Slab resting on walls or sufficiently deep and rigid beams on all sides. One way and twoway slabs one way slabs transfer the imposed loads in one direction only. May 20, 2020 the slab is known as two way slab when the ratio of the long span is less than 2 and infloor of multistory buildings this type of slabs are mostly used. Yield line pattern for the general case of two way slab. 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. The following example illustrates the example building. Direct design method limitations there is a minimum of three continuous spans in each direction aci 31814 8. Here are the steps for the design procedure for one way slab in steps. Design two way slab as shown below to carry the live load 300kgm 2 fc 240 kgcm 2, f y 2,400 kgcm 2 3.
Now, let us move toward the design of one way slab. Determine whether the slab is one way or two way slab by calculating aspect ratio. Rectangular beams and one way slabs page 2 of 9 two methods. Allowable stress design or working stress design wsd 2. One way slab design procedure with example design of one. The output of the program for the slab in the example is shown in the following pages. Slab thickness, h clear span of the slab, ln long span ratio of long to short span. Flat slab design includes flexure worked example exercise punching shear.
If the ratio is greater than 2, it is identified as a one way slab. How to design a twoway continuous slab as per indian standards. Ec2 webinar autumn 2016 lecture 5 2 designing for shear in slabs when shear reinforcement is not required e. They may be supported on two opposite sides only fig. Recent development in reinforced concrete slab analysis, design, and. Here ratio of longer span of slab to the shorter span of slab is greater than 2. Quick guide to design of one way slab with is code 456. This system consist of both one way and two way slabs. In lieu of detailed calculation for deflections, csa a23. Two way concrete slab having 100mm thickness and dimension as shown in figure below, supported deal load of 6knm2 and live load of 3knm2 wu 1. Reinforced concrete design 1 design of slab examples. Ce 433, fall 2006 slab design example 1 6 design a one way slab for an exterior bay of a multistory office building using the information specified below. Mathcad program and show its impact on teaching the analysis and design of twoway ribbed slabs.
Design of slab examples and tutorials by sharifah maszura syed mohsin example 2. Keep in mind, while analyzing or designing slab, we always take the width of the slab as one meter. Aait, school of civil and environmental engineering reinforced concrete ii. 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. Two way restrained slab if the slabs consist more than one panel or corner of the slab are prevent against lifting it is define as two way restrained slab. Two way slab design static equilibrium of twoway slabs total moment in both beams full load was transferred eastwest by the planks and then was transferred northsouth by the beams. Concrete slab design two way slab direct design method. Member design reinforced concrete two way spanning slab. Aci 318 provides two alternative methods for designing twoway slabs for concrete, the equivalent frame method. Wikiengineer structural two way slab direct design. Two way slabs have two way bending unlike one way slab. This section will explain how the direct design method is used. Basic steps in two way slab design choose layout and type of slab.
Proper use of this document includes periodically checking for errata for the most uptodate. Example for finding for panel 1 for panel 5 so h to be used should be. All the design procedure are explained under the topic design of two way slab. Member design rc two way spanning slab 030915 consulting e n g i n e e r s all beams beam y sag beam y hog beam x sag beam x hog made by date chd. Reinforced concrete design s u r a n a r e e institute of engineering university of technology school of civil engineering design of two way slab moment coefficient method load transfer from two way slab bar detailing design example slab on ground design of slabs 2 g g b b b b b b l s. If the longer span of the slab is l y and the shorter span is l x, then for a two way slab, l y l x is less than 2. Alternate design method design procedure of twoway slabs. Columns are 30cm x 30cm, equivalent partitions load250 kgm2, live load 400kgm2, 280 kgcm2 4200 kgcm2, slab thickness 16cm 11. If ratio of longer span to shorter span is less than 2, then it is two way slab, otherwise one way slab. Shear due to loads always must be less than the shear strength of concrete. Columns are 30cm x 30cm, equivalent partitions load250 kgm2, live load 400kgm2, 280 kgcm 2 4200 kgcm 2, slab thickness 16cm. European commission joint research centre institute for the protection and security of the citizen contact information address. A system where a two way slab is continuous with a one way slab or vice versa is called a mixed slab system.
Chapter 3 design of rectangular beams and oneway slabs. Twoway concrete slab on beams floor analysis and design aci. Framed, twoway, conventionally reinforced, concrete flat. 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. The design bending moment of two way restrained slab can be calculated as follows. Direct design method ddm two way slabs satisfying the limits in aci 31814 8. A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. Assume partitions cannot be damaged by deflections. Joint research centre, via enrico fermi 2749, tp 480, 21027 ispra va, italy. Design of slabs 2 suranaree university of technology. Introduction in reinforced concrete construction, slabs are used to provide flat, useful surfaces. Please read the lauses mentioned in the video while solving the problem.
The slab is supported on beams of size 225 x 500 mm spaced at 4. Design procedure steps for one way slab slab design steps. Design the steel tension bars for design strip shown perpendicular to. Eurocode 2 is less restrictive than existing codes. Hence, the reinforcement is provided along shorter and longer sides of the slabs.
Thickness requirements factors affecting deflection of a slab. Twoway concrete floor slab with beams design and detailing csa. Job title xx plan layout multispan lx multispan ly floor plate longer span, ly 6. Design the slab following the provisions of the aci code. Determine the minimum thickness of slab from serviceability criteria of deflection control.
How to design a twoway continuous slab as per indian. In case of slabs thin members, no need of even minimum shear reinforcement. Teaching twoway ribbed slab analysis and design using. Plan view of floor system assume partitions will not be damaged by deflections. Design of reinforced concrete structures ii twoway slabs. Cross sectional constant defines torsional properties c x. Design of reinforced concrete structures ii two way slabs 8 c. Chapter 3 design of rectangular beams and oneway slabs 12. The two way slabs distribute the loads in both directions. Reinforced concrete design 1 design of slab examples and. May 22, 2020 two way slabs are supported on unyielding supports on all four sides and the ratio of longer span to shorter span is less than 2. Analysis and design of slabs two way civil engineers pk.
The slabs having supports on all sides acts as two way slab figure 1b and 2 b where there are bending about the both axes, but acts as one way slab where lb. Design of concrete structures 14th edition, 2009, by arthur h. Flat plate l n30 flat plate with spandrel beams l n33 flat slab l n33 flat slab with spandrel beams l n36 two way beamsupported slab l n33. One way slab being supported on two opposite sides only leads to the structural action in single direction.
Two way slab design spreadsheet spreadsheet, slab, hospital. Eurocode 2 should result in more economic structures than bs 8110. Two way concretefloor slab withbeams design detailing. The following table may be used to determine minimum thickness of various two way slabs based on deflection. In this video deisgn of two way slabs has been covered using is 456. Cornell university, david darwin university of kansas, charles dolan university of wyoming 3. Two way concrete floor slab with beams design and detailing csa. The program covers wide range of two way slab systems and can be used for more complex slab layouts. Shear strength of slabs in two way floor systems, the slab must have adequate thickness to resist both bending moments and shear forces at critical section. Twoway slab example 1 beam structure classical mechanics.
For those who do not know what are the des ign requirements of a slab. The two classifications are one way slab and two way slab. Two way slabs prestressing tendons cgs at top 48 mm at bottom 48 mm nonprestressing reinforcement cover at top 25 mm at bottom 25 mm 143 design criteria 143. For the direct design method moments are found using a simplified. The same is true for a two way slab or any other floor system.
Use the direct design method to design the two way slab for the design strip in the direction shown. Two way slabs supported on beams two way slabs without beams shear reinforcement in two way slabs without beams. 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. Design of 2 way slabs beam structure prestressed concrete. Slab is checked for deflection shear and development length. Design of two way edgesupported slab by coefficient method a two way edgesupported concrete floor panel of 21 x 26 ft is supported by four beams of 12 in. Design of two way slab moment coefficient method load transfer from two way slab bar detailing design example slab on ground. Pdf reinforced concrete twoway slabs have evolved in the past century. Design of reinforced concrete structures ii twoway slabs 1.
Rooms two way slabs are continuous with verandah one way slab. Cover to outer tension reinforcement resisting sagging. Design of reinforced concrete structures ii two way slabs 1. Pdf twowayconcretefloorslabwithbeamsdesigndetailing. Under the action of loads, the two way slab will deflect in a dish or saucerlike form and if the slab is not cast monolithically with the supports like walls or beams, corners of the two way. Nov 30, 2018 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.
Member design reinforced concrete two way spanning. One way slabs are such slabs in which the loads are shared only by the shorter direction of the slab. 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. Continuous one way slab figure 1 shows a clear area of 12 m x 8. Minimum suggested thickness h for two way slabs two way slab system. The graphical and text results will be provided from the spslab model in a future revision to this document. Aci318 code provides two design procedures for slab systems. If the minimum slab thickness specified by aci is not used, then as was the case with one way slabs, joists and beams, the actual immediate and longterm deflections must be calculated per the. For the given data, design strip 1 2 34 of the two way slab for flexure. Pdf reinforced concrete two way slabs have evolved in the past century.
Oct 23, 2019 two way slab design spreadsheet this spreadsheet performs an analysis and design of two way spanning reinforced concrete slab. The same is true for a two way slab or any other floor system where. Twoway concrete slab with beams spanning between supports. Two way slab design by direct design method as per aci 31811. Analysis and design of twoway slabs page 1 chapter 3. Time saving design aids two way slabs page 6 of 14 the pca computer program pcaslab can be used to expedite the design of different slab systems. Generally, there are two types of slab which are one way and two way slabs. Select representative 1 m wide design stripstrips to span in the short direction, as. The eurocodes are logical and organised to avoid repetition. A reinforced concrete slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so. Use of the eurocodes will provide more opportunity for designers to work throughout europe. Jan 10, 2016 design of reinforced concrete structures ii two way slabs 10 example 1. Analysis and design of slabs two way two way edge supported slabs two way slabs. Design of twoway floor slab system comparison of one way and two way slab behavior one way slabs carry load.
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