For example, the minimum slab thickness for a two hour fire rating is 4. Allowable stress design or working stress design wsd 2. Oneway and twoway slabs university of asia pacific. The objective of the study conducted was to identify and address concerns with aci 318 section 9. This example is to be used for educational purposes only. Design of reinforced concrete structures ii two way slabs 1 1. Two way slab design spreadsheet the engineering community. The flexural stiffness of the slab is increased with increasing the thickness of the slab. Twoway joist waffle slab design approach and methodology. The efm solution is also used for a detailed comparison with the analysis and design results of the engineering software program spslab. Two way slab design based on aci 318 11 using finite element method the slab is designed as two way 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. Use the aci 318 direct design method to design an interior bay of a flat plate slab system of multi bay building. In this example deflection will be calculated and checked to satisfy.
Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. The following example illustrates the example building. Oneway and twoway slabs oneway slabs transfer the imposed. These conclusions are further formatted to satisfy the aci code language, since they are to be implemented upon approval by the presiding committee, as a modificationaddition to the existing deflection control provisions of aci 318 section 9. Bending will take place in the two directions in a dishlike fo. Two way slab analyzed by the direct design method 47. Download free excel spreadsheet for concrete design of two way slab, voided biaxial slab, anchorage to concrete, anchorage to pedestal, circular column, concrete column, super. Use i wsd, ii usd to design the twoway slab shown below, carrying floor finish 30 psf, random wall 50 psf and live load 60 psf given.
The solution per ddm can be found in the twoway plate concrete floor system design example. Any applicable errata are included with individual documents at the time of purchase. Analysis and design of slabs two way civil engineers pk. The application of these recommendations is illustrated through a numerical example. Concrete slab design two way slab direct design method. Twoway slab design based on aci 31811 using finite. The slab has to carry a distributed permanent action of 1. Two way slabs direct design method ddm by bilal alzubaidi. Aci318 code provides two design procedures for slab systems. 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 slab analysis and design aci 318 states that a slab system shall be designed by any procedure satisfying equilibrium and geometric compatibility, provided that strength and serviceability criteria are satisfied. Oct 28, 2014 two way slab systems of reinforced concrete. 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 aids for building codes, whose mission was to develop handbook editions in accordance with the aci 318 building code. Its scope includes proposing the inclusion of two new equations.
Voided two way slab design based on aci 318 14 spreadsheet. Slabs are usually used in floor and roof construction. Aci 318 sets out the principles of design for slab shear reinforcement and ma kes specific reference to stirrups and shear heads. Design of concrete structures 14th edition, 2009, by arthur h. Efm is the most comprehensive and detailed procedure provided by the aci 318 for the analysis and design of twoway slab systems where the structure is modeled by a series of equivalent frames interior and exterior on. Twoway flat plate concrete floor system design structurepoint.
Two way slab design as per method 3 aci concrete code. Chapter 3 design of rectangular beams and oneway slabs. Foreword this spreadsheet performs an analysis and design of two way spanning reinforced concrete slab. The proposed slab system must be able to be constructed at a reasonable cost. Pile cap design for piles according to aci 318 08 spreadsheet. Next, the general requirements for twoway slabs in aci 31811. The proposed slab system must meet the current code. Aci 31811 code provides two methods for two way slab design one of which is. Overview punching shear calculation applies to columnsupported slabs, classified as twoway structural systems. 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. One way and twoway slabs one way slabs transfer the imposed loads in one direction only. Ce 403, fall 20 one way slab design 3 4 aci 318 11 referenced pp 2 4 rating. One way slab design procedure with example design of one. For this flat plate slab systems the minimum slab thicknesses per aci 31811 are.
Direct design method the ddm can be utilized for two way slab design only if the criteria in aci 318. Aci 31808 code minimum bars at column for twoway pt slab. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. Ce 403, fall 20 oneway slab design 3 4 aci 31811 referenced pp 2 4 rating. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. Efm is the most comprehensive and detailed procedure provided by the aci 318 for the analysis and design of two way slab systems where the structure is modeled by a series of equivalent frames interior and exterior on. Rectangular beams and one way slabs page 2 of 9 two methods. Minimum thickness of two way slab as per aci 31811 for deflection control. Minimum thickness of two way slab as per aci 318 11 for deflection control.
This method was provided in the american concrete institute aci in 1963 to design two way slabs. 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. Twoway slab design using the coefficient method beam. Twoway slab analysis and design using equivalent frame method efm aci 318 states that a slab system shall be designed by any procedure satisfying equilibrium and geometric compatibility, provided that strength and serviceability criteria are satisfied. Two way slab design as per method 3 minorchord2000 structural 24 oct 07 18. May 31, 2019 foundation design spreadsheet as per aci 318 download link more from my siteconcrete pier isolated deep foundation design spreadsheet toggle navigation about us. Aci provides a minimum steel ratio, min min 3 vvfc f y, but not less than 200fy minimum slab thickness. Rc slab design ec2 worked example bending reinforcement duration. Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement.
They may be supported on two opposite sides only fig. Two way slab design by direct design method as per aci 31811. Download free excel spreadsheet for concrete design. Two way slab design by direct design method as per aci 318 11, step by step procedure and limitations of direct design method for two way slab is presented. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. The reinforced concrete design handbook now provides dozens of design examples of various reinforced concrete members, such as one and two way slabs, beams, columns, walls, diaphragms, footings, and retaining walls. Generally, there are two types of slab which are one way and two way slabs. 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. One way and two way slabs one way slabs transfer the imposed loads in one direction only. Twoway slabs structural engineering forum of india, sefi. Some design engineers consider biaxial moments for twoway slabs and other elements such as corner columns when pushing the lower limits of the code. The deflection of two way slab is based on a number of parameters for example the flexural stiffness of the slab which is the function of slab thickness. Finally, since shear reinforcement is not used in one way slabs, the concrete must be able to. Mar 09, 2019 direct design method ddm is the preferable method for designing the conventional two way slab system and other floor system like flat slabs and flat plate slab system.
Flexural design of twoway slabs following the direct design method and the equivalent frame method is shown, and the seminar concludes with a design example of a reinforced concrete flat plate. 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. Interactive calculation templates to us codes aci 318 11 nothing beats a great template preface content interactive design aids in accordance to us codes aci 318 11, aisc 14th edition and asce710 guidelines of use. 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. The aci coefficient method is declared obsolete because the end results are more conservation more factor of safety. It would seem prudent that, if the designer is trying to get down to the halfinch, shear would be checked for the biaxial condition. Concrete design aci 318 design of corbel as per aci 318 11 chapter 11 corbel design av h vu nuc d co ah 2 3 d asc system. The service live load is 100 psf, and 4000 psi concrete is specified for use with steel with a yield stress equal to 60,000 psi. Chapter 3 design of rectangular beams and oneway slabs 12. In lieu of detailed calculation for deflections, aci 318 code gives minimum. A reinforced concrete slab is built integrally with its supports and consists of two equal spans, each with a clear span of 15 ft. Twoway slab design based on aci 31811 using finite element. Posttensioned oneway slab pennsylvania state university.
In this example, an interior strip of a flat plate floor system is designed and detailed for the effects of gravity loads according to aci 31805. For consistency, many of the numerical examples are based on a fictitious sevenstory reinforced concrete building. Twoway concrete floor slab with beams design and detailing. The codes governing the design of the one way slab will be aci 318 02 and ibc 2003.
Design criteria there are three criteria which must be considered for the design of a conventional one way slab system. Examples to aci, aisc and asce interactive calculation templates to us codes u. 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. Shear strength of beamless slabs usually a controlling factor. The dimensions of an interior bay are shown in figure 1.
Distinction of twosystems from oneway systems is given by aci 31814 r 8. Design the slab, following the provisions of the ack code. Bending will take place in the two directions in a dishlike form. Some design engineers consider biaxial moments for two way slabs and other elements such as corner columns when pushing the lower limits of the code. Nilsons concrete textbook, design of concrete structures, has some nice charts for two way slabs, using the ratio of the sides and the slab end conditions as the entering arguments. Nilsons concrete textbook, design of concrete structures, has some nice charts for two way slabs, using the ratio of the sides and the slab. However, when i look at the code minimum design topbottom reinforcement plans, i see the same code minimum bars detailed at the top and bottom in many locations whereas i would expect to see minimum bars only pver the top. Aci 318 provides two alternative methods for designing two way slabs for concrete, the equivalent frame method. Reinforced concrete design 1 design of slab examples. A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. Using aci 31814 minimum slab thickness for twoway construction. The oneway slab is deflected in one way direction and primary reinforcement is placed in one direction whereas the twoway slab deflect in two directions and primary reinforcement placement is in two directions. Two way slab design using the coefficient method free download as pdf file.
For example, the minimum slab thickness for a twohour fire rating is 4. Aci coefficient method for analysis of twoway slabs. Distinction of two systems from one way systems is given by aci 318 14 r8. Aci 318 19 sections on one way shear and two way punching shear consolidate what were previously a wide range of equations. Minimum depth of 2 way slab for deflection control. Assume partitions cannot be damaged by deflections. Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need to be taken into account to reduce the complexity of calculations needed when. Aci 318 permits the use of direct design method ddm and equivalent frame method efm for the design of two way slab systems. The coefficient method is a method of designing two way slabs that are supported by edge beams.
Two way slab design based on aci 318 11 using finite element method. When the ratio of long span to short span is less than. Aci 31811 code provides two methods for two way slab design one of which is direct design method. This section will explain how the direct design method is used. This web seminar follows up on the october 22nd web seminar.
Errata are not included for collections or sets of documents such as. The equivalent frame method efm presented in aci 31814 is illustrated to analyze and design twoway waffle slab system. The corner reinforcement can be arrange in two way as shown below. Design the slab following the provisions of the aci code. Reinforced concrete, 2014, 9th edition, aci 318 11 code edition, by jack c. The reorganized aci 31814 code iowa state university.
Rectangular section deflection check to aci 318m02 spreadsheet. Slabs can be designed by direct design method known as ddm and another method for design is coefficient method which is the easier one. 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. Fanella, which appeared in the october 2001 edition of structural engineer magazine. Aci 318 states that a slab system shall be designed by any procedure satisfying equilibrium and geometric compatibility, provided that strength and serviceability criteria are satisfied.
Design of reinforced concrete structures ii twoway slabs. Design the 4 marked slab panels of an ordinary house. In this article, it is assumed that slab thickness is determine but calculation of. Aci 31819 sections on oneway shear and twoway punching shear consolidate what were previously a wide range of equations. Minimum thickness for solid one way slabs unless deflections are calculated for slab not supporting or attached to partitions or other construction likely to be deamaged by large deflection. Minimum thickness of two way slab as per aci 31811 for. Oneway simply supported slab, span length, l 10 ft normal. Twoway concrete slab with beams spanning between supports. Hi, i am designing a two way pt slab with aci 318 08. Finally, since shear reinforcement is not used in oneway slabs, the concrete must be able to resist the maximum shear force. They also provide a method to include size effect in shear design to avoid issues wherein increasing a members size can reduce the design unit shear strength of a section. This guide presents analysis methods, design procedures, slab reinforcement and detailing practices, and strength and serviceability. 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. This writing i defines the different conditions for punching shear calculation, ii presents the.
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