the foundation depth along that interior wall must be at least 18 inches below the top of the slab as shown in figure 3. Optimum design of reinforced concrete waffle slabs alaa c. Dynamic features of precast waffle slabs in cleanroom. Evaluation of dynamic behavior of waffle slab to gym center. Where concrete is relatively expensive, spans are generous, and it is not critical to select the smallest floor thickness, a posttensioned waffle slab construction is.
The cost function represents the cost of concrete, steel, and formwork for the slab. In this paper, the optimum design of reinforced concrete waffle slabs is sought using the simple genetic algorithm. Act,ext denotes the area of the tensile concrete external to the links. Pdf this paper focuses on analysis of twoway ribbed and waffle.
See more ideas about waffle ceiling, architecture details and architecture design. Analysis and design of waffle slabs architectural elements civil. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. To compare the results obtained for a waffle slab with openings to a waffle slab without openings and find out the percentage reduction in the strength of the slab. Feasibility of structural design of members has been ensured under the provision of is. Flat slab system is an important division of concrete floor system. Manual for design and detailing of reinforced concrete to the september 20 code of practice for structural use of concrete 20 2. A civil engineer must know all the aspects regarding the flat floor system. Waffle raft slab this is the strongest form of standard slab. A mockup precast waffle slab building has been tested with an instrumented hammer fig. For longerribbed slabs, the restraint due to the beams should be taken into. Analysis and design of waffle slabs free download as pdf file.
Calculations for waffle pod slab requirements for plan take off and estimating. Waffle pod slabs vs raft slabs simon anderson consultants. A grid slab is a type of building material that has two directional reinforcement on the outside of the material, giving it the shape of the pockets on a waffle. Direct design method is used for the structural analysis and design of slabs. The simplest and most economical floor system is the flat plate, where a plain floor slab about 20.
Analytical study on strengthening of waffle slab with. Dynamic features of precast waffle slabs in cleanroom design ning tang, chris wu, blong xiong, michael gendreau, and hal amick. The shaded section depicts the area of the slab only 100mm thick whilst the lighter areas are beams typically 400mm deep. Bending will take place in the two directions in a dishlike form. Waffle slabs are a reinforced concrete footing and slab system constructed on the ground. Irregular cracks are unsightly and difficult to maintain but generally do not affect the integrity of concrete. The structural modeling used in most commercially available software, where stems are considered as disjointed from the topping slab does not deliver the advantages associated with waffleslab slab construction. The analysis by stiffness method is carried out using, application. Twoway joist concrete slab floor waffle slab system analysis and. Waffle slabs are quickly gaining in popularity in construction projects as they can be shipped to site in different modes including. The whole footing and slab system is constructed on top of the ground. In fact, a lot of builders refer to this type of slab as a floating slab.
The overall tendency is to shrink and this can cause cracking at an early age. One hundred and thirty real models were tested for the sake of comparing the traditional oneway composite slab and waffle composite slab in both construction and composite stages. Manual for highways and railways issued by the highways department. Concrete waffle slabs may be purchased and shipped to the construction site as prefabricated the most expensive type or precast sections, or poured onsite. Ribraft floors foundations concrete flooring nz firth.
Architectural floor plan, engineer plan and slab detail or soil test report. The designing team, structural engineers and architects, works together to find the best possible solution that will fulfill the owners whishes. Analytical study on strengthening of waffle slab with opening using cfrp sheets and stiffening ribs jeenu mary victor1, soni syed2 1m. Twoway joist concrete slab floor waffle slab system analysis and design. The prefabricated waffle slab usually costs higher than the other two options.
The behaviour and response of flat slab and post tensioned flat slab during earthquake is an important aspect which needs to be explored. The static analysis of waffle slabs aims to determine the range and distribution of displacements and stresses, and ultimate load carrying capacity of the structure, considering a nonlinear behaviour. Pdf analysis of two way ribbed and waffle slabs with. Avinash deshapande kurdi suhaib r16mce07 rahil aziz r16mce09. File type cad dwg plan reinforcement drawing format zip file containing. Grid waffle slab compiled by, submitted to, husen khorajiya r16mce06 prof. Nowadays, waffle slabs are a demand for structural designers, as a consequence of architectural design evolution. Upon completion of the waffle slab house, the ground around the slab is built up by the builder to reduce the height of the slab above the surrounding ground. Because the waffle slab is constructed on the ground, when the waffle slab is finished it sits about 400mm higher than the surrounding ground. 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. Manual for design and detailing of reinforced concrete to. 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. A slab on grade with an independent stem wall is a concrete floor supported by the soil independently of the rest of the building. They are either oneway spanning systems known as ribbed slab or a twoway ribbed system known as a waffle slab.
If prefab concrete is not in the budget, consider purchasing casts for the concrete waffle slabs. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. Code of practice for structural use of concrete 20 buildings. There are various approaches available for analyzing the waffle slab system. Waffle slabs moulds fg 900 moulds fg 900 moulds are used on the construction of waffle slabs with bidirectional orthogonal ribs, also called fungiform slabs, producing modules with 900 mm distance between the ribs axis. There are two common ways to build a slab for a house. The historical discussion includes the evolution of the floor slab from a nonstructural element to an inspired structural system, culminating in nervis patented. Optimum design of reinforced concrete waffle slabs. Placing the steel any lower than this limit could, however, adversely affect the performance of the slab. The waffle slab has been considered as monolithically connected to band beams. There are three different types of fg 900 moulds, with heights of 225 mm, 325 mm and 425 mm. Design of reinforced concrete structures ii twoway slabs. They consist of a perimeter footing edge beam and a series of narrow internal beams strip footings at one metre nominal centres running each way.
In this paper, the optimum design of reinforced concrete waffle slabs is so ught using the simple genetic algorithm. This form of construction is not very common because of the formwork costs and the low fire rating. Design of reinforced concrete structures ii twoway slabs 1 1. Technical note 5 slab does not adequately represent the mechanical properties of a stemmed floor system for analysis and design. Flat slab analysis, design and detailing pdf civil. In present study some of these approaches are studied and compared with each other. Slabs are usually used in floor and roof construction. They provide a very good form of construction where slab vibration is an issue, such as laboratories and hospitals. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. This paper focuses on analysis of twoway ribbed and waffle slabs with hidden beams. Analysis of steel concrete composite waffle slab with opening. Waffle slab plan view reinforcement detail concrete structure. The waffle pod slab systems allows more accurate specification of concrete quantities, reduces waste and provides a substantial boost to building site efficiency.
Pdf optimum design of reinforced concrete waffle slabs. Design of waffle slab without beams by direct design method. Solid, waffle and banded flat slab systems were analysed. The lateral loads are independently resisted by shear walls. With an interesting name, it can make you think that the slab floats like a raft. 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. Ribraft floors are an innovative method of raft concrete floor construction is quick and efficient to lay, it offers excellent insulation benefits and is seismically. 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.
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