Oneway and twoway slabs university of asia pacific. 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 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. Reinforced concrete design to bs8110 structural design 1. 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.
Design of a two way rcc slab structural engineering forum. Two way slab design design of two way slab rc design. It can be used by both practicing engineers and students. 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. 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. Shear failure occurs when inclined cracks form due to flexural and shearing stresses. In a two way slab the slab has to resist the following forces. Preliminary design of slab thickness thickness design depends on boundary conditions supports. The same is true for a two way slab or any other floor system. One way and two way slabs one way slabs transfer the imposed loads in one direction only. Slabs may span in one direction or in two directions and they may be supported on monolithic concrete beams, steel beams, walls or directly by the structures columns.
Rectangular beams and oneway slabs page 2 of 9 two methods. In two way prestressed slabs, many designers also provide a nominal grid of nonprestressed reinforcing steel typically no. Application of the yield line theory for more complex situations 8. Reinforced concrete design to bs8110 structural design 1 lesson 5 6 4. The simplified design for concrete buildings book from pca has a 40 page section on two way slabs.
Slab slabs are an important structural component where prestressing is applied. The basic design procedure of a two way slab system has five steps. For designing two way slab refer is code 4562000 and sp16. Ce 433, summer 20 slab design example 1 5 design a one. Civil spreadsheet download free like design of slab,column,beam,footing. Bending will take place in the two directions in a dishlike fo. Design of two way ribbed slab 18 x 25 m clear span 1.
A twoway slab spreads in two directions and bends about two axes. Design of a two way rcc slab structural engineering. Pdf influence of longitudinal reinforcement strength on oneway. Example design of two way edgesupported solid slab. 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. Design of slabs direct design method civil engineering. They may be supported on two opposite sides only fig. Reinforced concrete slabs are used in floors, roofs and walls of buildings and as the decks of bridges.
Analysis and design of slabs two way two way edge supported slabs twoway slabs. Twoway concrete slab with beams spanning between supports. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Two way slabs have two way bending unlike one way slab.
Therefore, primary reinforcement is presented in both directions for resisting the loads. 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. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. Design of reinforced concrete structures ii two way slabs 1 1. Two way slabs can be divided in following three categories. One way and twoway slabs one way slabs transfer the imposed loads in one direction only. 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. Assume partitions cannot be damaged by deflections. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems.
Reinforced concrete slab and beam design software adaptrc 2017 product overview an easytouse and learn software for the design, analysis, and investigation of reinforced nonprestressed concrete beams, beam frames, slabs and floor systems a must have production tool in every structural engineering office. Two way slab design by direct design method as per aci 31811. Design of a structural member is governed by what kind of forces it has to resist. Analysis and design of slabs two way two way edge supported slabs two way slabs. In reinforced concrete construction, slabs are used to flat, useful surfaces a reinforced slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or.
Master of science and hereby certify that, in their opinion, it is worthy of acceptance. Accordingly, main reinforcement is required in the two directions. Reinforced concrete design 1 design of slab examples and. Plan view of floor system assume partitions will not be damaged by deflections. Design of twoway slabs for oneway shear and for twoway shear. Two way flat plate slab moments, critical moments and. 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. Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement.
Distribute moments transverse at critical sections to column and middlestrip and if. However, plastic method can be the best method for designing such cases of two way slabs. Reinforced concrete, 2014, 9th edition, aci 31811 code edition, by jack c. Basic steps in two way slab design choose layout and type of slab. The solution per ddm can be found in the twoway plate concrete floor system design example. The orientation of the principle axes of bending modifies all through the slab. Slab resting on walls or sufficiently deep and rigid beams on all sides.
Mar, 2014 this video demonstrates how you can use risa 3d to analyze and get a preliminary design for a one way slab with reinforced concrete. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. 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. In two way slabs, load will be carried in both the directions. Download the design of reinforced concrete slabs in pdf. It looks like it is mostly geared towards flat slabs on columns, not slabs on beams. Two way posttensioned slabs with unbonded tendons offer further advantages in the prevention of local or. Computational analysis of rcc slab simply supported ijrte. 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. Strengthening and repair of oneway and twoway selfcompacted. Apr 28, 2017 one way reinforced concrete slab how to design it. Punching shear of twoway slabs retrofitted with prestressed or.
In our case, in few next few days, we shall design slabs, so we shall take here slab only. In two way slab, load is delivered in both the directions. Allowable stress design or working stress design wsd 2. Twoway slabs belong to the types of construction forms made with reinforced concrete. No certain method can be found in the design codes or references for designing two way slabs subjected to concentrated loads. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan.
Aug 03, 2016 the design steps have been presented in the following question how do i degisn two way slab. Reinforced concrete design to bs8110 structural design 1 lesson 5 1 lesson 5. This spreadsheet performs an analysis and design of two way spanning reinforced concrete slab. Accurately determining the moments on a two way slab is typically accomplished by finite element computer analysis. Look at example 7 design of a flat plate floor without spandrel beams direct design method look at example 9 design of a twoway slab with beams in both directions. Bending will take place in the two directions in a dishlike form. The following example illustrates the example building. This spreadsheet is an extremely efficient tool and allows to quickly design two way slabs to aci code. Analysis and design of slabs two way civil engineers pk. Hibbitt, karlsson sorensen 2014 abaqus standard users manual. Pdf analysis of slabs spanning in two directions under. April 28, 2017 tose architecture, architecture article, architecture news, architecture tips, home design ideas, interior design 0 these slabs are utilized in floors and roofs of buildings and usually combined with the supporting beams, bear the distributed loads mainly by bending.
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 on. Influence of longitudinal reinforcement strength on one. These are the direct design method presented in chap. Design of concrete structures 14th edition, 2009, by arthur h. Slab shear strength two way shear check the adequacy of slab thickness for punching shear two way shear at an interior column figure 4. Chapter 3 design of rectangular beams and oneway slabs 12. All available load test results indicated that the flat plate or flat slab was a most efficient design with an adequate safety factor. The effect of fixing the corners of the slab against lifting 5. A monolithic reinforced concrete floor is to be composed of rectangular bays measuring, as shown. A concrete slab is a common structural element of modern buildings, consisting of a flat. A oneway slab has momentresisting reinforcement only in its short axis, and is used when the moment in.
Two way slab is a slab supported by beams on all the four sides and the loads are carried by the supports along both directions, it is known as two way slab. Twoway slab analysis and design using equivalent frame method efm aci 318 states that a slab system shall be designed by any procedure satisfying. For increased ratio of sides, the slab virtually spans along the shorter side and it is designed as one way slab. Two way rcc slab designing tool in microsoft excel developed by shankar tayal a 3rd year student of school of infrastructure, indian institute of technology, bhubaneswar. Two way slab design spreadsheet the engineering community. Min and max reinforcement as a percentage of the gross csa.
Pdf download for punching shear of twoway slabs retrofitted with. 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. Chapter 3 design of rectangular beams and oneway slabs. Simply supported slab upliftment of corners continuous slab no upliftment. Two way slab design to aci free download and software. I have developed a microssoft excel software for design of a two way rcc slab. The increase in ultimate strength for strengthened twoway slabs was. Rectangular beams and one way slabs page 2 of 9 two methods. Slabs are usually used in floor and roof construction.
This type of behaviour holds good when the ratio between length and breadth of the slab is less than two. Aci 318 provides two alternative methods for designing twoway slabs for concrete, the equivalent frame method. Please enter the practically physible spacing for main steel of two way slab based on summary. Design of oneway slab free download as powerpoint presentation. Oneway and twoway slabs oneway slabs transfer the imposed. One way spanning slabs should be treated as beams of unit width and chapter 2 should be followed except for minimum shear reinforcement. Twoway slabs have two way bending unlike oneway slab. Design of reinforced concrete structures ii twoway slabs 1 1. The floor system of a structure can take many forms such as in situ solid slabs, ribbed slabs or precast units. In a finite element software like scia engineer, when the slab is supported. Please enter the practically physible spacing for main steel of twoway slab based on summary.
There are many methods that are used to analyze twoway slabs and the precision of these methods vary depending. This method requires various formulas for different conditions of rc slab. Bridge approach slab analysis and design incorporating elastic soil support presented by. Fanella, which appeared in the october 2001 edition of structural engineer magazine. I am submitting it to you and i want students or professional engineers to download it and use it for their studies or projects. Two types of shear failure mechanism in 2way slabs.
This spreadsheet designs both oneway and twoway slab acc. Generally, there are two types of slab which are one way and two way slabs. Beams of width and depth are provided on all column lines. Reinforced concrete slab and beam design software adaptrc. The basic design procedure of a twoway slab system has five steps. Depending upon the building plan, or the arrangement of main beams andor secondary beams, the slab may have only one span, or it may be continuous over several supports. 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. In case of twoway slab main reinforcements are provided both along the length as well as along the width of the room. Analysis and design of slabs one way civil engineers pk. A simplified method for designing rc slabs under concentrated. Article information, pdf download for strengthening and repair of oneway and twoway. Slab design is done mainly by manual method or using design and.
Flat plate concrete floor system does not use beams between columns or. An optimal plan geometry with all same supports is a square, based on load distribution into both directions. The design steps have been presented in the following question how do i degisn two way slab. Analysis of two way ribbed and waffle slabs with hidden beams. Department of mechanics, materials and structures english. Mention the parameters governing slab moment coefficients and explain their effects on moment. Redistribution of 10% may be allowed when method 3 or method 4 is adopted. There are many methods that are used to analyze two way slabs and the precision of these methods vary depending.
This condition occur when the slabs are connected monolithically with support. Ive input the information as shown on page 1 and tried to see if i could obtain the critical moments and moments along axis 2 in the ew direction for load case 1. Design aids were proposed, with implications for design presented through a case study of a multispan one way slab system. This study presents punching shear behavior of twoway slabs. 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 slab design panel select boundary condition of slab for upliftment of corners. So, its a confusing design project for me and i wish there was a conservative prescriptive guide to avoid an analytical solution.
This section will explain how the direct design method is used. The slab has to carry a distributed permanent action of 1. In contrast to the current implicit provisions, the design strength of the longitudinal reinforcement did not have a significant effect on the minimum slab thickness required to satisfy common deflection criterion. Some researchers have investigated the analysis of slabs spanning in two directions under concentrated load an alternative approximate method for determining the bending moments of the slab under. The design bending moment of twoway restrained slab can be calculated as follows. This is a part of his project economic design of two way rcc slabs under prof s. Design of reinforced concrete structures ii twoway slabs. The design of a oneway slab will lead to reinforcement mainly in the bearing direction. So, clear span plus effective depth of slab or beam. Dissatisfaction with results of previously required procedures of analysis and design for two way slab beam systems was the original reason for the massive research upon two way slab systems begun about 1955. This paper focuses on analysis of twoway ribbed and waffle slabs with hidden beams. 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.
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