I have developed a microssoft excel software for design of a two way rcc slab. The main variation among the two types of slabs in one way slab load is delivered to one direction only that is the smaller one and therefore, primary reinforcement is presented parallel to the span while temperature or shrinkage reinforcement is presented perpendicular to the primary reinforcement. Here are the differences between one way slab and two way slab. In one way slab, the slabs are supported by the beams on the two opposite sides. Oneway and twoway slabs oneway slabs transfer the imposed. Oct 27, 2016 difference between one way slab and two way slab. Two way slabs page 6 of 14 the pca computer program pcaslab can be used to expedite the design of different slab systems. In one way slab, the loads are carried along one direction. Comparison of oneway and twoway slab behavior economic choices. The behavior of a twoway slab is similar to that of a oneway slab the only difference being that now the slab loads will be carried in both directions. Here the ratio of longer span of slab to the shorter span of slab is less or equals to 2. Pdf experimental and fe study on rc oneway slabs upgraded. Allowable stress design or working stress design wsd 2.
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. These slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs or other types of structures. 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 slab, the slabs are supported on all the four sides. I am submitting it to you and i want students or professional engineers to download it and use it for their studies or projects.
Slabs may be simply supported or continuous over one or more supports and are classified according to the method of support. Depending on their load carrying behavior, they are classified as one way slab and two way slab. One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. What are the basic differences between oneway and twoway slabs. Jul 02, 2018 difference between one way slab and two way slab learning technology official website. Two way slabs are such slabs in which the loads are shared by both the shorter and longer direction of the slab. Slab thickness of 190 mm is adequate for oneway shear. Posttensioned oneway slab pennsylvania state university. Flat plate for relatively light loads as in apartments or offices suitable span 4. Reinforced thin plate elements are supported over beams, masonry walls or directly over columns.
Slab supported on two sides and bending takes place predominantly in one direction only is called one way slab. Waffle slab twoway pan joist twoway joist slab, also called a waffle slab. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. A rectangular reinforced concrete slab is simply supported on two masonry walls 250 mm thick and. Generally, there are two types of slab which are one way and two way slabs. One way slab is supported by two parallel beams or walls. Rectangular beams and oneway slabs page 2 of 9 two methods. Reinforced concrete design 1 design of slab examples and. Deep ribs, the concrete and steel quantities are relative low expensive formwork expected. Calculate factored moment and shear force by considering the onemeter width of the slab. In two way slabs, load will be carried in both the directions.
They may be supported on two opposite sides only fig. The twoway slab is designed for both the directions as it bends in both directions. Difference between one way slab and two way slab civil read. 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. The following example illustrates the example building. Difference between one way slab and two way slab daily civil. So, main reinforcement is provided in both direction for two way slabs. Here are the differences between oneway slab and twoway slab. One way slab being supported on two opposite sides only leads to the structural action in single direction. Two way slabs are the slabs that are supported on four sides and the ratio of longer span l to shorter span b is less than 2. To connect with me personally subscribe hinditalkwithmukesh. One way slabs are such slabs in which the loads are shared only by the shorter direction of the slab.
Chapter 3 design of rectangular beams and oneway slabs. The problem of oneway shear in slabs, as encountered by bridge engineers when. The simplest routine structural element for illustration of design provisions in the code is the oneway slab. Design of reinforced concrete structures ii two way slabs 1 1.
In this video we learn that what is one way and two way slab and what is difference between of them. Beam and slab arrangement can be the best example for one way and two way slabs. Mention the parameters governing slab moment coefficients and explain their effects on moment. Because there are joists in both directions, this floor system is the strongest and will have the least deflection. Twoway flat plate concrete floor system analysis and design. So how do you differentiate a oneway and twoway slab. Corners of the two way slab lift up if the slab is not cast monolithically with the supports wallsbeams. When discussing the differences between one way slabs and two way slabs it is important to note that we are talking about concrete slabs. One way slab is supported by beams in only 2 sides. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Normally it works fine but this time after carrying out the calculations the slabs fail in shear because of there are some huge point loads near the support.
Reinforcement detailing of reinforced concrete slabs. Then determine is the ratio between the longer span and shorter span is more. The two way slab will deflect in a dish or saucerlike form under the action of loads. Design procedure steps for one way slab slab design steps. But in case of two way slab when loaded such slabs bend into a dished surface rather than a cylindrical surface. The codes governing the design of the one way slab will be aci 31802 and ibc 2003. The proposed slab system must be able to be constructed at a reasonable cost. Based on the stiffness requirement assume suitable depth and calculate the effective span. Slab supported directly by columns are called flat slab.
Two way joist slab often called two way ribbed slab or waffle slab is an economical floor system when the spans are long andor loads are high. Slabs are usually used in floor and roof construction. Transition from oneway to twoway shear in slabs under concentrated loads article pdf available in magazine of concrete research 6717 april 2015 with 3,150 reads how we measure reads. In this video deisgn of two way slabs has been covered using is 456. Comparison of oneway and twoway slab behavior economic choices oneway slab on beams suitable span 3 to 6m with ll 35knm2. Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need to be taken into account to reduce the complexity of calculations needed when. Please read the lauses mentioned in the video while solving the problem. Dec 20, 2017 in this video deisgn of two way slabs has been covered using is 456. Here ratio of longer span of slab to the shorter span of slab is greater than 2.
Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement. Here are the steps for the design procedure for one way slab in steps. Ce 403, fall 20 oneway slab design 3 4 aci 31811 referenced pp 2 4 rating. Fanella, which appeared in the october 2001 edition of structural engineer magazine. As they are oneway slabs i treat them as wide beams. Reinforced concrete design 1 design of slab examples. Finally, since shear reinforcement is not used in oneway slabs, the concrete must be able to. Slabs can be designed by direct design method known as ddm and another method for design is coefficient method which is the easier one. That means at any point the slab is curved in both direction. When the ratio of the longer to the shorter side l s of the slab is at least equal to 2. The output of the program for the slab in the example is shown in the following pages. To clear the concept of one way and two way slabs a table is shown below.
Difference between one way slab and two way slab simple. A oneway slab is defined for purposes of this book as a flexural member with depth small relative to other dimensions, supporting gravity loads applied normal to and directly over its surface, spanning in one direction between parallel supports, and reinforced for flexure. The one way and two way slab systems are the most commonly used floor system in the reinforced concrete structure. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. The two way slab is designed for both the directions as it bends in both directions. Pdf transition from oneway to twoway shear in slabs under. Difference between one way and two way slab in terms of. Slab shear strength twoway shear check the adequacy of slab thickness for punching shear twoway shear at an interior column figure 4. There are some basic differences between one way slabs and two way slabs. To determine if the slab is one way, look to see if it is supported by all four sides. The four slabs of the last two groups were externally upgraded with unidirectional carbon or eglass fiber fabric impregnated with an epoxy resin. The slab has to carry a distributed permanent action of 1. When a slab is supported on the two different sides and the ratio of longer span to shorter span is equal to or greater than 2, it will be considered as one way slab.
The steel fixers formwork drawing of a twoway slab. Difference between one way slab and two way slab learning technology official website. 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. One way slab reinforcement details daily civil engineering. 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. When a reinforced concrete slab is 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. Difference between oneway slab and twoway slab gharpedia. Two way slab is supported by beams in all four sides. An experimental program was designed to elucidate the structural behavior of twoway solid slabs with different supporting beams under uniform load up to failure. The codes governing the design of the oneway slab will be aci 31802 and ibc 2003. Design of a two way rcc slab structural engineering forum.
The reinforcement rules are also similar in both directions. My name is sl khan and you are watching an engineer boy. Pdf transition from oneway to twoway shear in slabs. Accordingly, main reinforcement is required in the two directions. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. Design of reinforced concrete structures ii twoway slabs. One way shear in slab structural engineering general. Design of a two way rcc slab structural engineering. The ratio of longer span l to shorter span b is equal or greater than 2, considered as one way slab because this s. Its typically used when stiffness is important or if there are abnormally heavy loads.
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. Bending will take place in the two directions in a dishlike form. 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. One way and two way slabs as floor systems are the most conventional forms of structural floor systems. In practices, the choice of one way slab and two way slab for a particular structure will largely depend upon the economy, build ability, loading conditions and length of the span. Distinction of twosystems from one way systems is given by aci 31814 r8.
Concrete slabs are used in all different forms of construction where a thick slab is poured to be able to construct the ground floor of a building. Slab may be supported on walls or beams or columns. In one way slab, one side is larger than the other one. 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. For example, the minimum slab thickness for a twohour fire rating is 4. May 02, 2017 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. Difference between one way and two way slab in terms of their structural behaviou for one way slab. One way slab is supported by beams in only 2 sides 2. In two way slab, the ratio of longer span l to shorter span b is less than 2. I am doing oneway slabs and hope you can clean up my doubts about the one way shear in slab. Pdf oneway and twoway slabs mohamed tiger academia. Main reinforcement is provided in only one direction for one way slabs. Comparison of one way and two way slab behavior economic choices one way slab on beams suitable span 3 to 6m with ll 35knm2. Design of reinforced concrete structures ii twoway slabs 1 1.
Difference between one way slab and two way slab learning. Corners of the twoway slab lift up if the slab is not cast monolithically with the supports wallsbeams. The proposed slab system must meet the current code. Twoway joist slab often called twoway ribbed slab or waffle slab is an economical floor system when the spans are long andor loads are high.
One more definition regarding oneway and two way slab is that if one direction span to other direction span ratio or more precisely if longer dimension to shorter dimension ratio is greater than 2 it is termed as two way slab. The thickness of the concrete will vary depending on the use of the slab. The ratio of longer span panel l to shorter span panel b is less than 2. 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 joist waffle slab design approach and methodology. The longstanding problem of shear in structural concrete elements is typically studied as oneway shear in beams, or as twoway shear in slabcolumn connections.
One way and two way slabs one way slabs transfer the imposed loads in one direction only. Can be used for larger spans with relatively higher cost and higher deflections one way joist system suitable span 6 to 9m with ll 46knm2. Oneway and twoway slabs university of asia pacific. Depending on their load carrying behavior, they are classified as oneway slab and twoway. In one way slab, as one side is greater than the other side, the maximum load is carried by the larger side just so giving main reinforcement comparing to that load carrying side will be adequate.
Reinforcement detailing of a slab is done based on its support conditions. Chapter 3 design of rectangular beams and oneway slabs 12. Can be used for larger spans with relatively higher cost and higher deflections oneway joist system suitable span 6 to 9m with ll 46knm2. Two way slab being supported on four sides the load will be carried in both the directions. The behavior of a two way slab is similar to that of a one way slab the only difference being that now the slab loads will be carried in both directions. In practices, the choice of oneway slab and twoway slab for a particular structure will largely depend upon the economy, build ability, loading conditions and length of the span. The program covers wide range of two way slab systems and can be used for more complex slab layouts.
Deep ribs, the concrete and steel quantities are relative low. Difference between one way slab and two way slab system. Unless otherwise noted, all referenced table, figure, and. For those who do not know what are the des ign requirements of a slab. Sep 08, 2017 do you know about one way slab and two way slab. Difference between one way slab and two way slab system civil. The twoway slab will deflect in a dish or saucerlike form under the action of loads. A cost analysis will be provided based on data from rs means.
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