Ntwo way slab design by coefficient method pdf

Introduction concrete slabs on grade are a very common type of concrete construction. 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 cross sectional dimensions 18 in. Alternate design method design procedure of twoway slabs. Design of slabs direct design method civil engineering. Design of concrete structures 14th edition, 2009, by arthur h. The most common method is the aci direct design method. Slabs of uniform thickness bending and reinforced in one direction. Preliminary design of slab thickness thickness design depends on boundary conditions supports. 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. Design of reinforced concrete structures ii twoway slabs. Analysis of twoway slabs by coefficient method the determination of exact moments in twoway slabs with various support conditions is mathematically formidable and not suited to design practice. Direct design method of flat plates per aci 31802 twoway slabs are inherently difficult to analyze by conventional methods of statics because of the twoway bending occurring. Experimental study of two way half slab precast using. This pdf file contains a chapter of 23 pages with various aspects of flat slabs including four example of flat slab design.

Reinforced concrete, 2014, 9th edition, aci 31811 code edition, by jack c. 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. How to design a beam in excel with coefficient method. The effect of fixing the corners of the slab against lifting 5. The construction and design of concrete slabs on grade d. Analysis of two way ribbed and waffle slabs with hidden beams. Use of the ultimate strength method of design with high strength concrete and reinforcing steels. Reinforced concrete slab design and detailing guide is456.

Department of mechanics, materials and structures english. The construction and design of concrete slabs on grade. While the wheel provides a way to quickly and efficiently produce multiple round forms, handbuilding allows me to slow down and enjoy the whole clay experience in a much more relaxing way. 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.

Slabs are primarily categorized as either one way or two ways. If slab is supported on all four sides and r shorter side longer side slabs. The basic design procedure of a twoway slab system has five steps. The following example illustrates the design methods presented in the article timesaving design aids for reinforced. Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement. Method 2 yieldlines may be successfully used for uniformly loaded slab. Design of a two way rcc slab structural engineering. The oneway slab is deflected in one way direction and primary reinforcement is placed in one direction whereas. The coefficient method was first included in the 1963 edition of the aci code as a method to design twoway slabs supported on all four sides by walls, steel beams, or deep beams. Bending will take place in the two directions in a dishlike form. Aci 318 provides two alternative methods for designing twoway slabs for concrete, the equivalent frame method. But, with proper application and enough safety factor yield line method. The coefficient method is a method of designing twoway slabs that are supported by edge beams. Twoway slab design using the coefficient method beam.

This method depends on determining the moments in the frames using coefficients. We assume that the verandah slab is a two way slab instead of one way slab in order to calculate mb,neg now, using moment coefficient method for analysis. Best is subjective, so i will give my opinion here. An optimal plan geometry with all same supports is a square, based on load distribution into both directions. Deflection estimation of twoway edgesupported slabs. Two way reinforced concrete slab design spreadsheet. Two way reinforced concrete slab design spreadsheet working stress design coefficient method.

In the strength design method, the service loads are increased sufficiently by factors in order to obtain the load at which teaching twoway ribbed slab analysis and design using the mathcad program mohammed s. This method was initially contained in the 1963 edition of the aci code as a method for creating design of twoway slabs which are supported on all four sides through walls, steel beams, or deep beams. Load transfer in a oneway slab, b twoway slab nilson fig. I am submitting it to you and i want students or professional engineers to download it and use it for their studies or projects. These are the direct design method presented in chap. Bridge approach slab analysis and design incorporating elastic soil support presented by. Alternate design method design procedure of two way slabs using aci moment coefficients and approved by bnbc 20 scope and limitations bnbc 6. In twoway slabs shorter direction strip carry greater %age of load. Asce, secb course content slab on grades construction. Application of the yield line theory for more complex situations 8. Assume partitions cannot be damaged by deflections. In a two way slab the slab has to resist the following forces.

This method was provided in the american concrete institute aci in 1963 to design twoway slabs carried by steel beams, deep beam, or walls. For the method of design coefficients use is made of the moment and shear coefficients given in the code, which have been obtained from yield line analysis. Generally, there are two types of slab which are one way and two way slabs. Chapter 3 design of rectangular beams and oneway slabs 12 h. Slabs may be simply supported or continuous over one or more supports and are classified according to the method of support. Here two examples for design of two way slab using the direct design method. Slab being the first element to be designed has pretty much importance as the whole structural design is based on the design of slab. 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. Pdf deflection estimation of twoway edgesupported slabs.

Design of two way slabs by coefficient method slab is one of the basic parts of a building. The following example illustrates the example building. Various simplified methods are therefore adopted for determining moments, shears. Reinforced concrete slab design and detailing guidelines for depth of slab, loads on slab, reinforcement guide for oneway and twoway slabs as per is 456. This paper focuses on analysis of twoway ribbed and waffle slabs with hidden beams. Coefficient method two way slab design with edge beams the coefficient method is a quick handmethod of calculating the moments in twoway slabs supported by edge beams. From the study it is considered that post tension slab is more economical than twoway slab. Oneway and twoway slabs university of asia pacific. Ce 433, summer 20 slab design example 1 5 design a one. Beams of width and depth are provided on all column lines. Two way slab design spreadsheet working stress design. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. Accurately determining the moments on a twoway slab is typically accomplished by finite element computer analysis.

This method requires various formulas for different conditions of rc slab. All available load test results indicated that the flat plate or flat slab was a most efficient design with an adequate safety factor. Design of reinforced concrete structures ii two way slabs 1 1. Slabs are usually used in floor and roof construction. The quantities of the materials are calculated and cost of construction for slabs are determined and compared. Design of reinforced concrete structures ii twoway slabs 1 1. These slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs or other types of structures. Siswosukarto 7 proposed semiprecast slab as an alternative method to promote the green construction residential house project. Twoway slab design using the coefficient method free download as pdf file.

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. However, plastic method can be the best method for designing such cases of twoway slabs. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. Flat plate concrete floor system does not use beams between columns or. Two way slab design spreadsheet working stress design coefficient method. Okay, i know it is based on upper bound thorem and the solution might be unsafe. Twoway slabs have two way bending unlike oneway slab.

Two way slab design by direct design method as per aci 31811. 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 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 moment coefficient method included for the first time in 1963 aci code is applicable to twoway slabs supported on four sides of each slab panel by walls, steel beams relatively deep, stiff, edge beams h 3hf. Analysis and design of slabs one way civil engineers pk. Analysis and design of slabs two way civil engineers pk.

No certain method can be found in the design codes or references for designing twoway slabs subjected to concentrated loads. Floor slabs can range from a simple residential basement slab to a heavyduty industrial floor. A monolithic reinforced concrete floor is to be composed of rectangular bays measuring, as shown. Flat slab analysis, design and detailing pdf civil. Multi storey, post tension, two way, design, comparison. Difference between one way slab and two way slab system the one way and two way slab systems are the most commonly used floor system in the reinforced concrete structure. Flat slabs carried on columns and edge beams or walls with no interior beams. Difference between one way slab and two way slab system. Design of a structural member is governed by what kind of forces it has to resist. This section will explain how the direct design method is used. There are many methods that are used to analyze twoway slabs and the precision of these methods vary depending. Following are the rcc slab design and detailing guidelines. In addition, i enjoy the ability to add textures and decoration at every step of the forming process from soft slab to leather. Direct design method alias ddm as well as coefficient method are used to design the slabs.

Plan view of floor system assume partitions will not be damaged by deflections. 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. The most recent version of the aci code 318 does not contain the coefficient method but you can apply it for two slab systems with edge beams. 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. Master of science and hereby certify that, in their opinion, it is worthy of acceptance. Then, the frame moments are distributed to the beam and the slab using tables. I have developed a microssoft excel software for design of a two way rcc slab. Teaching twoway ribbed slab analysis and design using the. The accuracy of these methods depends on the assumptions that are stated in the method procedure. If the proportion of longer dimension of the slab panel to the shorter dimension is more than or equivalent to 2 then it is defined as one way slab.