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