Design of waffle slab without beams by direct design method 32 32 32 c 1 c 2 c 3 c 4 2 c. They are either oneway spanning systems known as a ribbed slab or a twoway ribbed system known as a waffle slab. 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. Dhang, department of civil engineering, iit kharagpur. Pdf design of waffle slab mamoun zoulghina academia.
Waffle slabs are most suitable for construction of slabs with long span. The slab is the flange of the beam and the extended part is the web. Analysis and design of waff le slab with different boundary. This paper deals with the problem of optimum design of reinforced concrete twoway ribbed waffle slabs using genetic algorithms.
The wafflemat system uses forms to create a waffle slab with a set geometry, with ribs typically spaced at 38 on center. Waffle slab twoway pan joist twoway joist slab, also called a waffle slab. 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. Waffle slab requires only 70% of concrete and 80 % of steel from the concrete and steel used for stiffened raft. Pdf optimum design of reinforced concrete waffle slabs.
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. Metropol parasol, italy it is the worlds largest wooden structure which is made up of waffle system. Typical waffle slab for parking structure,with columns on a 33. Ribbing beams reinforcement, slab top wire mesh, waffles dimensioning, voids width and depth, slab thickness. Because there are joists in both directions, this floor system is the strongest and will have the least deflection. Design of waffle slab without beams by direct design method.
This technical note offers several views of posttensioned. Pti recommendations for ribbed slab design include spacing limitations for the ribs and limits on the rib depth and width. Ribbed slab design spreadsheet free download description. Waffle slab or ribbed slab construction procedure and advantages. Waffle slab foundation features and construction details. Analysis and design of waffle slabs architectural elements civil. 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 share in autocad or pdf for what ever projects, would be extremely appreciated. The spacing between the ribs should be in general 2030 inch. Numerical and experimental study of a real scale waffle slab. It is used where vibration is an issue and where large span slabs are to be constructed i. Waffle slab or ribbed slab construction procedure and.
Design of reinforced concrete structures ii twoway slabs 1 1. The comparison is done on the basis of flexural parameters such as bending moments and shear forces obtained from various methods. Jul 02, 2015 oneway concrete slab design part 1 concept explained and minimum slab thickness canadian code duration. 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. See more ideas about waffle ceiling, architecture details and architecture design. 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. However, recently there is a preference for large floor areas with columnfree space and spans. The following are rules of thumb, which are explained further in the accompanying diagrams. Design of reinforced concrete structures ii twoway slabs. Twoway joist concrete slab floor waffle slab system analysis and design. Analysis and design of waff le slab with different. Waffle slab warning for melbournes western suburbs homeowners of nearnew homes or people in the process of building a home in melbourne.
This form of construction is not very common because of the formwork costs and the low fire rating. This waffled feature in slabs will help to take up heavy loads. The lateral loads are independently resisted by shear walls. Different guides have been made for architects and engineers to determine various parameters of waffle slabs, primarily the overall thickness and rib dimensions. Slabs that have span greater than 16m can make use of a waffle slab design. 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. International journal of pure and applied mathematics. Concrete slabs on ground are becoming the more common type of construction especially in the new subdivisions which are flat sites. Ribbed or waffle slab is a slab system which consists of series of parallel reinforced concrete t beams framing into reinforced concrete girders. 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. May182017 twoway joist concrete slab floor waffle slab system analysis and 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.
Please share data design example of waffle slab either manually or using etabs etc. This gives you complete waffle slab design with rebar detailing and schedules. There are three different types of fg 900 moulds, with heights of 225 mm, 325 mm and 425 mm. There are two types of raft slabs, a traditional raft and a waffle raft. Following is the recommended procedure for designing wafflemat system foundations according to pti methodology. In general, it is seen that in solid slab a portion of concrete below the. 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. Waffle slab is good against shrinkage and it is lower than stiffened rafts and footing slabs. The name waffle comes from the grid pattern created by the reinforcing ribs. Thecost function represented the cost of concrete, steel, and formwork for the slab. For 1m slab width, moment, shear force, oneway continuous slab for continuous slab, moment and shear force can be obtained from table 3. Feasibility of structural design of members has been ensured under the provision of is. In this paper, the optimum design of reinforced concrete waffle slabs is so ught using the simple genetic algorithm.
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. Each combines a flat top surface with a modulated underside in a corrugated, ribbed or waffle design. Its typically used when stiffness is important or if there are abnormally heavy loads. Each was examined through different slab aspect rations r of 1, 1. Pdf this paper deals with the problem of optimum design of reinforced concrete twoway ribbed waffle slabs using genetic algorithms. Oneway simply supported slab analysis and design of the slab similar to design of simply supported beam as indicate in the previous chapter. Design the concrete floor slab system shown below for an. Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. Jul 02, 2010 lecture series on design of reinforced concrete structures by prof. 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 dimension of posttension concrete waffle slabs. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. The innovative concrete waffle slab design adds strength in perpendicular directions. 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.
Pdf twoway joist concrete slab floor waffle slab system. 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. Twoway joist concrete slab floor waffle slab system. The speed of construction for such slab is faster compared to conventional slab. Optimum design of reinforced concrete waffle slabs alaa c. The slab itself is usually set at a thickness of 0. Waffle slab or ribbed slab is a structural component which is plain on its top and contains grid like system on its contents. Twoway joist waffle slab design approach and methodology. Dynamic features of precast waffle slabs in cleanroom. Analysis and design of the slab similar to design of simply supported beam as indicate in the previous chapter. Actually the introduction of support hoists made waffle slab very stiff. Waffle slab purpose, uses, advantages and disadvantages. Direct design method is used for the structural analysis and design of slabs. Calculations for waffle pod slab requirements for plan take off and estimating.
In present study some of these approaches are studied and compared with each other. The materials for construction are grade c30 concrete and grade 500 reinforcement. This is necessary to get a better understanding of the problem. Waffle slabs provide stiffer and lighter slabs than an equivalent flat slab. The objective of this work was to analyze the adequacy of a design method widely used in the modeling of. They provide a very good form of construction where slab vibration is an issue, such as laboratories and hospitals. In the design of a wafffe slab, the top slabs with each rib form a. There are 3 basic designs for concrete slabs that improve the strengthtoweight ratio. Bending will take place in the two directions in a dishlike form. Optimum design of reinforced concrete waffle slabs researchgate. The concrete centre provides material, design and construction guidance. There are various approaches available for analyzing the waffle slab system.
Analysis and design of waffle slabs free download as pdf file. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. 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. Ribbed and waffle slabs types, advantages, disadvantages. 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. Iconic landmarks using grid slabs chattrapati shivaji terminal, india it is recognized for its innovative column design which also consists waffle design. Architectural floor plan, engineer plan and slab detail or soil test report. Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need. They are either oneway spanning systems known as ribbed slab or a twoway ribbed system known as a waffle slab.
Waffle slab design example structural engineering general. 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. Reinforced waffle slabs can be constructed for the span up to 16 meters while beyond that length prefabricated waffle slab is preferable. 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. The ribs are formed due to the pouring of concrete over a set of plastic waffles arranged in series on the ground.
It uses 30% less concrete and 20% less steel than a raft slab. Although sloping sites can be accommodated for with slab on ground construction. They may be supported on two opposite sides only fig. The waffle slab has been considered as monolithically connected to band beams.
It has got detailed worked example of all cocncete elements, including ribbed and waffle slabs. One major concern of their utilization in cleanroom design is whether the dynamic performance of the slabs would meet the desired vibration criteria. 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. To compare these systems, a typical interior panel was selected from the northeast wing, which is highlighted in figure 1 on page 7.
795 1160 1430 1049 639 982 1095 476 1190 1166 1384 145 230 1269 287 270 1222 1183 285 1414 259 468 1308 345 1487 178 740 786 1171 520 1091