Pdf analysis of two way ribbed and waffle slabs with. Teaching two way ribbed slab analysis and design using the mathcad program mohammed s. 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. A reinforced concrete slab is the one of the most important component in a building. In case of ribbed slab the blocks are not permanent. Design of reinforced concrete structures ii twoway slabs 1 1.
The overall depth of the slab without finishing materials is 300mm. To contribute to a better understanding of the behavior of these slabs were fabricated in the laboratory 8 oneway reinforced concrete ribbed slab. In this section, two types will be discussed, one way solid slabs and one way ribbed slabs. 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. The ribbed slab was analyzed exactly by finite element theory through sap 2000 program. The results of this analysis are compared with the results of the finite element method by sap program.
Two way slab lylx way slab usually have a rectangular plan and tend to bend along the direction of longer span if we assum. Structural ribbed concrete slabs the cupolex floor slab can be fully or partially suspended on piles, stem walls or gradeedge beams. In this article, the author presents a parallel approach to the traditional teaching method of twoway ribbed slabs. Chajjas and verandahs are an practical example of one way slab. Bridging the gap between oneway and twoway shear in slabs. I added a bunch of telemetry and while investigating i noticed something. Corners of the twoway slab lift up if the slab is not cast monolithically with the supports wallsbeams.
Comparison between ribbed slab structure using lightweight foam concrete and solid slab structure using normal concrete. Chapter 3 design of rectangular beams and oneway slabs. Analysis and design of two way slabs page 1 chapter 3. The following example illustrates the example building. Lecture 25 design of twoway floor slab system is the property of its rightful owner. 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. For health and safety information please refer to the relevant tarmac health and safety data sheet. Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. This document is a technical summary of the unpublished federal highway administration report, analysis of an ultrahigh performance concrete twoway ribbed bridge deck slab, available only through the national technical information service. In two way slabs, load will be carried in both the directions. Teaching twoway ribbed slab analysis and design using the. Analysis of an ultrahigh performance concrete twoway.
Introduction in reinforced concrete construction, slabs are used to provide flat, useful surfaces. Difference between one way slab and two way slab system the one way and two way slab systems are the most commonly used floor system in the reinforced concrete structure. Two way slabs are those slabs supported by columns arranged generally in rows so that they can deflect in two directions. The spacing between the ribs should be in general 2030 inch.
In general, the beam slab flexural stiffness ratio is about 0. 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. Pdf oneway shear in wide concrete beams with narrow supports. The concrete centre held a ribbed slabs seminar in may, underneath the stunning ribbed slabs of the recentlycompleted royal. Different types of slabs in construction civil snapshot. Bridging the gap between one way and twoway shear in slabs. Sheplers, a 115year old western lifestyle company with 25 retail locations across the united states and an industryleading ecommerce business.
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. The ratio of steel in a slab can be determined by dividing the sectional area of. In site how we can identify one way slab and two way slab. Jun 30, 2014 civilax is the knowledge base covering all disciplines in civil engineering. Introduction hollow block and ribbed slabs are formed by placing blocks on the slab and concrete ribs. Description phoenix is the tarmac cement brand name for bulk portlandfly ash cement. Redesign the typical exterior panel of the floor of example. Bending will take place in the two directions in a dishlike form. A twoway slab with beams is a type of economical flooring system, often used as it costs less than flat plates or flat slabs.
I hear that if ribbed slab is resting on shear wall, it is a must to provide perpendicular rib parallel to shear wall,and note to let the block in touch with shear wall,since it is not safe for shear. Ribbed slabs are made up of wide band beams running between columns with narrow ribs spanning the. A reinforced concrete slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so. Boot today announced the completion of its previously announced acquisition of sheplers, inc. The basic design procedure of a twoway slab system has five steps. Beyond a certain span the slab becomes so thick that its own weight becomes an excessive burden, unless a substantial portion of the nonworking concrete in the lower part of the slab can be eliminated to lighten the load. Shear strength of reinforced concrete oneway ribbed slabs scielo. Design of two way ribbed slab 18 x 25 m clear span 1. Example on design of slab bridge design data and specifications superstructure consists of 10m slab, 36m box girder and 10m tgirder all simply supported.
This paper focuses on analysis of two way ribbed and waffle slabs with hidden beams. Twoway joist waffle slab design approach and methodology. May 02, 2017 chajjas and verandahs are an practical example of one way slab. Design calculation for twoway slab civil engineering community. Behavior and reinforcement of one way slab the structural frame consists of four columns, two beams and one slab. Mathematical structural analysis of one way ribbed slabs was introduced in this paper. Two way joist concrete slab floor waffle slab system analysis and design. While punching shear capacity on a perimeter around the column must be checked in the latter case, design code provisions require that one way shear capacity be assessed for a crosssection. There are 16 different types of slabs in construction. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs, bridges, and other types of structures. The blocks are considered as nonstructural element as they do not contribute to strength of. Structural consideration in design of reinforced concrete slabs with openings.
Dec 09, 20 one way slab two way slab flat plate flat slab grid or waffle slab 7. Enprecast concrete bridge column set small this is a ho1. Guidelines for a twoway concrete flooring system brewer. A widely spread type of the two way slabs used is the two way ribbed slab or waffle slab composed of closely spaced parallel tsection small beams in each of the two directions of the slab. Ribbed slab floors are most economical for buildings such as hospitals, schools, hotels, and.
Difference between one way slab and two way slab system. The slab is the flange of the beam and the extended part is the web. The slab has to carry a distributed permanent action of 1. Waffle slab or ribbed slab is a structural component which is plain on its top and contains grid like system on its bottom surface. Oneway concrete slab design part 3 minimum spacing, shrinkage reinforcement, crack control duration. They provide a very good form of construction where slab vibration is an issue, such as laboratories and hospitals. Obtain sample after 10 percent of batch has been discharged and before the last 10 percent is discharged. 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.
The cost is managed by supervision of non skilled laborers, following the recommendations in. We aim to close the gap to the industry by improving the awareness about latest trends in civil engineering. Reinforced concrete ribbed slabs with widebeam lajes. They may be supported on two opposite sides only fig. Minimum thickness for two way slab construction designed as per methods provided by aci 31811 code namely. The minimum spacing of reinforcing bars should preferably be 6 in. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. Ribbed slab system which consists of a series of parallel reinforced concrete t beams framing into reinforced concrete girders.
Either drop or hidden beams can be used to support these slabs depending on the span. In reality, sandwich slabs are ribbed slabs with a slab placed both to their upper and lower surface. Skydome is a system of modular formwork in plastic used to build twoway ribbed slabs in residential and commercial buildings. If the ribs are provided in one direction only, the slab is classified as being one way, regardless of the ratio of longer to shorter panel dimensions. Approved plans were obtained and analyzed with emphasis on detailing. The column tends to punch through the slab in flat slabs, which can be treated by three methods. Flat plate concrete floor system does not use beams between columns or. Aug 02, 2017 most students directly relate the lylx ratio or support provided with the type of slab.
Mar 15, 20 2x4 sleepers shimmed over concrete slab once all the floors were ripped out, we started to reconstruct the new floors to the same specifications to the old floor. Field concrete technician study guide 5 gsp17 sampling procedures for freshly mixed structural concrete transit mixers and agitators. The following example illustrates the design methods presented in the pca book simplified design reinforced concrete buildings of moderate size and height third edition. A 2 inch thick slab is 10 inches wide and 12 ft long. Pdf comparison between ribbed slab structure using. In a oneway slab, this lateral expansion is resisted by adjacent slab strips, which tend to expand also. In other words, when the loads or spans or both become quite large, the slab thickness and column sizes required for flat plates or flat slabs are of such magnitude that it is more economical to use twoway slabs with. One more definition regarding oneway and two way slab is that if one direction span to other direction span ratio or more precisely if longer dimension to shorter dimension ratio is greater than 2 it is termed as two way slab. Slab design reading assignment chapter 9 of text and, chapter of aci31802. The twoway slab is designed for both the directions as it bends in both directions. This set is a column for the precast concrete bridge or flyover. Apr052017 twoway 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.
Civilax is the knowledge base covering all disciplines in civil engineering. According to the invention, the surface profiling of the upper flange of each rib consists. First we laid a heavy 30 felt paper as a moisture barrier. A one way slab is simply a very wide beam that spans between supports. In two way slab, the ratio of longer span l to shorter span b is less than 2. Teaching twoway ribbed slab analysis and design using the mathcad program mohammed s. Longitudinal steel should be detailed in a 2bar alternating pattern, with one of the bars continuous through the slab.
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. No file limit, no ad watermarks a free and beautiful tool to combine your pdf files exactly the way you want it. The result is a slight strengthening and stiffening in the span direction, but this effect is small and can be disregarded. Oct 29, 2016 bridging the gap between one way and two way shear in slabs 1. The joists which are spaced at 400mm are supported by girders. In case of hollow block slab voided blocks are placed to reduce the total weight of the slab. These slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs or other types of structures. The flat slab is a twoway reinforced concrete slab that usually does not have beams and girders, and the loads are transferred directly to the supporting concrete columns. In site how we can identify one way slab and two way slab answer suresh the slab will be supported on all the four sides if it is two way slab. Current study, such as lau and clark 4, assesses the performance of one and twoway ribbed slabs with widebeams by analyzing the structural. When slab is supported at all sides and lengthwidth 2 of a slab panel. Unless otherwise noted, all referenced table, figure, and equation numbers are from that book.
Feb 17, 2017 i have been trying to track down an issue where we have nodes become unresponsive momentarily, causing the cluster to think they have left. Design of reinforced concrete structures ii twoway slabs. Teaching twoway ribbed slab analysis and design using. The ribs are tapered in crosssection in its lower part. But its not like that, they are just the criterias or the formulas to have a ease in determination of slab type. Start studying chapter 14 sitecast concrete framing systems. Different types of slabs in construction december 25, 2017 january 26, 2018 by kathir 2 comments. The model consists of strips that work with arching action oneway shear and slab quadrants that work in twoway shear. Some of them are outdated and many of them are frequently used everywhere. Ribbed slab structural engineering general discussion. A slightly deeper section is required but these stiffer floors facilitate longer spans and provision of holes. Mathcad program and show its impact on teaching the analysis and design of twoway ribbed slabs. Reinforced concrete design 1 design of slab examples. Determine moments at critical sections in each direction, normally the negative.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. Each step will reduce the slab to 75% of its previous thickness. If so, share your ppt presentation slides online with. Ribbed slabs oneway joists introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section. Thickness is to be reduced in three steps in a hot rolling operation. Analysis and design of twoway slabs page 1 chapter 3. May182017 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. There are many methods that are used to analyze twoway slabs and the precision of these methods vary depending. If there is a slab with a ratio of lylx 2, but it is. This type of cement is designated in the british standard for cement bs en 19711 as.
Usually, when a slab is supported by a beam the support is considered to be pinned. Ribbed slab design in sap2000 civil engineering downloads. As such, the resulting extended strip model is suitable for the design and assessment of elements that are in the transition zone between oneway and twoway shear. We then had to use a selfleveling laser level to make sure the sleepers were 100% level with shims. Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need. Reinforced concrete structures ii ribbed slab example 2 1 example 2. Two way joist waffle slab design approach and methodology two way joist slab often called two way ribbed slab or waffle slab is an economical floor system when the spans are long andor loads are high. Answer to packer concrete company pours concrete slabs for singlefamily dwellings. The first person to truly combine the theory of trabeculae and apply it to a structure was the italian.
Twoway flat plate concrete floor system analysis and design the concrete floor slab system shown below is for an intermediate floor to be designed considering partition weight 20 psf, and unfactored live load 40 psf. Learn more before you buy, or discover other cool products in scenery. Only the design of slab bridge will be used for illustration. Two way slabs are the slabs that are supported on four sides and the ratio of longer span l to shorter span b is less than 2. In this article, ill give a detailed explanation of each slab where to. Analysis of two way ribbed and waffle slabs with hidden beams. Structural consideration in design of reinforced concrete.
If the entry speed is 40ftmin and the roll speed is the same for all three steps. Slabs are usually used in floor and roof construction. Ribbed slabs can be used in one way and two way edge supported slabs. This work compares experimental results of six twoway reinforced concrete ribbed flat slabs with rectangular holes close to the column and. 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 14 sitecast concrete framing systems flashcards. Main reinforcement is provided in which direction for one way. Oct 09, 1973 the present disclosure relates to a method and means of building two way slabs and flat slabs, reinforced concrete floors and roofs employing composite concrete flexural construction which require little or no formwork, greatly reduce the use of temporary stringers and shores, increase the speed of construction, reduce the number of skilled. In this chapter, several ribbed floor slab systems are analyzed.
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. Packer concrete company pours concrete slabs for s. In this article, the author presents a parallel approach to the traditional teaching method of two way ribbed slabs. 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. The reinforcement rules are also similar in both directions. Ribbed slabs types and its advantages in construction. Twoway joist concrete slab floor waffle slab system. Difference between one way slab and two way slab slab. This paper focuses on analysis of twoway ribbed and waffle slabs with hidden beams. But i dont buy this,block is not structural element,and if rib is design for shear,why i shall do this. The variations presented later in this paper have been derived empirically. The invention relates to a ribbed plate for a composite slab, the profile of which consists of protruding ribs formed in an essentially planar plate, the upper flanges of the ribs being surface profiled in order to achieve better adhesion between the ribbed plate and the concrete of the composite slab.
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 345 length and l2 is the transverse distance or frame width. When slab is supported on two opposite sides only, total load is carried along the perpendicular direction of supporting beams. As one way solid slab spans increase, a thicker slab is required. The model provides the actual behavior for ribbed slab by analyzing the structure as oneunite in two dimensions. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. Ribbed slabs provide a stiffer floor than the equivalent flat slab and are therefore better at reducing footfall vibration or vibration from equipment. Redesign the typical exterior panel of the floor of exa. There are many methods that are used to analyze two way slabs and the precision of these methods vary depending. I have assumed this to be a gc issue and have been trying to optimize to that end. But if the slab is supported on four sides then we have to consider the aspect ration lxly. The twoway slab will deflect in a dish or saucerlike form under the action of loads.
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