Two way flat plate slab design example pdf

Design of two way floor slab system comparison of one way and two way slab behavior one way slabs carry load. 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. Summary and comparison of twoway slab design results. This example is to be used for educational purposes only. How to design a flat slab, step by step explained in this video.

The program covers wide range of two way slab systems and can be used for more complex slab layouts. Unless otherwise noted, all referenced table, figure, and equation numbers are from these books. Can be used for larger spans with relatively higher cost and higher deflections oneway joist system suitable span 6 to 9m with ll 46knm2. Deep ribs, the concrete and steel quantities are relative low expensive formwork expected. In flat plate floors, slab column connections are subjected to high shear stresses produced by the transfer of axial loads and bending moments between slab and columns. The flat slab is a two way reinforced structural system that includes either drop panels or column capitals at columns to resist heavier loads and thus permit longer spans. Analysis and design of twoway slabs page 1 chapter 3. Analysis and design of slabs two way civil engineers pk. Flatplate and flatslab roofs concrete construction. Design of a two way slabs for punching shear resistance. Reference 5 focused on analysis of two way ribbed slabs with. Analysis of two way ribbed and waffle slabs with hidden beams.

For the solution per ddm, check the flat plate example. Comparison of oneway and twoway slab behavior oneway slabs carry load in one direction. Shear design in flat plates and flat slabs when twoway slabs are supported directly by columns, as in flat slabs and flat plates, or when slabs carry concentrated loads, as in footings, shear near the columns is of critical importance. Two way slab beam structure column free 30day trial. The lateral loads are independently resisted by shear walls. The design bending moment of two way restrained slab can be calculated as follows. The design shear force can be reduced to account for the loads applied inside the outer perimeter. The following example illustrates the example building. Founded in 1904 and headquartered in farmington hills, michigan, usa, the american concrete institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensusbased standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design. Optimum cost design of reinforced concrete slabs using 543 continuous slab that depends on the type of slab supports.

Two way slab design by direct design method as per aci 31811. Load transfer in a one way slab, b two way slab nilson fig. Flat slab for short span lengths and light distributed weight e. 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. Bending of twoway slab m 2 bending of slabs along both x and y directions. 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. The pca computer program pcaslab can be used to expedite the design of different slab systems.

In twoway slabs shorter direction strip carry greater %age of load. Oct 28, 2014 flexural design of two way 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. Design of concrete structures 14th edition, 2009, by arthur h. Twoway slabs have two way bending unlike oneway slab. The twoway slab is designed for both the directions as it bends in both directions. This condition occur when the slabs are connected monolithically with support. 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. 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. How to design a two way slab free download as powerpoint presentation.

In this example deflection will be calculated and checked to satisfy project deflection. Interior bay dimensions 20 24 this example is to be used for educational purposes only. In this example, an interior strip of a flat plate floor system is designed and detailed for the effects of gravity loads. Design of reinforced concrete structures ii twoway slabs 1 1. Oneway and twoway slabs university of asia pacific. The flat plate is a two way reinforced concrete framing system utilizing a slab of uniform thickness, the simplest of structural shapes. Twoway flat slab concrete floor with drop panels system. Flat plate concrete floor system does not use beams between. 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. 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. A reinforced concrete slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so. The twoway slab shown in figure below has been assumed to have a thickness of 7 in. Flat plate reinforce concrete slab design architectural engineering senior thesis washington park condominiums final report mt. 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 1 knm2, and unfactored live load 1.

The same is true for a two way slab or any other floor system where. Figure 5 sample calculations using ddm from twoway flat plate concrete slab floor analysis and design. This design is a complete flat plate slab design, from shear to bending along with design of columns and shear head reinforcement. Accordingly, main reinforcement is required in the two directions. In this article, it is assumed that slab thickness is determine but calculation of. Traditionally, the term flat slab has represented a solid uniform depth slab with thicker drop panels supported upon mushroom head conical capitals with round columns or various prismatic brackets with square columns. In two way slabs shorter direction strip carry greater %age of load. Dissatisfaction with results of previously required procedures of analysis and design for twoway slabbeam systems was the original reason for the massive research upon twoway slab systems begun about 1955. Twoway flat plate concrete floor system design structurepoint. The example presented here is for twoway posttensioned design. Introduction in reinforced concrete construction, slabs are used to provide flat, useful surfaces.

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. Reinforced concrete, 2014, 9th edition, aci 31811 code edition, by jack c. Ultimate behavior of oneway spanning slab linear elastic analysis methods such as moment distribution are linear elastic methods. Flat plates flat slabs waffle slabs twoway edgesupported slabs twoway edgesupported slabs.

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. 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. Analysis of flat sanalysis of flat sllabab moment division example 6000 6000 6000 6000 6000 5000 layout of building 7000 5000 a floor slab in a building where stability is provided by shear walls. 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. Design of twoway floor slab system comparison of oneway and. Flat plate with spandrel beams and flat slab two way beams supported slab. Aci 31811 code provides two methods for two way slab design one of which is direct design method. Comparison of one way and two way slab behavior one way slabs carry load in one direction. Oneway and twoway slabs oneway slabs transfer the imposed. Flat slab analysis, design and detailing pdf civil engineering.

A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. The flat slab is a twoway reinforced structural system that includes either drop panels or column capitals at columns to resist heavier loads and thus permit longer spans. One way slab design how to design one way slab daily civil. The basic design procedure of a twoway slab system has five steps. The dimensions of an interior bay are shown in figure 1. The twoway slab will deflect in a dish or saucerlike form under the action of loads. The slab has to carry a distributed permanent action of 1. The following example illustrates the design methods presented in the pca book simplified design. Here the slab or slab panel is supported along its four edges by relatively deep, stiff, monolithic concrete beams or walls. Flat slab types of flat slab design and its advantages. Flat plate concrete floor system does not use beams between columns or. Both vertical and horizontal loads may be transferred from one member to another properly if the beams and slabs are designed succesfully. Slab resting on walls or sufficiently deep and rigid beams on all sides. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types.

The ratio of the total costs was found to be within the range 1. Load transfer in a oneway slab, b twoway slab nilson fig. Analysis and design of slabs by the finite element method users manual, 1998. Time saving design aids two way slabs page 1 of 14 the following example illustrates the design methods presented in the article. Design of reinforced concrete structures ii twoway slabs. The design i am going to share with you today is design of flat plate slab as by definition.

While designing structure layout and during implementation using sub frame method, one way to evaluate midpanel deflection is to use at least two parallel. The design bending moment of twoway restrained slab can be calculated as follows. For the purposes of design, a typical flat slab panel is divided. Flat slabs are two way slabs supported by pointlike supports. Two way punching shear concept explained and flat plate example csa a23. Aug 30, 2014 the design i am going to share with you today is design of flat plate slab as by definition. Distribute moments transverse at critical sections to column and middlestrip and if. Comparison of oneway and twoway slab behavior economic choices oneway slab on beams suitable span 3 to 6m with ll 35knm2. Flat plate slabs therefore, the following figure is a more practical and generally acceptable layout. Slabs are usually used in floor and roof construction. Punching of flat slabs design for shear at th e column heads 12. 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. Reinforced concrete design 1 design of slab examples.

Corners of the twoway slab lift up if the slab is not cast monolithically with the supports wallsbeams. Jul 12, 2018 how to design a flat slab, step by step explained in this video. Reference 5 focused on analysis of twoway ribbed slabs with. The example presented here is for two way posttensioned design. Plan view of floor system assume partitions will not be damaged by deflections. Contains all design checks required by the american concrete institute code and all the conditions that must be met during the design process. Direct design method, that could have been named the direct analysis method because it determines or prescribes moments for different parts of the slab panel without the need to conduct structural analysis, is explained in the following sections. A flat plate is a one or twoway system usually supported directly on columns or load bearing walls. Different types of shear reinforcement used at column heads.

The slab is for an offi ce where the specifi ed load is 1. How to design a twoway slab free download as powerpoint presentation. Slab design in case of oneway slabs, the reinforcement against bending is estimated only for short. In this example, the calculating value of the effective depth d v is equal to the effective depth d minus the concrete cover c on the bottom surface of the slab. Pdf design of flat slab worked example mohamed hussein. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3.

The thickness of a twoway, posttensioned slab for typical hotel. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. The flat plate is a twoway reinforced concrete framing system utilizing a slab of uniform thickness, the simplest of structural shapes. All available load test results indicated that the flat plate or flat slab was a most efficient design with an adequate safety factor. Fundamentals of post tensioned design for buildings. Twoway restrained slab if the slabs consist more than one panel or corner of the slab are prevent against lifting it is define as twoway restrained slab. Framing dead load selfweight superrimposed dead load 25 psf partitions, me, misc. Flat plate slab is that in which slab is directly supported on columns without column capital, drop panel or beams.

To see their result for this slab we will find the load factor. The slab is 300 mm thick and columns are 400 mm square. Twoway concrete slab with beams spanning between supports. Twoway flat slab concrete floor with drop panels system analysis and design design the concrete floor slab system shown below for an intermediate floor considering partition weight 20 psf, and unfactored live load 60 psf. Section aa in the figure shows the beam cross section. Below is a partial floor framing plan, such as for a hotel. Equivalent frame method efm 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. This method was provided in the american concrete institute aci in 1963 to design twoway slabs carried by steel beams, deep beam, or walls. The basic design procedure of a two way slab system has five steps. The following example illustrates the design methods presented in aci 31805 and ibc 2003. Use the aci 318 direct design method to design an interior bay of a flat plate slab system of multi bay building.

Department of mechanics, materials and structures english. Aci318 code provides two design procedures for slab systems. The output of the program for the slab in the example is shown in the following pages. Slab load transfer to the beams and then in to the columns. This pdf file contains a chapter of 23 pages with various aspects of flat slabs including four example of flat slab design. Bending will take place in the two directions in a dishlike form.

Design of reinforced concrete structures ii two way slabs 1 1. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. Flat slab analysis, design and detailing pdf civil. For flat plates and slabs the column connections can vary between. Shear design in flat plates and flat slabs when two way slabs are supported directly by columns, as in flat slabs and flat plates, or when slabs carry concentrated loads, as in footings, shear near the columns is of critical importance. 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 determination of exact moments in twoway slabs with various support conditions is mathematically formidable and not suited to design. Flat plates flat slabs waffle slabs two way edgesupported slabs two way edgesupported slabs. Beams, see lecture 3 punching shear requirements e. Tests of flat plate structures indicate that, in most practical cases, the capacity is governed by shear. Approximately, 75% of the tendons in each direction are located in the column strips, as shown, the remainder being uniformly spread across the middle strip regions. Two way slabs have two way bending unlike one way slab. Definition of beamtoslab stiffness ratio, accounts for.