Chapter 3 design of rectangular beams and oneway slabs. Therefore, primary reinforcement is presented in both directions for resisting the loads. Two way slab design based on aci 31811 using finite element method. Distribute moments transverse at critical sections to column and middlestrip and if. Two way slabs are normally supported from four sides. One way and twoway slabs one way slabs transfer the imposed loads in one direction only. Multi storey, post tension, two way, design, comparison. Design of reinforced concrete 10th edition pdf free download.
Accordingly, main reinforcement is required in the two directions. 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. Twoway concrete floor slab with beams design and detailing csa a23. Design of reinforced concrete structures ii twoway slabs. Dissatisfaction with results of previously required procedures of analysis and design for two way slab beam systems was the original reason for the massive research upon two way slab systems begun about 1955. Ce 433, fall 2006 slab design example 1 6 design a oneway slab for an exterior bay of a multistory office building using the information specified below. This paper focuses on analysis of two way ribbed and waffle slabs with hidden beams. There are several methods by which two way slabs can be designed. The ratio lb which is less than 2 is known as two way slab. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. Two way slab design by direct design method as per aci 31811. Jul 10, 2017 this example goes through the design of a simplysupported oneway slab on beams. In this video deisgn of two way slabs has been covered using is 456.
For concrete slab design, the slab dimensions and the size and spaci ng of reinforcement shall. When the ratio of long span to short span is less than 2, then the slab is known as a slab spanning in two directions or two way slab. Slabs can be designed by direct design method known as ddm and another method for design is coefficient method which is the easier one. Abstractdesigning two way slabs under transverse concentrated loads is one of the challenges in designing such structures. Step 2 design forces draw panel of slab and indicate maximum design moments, shears and in plane loads, if any, per unit width of slab. A slab is a concrete structure constructed to provide a flat surface. Septic tank pdfpdf documentd small septic tank, septic tank design, septic. Tributary areas many floor systems consist of a reinforced concrete slab supported on a rectangular grid of beams. Allowable stress design or working stress design wsd 2. If the first slab is a twoway slab, both the behavior and the reinforcement rules are proportionate. Reinforced concrete design 1 design of slab examples and. The same is true for a two way slab or any other floor system. Fanella, which appeared in the october 2001 edition of structural engineer magazine.
I have developed a microssoft excel software for design of a two way rcc slab. Consider the simplysupported, unreinforced concrete beam shown in fig. The slab has to carry a distributed permanent action of 1. Design of reinforced concrete structures ii two way slabs 1 1. A reinforced concrete slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so. The publication of the document is at the request of the relevant centc250 sub.
The coefficient method may be the simplest, easiest and the quickest approach for the design of two way slab supported by edge beam on all slab sides. Two way edgesupported slabs two way edgesupported slabs. Foreword the reinforced concrete design manual sp1711 is intended to provide guidance and assistance to professionals engaged in the design of castinplace reinforced concrete structures. Design of a structural member is governed by what kind of forces it has to resist. A simplified method for designing rc slabs under concentrated. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. Strength design or ultimatestrength design usd strength design or ultimatestrength design usd with strength design method, the working dead load dl and live load ll are. There are many methods that are used to analyze two way slabs and the precision of these methods vary depending. May 02, 2017 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 dimensions of an interior bay are shown in figure 1.
Design of a two way rcc slab structural engineering forum. Twoway slab example 1 beam structure classical mechanics. In two way slab, the ratio of longer span l to shorter span b is less than 2. Moments at design sections of rectangular slabs with square column capitals 0 0 0 0 0 0 0 0 0 0 149 46. I am submitting it to you and i want students or professional engineers to download it and use it for their studies or projects. In two way slabs, load will be carried in both the directions. Time saving design aids twoway slabs page 1 of 14 the following example illustrates the design methods presented in the article timesaving design aids for reinforced concrete, part 2. Besides being a medic, he loves blogging, and he always strives hard to share the highquality content with others. Twoway slab analysis and design using equivalent frame method efm. Analysis and design of slabs two way civil engineers pk. Static equilibrium of two way slabs total moment in both beams full load was transferred eastwest by the planks and then was transferred northsouth by the beams.
Design of two way slabs is 456 limit state method youtube. Reinforced concrete slab design and detailing guidelines for depth of slab, loads on slab, reinforcement guide for one way and two way slabs as per is 456. In case of one ways slabs, the aci approximate analysis is applicable to one way slab system where a one way slab is continuous with a one way slab. In two way prestressed slabs, many designers also provide a nominal grid of nonprestressed reinforcing steel typically no. If the ratio of longer dimension of the slab panel to the shorter dimension is greater than or equal to 2 then it is designed as one way slab. Slabs having supports on less than four sides can be designed as one way. For designing two way slab refer is code 4562000 and sp16. One way and two way slabs one way slabs transfer the imposed loads in one direction only. A slab or panel is said to be two way slab if the ratio of longer span to the shorter span is not greater than 2 two. In flatplate floors, slab column connections are subjected to high shear stresses produced by the transfer of axial loads and bending moments between slab and columns. Jul 22, 2015 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. One way spanning slabs should be treated as beams of unit width and chapter 2 should be followed except for minimum shear reinforcement. Example design of two way edgesupported solid slab.
However, plastic method can be the best method for designing such cases of two way slabs. 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. Slab moments calculated by various slab analysis methods are compared with each other for idealized flatplate and two way slab onbeam structures. To see their result for this slab we will find the load factor. One way slab is supported by two parallel beams or walls. Plan view of floor system assume partitions will not be damaged by deflections. Basic steps in two way slab design choose layout and type of slab. In two way slab, load is delivered in both the directions. Such a grid of beams reduces the span of the slab and thus permits the designer to reduce the slab thickness. Layout of posttensioning reinforcement in floor slabs by dr.
Ultimate behavior of one way spanning slab linear elastic analysis methods such as moment distribution are linear elastic methods. Design of reinforced concrete components of a house. The proposed slab system must be able to be constructed at a. The basic design procedure of a two way slab system has five steps.
In case of two way slabs, the moment coefficient tables are applicable to two way slab system where a two way slab is continuous with a two way slab. Two way posttensioned slabs with unbonded tendons offer further advantages in the prevention of local or. Chapter 3 design of rectangular beams and oneway slabs 12. Part three is an exampleintensive course, with key concepts introduced. Two way concrete slabs with openings the static system and the design of reinforcement. Mass and volume are the two types of batching for measuring cement, sand, coarse aggregates, admixtures and water. I would like to thank the authors and all those who in some way have made a contribution to the realization of this report for their excellent work. Analysis and design of twoway slabs page 1 chapter 3. Dec, 2017 beam and slab arrangement can be the best example for one way and two way slabs. Slabs are constructed to carry the heavy loads and to sustain the building. Design of concrete structures as easy as possible by. 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 crosssectional dimensions 18 in. The first aa solution is a twoway concrete solid slab with depth3 h 18 cm supported. This case occurs when the two way slab is supported by beams on all four sides.
Generally, load set 2 will be used for beams and slabs in the uk as it. Ce 433, summer 20 slab design example 1 5 design a one. That is, the load factor at which the uls moment equals the moment capacity. Difference between one way slab and two way slab simple.
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. Design of reinforced concrete 10th edition pdf free. Here the slab or slab panel is supported along its four edges by relatively deep, stiff, monolithic concrete beams or walls or steel girders. Each single slabs are referred to as panels, if the slab is continuous over supports. Time saving design aids two way slabs page 1 of 14 the following example illustrates the design methods presented in the article timesaving design aids for reinforced concrete, part 2. The design bending moment of twoway restrained slab can be calculated as follows. Assume partitions cannot be damaged by deflections. No certain method can be found in the design codes or references for designing two way slabs subjected to concentrated loads. All methods are viable provided that the safety and serviceability of the elements are within the acceptable limits. Concrete slabs are commonly divided into the following types. Beamless slabs beamless slabs are supported only on columns and are applied mostly in large industrial and public buildings. Example design combinations for deflection quasipermanent derived for typical. Twoway concrete slab with beams spanning between supports. Reinforced concrete slab design and detailing guide is456.
The distribution of floor loads on floor beams is based on the geometric configuration of the beams forming the grid. A monolithic reinforced concrete floor is to be composed of rectangular bays measuring, as shown. The building is located in seismic zone iii on a site with medium soil. Fundamentals of posttensioned concrete design for buildings part one. Concrete 3 design of concrete beam and slab twoway slab. Oneway and twoway slabs university of asia pacific. From the study it is considered that post tension slab is more economical than two way slab. Moments at design sections of rectangular slabs with. Rectangular beams and one way slabs page 2 of 9 two methods. A six storey building for a commercial complex has plan dimensions as shown in figure 1. The loads from the slab are transferred to all four supporting beams, which, in turn, transfer the loads to the columns. January 2019 189 ignore any influence of adtt on multiple presence factor, m, in. Recommendations for finite element analysis for the design of.
This method requires various formulas for different conditions of rc slab. Posttensioned oneway slab pennsylvania state university. Download free demo updated august 8, 2019 soilstructure slab on grade software simplifies the calculation of a. Please read the lauses mentioned in the video while solving the problem. The following example illustrates the example building. Analysis of two way ribbed and waffle slabs with hidden beams. The first reinforced concrete design manual formerly titled aci design handbook was developed in accordance with the design provisions of 1963 aci 318 building code by aci committee 340, design. If the ratio of long span to short span is less than or equal to 2, the slab is to be defined as two way slab or slab spanning in one direction. Introduction in reinforced concrete construction, slabs are used to provide flat, useful surfaces.
Coarse aggregates may be gravel, grade stone chips or other man made. The behaviour of reinforced concrete beam sections at ultimate loads has. In a two way slab the slab has to resist the following forces. Beams of width and depth are provided on all column lines. Use the aci 318 direct design method to design an interior bay of a flat plate slab system of multi bay building. Yield line pattern for the general case of twoway slab. Brief on the construction planning of the burj dubai. They may be supported on two opposite sides only fig. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. A flat slab is a two way slab reinforced in two directions that usually. The one way slab is deflected in one way direction and primary reinforcement is placed in one direction whereas.
Two way columnsupported slabs two way columnsupported slabs. Bending will take place in the two directions in a dishlike form. If slab is supported on all four sides and r shorter side longer side way slab. Design of two way ribbed slab 18 x 25 m clear span 1. Twoway joist concrete slab floor waffle slab system. Flat plate concrete floor system does not use beams between columns or. Analysis and design of slabs one way civil engineers pk. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. How to design concrete structures using eurocode 2. Design of one way and two way slabs, design of staircases. The lateral loads are independently resisted by shear walls.
Flat slab analysis, design and detailing pdf civil. It is recommended to create the design of slab with the use of excel sheet as the process will be very simple and lots of time will be saved. This condition occur when the slabs are connected monolithically with support. Two way 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. Reinforced concrete design 1 design of slab examples. Twoway restrained slab if the slabs consist more than one panel or corner of the slab are prevent against lifting it is define as twoway restrained slab. All available load test results indicated that the flat plate or flat slab was a most efficient design with an adequate safety factor. The explicit transverse torsional member method is found to give good results for drifts and slab beam actions, and is recommended for analysis and design of two way slab systems under combined. This pdf file contains a chapter of 23 pages with various aspects of flat slabs including four example of flat slab design. Fundamentals of posttensioned concrete design for buildings. Generally, there are two types of slab which are one way and two way slabs.
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