Dec 01, 2016 iconic landmarks using grid slabs chattrapati shivaji terminal, india it is recognized for its innovative column design which also consists waffle design. Analysis and design of waff le slab with different boundary. This is necessary to get a better understanding of the problem. Dynamic features of precast waffle slabs in cleanroom design. For ribs with depth 152mm, the domes of dimension 762mm can be used. In fact, there is no deemed to comply raft footing design for class e sites either the footing and slab system for a class e site must be designed by a relevantly qualified engineer. To compare these systems, a typical interior panel was selected from the northeast wing, which is highlighted in figure 1 on page 7. Bending will take place in the two directions in a dishlike form. Analysis and design of waff le slab with different. Twoway joist waffle slab design approach and methodology.
Slabs that have span greater than 16m can make use of a waffle slab design. Each was examined through different slab aspect rations r of 1, 1. Metropol parasol, italy it is the worlds largest wooden structure which is made up of waffle system. The wire reinforcing institute recommends the use of the subgrade drag theory for slabs up to 150 feet in length. The minimum slab thickness allowed for joist slabs is onetwelfth the clear rib spacing or 1. They may be supported on two opposite sides only fig. In general, it is seen that in solid slab a portion of concrete below the neutral axis remains ineffective. A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft.
Pdf design of waffle slab mamoun zoulghina academia. They provide a very good form of construction where slab vibration is an issue, such as laboratories and hospitals. Design of beam and slab sections for flexure, shear and torsion. A waffle slab foundation, also termed as ribbed slab foundation, is a structure that is plain at the top and has a gridlike system called the ribs at the bottom. This waffled feature in slabs will help to take up heavy loads. See more ideas about ceiling design, architecture design, interior architecture.
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. 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. Oneway and twoway slabs university of asia pacific. Aci 360, design of slabsongrade, refers to this as a type b slab. They are either oneway spanning systems known as ribbed slab or a twoway ribbed system known as a waffle slab. Design of waffle slab without beams by direct design method 32 32 32 c 1 c 2 c 3 c 4 2 c. There are 3 basic designs for concrete slabs that improve the strengthtoweight ratio. The relative position of one with respect to the other provides the stiffness characteristic of a ribbed slab. Waffle slab or ribbed slab construction procedure and.
Twoway joist concrete slab floor waffle slab system. Technical note 4 2 structural modeling design considerations the principal advantage of a waffle slab or joist constriction is the composite interaction of the stem and the topping slab. A waffle slab gives a substance significantly more structural stability without using a lot of additional material. The waffle slab has been considered as monolithically connected to band beams. For 1m slab width, moment, shear force, oneway continuous slab for continuous slab, moment and shear force can be obtained from table 3. Optimum design of reinforced concrete waffle slabs alaa c. Ce 433, fall 2006 slab design example 1 6 design a oneway slab for an exterior bay of a multistory office building using the information specified below.
The wafflemat system uses forms to create a waffle slab with a set geometry, with ribs typically spaced at 38 on center. There is no deemed to comply design for waffle slabs for extremely reactive sites class e sites. Waffle slab structural engineering general discussion. The materials for construction are grade c30 concrete and grade 500 reinforcement.
Design of twoway floor slab system comparison of oneway and. This modular formwork is mainly oriented towards nonresidential construction and is ideal for car park construction. Analysis and design of waffle slabs architectural elements civil. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. However, damaged structures had to be repaired as soon as possible after the earthquake to respond to the demands of the inhabitants of the buildings in question. Dynamic features of precast waffle slabs in cleanroom. Experimental data on performance of rehabilitated systems was needed. After this publication, it was subsequently adopted by the uniform building. Pdf this paper deals with the problem of optimum design of reinforced concrete twoway ribbed waffle slabs using genetic algorithms. Ibrahim2 used mathematical programming techniques to minimize the cost of reinforced concrete tbeam floor. Calculations showed that the wafflemat system is equivalent to a posttensioned slab on grade that complies with pti requirements, with ribs spaced at 6 0 on center. Also, you need to provide cracking moi icr for deflection purposes. Oneway simply supported slab analysis and design of the slab similar to design of simply supported beam as indicate in the previous chapter. This form of construction is not very common because of the formwork costs and the low fire rating.
Twoway joist concrete slab floor waffle slab system analysis and design. Each combines a flat top surface with a modulated underside in a corrugated, ribbed or waffle design. Jul 02, 2010 lecture series on design of reinforced concrete structures by prof. Waffle slab or ribbed slab is a structural component which is plain on its top and contains grid like system on its bottom surface. Rectangular and circular columns, and also columns with any general shape. Waffle slabs are most suitable for construction of slabs. Waffle slabs are most suitable for construction of slabs with long span. Design the concrete floor slab system shown below for an. Example of design of a waffle slab design a waffle slab for an internal panel of a floor system that is constructed on an 8 m square module. Feasibility of structural design of members has been ensured under the provision of is. In waffle slab the waffles are formed as domes like structure which in general are of standard dimension of 483mm if the ribs are having a width of 127mm and the module formed will have a dimension of 610mm.
Design of reinforced concrete structures ii twoway slabs. Design of twoway floor slab system comparison of oneway and twoway slab behavior oneway slabs carry load. Plan view of floor system assume partitions will not be damaged by deflections. 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. Waffle slab cost optimum design of reinforced concrete structures is receiving more and moreattention from the researchers. Analysis and design of waffle slabs free download as pdf file. In realty, precast slab floor would have a better vibration performance than the model predicts, since it is partially restrained. The service live load is 100 psf and 4000 psi concrete is specified for use with steel with a yield stress equal to 60000 psi. In ribbed slab, there is oneway spanning and in a waffle slab, there is twoway ribbed system. Optimum design of reinforced concrete waffle slabs integrated.
The prokon suite includes a series of modules for designing concrete elements. Direct design method is used for the structural analysi s and design of slabs. Bending will take place in the two directions in a dishlike fo. The lateral loads are independently resisted by shear walls. In this paper, the optimum design of reinforced concrete waffle slabs is so ught using the simple genetic algorithm. Pdf twoway joist concrete slab floor waffle slab system. 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 this type of reinforcement is common on concrete, wood and metal construction. Pdf analysis and design of waffle slab with different boundary. Iconic landmarks using grid slabs chattrapati shivaji terminal, india it is recognized for its innovative column design which also consists waffle design. The cost function represents the cost of concrete, steel, and formwork for the slab. I have the national building code of canada 1960, so i know what was done then 90 psi permissible shear stress and check d from support face, but that may have been different from what was in 1956, and in any event i suspect the waffle design would have been selected from the crsi tables, if there were crsi waffle slab tables in 1956. Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. 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.
Dhang, department of civil engineering, iit kharagpur. Slabs of uniform thickness bending and reinforced in two directions and supported directly by columns without beams. Design the slab following the provisions of the aci code. 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. The waffle slab system can be called as a two way joist slab system which comprises of ribs constructed in perpendicular direction. Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Able to carry heavier loads and span longer than ribbed slabs. Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need to be taken into account to reduce the complexity of calculations needed when using exact geometry of the twoway joists. Waffle slab foundation features and construction details. Waffle slabs are preferred for spans greater than 40 feet 12 m, as they are much stronger than flat slabs, flat slabs. Waffles are generally limited to the interior of a slab. Are you going to design the waffle slab using etabs. The name waffle comes from the grid pattern created by the reinforcing ribs.
Due to the high formwork cost and degraded fire rating, this type of construction generally is not recommended. Waffle slab structural engineering general discussion eng. One way slab design procedure with example design of one. Lecture series on design of reinforced concrete structures by prof. Ribbed slabs are made up of wide band beams running between columns with narrow ribs spanning the. Design of waffle slab without beams by direct design method.
Waffle slab or ribbed slab construction procedure and advantages. 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. Ribbed slab design spreadsheet free download description. Mar 01, 2018 the waffle slab system can be called as a two way joist slab system which comprises of ribs constructed in perpendicular direction. This technical note offers several views of posttensioned. 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. A waffle slab or twoway joist slab is a concrete slab made of reinforced concrete with concrete ribs running in two directions on its underside. Direct design method is used for the structural analysis. Numerical and experimental study of a real scale waffle slab. This paper deals with the problem of optimum design of reinforced concrete twoway ribbed waffle slabs using genetic algorithms. The design procedure set forth in that publication had at that time been in use by the author for about 15 years.
They are either oneway spanning systems known as a ribbed slab or a twoway ribbed system known as a waffle slab. Pdf optimum design of reinforced concrete waffle slabs. The innovative concrete waffle slab design adds strength in perpendicular directions. Design of reinforced concrete structures ii twoway slabs 1 1. The ribs are formed due to the pouring of concrete over a set of plastic waffles arranged in series on the ground.
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