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. Optimum design of reinforced concrete waffle slabs researchgate. Waffle slab foundation features and construction details. However, recently there is a preference for large floor areas with columnfree space and spans. Each combines a flat top surface with a modulated underside in a corrugated, ribbed or waffle design.
The name waffle comes from the grid pattern created by the reinforcing ribs. They are either oneway spanning systems known as ribbed slab or a twoway ribbed system known as a waffle slab. Because there are joists in both directions, this floor system is the strongest and will have the least deflection. Oneway simply supported slab analysis and design of the slab similar to design of simply supported beam as indicate in the previous chapter. There are two types of raft slabs, a traditional raft and a waffle raft. Waffle slab or ribbed slab construction procedure and advantages. 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. Traditionally column spacings and floor spans in these buildings have been in the range of 6 to 9 metres, to both contain costs and simplify construction.
Jul 02, 2010 lecture series on design of reinforced concrete structures by prof. Analysis and design of waffle slabs architectural elements civil. Pdf optimum design of reinforced concrete waffle slabs. Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. The materials for construction are grade c30 concrete and grade 500 reinforcement.
Ribbed or waffle slab is a slab system which consists of series of parallel reinforced concrete t beams framing into reinforced concrete girders. A share in autocad or pdf for what ever projects, would be extremely appreciated. The innovative concrete waffle slab design adds strength in perpendicular directions. Twoway joist waffle slab design approach and methodology.
Analysis and design of the slab similar to design of simply supported beam as indicate in the previous chapter. 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. Pdf design of waffle slab mamoun zoulghina academia. There are 3 basic designs for concrete slabs that improve the strengthtoweight ratio. 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. Waffle slabs provide stiffer and lighter slabs than an equivalent flat slab. Waffle slab is good against shrinkage and it is lower than stiffened rafts and footing slabs. The waffle slab has been considered as monolithically connected to band beams. This is necessary to get a better understanding of the problem. It has got detailed worked example of all cocncete elements, including ribbed and waffle slabs. This waffled feature in slabs will help to take up heavy loads. Twoway joist concrete slab floor waffle slab system. Bending will take place in the two directions in a dishlike form. Design of waffle slab without beams by direct design method 32 32 32 c 1 c 2 c 3 c 4 2 c.
Design of reinforced concrete structures ii twoway slabs. The following are rules of thumb, which are explained further in the accompanying diagrams. The ribs are formed due to the pouring of concrete over a set of plastic waffles arranged in series on the ground. Oneway and twoway slabs university of asia pacific. There is no deemed to comply design for waffle slabs for extremely reactive sites class e sites. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. Apr 22, 2012 this reinforced concrete waffle slab ribbed slab cross section reinforcement cad drawing detail includes ribbing beams reinforcement, slab top wire mesh, waffles dimensioning, voids width and depth, slab thickness. Analysis and design of waffle slabs free download as pdf file. The lateral loads are independently resisted by shear walls. Pdf twoway joist concrete slab floor waffle slab system. Pti recommendations for ribbed slab design include spacing limitations for the ribs and limits on the rib depth and width. Analysis and design of waff le slab with different boundary.
Dynamic features of precast waffle slabs in cleanroom. 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. Although sloping sites can be accommodated for with slab on ground construction. In the design of a wafffe slab, the top slabs with each rib form a. 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. The speed of construction for such slab is faster compared to conventional slab. Design the concrete floor slab system shown below for an. Please share data design example of waffle slab either manually or using etabs etc. Jul 02, 2015 oneway concrete slab design part 1 concept explained and minimum slab thickness canadian code duration. 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.
Thecost function represented the cost of concrete, steel, and formwork for the slab. Concrete slabs on ground are becoming the more common type of construction especially in the new subdivisions which are flat sites. Ribbed and waffle slabs types, advantages, disadvantages. Architectural floor plan, engineer plan and slab detail or soil test report. Design of reinforced concrete structures ii twoway slabs 1 1. The primary design issues for stiffened slabs on grade are the sizing of the beams that stiffened the slab and the spacing of the beams. Waffle slab or ribbed slab is a structural component which is plain on its top and contains grid like system on its contents. The wafflemat system uses forms to create a waffle slab with a set geometry, with ribs typically spaced at 38 on center. Waffle slab warning for melbournes western suburbs homeowners of nearnew homes or people in the process of building a home in melbourne. This technical note offers several views of posttensioned. The comparison is done on the basis of flexural parameters such as bending moments and shear forces obtained from various methods. Its typically used when stiffness is important or if there are abnormally heavy loads. Design of waffle slab without beams by direct design method.
The spacing between the ribs should be in general 2030 inch. International journal of pure and applied mathematics. Waffle slab twoway pan joist twoway joist slab, also called a waffle slab. To compare these systems, a typical interior panel was selected from the northeast wing, which is highlighted in figure 1 on page 7. This form of construction is not very common because of the formwork costs and the low fire rating. In present study some of these approaches are studied and compared with each other. Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need. It uses 30% less concrete and 20% less steel than a raft slab.
Direct design method is used for the structural analysis. The slab itself is usually set at a thickness of 0. The slab is the flange of the beam and the extended part is the web. Oneway concrete slab design part 1 concept explained and minimum slab thickness canadian code duration. 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. 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. Waffles are generally limited to the interior of a slab. Ribbed slab design spreadsheet free download description. There are various approaches available for analyzing the waffle slab system.
Slabs and flat slabs lecture 5 19 th october 2016 contents lecture 5 designing for shear in slabs including punching shear detailing solid slabs flat slab design includes flexure worked example exercise punching shear. Iconic landmarks using grid slabs chattrapati shivaji terminal, india it is recognized for its innovative column design which also consists waffle design. They are either oneway spanning systems known as a ribbed slab or a twoway ribbed system known as a waffle slab. Optimum design of reinforced concrete waffle slabs alaa c. There are three different types of fg 900 moulds, with heights of 225 mm, 325 mm and 425 mm. Typical waffle slab for parking structure,with columns on a 33. 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. Under the general provisions of the 1995 code, chapter, the twoway joist portion may be combined with a solid column head or with solid wide beam sections on the column centerlines for uniform depth construction. Calculations for waffle pod slab requirements for plan take off and estimating. Feasibility of structural design of members has been ensured under the provision of is.
In general, it is seen that in solid slab a portion of concrete below the. 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. Waffle slab requires only 70% of concrete and 80 % of steel from the concrete and steel used for stiffened raft. Following is the recommended procedure for designing wafflemat system foundations according to pti methodology. 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. Waffle slab or ribbed slab construction procedure and. The objective of this work was to analyze the adequacy of a design method widely used in the modeling of. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. It is used where vibration is an issue and where large span slabs are to be constructed i. Waffle slab purpose, uses, advantages and disadvantages. This paper deals with the problem of optimum design of reinforced concrete twoway ribbed waffle slabs using genetic algorithms. Analysis and design of waff le slab with different.
Twoway joist concrete slab floor waffle slab system analysis and design. One major concern of their utilization in cleanroom design is whether the dynamic performance of the slabs would meet the desired vibration criteria. Ribbing beams reinforcement, slab top wire mesh, waffles dimensioning, voids width and depth, slab thickness. Slabs that have span greater than 16m can make use of a waffle slab design. Flat slab analysis, design and detailing pdf ribbed and waffle slabs types, advantages, disadvantages ribbed or waffle slab is a slab system which consists of series of parallel reinforced concrete t beams framing into reinforced concrete girders.
They provide a very good form of construction where slab vibration is an issue, such as laboratories and hospitals. In this paper, the optimum design of reinforced concrete waffle slabs is so ught using the simple genetic algorithm. Different guides have been made for architects and engineers to determine various parameters of waffle slabs, primarily the overall thickness and rib dimensions. Direct design method is used for the structural analysis and design of slabs. May182017 twoway joist concrete slab floor waffle slab system analysis and design. Reinforced waffle slabs can be constructed for the span up to 16 meters while beyond that length prefabricated waffle slab is preferable. Pdf this paper deals with the problem of optimum design of reinforced concrete twoway ribbed waffle slabs using genetic algorithms.
Numerical and experimental study of a real scale waffle slab. Metropol parasol, italy it is the worlds largest wooden structure which is made up of waffle system. Waffle slabs are most suitable for construction of slabs with long span. Dhang, department of civil engineering, iit kharagpur. Optimum dimension of posttension concrete waffle slabs. They may be supported on two opposite sides only fig. This gives you complete waffle slab design with rebar detailing and schedules. Actually the introduction of support hoists made waffle slab very stiff. 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. For 1m slab width, moment, shear force, oneway continuous slab for continuous slab, moment and shear force can be obtained from table 3.
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