Assume partitions cannot be damaged by deflections. Closed form formulas closed form formulas are readily available for beams and oneway slabs. Shear strength of beamless slabs usually a controlling factor. 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. Reinforced concrete slab slabs are plate elements forming floors, roofs. Oneway and twoway slabs university of asia pacific. The two way slab on beams, analyzed as separate elements, appeared overdesigned with unnecessarily high safety factors.
This condition occur when the slabs are connected monolithically with support. Abstractdesigning twoway slabs under transverse concentrated loads is one of the challenges in designing such structures. In two way slab, load is delivered in both the directions. The pca computer program pcaslab can be used to expedite the design of different slab systems. Since 1971, all two way reinforced systems, with or without beams, have been subject to the same integrated analysis and design procedures chapter. The effect of fixing the corners of the slab against lifting 5. I have developed a microssoft excel software for design of a two way rcc slab. Abcd is a two way slab lb concrete slab structures january 2019 188 18. Pdf cost optimum design of reinforced concrete simply. Load transfer in a one way slab, b two way slab nilson fig. If a slab is supported on all the four sides but the ratio of longer span l to shorten span b is greater than 2, then the slab will be considered as one way slab. A discreteelement method of multipleloading analysis for. Slab moments calculated by various slab analysis methods are compared with each other for idealized flatplate and two way slab onbeam structures. Design of reinforced concrete structures ii two way slabs 1 1.
Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The variables that describe the geometry of a twoway panel within a floor system, however, are so extensive that it becomes impractical to compile a meaningful set of tables or relationships without extensive approximation. The twoway waffle slab is economical when it is used in the modular or prefabricated form. In case of one ways slabs, the aci approximate analysis is applicable to one way slab system where a one way slab is continuous with a one way slab. Existing twoway slab design procedures the example structure a preliminary girder design structure details specified loadings a oneway design. Department of mechanics, materials and structures english. Rectangular beams and one way slabs page 2 of 9 two methods.
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 a two way rcc slab structural engineering forum. In lieu of detailed calculation for deflections, csa a23. Step 2 design forces draw panel of slab and indicate maximum design moments, shears and in plane loads, if any, per unit width of slab. The basic design procedure of a two way slab system has five steps. The ratio of the total costs was found to be within the range 1. However, plastic method can be the best method for designing such cases of twoway slabs.
Useful illustration example is presented in this study according to the available. Since 1971, all twoway reinforced systems, with or without beams, have been subject to the same integrated analysis and design procedures chapter. 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. The 2012 edition of the reinforced concrete design manual sp1711 was developed in accordance with the design provisions of aci 31811, and is consistent with the format of sp1709. The twoway slab on beams, analyzed as separate elements, appeared overdesigned with unnecessarily high safety factors. Design of two way slab example pdf flat slab design pdf bs 8110 concrete design for slab post tension slab slab on grade foundation how to calculate formwork for slab how to pour a concrete slab concrete beam and slab bridge how to pour a 26x36 concrwte concrete slab operation management 9th edition myomlb nigel slab usercentered design, activitycentered design, and goaldirected design. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. 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. Design of reinforced concrete structures ii twoway slabs 1 1. The numbering of the members is explained as below. Twoway slab design based on aci 31811 using finite element method. In twoway slabs shorter direction strip carry greater %age of load.
Allowable stress design or working stress design wsd 2. 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. Example design of two way edgesupported solid slab. Twoway concrete floor slab with beams design and detailing. Analysis and design of slabs two way civil engineers pk. The slab has to carry a distributed permanent action of 1. Twoway 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. Due to building limitations, the slab has to be one thickness. A monolithic reinforced concrete floor is to be composed of rectangular bays measuring, as shown. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. The program covers wide range of two way slab systems and can be used for more complex slab layouts. For designing two way slab refer is code 4562000 and sp16. Analysis of two way ribbed and waffle slabs with hidden beams. Use the aci 318 direct design method to design an interior bay of a flat plate slab system of multi bay building.
Learning outcomes at the end of this lecture, the student should be able to a classify all types of solid slabco1 b identify one way and two way solid slab co1 c use a relevant clauses in code of practice co1 d design oneway slabs co2 e details the slabsco1. In two way slabs shorter direction strip carry greater %age of load. These are the direct design method presented in chap. Twoway concrete slab with beams spanning between supports. Accordingly, main reinforcement is required in the two directions. Therefore, primary reinforcement is presented in both directions for resisting the loads. Aci 31811 code provides two methods for two way slab design one of which is direct design method. The program covers wide range of twoway slab systems and can be used for more complex slab layouts.
A detailed explanation will be given of the checksto be carried out, the aspects to be considered in the design and the construction procedures and sequences of a posttensioned slab. Design of a two way rcc slab structural engineering. Two way slabs have two way bending unlike one way slab. Interior bay dimensions 20 24 this example is to be used for educational purposes only. A simplified method for designing rc slabs under concentrated. 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 reinforced concrete slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so. However, plastic method can be the best method for designing such cases of two way slabs. One way slab is supported on two opposite side only thus structural action is only at one direction. 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. Total load is carried in the direction perpendicular to the supporting beam. The explicit transverse torsional member method is found to give good results for drifts and slab beam actions, and is recommended for analysis and design of two way slab systems under combined. One way spanning slabs should be treated as beams of unit width and chapter 2 should be followed except for minimum shear reinforcement. I am submitting it to you and i want students or professional engineers to download it and use it for their studies or projects.
Partitioning a twoway slab size of the model edge restraint springs. Abstractdesigning two way slabs under transverse concentrated loads is one of the challenges in designing such structures. Fanella, which appeared in the october 2001 edition of structural engineer magazine. It is recommended to create the design of slab with the use of excel sheet as the process will be very simple and lots of time will be saved. Beams of width and depth are provided on all column lines. Design walls and floors to resist the potential tank loads and the hydrostatic and wheel loads that they may be subjected to. Two way slab design based on aci 31811 using finite element method.
Id assume a two way slab design would be best, but when looking at aci 318, there is no analysis information when a slab is supported by continuous walls. Slabs are usually used in floor and roof construction. It is convenient to think of such slabs as consisting of two sets of parallel strips, in each direction and intersecting each other. What is the formula for taking load from two way slab for. My graduation project with my mate ghassan faris, a two way ribbed slab of clear span of 18 x 25 m was designed by safe 2014, the building is 3storey concrete. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. Deflections in twoway slab systems shall be calculated taking into account size and shape of the panel.
Design of two way slabs is 456 limit state method youtube. Two way slab design by direct design method as per aci 31811. The execution of the design will be explained with reference to an example. Analysis and design of two way slabs page 1 chapter 3. No certain method can be found in the design codes or references for designing two way slabs subjected to concentrated loads. Apr 12, 2018 two way slab full detail explanation diagrams with site below these links are our civil videos learn field work watch and subscribe for more videos building drawings analysis in telugu. Twoway concrete floor slab with beams design and detailing csa. Application of the yield line theory for more complex situations 8.
Point load this problem is designed to demonstrate how to check the ability of a composite slab to carry a 3000 lb point load over an area of 4. Design of slab examples and tutorials by sharifah maszura syed mohsin. Pdf slabs are the flooring systems of most structures including office. 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. The dimensions of an interior bay are shown in figure 1. Load transfer in a oneway slab, b twoway slab nilson fig.
So part of the load is carried by one set and the remainder by the other. Two slab supported by 4 walls structural engineering. Chapter 3 design of rectangular beams and oneway slabs 12. Slab shear strength twoway shear check the adequacy of slab thickness for punching shear twoway shear at an interior column figure 4. The basic design procedure of a twoway slab system has five steps. No certain method can be found in the design codes or references for designing twoway slabs subjected to concentrated loads. Twoway concrete slab on beams floor analysis and design.
The following example illustrates the example building. Twoway slabs have two way bending unlike oneway slab. Beams, see lecture 3 punching shear requirements e. Storey number storey numbers are given to the portion of the building between two successive grids of beams. Generally, there are two types of slab which are one way and two way slabs. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. This example is to be used for educational purposes only. Cost optimum design of reinforced concrete simply supported. Pdf design of reinforced concrete circular slabs by twoway. Introduction in reinforced concrete construction, slabs are used to provide flat, useful surfaces. The other ways of analysis of twoway slabs are the direct design method and. Jul 02, 2010 lecture series on design of reinforced concrete structures by prof. Bending will take place in the two directions in a dishlike form.
In this video deisgn of two way slabs has been covered using is 456. Look into yield line analysis for a simply supported slab on all sides. 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. 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. The following example illustrates the design methods presented in the pca book simplified design reinforced concrete buildings of moderate size and height third edition. Liquid fertilizers are heavier than water and hydrostatic design loads range from to 70100 lbft3ft of depth. Dhang, department of civil engineering, iit kharagpur. Reinforced concrete design 1 design of slab examples. Aci318 code provides two design procedures for slab systems. Reinforced concrete design 1 design of slab examples and. Top view of continuous rc circular twoway ribbed slab. Concrete structural design design all concrete facilities with two criteria in mind.
Ce 433, summer 20 slab design example 1 5 design a one. Chapter 18 concrete slab structures january 2019 188 18. Closed form equations have been driven by author for the purposes of analysis. The output of the program for the slab in the example is shown in the following pages. Oneway and twoway slabs oneway slabs transfer the imposed. For the example building, the storey numbers are defined as follows. Distribute moments transverse at critical sections to column and middlestrip and if. Reference 5 focused on analysis of two way ribbed slabs with.