Manual for design and detailing of reinforced concrete to. Pdf structural design versus cost comparison of solid and. One method is to ignore the weight of the solid part of the slab in the analysis of the ribbed slab and the weight of the solid area added to the supporting beam. The relative position of one with respect to the other provides the stiffness characteristic of a ribbed slab. Ribbed slab design spreadsheets to eurocode engineering books. In the one way ribbed slab where the ribs are in one direction, it is assumed. Twoway joist waffle slab design approach and methodology.
In case of hollow block slab voided blocks are placed to reduce the total weight of the slab. Slabs are usually used in floor and roof construction. Introduction hollow block and ribbed slabs are formed by placing blocks on the slab and concrete ribs. Pdf structural design versus cost comparison of solid. Sandwich slabs may have the disadvantage of a larger weight compared to the ribbed ones but on the other hand, they have the advantage that their spans and supports behave in the same proper way. 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. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. The cost is managed by supervision of non skilled laborers, following the recommendations in this manual. Slabs may be supported on monolithic concrete beam, steel beams, walls or directly over the columns. Structural ribbed concrete slabs cupolex sustainable. Which slab is better ribbed slab or solid slab one way. They are either oneway spanning systems known as a ribbed slab or a twoway ribbed system known as a waffle slab. They may be supported on two opposite sides only fig. Comparison between ribbed slab structure using lightweight foam concrete and solid slab structure using normal concrete.
Ribbed slab system which consists of a series of parallel reinforced concrete t beams framing into reinforced concrete girders. In case of ribbed slab the blocks are not permanent. The spacing between the ribs should be in general 2030 inch. First of all, it depends on the use of the structure. A slightly deeper section is required but these stiffer floors facilitate longer spans and provision of holes. Oneway and twoway slabs university of asia pacific. 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. Twoway joist concrete slab floor waffle slab system. This answer will be easy if i make you understand with a building structure. Reinforced concrete ribbed slabs with widebeam lajes.
Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. The slab has to carry a distributed permanent action of 1. Teaching twoway ribbed slab analysis and design using. Design of reinforced concrete structures ii twoway slabs 1 1. Using udls simplifies the analysis and remains popular. Ribbed slab design spreadsheet free download description. Design of waffle slab without beams by direct design method 32 32 32 c 1 c 2 c 3 c 4 2 c. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. What is the difference between a flat slab and a ribbed. Structural design versus cost comparison of solid and ribbed slab constructed building. For 1m slab width, moment, shear force, oneway continuous slab for continuous slab, moment and shear force can be obtained from table 3. Ribbed slabs oneway joists introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section. The method modifies the current uk code design method for solid slabs by applying a shear area factor which reduces the area of the code critical shear perimeter to take.
This type of slabs or flooring system consists of series of small closed. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. Waffle slab or ribbed slab is a structural component which is plain on its top and contains grid like system on its bottom surface. Ribbed slabs types and its advantages in construction purpose. Ribbed slab design beam structure building engineering. Dec 06, 2017 basic of ribbed slab with aci 31802 code requirements. Ribbed slab floors are most economical for buildings such as hospitals, schools, hotels, and.
It would be a design delimiter for ribbed slabs since these widebeams are only dimensioned to resist the bending moment and beam shear. 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. Jul 02, 20 introduction hollow block and ribbed slabs are formed by placing blocks on the slab and concrete ribs. Mathcad program and show its impact on teaching the analysis and design of twoway ribbed slabs. After this publication, it was subsequently adopted by the uniform building. Ribbed slab design spreadsheets to eurocode engineering. Monodirectional ribbed slab lighting clay elements b 500 mm, bw 120 mm bbw 4,2 3 50 mm flange made of. 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. Scribd is the worlds largest social reading and publishing site. The traditional method doesnt take into consideration a lot of factors in the analysis such as thickness of slab and depth of the ribs. They may be solid of uniform thickness or ribbed with ribs running in one direction or two directions waffles.
Oneway concrete slab design part 1 concept explained and minimum slab thickness. The cost is managed by supervision of non skilled laborers, following the recommendations in. There are various established methods for analysing ribbed slabs and dealing with the solid areas. For design such this slab i mean detailed reinforcement can be in robot. 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. In reality, sandwich slabs are ribbed slabs with a slab placed both to their upper and lower surface. Ce tcc ribbed slab rei60 01 bruninghoffgruppe free bim. Analysis of two way ribbed and waffle slabs with hidden beams. This form of construction is not very common because of the formwork costs and the low fire rating. In addition, the scope of this study is to design oneway ribbed slab and twoway solid slab by using esteem software. Continuous ribbed slabs concrete structures eurocode.
Reinforced concrete design 1 design of slab examples. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. The waffle slab is also sometimes termed as ribbed slab system but you would find it interesting to know that ribbed and waffle slab are somehow two different things. Pdf comparison between ribbed slab structure using. Waffle slab or ribbed slab construction procedure and advantages. Structural ribbed concrete slabs the cupolex floor slab can be fully or partially suspended on piles, stem walls or gradeedge beams. Concrete rib construction method, crcm uses the engineering technology to design the elements structurals to handle the loads originated by climatic and or geographical location of the project. Design is defined as the decisionmaking process of planning, sizing, detailing, and developing specifications preceding construction of slabsonground. Information on other aspects, su ch as materials, construction methods, placement of concrete, and finishing techniques, is.
This is attributed to the rapid shattering, ease of construction, and the reduction in the time of erection. Ribbed slabs types and its advantages in construction. Particularly noteworthy is the weatherproof design, which guarantees a flawless and. Analysis of two way ribbed and waffle slabs with hidden beams article pdf available in international journal for computational civil and structural engineering volume 4, no 3, 2014 january. Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need. Ribbed slabs are made up of wide band beams running between columns with narrow ribs spanning the. From the previous analysis of the ribbed slab in the traditional methods it is. Design of reinforced concrete structures ii twoway slabs. They are either oneway spanning systems known as ribbed slab or a twoway ribbed system known as a waffle slab. Ribbed slab design spreadsheets to eurocode ribbed slabs are widely used in many countries.
The blocks are considered as nonstructural element as they do not contribute to strength of. Wide beam ribbed slab abstract a method for the shear design of wide beam ribbed slabs is proposed. Considering a building structure structurally we generally found the following components 1. Ribbed or waffle slab is a slab system which consists of series of parallel reinforced concrete t beams framing into reinforced concrete girders. In the analysis of ribbed slab as solid slab traditional, the structural system of. Which slab is better ribbed slab or solid slab one way or two way. Concrete slab behave primarily as flexural members and the design is similar to that of. Design of two way ribbed slab 18 x 25 m clear span 1.
Bending will take place in the two directions in a dishlike fo. This document provides guidance for the design and construction of conventionally reinforced ribbed mat slab rrms foundation systems. Additional reinforced internal ribs are then used in the slab by introducing pontex, the structural cupolex accessory to provide a structure capable of spanning between foundations or piles. When one says ribbed slab it is actually a one way spanning system with ribs where as in waffle slab the joists form a two way system. The saving of materials tends to be offset by some. Experimental and computational results showed that the widebeam ribs connection is a critical point in the design of the slabs due to the. One way slab design procedure with example design of one.
Jul 22, 2015 design of two way ribbed slab 18 x 25 m clear span 1. Ribbed slab design beam structure building engineering scribd. Waffle slab or ribbed slab construction procedure and. 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. Designed as a series of parallel tbeams and economical for medium spans with light to medium live loads. Manual for design and detailing of reinforced concrete to the september 20 code of practice for structural use of concrete 20 2. Ribbed and waffle slabs types, advantages, disadvantages. Ribbed slab floors are most economical for buildings such as hospitals, schools, hotels, and apartment construction where loads are somewhat small and the spans are relatively large. Particularly noteworthy is the weatherproof design, which guarantees a flawless and high. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1.
The slab is the flange of the beam and the extended part is the web. Optimum design of reinforced concrete waffle slabs alaa c. Egyptian code for design and construction of reinforcement concrete structures. Design the slab following the provisions of the aci code. Slab depth calculation based on the design span and the imposed load it is possible to make a preliminary assessment of the required thickness of a skydome slab, as shown in the chart to the right. For the purpose of this document, rrms is defined as a system of stiffening beams and slab constructed of. Bending will take place in the two directions in a dishlike form. Oneway concrete slab design part 1 concept explained and minimum slab thickness canadian code duration.
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