Teaching twoway ribbed slab analysis and design using the. Ribbed slab design spreadsheet free download description. Jul 22, 2015 design of two way ribbed slab 18 x 25 m clear span 1. Dec 06, 2017 basic of ribbed slab with aci 31802 code requirements. Two way slab design by direct design method as per aci 31811. The aim of this study is to demonstrate that one way ribbed slab with lightweight foam concrete can be used to reduce the dead load on slab concrete structure. No beam, free layout and large windows create bright and open spaces in flat slab floors. 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. Two way slab is a slab supported by beams on all the four sides and the loads are carried by the supports along both directions, it is known as two way slab. Chapter 3 design of rectangular beams and oneway slabs 12. Analysis and design of slabs one way civil engineers pk. Analysis and design of two way slabs page 1 chapter 3.
Ribbed slab article about ribbed slab by the free dictionary. Oneway and twoway slabs university of asia pacific. Twoway concrete slab with beams spanning between supports. Generally, there are two types of slab which are one way and two way slabs. This paper presents an experimental and computational study on ribbed slabs with widebeam, two one way slabs and two two way slabs, with variable. The concrete centre provides material, design and construction guidance. Oneway and twoway slabs oneway slabs transfer the imposed. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. Suspended slab formwork and rebar in place, ready for concrete pour. Slabs having supports on less than four sides can be designed as one way. Ribbed slabs one way joists introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section. There are many methods that are used to analyze twoway slabs and the precision of.
Two way concrete slabs with openings these problems cannot be solved by analytical methods since such structures like concrete slabs with openings, especially strengthened with carbon fibres, are too complicated. Thermal conductivity of a concrete slab indicates the rate of heat transfer. There are many methods that are used to analyze two way slabs and the precision of these methods vary depending on method assumptions. Suspended slab under construction, with the formwork still in place. This 300 mm deep ribbed slab is required for an office to support a variable action of 5 kn m2 it is supported on wide beams that are the same depth as the slab, as shown in figure 3. Design of reinforced concrete structures ii twoway slabs. Bending will take place in the two directions in a dishlike form. Two way slab design by direct design method as per aci 31811, step by step procedure and limitations of direct design method for two way slab is presented. This paper focuses on analysis of two way ribbed and waffle slabs with hidden beams. A reinforced concrete slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so. This program is more effective for analysis the two way slab. The saving of materials tends to be offset by some.
Comparison between ribbed slab structure using lightweight. Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. Two way 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. Advantages of rib clay pot slab over solid concrete slab. Rectangular beams and oneway slabs page 5 of 9 maximum permissible steel ratio, max an overreinforced beam will fail in a brittle manner while an underreinforced beam will. The two methods ive seen the most to perform this has either been. Bending will take place in the two directions in a dishlike fo. So in order to use same thickness and not have to change the structural system of that portion or make it thicker, two way ribbed slab bed are used. Introduction in reinforced concrete construction, slabs are used to provide flat, useful surfaces. This work compares experimental results of six twoway reinforced concrete ribbed flat slabs with rectangular holes close to the column and. Comparison between ribbed slab structure using lightweight foam concrete and solid slab structure using normal concrete. If slab is supported on all four sides and r shorter side longer side way slab. Twoway slabs supported on beams the critical location is found at d distance from the column, where the supporting beams are stiff and are capable of transmitting floor loads to the columns.
In two way slabs shorter direction strip carry greater %age of load. Behavior of two way slab since, the slab rest freely on all sides, due to transverse load the corners tend to curl up and lift up. In sap program, the model has been divided to frame elements to represent ribs and beams and shell elements to represent the slab and solid part. A slightly deeper section is required but these stiffer floors facilitate longer spans and provision of holes. Analysis and design of slabs two way civil engineers pk.
Load transfer in a oneway slab, b twoway slab nilson. Accordingly, main reinforcement is required in the two directions. One way and two way slabs one way slabs transfer the imposed loads in one direction only. Apr052017 two way concrete floor slab with beams design and detailing design the slab system shown in figure 1 for an intermediate floor where the story height 12 ft, column cross. Description download two way slab analysis comments. Design of reinforced concrete structures ii two way slabs 1 1. They are either one way spanning systems known as a ribbed slab or a two way ribbed system known as a waffle slab. I havent heard of anyone creating a family to generate a ribbed slab. Ribbed slab design spreadsheet civil engineering community. The results of this analysis are compared with the results of the finite element method by sap program. Design of oneway slab free download as powerpoint presentation. Analysis of two way ribbed and waffle slabs with hidden beams.
Pdf analysis of two way ribbed and waffle slabs with. This form of construction is not very common because of the formwork costs and the low fire rating. Determine v max v eff u od where u o is the length of column perimeter check v ma jun 01, 2016 sometimes ribbed slabs cannot pass as one way slabs with the same thickness and in order not to create two different thicknesses. Twoway joist concrete slab floor waffle slab system. Structural ribbed concrete slabs the cupolex floor slab can be fully or partially suspended on piles, stem walls or gradeedge beams. Analysis of two way ribbed and waffle slabs with hidden beams ibrahim mohammad arman international journal of civil and structural engineering volume 4 issue 3 2014 343 four slabs are taken in this study to show the moments distribution in two way ribbed slab with hidden beams systems. Nowadays, access to powerful computers and advanced software gives possibility to create accurate models by means of the finite. This would allow the structural designer to reduce the size of column, footing and other load bearing elements. The one way slab is deflected in one way direction and primary reinforcement is placed in one direction whereas. Pdf comparison between ribbed slab structure using. The main reinforcement for two way slab are designed in two directions which are xdirection and ydirection.
The lateral loads are independently resisted by shear walls. In case of ribbed slab the blocks are not permanent. A panel composed of a thin slab reinforced by ribs in one or two directions, usually at right angles to one an other. They are either one way spanning systems known as ribbed slab or a two way ribbed system known as a waffle slab. They may be supported on two opposite sides only fig. This condition occur when the slab are supported at four side of the beams or walls and the ratio of long span to short span is equal or less than 2. Report two way slab analysis please fill this form, we will try to respond as soon as possible. Jan, 2017 advantages of rib clay pot slab over solid concrete slab published on january, 2017 january, 2017 25 likes 2 comments. In two way slab, the ratio of longer span l to shorter span b is less than 2.
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. Civilax is the knowledge base covering all disciplines in civil engineering. In this article, the author presents a parallel approach to the traditional teaching method of two way ribbed slabs. Mathematical structural analysis of one way ribbed slabs was introduced in this paper. Bending moment and shear force of two way slab are depend on l y l x ratio and. There are many methods that are used to analyze two way slabs and the precision of these methods vary depending. Jul 02, 20 introduction hollow block and ribbed slabs are formed by placing blocks on the slab and concrete ribs.
They provide a very good form of construction where slab vibration is an issue, such as laboratories and hospitals. Continuous ribbed slabs concrete structures eurocode. Crcm manual 10 floor slab reinforced with fiber glass, when concrete is mixed with an additive which seal cracks with moisture, no sand and waterproof membrane are required, by exception r506. Analysis of two way ribbed and waffle slabs with hidden. Teaching two way ribbed slab analysis and design using the mathcad program mohammed s. This paper focuses on analysis of twoway ribbed and waffle slabs with hidden beams. May 02, 2017 chajjas and verandahs are an practical example of one way slab. Ribbed slabs are made up of wide band beams running between columns with narrow ribs spanning the.
1362 177 439 964 28 1502 395 812 477 1444 1020 1076 548 1387 1468 616 1151 1170 884 1383 1515 1251 727 1357 960 366 1125 218 338 1159