One way slab and two way slab pdf

The ration of longer span pannel l to shorter span panel b is equal or greater than 2 thus lb 2. Reinforcement detailing of reinforced concrete slabs. One way and two way slab design aspect online civilforum. The three basic types are one way slabs, two way edge supported slabs and pointsupported slab systems. Mention the parameters governing slab moment coefficients and explain their effects on moment. Edge supported two way slabs free pdf file sharing. Can be used for larger spans with relatively higher cost and higher deflections oneway joist system suitable span 6 to 9m with ll 46knm2. The twoway slab is designed for both the directions as it bends in both directions. Reinforced concrete design 1 design of slab examples. Twoway slabs supported on beams the critical location is found at d distance from the column, where the supporting beams are stiff and are capable of transmitting floor loads to the columns. A two way slab has the main load carried in both directions.

Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Behavior and reinforcement of oneway slab the structural frame consists of four columns, two beams and one slab. The basic difference between these slabs are oneway slab bends only in one direction and twoway slab bends in two directions as shown in the below figure. Difference between one way slab and two way slab simple. But before that i had written a answer of one another question requested by someo. Introduction in reinforced concrete construction, slabs are used to provide flat, useful surfaces. Good morning, there are lots of advantages of one way slab and two way slab. Oneway slabs, slab beam interaction, finite element analysis, regression analysis.

The main supports are found going in both directions. Difference between one way slab and two way slab daily civil. This condition occur when the slab are supported at four side of the beams or walls and the ratio of long span to short span is equal or less than 2. In reality, sandwich slabs are ribbed slabs with a slab placed both to their upper and lower surface. 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. If less than 2 then it is designed as a two way slab. Pdf transition from oneway to twoway shear in slabs.

Corners of the twoway slab lift up if the slab is not cast monolithically with the supports wallsbeams. The longstanding problem of shear in structural concrete elements is typically studied as oneway shear in beams, or as twoway shear in slabcolumn connections. Thus, lb two types of slab classification based on the direction of bending occurs in these slabs. The first two systems consist of a concrete slab supfilename. One way slab oneway slabs are those slabs with an aspect ratio in plan of 2. Here are the steps for the design procedure for one way slab in steps. The slab has to carry a distributed permanent action of 1. Types of one way slab one way slab may be solid hollow ribbed 6. The oneway slab is a slab, which is supported by parallel walls or beams, and whose length to breadth ratio is equal to or greater than two and it bends in only one direction spanning direction while it is transferring the loads to the two supporting walls or beams, because of its geometry.

For those who do not know what are the des ign requirements of a slab. What are the advantages of one way slab and two way slab. Ce 403, fall 20 oneway slab design 3 4 aci 31811 referenced pp 2 4 rating. In two way slab, the ratio of longer span l to shorter span b is less than 2. 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. Oneway and twoway slabs oneway slabs transfer the imposed. Mainly shorter span is carring larger load than longer span. Pdf cost optimum design of reinforced concrete simply. Two way slabs are normally supported from four sides. The basic difference between one way and two way slab is load distribution which is depends on support condition and span lengths. Distinction of twosystems from one way systems is given by aci 31814 r8. The problem of oneway shear in slabs, as encountered by bridge engineers when. Design of oneway slabs check if it is oneway slab system if clear span in one direction, l1, is greater than or equal to two times the clear span in other direction, l2, then it is. Oneway slab is the most basic and common type of slab.

Design of oneway slabs the structural action of a oneway slab may be visualized in terms of the deformed shape of the loaded surface. Flat plate for relatively light loads as in apartments or offices suitable span 4. Analysis and design of slabs one way civil engineers pk. What is the difference between one way and two way slab. Here the ratio of longer span of slab to the shorter span of slab is less or equals to 2. 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. Analysis and design of twoway slabs page 1 chapter 3. A bentup bar called as crank bar is provided to make rcc slab safe from compressive stresses. However main reinforcement bar and distribution bar in transverse direction. One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. Bending moment and shear force of twoway slab are depend on l y l x ratio and. Oneway and twoway slabs university of asia pacific. My name is sl khan and you are watching an engineer boy. Usually, when a slab is supported by a beam the support is considered to be pinned.

The main reinforcement for twoway slab are designed in two directions which are xdirection and ydirection. Slabs are usually used in floor and roof construction. The ratio of longer span panel l to shorter span panel b is equal or greater than 2. In two way slabs, load will be carried in both the directions. One way slab here i solve a probleam based on the one way slab, the diamentions are provided in the probleam 1st determine the aspect ration and with respect to. Two way slabs are such slabs in which the loads are shared by both the shorter and longer direction of the slab. Application of lb ratio in first figure slab is supported on two opposite sides only. One way slab is supported by beams in only 2 sides. 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 compatibility, provided that strength and serviceability criteria are satisfied. Design procedure steps for one way slab slab design steps.

Powered by the equivalent frame method of analysis and design per latest american aci 31814 and canadian csa a23. The ratio of longer span panel l to shorter span panel b is less than 2. To determine if the slab is two way, figure the ratio between the longer span and the shorter span. In this paper the cost optimization of reinforced concrete twoway slabs under uniformly distributed load with the nonlinear programming approach has been presented and it is a continuation of the. The actual structural support of a one way slab is found on the shortest spans. The twoway slab will deflect in a dish or saucerlike form under the action of loads. They may be supported on two opposite sides only fig. Verandah slab is a type of one way slab, where the slab is spanning in the shorter direction with main reinforcement and the distribution of reinforcement in the transverse direction what is two way slab. Learning outcomes at the end of this lecture, the student should be able to a classify all types of solid slab co1 b identify one way and two way solid slab co1 c use a relevant clauses in code of practice co1 d design one way slabs co2 e details the slabs co1. When a slab is supported on all four sides and the ratio of long span to short span is equal or greater than two, it will be considered as one way slab. And its depend upon the condition of the structure design and longer to shorter span. So how do you differentiate a oneway and twoway slab. Finally, since shear reinforcement is not used in oneway slabs, the concrete must be able to resist the maximum shear force. A reinforced concrete slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so.

The ratio lb which is less than 2 is known as two way slab. Reinforced concrete slab slabs are plate elements forming floors, roofs in buildings. Two way slab being supported on four sides the load will be carried in both the directions. If slab is supported on all four sides and r shorter side longer side of twoway slabs by gerald c.

One way and two way slab design aspect the slab provides a horizontal surface and is usually supported by columns,beams or walls. One way slab is supported by two parallel beams or walls. Define the term slab, one way slab, two way slab, shrinkage. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. Comparison of oneway and twoway slab behavior economic choices oneway slab on beams suitable span 3 to 6m with ll 35knm2.

Load transfer in a oneway slab, b twoway slab nilson fig. A rectangular reinforced concrete slab is simply supported on two masonry walls 250 mm thick and. The load on the slab is carried by the short span in one direction. Main reinforcement is provided in only one direction for one way slabs. For example, the minimum slab thickness for a twohour fire rating is 4. Figure 1 shows a rectangular slab, simply supported along its two opposite long edges and free of any support along the two. Deep ribs, the concrete and steel quantities are relative low expensive formwork expected. Sandwich slabs may have the disadvantage of a larger weight compared to the ribbed ones but on the other hand, they have the advantage that their spans and supports behave in the same proper way. Two way slab is supported by beams in all four sides. Assume partitions cannot be damaged by deflections. The basic design procedure of a twoway slab system has five steps. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. If the ratio of longer dimension of the slab panel to the shorter dimension is greater than or equal to 2 then it is designed as one way slab.