Slab may be supported on walls or beams or columns. This alternate interpretation is further supported by the analogy between one way beam and slab framing and two way posttensioned slabs with a banded tendon distribution, where no reinforcement is normally supplied parallel to and between the banded tendons. Behavior and reinforcement of oneway slab the structural frame consists of four columns, two beams and one slab. Drawing shows typical slab structure detail through plan, sections and required legendguidelines. Analysis and design of slabs two way civil engineers pk. The first reinforced concrete design manual formerly titled aci design handbook was developed in.
Bubble deck slab joints have a chamfer on the inside to ensure that concrete surrounds each bar and does not allow a direct route to air from the rebar surface. It is possible that designers who specify these arrangements of reinforcement in two way posttensioned. However, twoway slabs with bonded tendons are widely used in other parts of the worldnotably, asia, europe, and australia. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Two way slab concrete design structural engineering.
Limit state design design design of beams and slabs a comprehensive book for reinforced concrete structures of all kind. One way slab is supported by two parallel beams or walls. Normally it works fine but this time after carrying out the calculations the slabs fail in shear because of there are some huge point loads near the support. Tensioning and passive reinforcement in floor slabs,4 section 3. Mathematical structural analysis of one way 763 3 comparison between the results of finite element method and traditional method two bays one way ribbed slab is analyzed by both traditional and finite element methods to determine the induced moments of the rib. Typical slab reinforcement structure design detail. Oneway slabs transfer the imposed loads in one direction only. These slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs or other types of structures.
When a rectangular slab is supported on all the sides and the lengthtobreadth ratio is less than two, it is considered to be. Design of slabtwo way excel sheet online civilforum. Bending will take place in the two directions in a. Twoway slabs structural engineering forum of india, sefi. Twoway slabs have two way bending unlike oneway slab. Oneway slab supported by two beams in the design and analysis of one way slab systems a 1m strip of.
Generally, there are two types of slab which are one way and two way slabs. The same goes for yield lines in the xdirection opposed by the y m capacity of the slab. Difference between one way slab and two way slab simple. 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. 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. There are multiple analysis methods, manual and computer analysis, available for analyzing twoway slabs. That isnt to say that it cant be used for twoway slabs. Difference between one way slab and two way slab system. For better view, please read this post in landscape mode if you are on the mobile device. Twoway concrete slab with beams spanning between supports. Beams of width and depth are provided on all column lines. Reinforced concrete slab design using the empirical method bridgesight solutions for the aashto lrfd bridge design specifications bridgesight software tm creators of effective and reliable solutions for the worlds bridge engineers. One way spanning slabs should be treated as beams of unit width and chapter 2 should be followed except for minimum shear reinforcement.
In twoway slabs shorter direction strip carry greater %age of load. Reinforcement detailing of reinforced concrete slabs. Structural consideration in design of reinforced concrete slabs with openings. Slab is one of the most famous part of a construction project. On the other hand, when slab is supported on all four sides and bending take place in two directions are said to be two way slab. Design of reinforced concrete structures ii twoway slabs. Only the design of slab bridge will be used for illustration. While there is a dearth of published research available describing the behavior of two. It is possible that designers who specify these arrangements of reinforcement in twoway posttensioned. Reinforced concrete slab design using the empirical method.
Fanella, which appeared in the october 2001 edition of structural engineer magazine. This spreadsheet performs an analysis and design of twoway spanning reinforced concrete slab. A bentup bar called as crank bar is provided to make rcc slab safe from compressive stresses. One way and two way slab reinforcement in detail at sit duration. These tendons run the full length of the slab between bands and are specified to be at the center of the slab with no vertical curved profile, as shown in fig. Its scope includes proposing the inclusion of two new equations. The one way slab is deflected in one way direction and primary reinforcement is placed in one direction whereas. Reinforced concrete slab design and detailing guide is456.
Two way slab design by direct design method as per aci 31811. While there is a dearth of published research available describing the behavior of twoway slabs with bonded tendons, the author has received. Analysis two way slabs are not direct as in one way slabs. Design of reinforced concrete structures ii twoway slabs 1 1.
Check slab reinforcement at exterior column for moment transfer between slab and column. Analysis and design of twoway slabs page 1 chapter 3. A monolithic reinforced concrete floor is to be composed of rectangular bays measuring, as shown. In two way slab, the ratio of longer span l to shorter span b is less than 2. Summary of bill of quantities civil works bar bending schedule. Punching shear strength of reinforced concrete slabs without transverse reinforcement by aurelio muttoni. Steps to be followed for the determination of punching shear reinforcement in slabs. The ratio lb which is less than 2 is known as two way slab. Typical slab reinforcement structure design detail autocad. The rest of the floor can be slightly thinner with less dead weight.
Punching shear strength of reinforced concrete slabs. Calculate the live load that can be carried by the slab shown below, if it is reinforced longitudinally as shown below. The basic design procedure of a two way slab system has five steps. The specified design strength of the concrete, is 25 mpa and the specified yield strength of the reinforcement, fy, is 400 mpa.
Download two way slab design excel sheet template for free. Testing on two way posttensioned slabs with a banded tendon distribution2 contained neither the nonprestressed reinforcement shown in fig. For a reinforcement bar to reach its yield stress at a critical cross. Bending will take place in the two directions in a dishlike form. Example on design of slab bridge design data and specifications superstructure consists of 10m slab, 36m box girder and 10m tgirder all simply supported.
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. They may be supported on two opposite sides only fig. Course objectives general by the end of this course, the student will be able to. Distribute moments transverse at critical sections to column and middlestrip and if. Shrinkage and temperature reinforcement in twoway post. A tendon may contain one or more sevenwire strands. Typical slab reinforcement detail with the detail of distribution bar, spacing between bars etc. As they are oneway slabs i treat them as wide beams. Slab supported directly by columns are called flat slab.
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. Behavior and reinforcement of one way slab the structural frame consists of four columns, two beams and one slab. Example design of two way edgesupported solid slab. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. Oneway and twoway slabs oneway slabs transfer the imposed. 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. Jun 14, 2017 download two way slab design excel sheet template. One way concrete slab bends or deflects in a direction perpendicular to the supporting. This paper introduces a strengthening technique of twoway slabs using steel plates and steel bolts. Designing of slabs depends upon whether it is a oneway or a two way slab, the end conditions and the loading. One way and two way slabs one way slabs transfer the imposed loads in one direction only. The original slab reinforcement ratio was chosen as 1. Experimental results by bollinger14 also confirm the role of the critical shear crack in the punching strength of slabs.
Consider the minimum development lengthrequired for the two. Member design reinforced concrete two way spanning slab bs8110 v2015. Unless otherwise noted, all referenced table, figure, and. Twoway concrete floor slab with beams design and detailing. Reinforcement detailing of a slab is done based on its support conditions. Introduction in reinforced concrete construction, slabs are used to provide flat, useful surfaces. Main reinforcementrft is provided in one direction for oneway slabs. Slab supported on two sides and bending takes place predominantly in one direction only is called one way slab. Two way rcc slab designing excel sheet civil engineering. The unit weight of reinforced concrete is assumed to be 24 knm3. Our friend mohit sharma has already highlighted the essentials for a one way slab. In practical, oneway is supported by only two parallel beams or walls. It can be used by both practicing engineers and students.
In this post, we are going to explain how to calculate steel quantity for the slab. Design of reinforced concrete slabs 115 1 the first failure zone is from the face of the loaded area to the perimeter 1. One way shear in slab structural engineering general. Two way slab is a slab in which the ratio of longer side to the shorter side is less than or equal to two.
Chapter 3 design of rectangular beams and oneway slabs. Design of reinforced concrete components of a house. Thus any yield line parallel to the yaxis will be opposed by xdirection reinforcement and hence the x m capacity of the slab. The program covers wide range of twoway slab systems and can be used for more complex slab layouts.
Accordingly, main reinforcement is required in the two directions. The twisting moments discussed earlier are usually of consequences only at exterior corners of a twoway slab system, where they tend to crack the slab at the bottom along. A reinforced concrete slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so. Behavior of two way slabs a rectangular slab supported on four edge supports, which bends in two orthogonal directions and deflects in the form of dish or a saucer is called two way slabs. Design of slab two way excel sheet design spreadsheets the specified design strength of the concrete, is 25 mpa and the specified yield strength of the reinforcement, fy, is 400 mpa. When a slab is designed as a continuous slab, negative moment capacity of the slab shall also be checked, as will be discussed later. Aug 23, 2017 this video describes how the the reinforcement is placed at the site. If playback doesnt begin shortly, try restarting your device. Bubbledeck is the patented integration technique of linking air, steel, and concrete in a two way structural slab. Twoway flat plate concrete floor system analysis and design.
The following example illustrates the design methods presented in the pca book simplified design. The reinforced concrete design manual sp1711 is intended to provide guidance and assistance to professionals engaged in the design of castinplace reinforced concrete structures. Triangular load distribution in two way slabs civildigital. Would love to provide these pictures for better clarity of the viewers.
The following example illustrates the example building. Pdf strengthening of twoway slabs using steel plates. Typically i stay away from using live load reduction when designing the slab because it may restrict the future use of this floor. Member design reinforced concrete two way spanning slab. Atr crosssectional area of the transverse reinforcement along the development length lsy. When a rectangular slab is supported on all the sides and the lengthtobreadth ratio is less than two, it is considered to be a twoway slab. Since slab spans in both directions, design reinforcement is provided in both the direction. Simplified design of reinforced concrete buildings, fourth edition, 2011.
Flat plate concrete floor system does not use beams between columns or. Apart from the column region, where a concentration of reinforcement becomes necessary to avoid column hinge failure fig. Structural consideration in design of reinforced concrete. In two way slabs, load will be carried in both the directions. Design of reinforced concrete structures ii two way slabs 1 1. Punching shear strength of reinforced concrete slabs without. So from the diagram, reinforcement in the xdirection provides a moment capacity of x m parallel to the yaxis. Introduction features in modeling and analysis distribution of moments to strips 9. Design of reinforced concrete structures by punmia pdf concrete bridges part v. This system is similar to the twoway flat plate system except there is a drop panel to provide extra thickness around the columns. Reinforced concrete slab design and detailing guidelines for depth of slab, loads on slab, reinforcement guide for oneway and twoway slabs as per is.
Usually, when a slab is supported by a beam the support is considered to be pinned. Use the equivalent frame method efm and compare the results with spslab model results. Draw the slab, and lebel all the reinforcement sizes and spacings. Reinforced concrete buildings of moderate size and height third edition. Structural calculations for posttensioned beam and oneway slab construction roya construction building division technical services unit kowloon august 16, 2009 revised. A tendon is defined as sheathing duct, the strands within it and the corrosion inhibiting grease or grout filling its voids.
Member design reinforced concrete two way spanning. 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. These tests demonstrated that adequate, codeconformant behavior in two way posttensioned slabs fig. I am doing oneway slabs and hope you can clean up my doubts about the one way shear in slab. 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. Chapter 3 design of rectangular beams and oneway slabs 12.
Figure 1 twoway slab with beams spanning between all supports. Minimum area of reinforcement at bottom of slab minimum area of reinforcement at top of slab reinforcement in ydirection to resist m x about xaxis reinforcement in xdirection to resist m about y. For b oth one way and two way slab with an example. Oneway and twoway slabs university of asia pacific. Two way rcc slab designing tool in microsoft excel developed by shankar tayal a 3rd year student of school of infrastructure, indian institute of technology, bhubaneswar this is a part of his project economic design of two way rcc slabs under prof s. 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. The flexural resistance in the positive bending, as well as the vertical shear capacity, determined per ansisdi c2017 are checked for simple supported slabs. Two way slabs are normally supported from four sides. The following observations can be made from the loadrotation. Two way slab design spreadsheet the engineering community. Approved plans were obtained and analyzed with emphasis on detailing. Layout of posttensioning reinforcement in floor slabs by dr.
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