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