Load transfer in a one way slab, b two way slab nilson fig. The determination of exact moments in twoway slabs with various support conditions is. Generally, there are two types of slab which are one way and two way slabs. Rectangular beams and oneway slabs page 3 of 9 design of rectangular beams and oneway slabs continued a. The overlapping rectangular slab is not supported on two sides like the one way slabs are by walls below. Slabs are usually used in floor and roof construction. The basic design procedure of a two way slab system has five steps. The ratio of longer span l to shorter span b is equal or greater than 2, considered as one way slab because this s. Design of reinforced concrete structures ii twoway slabs. One way and two way slabs as floor systems are the most conventional forms of structural floor systems. One way slab being supported on two opposite sides only leads to the structural action in single direction.
Design of two way floor slab system comparison of one way and two way slab behavior one way slabs carry load. Design of reinforced concrete structures ii two way slabs 1 1. One way slab is supported by two parallel beams or walls. Accordingly, main reinforcement is required in the two directions.
Design by oneway shearbond regression analysis 12 yieldline method of analysis 15 general remarks 15 application of yieldline theory to steeldeck reinforced slabs 16 formation of fans 20 twoway slab behavior as predicted by orthotropic plate theory 22 slab behavior based on curve fitting of deflected surfaces 30 chapter 3. Load transfer in a oneway slab, b twoway slab nilson fig. Reinforced thin plate elements are supported over beams, masonry walls or directly over columns. Civilax is the knowledge base covering all disciplines in civil engineering. In the design of twoway reinforced concrete slabs, e. Total load is carried in the direction perpendicular to the supporting beam. Pdf in the design of twoway reinforced concrete slabs, e.
Two way slabs have two way bending unlike one way slab. According to structural point of view, in 2 way slab loads will be carried in 2 directions, so main reinforcement is provided in 2 ways. These slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs or other types of structures. The program covers wide range of twoway slab systems and can be used for more complex slab layouts. Chapter 3 design of rectangular beams and oneway slabs 12. Twoway slab analysis and design using equivalent frame method efm aci 318 states that a slab system shall be designed by any procedure satisfying equilibrium and geometric. One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. A 175 mm thick continuous slab is required to support screed, finishes, an office variable action of 2. Chapter 3 design of rectangular beams and oneway slabs. Analysis and design of slabs two way civil engineers pk.
The dimensions of an interior bay are shown in figure 1. Figure 1 twoway slab with beams spanning between all supports. If this roof is not supporting nor attached to non structural elements likely to be. To determine if the slab is two way, figure the ratio between the longer span and the shorter span. 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. 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. Distribute moments transverse at critical sections to column and middlestrip and if. Analysis of two way ribbed and waffle slabs with hidden beams. One way and two way slab design aspect the slab provides a horizontal surface and is usually supported by columns,beams or walls. The oneway slab is deflected in one way direction and primary reinforcement is placed in one direction whereas. The transfer of the load is on all of the walls, all four become support walls. Reference 5 focused on analysis of two way ribbed slabs with. Twoway slabs page 6 of 14 the pca computer program pcaslab can be used to expedite the design of different slab systems.
The ratio of the total costs was found to be within the range 1. Mathematical structural analysis of one way 763 3 comparison between the results of finite element method and traditional method two bays one way ribbed slab is analyzed by both traditional and finite element methods to determine the induced moments of the rib. In twoway slabs shorter direction strip carry greater %age of load. Feb 24, 2019 this calculation is intended to show in detail the provisions of designing a slab to eurocode 2 using essentially the same slab as used in example 3.
Slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs, bridges, and other types of structures. Oneway slab design spreadsheet civil engineering community. In high rise buildings and skyscrapers, thinner, precast concrete slabs are slung between the steel frames to form the floors and ceilings on each level. Rectangular beams and oneway slabs page 5 of 9 maximum permissible steel ratio, max an overreinforced beam will fail in a brittle manner while an underreinforced beam will. The corner reinforcement can be arrange in two way as shown below. Nov 27, 20 one way slab oneway slabs are those slabs with an aspect ratio in plan of 2. On the technical drawings, reinforced concrete slabs are often abbreviated to r. The following example illustrates the example building. Dec 24, 2017 type of slabs, one way slab and two way slab,the steel reinforcement in slabs.
Figure a shows a slab supported over masonry wallbeam on both sides is expected to bend in the shorter direction due to its self weight. Types of one way slab one way slab may be solid hollow ribbed 6. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Design the slab system shown in figure 1 for an intermediate. These are the direct design method presented in chap. Use the aci 318 direct design method to design an interior bay of a flat plate slab system of multi bay building. The program covers wide range of two way slab systems and can be used for more complex slab layouts. All available load test results indicated that the flat plate or flat slab was a most efficient design with an adequate safety factor. One way slab is the most basic and common type of slab. In site how we can identify one way slab and two way slab. If lylx way slab this is the main criteria for identifying 2 way slab or 1 way slab. If slab is supported on all four sides and r shorter side longer side slabs. Oneway and twoway slabs one way slabs transfer the imposed loads in one direction only. Oneway slab is the most basic and common type of slab.
The slab may be supported by walls, by reinforced concrete beams usually cast monolithically with the slab, by s. Powered by the equivalent frame method of analysis and design per latest american aci 31814 and canadian csa a23. One way slab is supported on two opposite side only thus structural action is only at one direction. The output of the program for the slab in the example is shown in the following pages.
The ratio of longer span l to shorter span b is equal or greater than 2, considered as one way slab because this slab will bend in one direction i. One way slab is the slab having ratio of longer span to shorter span equal to or more than 2. Continuous oneway solid slab concrete structures eurocode. Application of lb ratio in first figure slab is supported on two opposite sides only. Slab resting on walls or sufficiently deep and rigid beams on all sides. Oneway and twoway slabs university of asia pacific. This paper presents an experimental and computational study on ribbed slabs with widebeam, two one way slabs and two two way slabs, with variable depths were tested to evaluate their resistance. In two way slab, the ratio of longer span l to shorter span b is less than 2.
Reinforced concrete, 2014, 9th edition, aci 31811 code edition, by jack c. Two way slabs are surface members acting in a both directions. Design of reinforced concrete structures ii twoway slabs 1 1. Difference between one way slab and two way slab daily civil. Minimum thickness for solid oneway slabs unless deflections are calculated for slab not supporting or attached to partitions or other construction likely to be deamaged by. The ratio lb which is less than 2 is known as two way slab. There is a wall running along beneath one edge of it and the other two opposite corners can. The basic design procedure of a twoway slab system has five steps. Twoway concrete floor slab with beams design and detailing csa a23. Twoway slabs have two way bending unlike oneway slab. 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 actual structural support of a two way slab is found on two. The oneway slab is deflected in one way direction and primary reinforcement is. 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. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. Verandah slab is a type of one way slab, where the slab is spanning in the shorter direction.
Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement. In one way slab main tensile reinforcement is placed parallel to shorter side which will be the main steel. 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. Plan view of floor system assume partitions will not be damaged by deflections. Analysis and design of slabs one way civil engineers pk. Hi guys, have this scenario whereby two one way slabs are intersecting. Pdf oneway and twoway slabs mohamed tiger academia. In many cases the slabs are of such proportions and are supported in such way that two way action. The analogy using the banded two way slab is irrelevant from a codeconformance standpoint since the shrinkage and temperature requirements of section 7. Two way slabs are normally supported from four sides.
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. If lylx waytwo way slab systems gmannix2012 structural op 4 oct 12 08. Design of concrete structures 14th edition, 2009, by arthur h. This calculation is intended to show in detail the provisions of designing a slab to eurocode 2 using essentially the same slab as used in example 3. The same behavior is expected when it is subjected to floor loads.
Lylx 2 one way slab one way slab longer spanshorter span 2. Aug 15, 2016 download code one way slab design spreadsheet. Two way slabs page 6 of 14 the pca computer program pcaslab can be used to expedite the design of different slab systems. Difference between one way slab and two way slab system. A one way reinforced slab may be stronger than a two way nonreinforced slab, depending on the type of load. One way slabs are such slabs in which the loads are shared only by the shorter direction of the slab. Twoway concrete floor slab with beams design and detailing. Aci 31811 code provides two methods for two way slab design one of which is.
Here ratio of longer span of slab to the shorter span of slab is greater than 2. The behavior and analysis of twoway simply supported. The one way slab is deflected in one way direction and primary reinforcement is placed in one direction whereas. One way and two way slab design aspect online civilforum. Beam and slab arrangement can be the best example for one way and two way slabs. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan.
Experimental study of shear in reinforced concrete oneway. In a two way slab the bars, rods or wires are placed at right angles to each other to resist bending stresses in two directions. A one way slab is designed to bend in one direction only and the steel is placed in that direction. 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. Pdf reinforced concrete oneway slabs subjected to concentrated loads are designed for shear by checking beam shear over an effective width and. In one way slab, the ratio of longer span l to shorter span b is equal or greater than 2, i. Difference between one way slab and two way slab simple. The calculation of one way slab reinforcement details design is extremely tedious and timeconsuming and after give more time is not 100% sure that design is best or not and also if some minor change comes in design if force to calculate. The ratio of length to width of one slab should less than 2 otherwise one way action is obtained, even though supports are provided on all sides. Parameters include support conditions nine cases, span ratios lalb. Oneway and twoway slabs oneway slabs transfer the imposed. Two way slab design by direct design method as per aci 31811. They may be supported on two opposite sides only fig. But if the slab is supported on four sides then we have to consider the aspect ration lxly.22 72 122 635 15 1340 882 974 36 1337 60 1358 1098 674 953 132 30 173 231 1050 1037 597 1231 49 254 1214 657 648 453 588 1357 953 1281 947 712 1325 722 506 420 333 1259 1073 222