Ndesign of two way slab with beams pdf

Slab supported on two sides and bending takes place predominantly in one direction only is called one way slab. 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. Here, we have tried to gather various reading materials available in the web about flat slab floor system in one place. Beams of width and depth are provided on all column lines. The slab is designed as a continuous slab, using theory of continuous beams slabs, or the simplified coefficient method where applicable i. Basic steps in two way slab design choose layout and type of slab. Nonprestressed bonded reinforcement in posttensioned. Bending will take place in the two directions in a dishlike form. A system where a two way slab is continuous with a one way slab or vice versa is called a mixed slab system. Generally, there are two types of slab which are one way and two way slabs. Two way slabs are such slabs in which the loads are shared by both the shorter and longer direction of the slab. Design of reinforced concrete structures ii two way slabs 1 1. Before going to this topic, please read it there are two types of slab classification based on the direction of bending occurs in these slabs.

To see their result for this slab we will find the load factor. This system consist of both one way and two way slabs. Two way slab design by direct design method as per aci 31811. Twoway concrete floor slab with beams design and detailing csa a23. Two way slabs are slabs in which the surface load is transferred in two directions. There are many methods that are used to analyze two way slabs and the precision of these methods vary depending. Pdf bending moments in beams of two way slab systems. Accordingly, main reinforcement is required in the two directions. Slab is a common term used to describe the structural elements such as floors and roofs where the thickness of the element is very small compared to the length and. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only.

The two classifications are one way slab and two way slab. The following example illustrates the example building. Two way concrete floor slab with beams design and detailing csa a23. 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. Two way slabs are normally supported from four sides. 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. Member design reinforced concrete two way spanning. In two way slabs, load will be carried in both the directions. For those who do not know what are the des ign requirements of a slab. A combination of these values will determine the slab stresses at the time of stressing and at service loads. 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 cross sectional dimensions 18 in. Posttensioned concrete design spreadsheet program a pdh.

A 2 2area 2 a c 2 2 posttensioned concrete design table 11 list of symbols used in the aci 31808 code cp area enclosed by the outside perimeter of the section, in a g gross area of concrete, in a 2 l total area of longitudinal reinforcement to resist torsion, in a o area enclosed by the shear flow path, sqin a oh area enclosed by the centerline of the outermost closed. Flat slab analysis, design and detailing pdf civil engineering. One way spanning slabs should be treated as beams of unit width and chapter 2 should be followed except for minimum shear reinforcement. Pdf oneway shear strength of thick slabs and wide beams. Dec, 2012 summary a beamandslab system, with a oneway slab, and beams cast compositely with the slab, is a highly efficient floor system. 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. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. Oneway and twoway slabs university of asia pacific. Moment variations of a uniformly loaded slab with simple supports on four sides. Distribute moments transverse at critical sections to column and middlestrip and if. Assume partitions cannot be damaged by deflections. View test prep concrete 3 design of concrete beam and slab two way slab part 22 from engineerin 101 at royal melbourne institute of technology. Design of reinforced concrete structures ii twoway slabs. Reinforced concrete, 2014, 9th edition, aci 31811 code edition, by jack c.

Reinforcement detailing of reinforced concrete slabs. This method has been used extensively since 1963 for slabs supported at the edges by walls, steel beams, or monolithic concrete beams. 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. A civil engineer must know all the aspects regarding the flat floor system.

Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. Two way reinforced concrete slab design clear longer span of slab please enter the longer span. Before the start of two way slab design, slab depth should be determined in addition to specify column strips and middle strips. Two way slabs have two way bending unlike one way slab.

Now if length to width ratio is 2 or greater, slab acts as one way slab even though supports are provided. Flat plate concrete floor system does not use beams between columns or. Concrete 3 design of concrete beam and slab twoway. Analysis and design of slabs two way civil engineers pk.

Rectangular beams and one way slabs page 5 of 9 maximum permissible steel ratio, max an overreinforced beam will fail in a brittle manner while an underreinforced beam will fail in a ductile manner. Design of a structural member is governed by what kind of forces it has to resist. Bending will take place in the two directions in a dishlike fo. Moduleiii design of short and long columns with axial and eccentric loading, design of isolated column footing. I am submitting it to you and i want students or professional engineers to download it and use it for their studies or projects. The program is divided into three separate screens, which correspond to the three major areas of concern in the design of a posttensioned member.

Two way slab a bending of center strip, b grid model figure. No redistribution is allowed when method 1 or method 2 of analysis in section 3. 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. Ultimate behavior of one way spanning slab linear elastic analysis methods such as moment distribution are linear elastic methods. Two way slab shear strength shear strength of the slab in the vicinity of columnssupports includes an evaluation of one way shear beam action and two way shear punching in accordance with aci 318 chapter 22. 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. Design procedure steps for one way slab slab design steps. One way slab and twofigure 1 way slab in figure 2a slab is supported on two opposite sides only. Slab may be supported on walls or beams or columns. View test prep concrete 3 design of concrete beam and slab twoway slab part 22 from engineerin 101 at royal melbourne institute of technology. 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. A st as distribution bars in longer direction of slab.

In this video deisgn of two way slabs has been covered using is 456. Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement. One way slab being supported on two opposite sides. One way slab design procedure with example design of one. Design of reinforced concrete structures ii two way slabs 8 c. What is the formula for taking load from two way slab for. A monolithic reinforced concrete floor is to be composed of rectangular bays measuring, as shown. Here the ratio of longer span of slab to the shorter span of slab. Design the slab system shown in figure 1 for an intermediate. Here ratio of longer span of slab to the shorter span of slab is greater than 2.

Unless otherwise noted, all referenced table, figure, and equation. Here are the steps for the design procedure for one way slab in steps. Chapter 3 design of rectangular beams and oneway slabs 12. Slabs may be classified into 2 types depending on ratio of larger side to shorter side, its recommended in is 456 to design slabs having lylx ratio greater than 2 as one way slab and slabs having lylx less than 2 as two way slab. Chapter 3 design of rectangular beams and oneway slabs. Calculate factored moment and shear force by considering the onemeter width of the slab. Design of a two way rcc slab structural engineering. The main reinforcement for two way slab are designed in two directions which are xdirection and ydirection. Analysis and design of slabs two way two way edge supported slabs two way slabs. Figure below shows floor plan of a rc beamcolumn slab, with. Step 2 design forces draw panel of slab and indicate maximum design moments, shears and in. Contains all design checks required by the american concrete institute code and all the conditions that must be met during the design process.

In design strips where there are slab bands, reinforcement. I have developed a microssoft excel software for design of a two way rcc slab. Sep 02, 2011 design of reinforced concrete beams 2. The band dimensions must be such that the two way characteristics of the floor system are retained.

The design of interior, edge, and corner columns is explained in the two way flat plate concrete floor slab design example. Twoway slabs supported on beams the critical location is found at d distance from the column, where the supporting beams are stiff and are capable of transmitting floor loads to the columns. This spreadsheet program provides for the design and analysis of posttensioned concrete one way beam and slab systems and two way flat plate slab systems. While the basic expression for one way shear in aci 31805 is the same for narrow beams, wide beams, and slabs, an engineer is permitted to design to higher shear stresses in the latter two cases. Analysis and design of two way slabs page 4 simple beam, uniformly loaded by its share of q. For panels with beams between supports on all sides, relative stiffness of the beams in the 2 perpendicular directions. Analysis and design of twoway slab with beams free download as pdf file. Direct design method ddm for slab systems with or without beams loaded only. Application of limit state method to rectangular beams for flexure, shear, bond and torsion. Steel design steel design software that easily designs or checks steel beams, columns and single span beam columns using the asd and lrfd standards. 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. The two way slab on beams, analyzed as separate elements, appeared overdesigned with unnecessarily high safety factors. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. How to design a twoway slab free download as powerpoint presentation.

Without beams, flat plates and flat slabs tests of flat plate structures indicate that in most practical cases, the capacity is governed by shear. The building is located in seismic zone iii on a site with medium soil. Rectangular beams and oneway slabs page 3 of 9 design of rectangular beams and oneway slabs continued a. Slabs are usually used in floor and roof construction. Example design of two way edgesupported solid slab. Twoway slab analysis and design using equivalent frame method efm. One way solid slabs 50 45 45 40 two way solid slabs 4548 4045 na na beams 35 30 30 26 one way joists 42 38 38 35 typically tendons are located near the bottom fiber at positive moment regions and near the top fiber at negative moment regions with the intent to. Reinforcement detailing of a slab is done based on its support conditions. In a two way slab the slab has to resist the following forces. A rectangular slab is supported by beams at all sides length width two way slab. The same is true for a two way slab or any other floor system. In two way slab, the ratio of longer span l to shorter span b is less than 2.

This condition occur when the slab are supported at four side of the beams or walls and the ratio of long span to short span is equal or less than 2. Please read the lauses mentioned in the video while solving the problem. Difference between one way slab and two way slab simple. 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 way and twoway slabs one way slabs transfer the imposed loads in one direction only. That is, the load factor at which the uls moment equals the moment capacity.

Slab resting on walls or sufficiently deep and rigid beams on all sides. Cross sectional constant defines torsional properties c x. One way and two way slabs one way slabs transfer the imposed loads in one direction only. A slab band wide shallow beam is a thickening of slab along the column line to allow additional tendon drape.

Design of one way and two way slabs, design of staircases. Design the slab system shown in figure 1 for an intermediate floor where the story height 12 ft, column cross sectional dimensions 18 in. Design of a two way rcc slab structural engineering forum. Twoway slabs structural engineering forum of india, sefi. The slab has to carry a distributed permanent action of 1. A six storey building for a commercial complex has plan dimensions as shown in figure 1. All available load test results indicated that the flat plate or flat slab was a most efficient design with an adequate safety factor. The basic design procedure of a twoway slab system has five steps. Concrete 3 design of concrete beam and slab twoway slab. A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. 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. Flat slab system is an important division of concrete floor system. Design of concrete structures 14th edition, 2009, by arthur h.

Bending moment and shear force of two way slab are depend on l y l x ratio and. In this case the structural action of the slab is essentially one way. 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. One way slab one way slabs are such slabs in which the loads are shared only by the shorter direction of the slab. Ce 433, summer 20 slab design example 1 5 design a one. This paper focuses on analysis of two way ribbed and waffle slabs with hidden beams. Analysis of two way ribbed and waffle slabs with hidden beams. What is the design of a one way slab and a two way slab. Two way concretefloor slab withbeams design detailing. Concrete beam design concrete design software that designs oneway flexural members, including beams, oneway slabs and continue reading. Member design reinforced concrete two way spanning slab bs8110 v2015. So, if it is simply supported beam or slab, the effective span of a member that is not built integrally with its.

Twoway concrete slab with beams spanning between supports. The behavior and analysis of two way simply supported concrete composite floor slabs constructed with coldformed steel decking max lee porter iowa state university follow this and additional works at. They may be supported on two opposite sides only fig. Unless otherwise noted, all referenced table, figure, and. The service live load is 100 psf and 4000 psi concrete is specified for use with steel with a yield stress equal to 60000 psi. Rooms two way slabs are continuous with verandah one way slab. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. Based on the stiffness requirement assume suitable depth and calculate the effective span. Oneway and twoway slabs oneway slabs transfer the imposed. Two types of shear may be critical in the design of the flat slabs.

Analysis and design of slabs one way civil engineers pk. Design of a two way slabs for punching shear resistance. Fanella, which appeared in the october 2001 edition of structural engineer magazine. Reinforced concrete design 1 design of slab examples. Use i wsd, ii usd to design the twoway slab shown below, carrying floor finish 30 psf, random wall 50 psf. The following example illustrates the design methods presented in the pca book simplified design reinforced concrete buildings of moderate size and height third edition. Design of slab examples and tutorials by sharifah maszura syed mohsin. Slab supported directly by columns are called flat slab. Analysis and design of twoway slab with beams beam structure. Since 1971, all two way reinforced systems, with or without beams, have been subject to the same integrated analysis and design procedures chapter.

One way slab is supported by two parallel beams or walls. The behavior and analysis of twoway simply supported. The parameter used to define the relative stiffness of the beam and slab spanning in either direction is. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. Equating the center deflections of the short and long strips gives 5544 384 l b ei 1 where qa. How to design a two way slab free download as powerpoint presentation. To attempt to make sure that only ductile failures can occur the aci code limits the maximum steel ratio as following. The ratio lb which is less than 2 is known as two way slab. Twoway concrete floor slab with beams design and detailing.