Two way slab design example aci

Aci 31811 code provides two methods for two way slab design one of which is. Reinforced concrete design 1 design of slab examples and. The twoway slab shown in figure below has been assumed to have a thickness of 7 in. Using aci 31814 minimum slab thickness for twoway construction. American concrete institute, aci 318, 2005 this equation can be found in aci 318. Design of reinforced concrete structures ii two way slabs 1 1. Two way slab design as per method 3 aci concrete code. In this article, it is assumed that slab thickness is determine but calculation of. To comply with aci 318, should a designer check punching shear stress with the simultaneous biaxial moments reported by such a model. Framing dead load selfweight superrimposed dead load 25 psf partitions, me, misc. One way slab design how to design one way slab daily civil.

The same is true for a two way slab or any other floor system where. If you continue browsing the site, you agree to the use of cookies on this website. The same is true for a twoway slab or any other floor system. Rectangular beams and one way slabs page 2 of 9 two methods. Basic steps in twoway slab design choose layout and type of slab. Chapter 3 design of rectangular beams and oneway slabs. Design criteria there are three criteria which must be considered for the design of a conventional one way slab system. Type of slab is strongly affected by architectural and construction considerations. 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. Nov 27, 20 one way slab design criteria with design example according to aci code slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. It tends to shear off the member along that plane, in. Two way slab design based on aci 31811 using finite element method. This case occurs when the twoway slab is supported by beams on all four sides.

Analysis of two way ribbed and waffle slabs with hidden beams. Twoway slab design based on aci 31811 using finite element method. Use the aci 318 direct design method to design an interior bay of a flat plate slab system of multi bay building. This spreadsheet is an extremely efficient tool and allows to quickly design two way slabs to aci code.

The basic design procedure of a twoway slab system has five steps. The proposed slab system must be able to be constructed at a reasonable cost. The loads from the slab are transferred to all four supporting beams, which, in. The ratio of the total costs was found to be within the range 1. The following example illustrates the design methods presented in aci 31805 and ibc 2003. This method was provided in the american concrete institute aci in 1963 to design twoway slabs carried by steel beams, deep beam, or walls. In flatplate floors, slabcolumn connections are subjected to high shear stresses produced by the transfer of axial loads and bending moments between slab and columns. 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 analysis and design using equivalent frame method efm. This lecture is continuation of previous lecture and. Load transfer in a oneway slab, b twoway slab nilson fig. Therefore if section 5 gave a factor for the twoway slab in question of 0. Reference 5 focused on analysis of twoway ribbed slabs with.

Bending will take place in the two directions in a dishlike form. Calculates bending moments using aci coefficients, and determines the required reinforcingbar spacing for continuous one way slabs. 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 twoway slab. 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. Slab shear strength twoway shear check the adequacy of slab thickness for punching shear twoway shear at an interior column figure 4. This example goes through the design of a simplysupported oneway slab on beams. 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. Aci 31811 code provides two methods for two way slab design one of which is direct design method. Twoway concrete floor slab with beams design and detailing. Slabs can be designed by direct design method known as ddm and another method for design is coefficient method which is the easier one. What is the different between one way shear and two way. I could not find aci design specifications for twoway singlespan slab simply supported on all sides. Wikiengineer structural two way slab direct design.

Twoway slab design based on aci 31811 using finite element. One way shear or beam shear is experienced or resisted by a single plane for example in beams and slabs. 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. The same is true for a two way slab or any other floor system. The example presented here is for twoway posttensioned design. Rectangular beams and oneway slabs page 2 of 9 two methods. Example slab a flat plate floor system with panels 24 by 20 ft is supported on 20 in. The dimensions of an interior bay are shown in figure 1. Design of two way slabs by coefficient method slab is one of the basic parts of a building. Deep ribs, the concrete and steel quantities are relative low expensive formwork expected. The codes governing the design of the one way slab will be aci 31802 and ibc 2003. The coefficient method may be the simplest, easiest and the quickest approach for the design of twoway slab supported by edge beam on all slab sides.

In twoway slabs shorter direction strip carry greater %age of load. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. 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. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. The codes governing the design of the oneway slab will be aci 31802 and ibc 2003. 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. It should be noted that twoway prestressed slab s have the f ollowing advantages over the oneway prestressed slabs with transverse beams. Jul 10, 2017 this example goes through the design of a simplysupported one way slab on beams.

Calculates bending moments for continuous rectangular or tshaped beams using aci coefficients and determines the required number and size of reinforcing bars. 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. Reinforced concrete, 2014, 9th edition, aci 31811 code edition, by jack c. Ptc mathcad prime worksheets directory civil engineering. Basic steps in two way slab design choose layout and type of slab. 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. Twoway slabs have two way bending unlike oneway slab. 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. Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement. The solution per ddm can be found in the twoway plate concrete floor system design example. Next, the general requirements for twoway slabs in aci 31811. With the advent and popularity of finite element analysis software, engineers can create sophisticated models of twoway slabs supported by columns. 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.

A single slab with twoway reinforcement rebars will be analyzed with rcsolver. Twoway slab design based on aci 31811 using finite. Two way slab design to aci free download and software. Analysis and design of slabs two way civil engineers pk.

It can be used by both practicing engineers and students. Plan view of floor system assume partitions will not be damaged by deflections. Comparison of oneway and twoway slab behavior economic choices oneway slab on beams suitable span 3 to 6m with ll 35knm2. In two way slabs shorter direction strip carry greater %age of load. 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 are usually used in floor and roof construction.

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 twoway slab. Two way slab design 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. Twoway slabs structural engineering forum of india, sefi. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. Section aa in the figure shows the beam cross section. Method uses a set of coefficients to determine the design moment at critical sections. For uniformly distributed loads of w per square foot of the slab, each strip acts approximately like a simple beam uniformly loaded by its share of w. Unless otherwise noted, all referenced table, figure, and equation numbers are from these books. Two way slab design spreadsheet the engineering community.

Apr 18, 2019 this spreadsheet performs an analysis and design of two way spanning reinforced concrete slab. Fanella, which appeared in the october 2001 edition of structural engineer magazine. This normally is taken critical at a distance equal to depth of member from the support. The example presented here is for two way posttensioned design.

Design of reinforced concrete structures ii twoway slabs 1 1. 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. Two way slab design by direct design method as per aci 31811. Two way slab design as per method 3 minorchord2000 structural 24 oct 07 18. The following example illustrates the example building.

Two way slab design based on aci 31811 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. 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. Design of twoway slabs for oneway shear and for twoway shear. Chapter 3 design of rectangular beams and oneway slabs 12. Two way slabs have two way bending unlike one way slab. Twoway flat plate concrete floor system design structurepoint. Can be used for larger spans with relatively higher cost and higher deflections oneway joist system suitable span 6 to 9m with ll 46knm2. Twoway slab system that do not meet the limitations of the aci code. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. 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. The slab has to carry a distributed permanent action of 1. The proposed slab system must meet the current code. Accordingly, main reinforcement is required in the two directions. This lecture is continuation of previous lecture and elaborates how the excel, a powerful.

Assume partitions cannot be damaged by deflections. With the advent and popularity of finite element analysis software, engineers can create sophisticated models of two way slabs supported by columns. Slab being the first element to be designed has pretty much importance as the whole structural design is based on the design of slab. 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. Allowable stress design or working stress design wsd 2. Twoway flat plate concrete floor system analysis and design. A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. Design of reinforced concrete structures ii twoway slabs. In this example deflection will be calculated and checked to satisfy.

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