Framing dead load selfweight superrimposed dead load 25 psf partitions, me, misc. In two way slabs shorter direction strip carry greater %age of load. 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. Next, the general requirements for two way slabs in aci 318 11 chapter, including provisions. One way slab design and analysis for reinforced concrete. Bending will take place in the two directions in a dishlike form.
Structural design highlights of aci 31819 part 2 of. 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. 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. Design of reinforced concrete structures ii two way slabs 1 1. Finally, since shear reinforcement is not used in one way slabs, the concrete must be able to resist the maximum shear force. The proposed slab system must meet the current code. Slab design example design a oneway slab for an interior bay of a. Ce 403, fall 20 one way slab design 3 4 aci 318 11 referenced pp 2 4 rating. 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. The design of reinforced concrete structural members may be done by two different methods. The critical section for oneway shear extends across the width of the footing at a distance d from the face of the loaded area see loaded area. For those who do not know what are the des ign requirements of a slab. The proposed slab system must be able to be constructed at a reasonable cost. In case of slabs thin members, no need of even minimum shear reinforcement.
With the advent and popularity of finite element analysis software, engineers can create sophisticated models of two way slabs supported by columns. Introduction concrete slabs on grade are a very common type of concrete construction. They are projections from wall face of lintel beams or floor slabs. Oneway and two way slabs one way slabs transfer the imposed loads in one direction only. The second step is to calculate the maximum factored moment, mu, that the slab will experience. The tensile strength of concrete is neglected in flexural strength calculations aci sec. 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. Chapter 1 designfor aci 31808 table 11 list of symbols used in the aci 31808 code shear strength reduction factor for lightweight concrete angle of compression diagonals, degrees 1.
Rc one way slab design aci318 strength of materials. Design of reinforced concrete structures ii twoway slabs. Examples to aci, aisc and asce interactive calculation templates to us codes u. Posttensioned oneway slab pennsylvania state university. The contractor shall provide lap splices in conformance with aci 318 14. They may be supported on two opposite sides only fig. The slab is supported on beams of size 225 x 500 mm spaced at 4. Comparison of concrete two way slab analysis and design methods a slab system can be analyzed and designed by any procedure satisfying equilibrium and geometric compatibility.
Chapter 3 design of rectangular beams and oneway slabs 12. Design a oneway slab for an interior bay of a multistory office building using the information specified. A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. For consistency, many of the numerical examples are based on a fictitious sevenstory reinforced concrete building. 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.
Minimum thickness of beams and one way slabs values given in this table shall be used directly on members with normalweight concrete and grade 60 reinforcement. 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. Oneway simply supported slab, span length, l 10 ft normal. The output of the program for the slab in the example is shown in the following pages.
To comply with aci 318, should a designer check punching shear stress with the simultaneous biaxial moments reported by such a model. Rectangular beams and oneway slabs page 3 of 9 design of rectangular beams and oneway slabs continued a. Some recent problems in applying aci 318 code deflection criteria. Oneway solid slabs are designed as rectangular sections subjected to shear and moment. Twoway concrete slab on beams floor analysis and design. Design of oneway reinforced concrete slabs class notes and examplepage 1 of 6 notes on designing oneway slabs aci 318 ch. Slab is checked for deflection shear and development length. Section 2 describes the detailed optimum design problem. 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 corbel width, b 14. Aci 318 08 design of retaining wall with counterfort.
According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. Oneway and twoway slabs university of asia pacific. Finally, since shear reinforcement is not used in oneway slabs, the concrete must be able to resist the maximum shear force. The basic design procedure of a two way slab system has five steps. 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. Distinction of twosystems from one way systems is given by aci 318 14 r8. One, called working stress design wsd, is based on the straightline distribution of compressive stress in the concrete fig. Design of isolated square and rectangular footings aci 31814.
Analysis and design of slabs one way civil engineers pk. Oct 28, 2014 the minimum thickness requirements of aci 318 11, based on deflection considerations, is covered. Figure 1 twoway slab with beams spanning between all supports. Brief contents preface xv 1 introduction 1 2 flexural analysis of beams 35 3 strength analysis of beams according to aci code 65 4 design of rectangular beams and one way slabs 82 5 analysis and design of t beams and doubly reinforced beams 112 6 serviceability 154 7 bond, development lengths, and splices 184 8 shear and diagonal tension 223 9. 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. Design criteria there are three criteria which must be considered for the design of a conventional one way slab system. In this section, objective function, design constraints, and design variables are described for one way rc slabs.
Rc one way slab design aci318 free download as pdf file. 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. One way slab is normally designed for gravity load only. Accordingly, main reinforcement is required in the two directions. One way simply supported slab analysis and design of the slab similar to design of simply supported beam as indicate in the previous chapter. Design procedure steps for one way slab slab design steps. Oneway and twoway slabs oneway slabs transfer the imposed. Twoway joist waffle slab design approach and methodology. Direct design method ddm for slab systems with or without beams loaded only. Reinforced concrete design 1 design of slab examples. Chapter 3 design of rectangular beams and oneway slabs. Design of slab examples and tutorials by sharifah maszura syed mohsin example 2. What are the assumptions for flexure theory in beam design. 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.
Rectangular beams and one way slabs page 3 of 9 design of rectangular beams and one way slabs continued a. One way shear in slab mrhershey structural 20 nov 17 15. The following example illustrates the design methods presented in aci 318 05 and ibc 2003. Assume partitions cannot be damaged by deflections. If slab is supported on all four sides and r shorter side longer side one way slab. Aci 318 11 code provides two methods for two way slab design one of which is direct design method. For other conditions, the following modifications should be applied. General drawing notes it is not intended that the contractor will need to read and interpret the 318 code. One way shear in slab structural engineering general. One way shear capacity is calculated assuming the shear cross section area consisting of ribs and the portion of slab above, decreased by the concrete cover. Positive and negative distribution of moments for interior spans, the total static moment is apportioned between critical positive and negative bending sections as see aci 318 02 sect. The trial depth is selected based on spandepth ratio of 7, as in is. The design is in accordance with aci 318, treating a stud as the equivalent of a vertical branch of a stirrup.
Slabs having supports on less than four sides can be designed as one way. Pdf aci 31805 building code requirements for structural. 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. The two classifications are oneway slab and two way slab. These recommendations are for the design of shear reinforcement using shear studs in slabs. Some recent problems in applying aci 318 code deflection. Fanella, which appeared in the october 2001 edition of structural engineer magazine. The program covers wide range of two way slab systems and can be used for more complex slab layouts. Slabs are usually used in floor and roof construction.
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. Analysis and design of slabs two way civil engineers pk. Two way slab design by direct design method as per aci 31811. Ce 403, fall 20 oneway slab design 3 4 aci 31811 referenced pp 2 4 rating. Here are the steps for the design procedure for one way slab in steps. The example presented here is for two way posttensioned design. Design beams if any, using procedures you learned in civl 45. Asce, secb course content slab on grades construction. The construction and design of concrete slabs on grade d. 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. Design of a oneway slab step1 selection of thickness, h aci 318 11building code requirements for structural concrete by american concrete institute, aci.
Design of cantilever slab spreadsheet engineering books. Twoway slab design based on aci 31811 using finite element. Thus, the maximum reinforcement ratio corresponds to a net tensile strain in the. 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. 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. Minimum thickness of beams and oneway slabs values given in this table shall be used directly on members with normalweight concrete and grade 60 reinforcement. The requirements for two of them are described in detail in aci 318. One way slab design how to design one way slab daily civil.
A 2 2area 2 a c 2 2 posttensioned concrete design table 11 list of symbols used in the aci 318 08 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. Determine moments at critical sections in each direction, normally the negative. Flexural deflection in aci 31802 controlled in section 9. Unless otherwise noted, all referenced table, figure, and equation numbers are from these books. The codes governing the design of the one way slab will be aci 318 02 and ibc 2003. Even while designing they are considered as one slabs with cantilever fixed or continuous at supports. Reinforced concrete design 1 design of slab examples and. Aci318 code provides two design procedures for slab systems. Page 4 of 18 design of a one way slab step1 selection of thickness, h aci 318 11building code requirements for structural concrete by american concrete institute, aci. If you continue browsing the site, you agree to the use of cookies on this website. Punching shear reinforcement on slab 39 one way joist 41 two way slab analyzed by the direct design method 47. 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. One way and two way slabs one way slabs transfer the imposed loads in one direction only. Allowable stress design or working stress design wsd.
The reorganized aci 31814 code iowa state university. Shear due to loads always must be less than the shear strength of concrete. The first step is to find the total slab thickness, h, with the aid of table 9. In order to simplify the design of the slab and columns, there was an assumption that shear walls would resist 100% of the lateral load. For example, the minimum slab thickness for a twohour fire rating is 4. Occurrence and configuration of tbeams commonconstructiontype. This method was provided in the american concrete institute aci in 1963 to design two way slabs carried by steel beams, deep beam, or walls. Aci 318 permits the use of direct design method ddm and equivalent frame method efm for the. Floor slabs can range from a simple residential basement slab to a heavyduty industrial floor. A 12 strip in a simply supported oneway slab h b12. Two way slabs have two way bending unlike one way slab. Continuous one way slab figure 1 shows a clear area of 12 m x 8. Jun 01, 2017 the first step is to find the total slab thickness, h, with the aid of table 9. The construction and design of concrete slabs on grade.
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