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. Pdf this paper studies experimentally the behavior of laced. Pdf enhancing the behavior of oneway reinforced concrete. Typical detailing of reinforcements in beams and slabs. Suresh19 introduction slabs could be simply supported, continuous or cantilever in two way slab the corners may be held down by restraints or may be allowed to lift up additional torsion reinforcement is required at corners when. Design beams if any, using procedures you learned in civl. Slab supported directly by columns are called flat slab one way slab two way slab 19. Design of rcc structures lecturer notes topic wise pdf. Reinforced concrete slab slabs are plate elements forming floors, roofs in buildings. Ce 403, fall 20 one way slab design 3 4 aci 31811 referenced pp 2 4 rating. Structural behavior of reinforced concrete oneway slabs.
Details of a bent bars, b integral beams with vertical stirrups. Difference between one way slab and two way slab daily civil. 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. Direct design method ddm for slab systems with or without beams loaded only. The following example illustrates the example building. Reinforcement detailing of reinforced concrete slabs with images. The slab may be supported by walls, by reinforced concrete beams usually cast monolithically with the slab, by s. Select reinforcing bars for the slab and concentrate bars near the column, if necessary 5. Slab supported on two sides and bending takes place predominantly in one direction only is called one way slab. Concrete slabs are commonly divided into the following types. Difference between one way slab and two way slab civil read. Chapter 3 design of rectangular beams and oneway slabs.
A civil engineer must know all the aspects regarding the flat floor system. Slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs, bridges, and other types of structures. In a one way system such as a one way slab and beam system, the members only carry the load in one direction. Oneway slabs transfer the imposed loads in one direction only. The slab has to carry a distributed permanent action of 1. Slab may be supported on walls or beams or columns. 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. Details of the test specimens all dimension are in mm. Pdf cost optimum design of reinforced concrete simply. Beams, see lecture 3 punching shear requirements e. Design procedure steps for one way slab slab design steps. Pdf behavior of one way reinforced concrete slabs with styropor. Slabs beam reinforcement detailing linkedin slideshare. Pdf cantilever slab design ramjan shehzaad academia.
Would love to provide these pictures for better clarity of the viewers. Further discussion of the differences between one and two way systems is given in reference aalami, 1993b. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. Enhancing the behavior of oneway reinforced concrete slabs by using laced reinforcement. Two way 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. One way shear in slab structural engineering general. As per the above figure floor slab 2 is a one way slab. In this kind of slab mains bars cranked bars are provided in shorter direction hence there is no need of calculating the crank bar length in ydirection from fig. The ratio lb which is less than 2 is known as two way slab.
Reinforcement detailing of a slab is done based on its support conditions. Designing of slabs depends upon whether it is a oneway or a two. For better view, please read this post in landscape mode if you are on the mobile device. For slabs 150 mm deep or greater, smdsc 21 standard detail recommends ubars lapping 500 mm with bottom steel and extending 0. Four slabs were fabricated using selfcompacting concrete. Department of mechanics, materials and structures english. Difference between one way slab and two way slab system. Reinforcement detailing of reinforced concrete slabs. Based on the stiffness requirement assume suitable depth and calculate the effective span.
Introduction, definitions flat slabs are two way slabs supported by pointlike supports. To attempt to make sure that only ductile failures can occur the aci code limits the maximum steel ratio as following. Define the term slab, one way slab, two way slab, shrinkage. Assume partitions cannot be damaged by deflections. Ce 433, summer 20 slab design example 1 5 design a one. Slab supported directly by columns are called flat 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. A free unsupported edge is required to use longitudinal and transverse reinforcement generally using ubars with legs at least 2h long. Twoway concrete floor slab with beams design and detailing. Load transfer in a oneway slab, b twoway slab nilson. 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.
In a two way system such as a columnsupported slab, the load is carried in both directions. Flat slab system is an important division of concrete floor system. Flat slab analysis, design and detailing pdf civil. One way slab reinforcement details daily civil engineering. Shear reinforcement to check if shear reinforcement and which system can be used, one can calculate the minimal needed value of factor k sys. To provide adequate support on the larger side, the main reinforcement bar is provided perpendicular to that side or parallel to the shorter direction.
Aci 318r emphasizes the importance of anchorage details and accurate placement of the shear reinforcement, especially in thin slabs. One way slab is supported by two parallel beams or walls. Detailing of reinforcement in concrete structures r. A general procedure for evaluation of the punching shear strength of slab. Continuous oneway solid slab concrete structures eurocode. Oneway and twoway slabs oneway slabs transfer the imposed. The thickness of the slab has to be increased or the slab has to be shear reinforced. 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. As can be seen from the figure2 below, the tension reinforcement are 100% at the midspan of the beam and slab, while it is curtailed at the distance of 0. Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement. Here, we have tried to gather various reading materials available in the web about flat slab floor system in one place. The biggest misconception is considering beam outer to outer as slab. Our friend mohit sharma has already highlighted the essentials for a one way slab. For a continuous beams and slabs, the shear force and bending moment diagrams are drawn and reinforcement details are provided based on the value of the shear force and bending moment.
Calculate factored moment and shear force by considering the onemeter width of the slab. Time saving design aids two way slabs page 5 of 14. For b oth one way and two way slab with an example. They may be supported on two opposite sides only fig. In this post, we are going to explain how to calculate steel quantity for the slab. Therefore, this paper presented an experimental investigation to assess the effect of voids size on the structural behavior of one way slabs. Sandwich slab reinforcement details in reality, sandwich slabs are ribbed slabs with a slab placed both to their upper and lower surface. Slab reinforcement detailing one way or two way 3 field expert. I am doing one way slabs and hope you can clean up my doubts about the one way shear in slab. Determine the area of steel considering meter width of the slab. As they are one way slabs i treat them as wide beams. For the purposes of analysis and design, the ribbed slab will be replaced with a solid slab of equivalent moment of inertia, weight, punching shear capacity, and oneway shear capacity. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. Eight slab specimens have casted as styropor block slabs hs.
Nonprestressed bonded reinforcement in posttensioned. Simplified design of reinforced concrete buildings, fourth edition, 2011 mahmoud e. For example, the minimum slab thickness for a twohour fire rating is 4. Usually, when a slab is supported by a beam the support is considered to be pinned. Determine the area of steel required in the slab at critical sections for column and middle strips. Slab reinforcement detailing one way or two way3 youtube. In two way slab, the ratio of longer span l to shorter span b is less than 2. Difference between one way slab and two way slab simple. Behavior and reinforcement of one way slab the structural frame consists of four columns, two beams and one slab. No redistribution is allowed when method 1 or method 2 of analysis in section 3. 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. Manual for design and detailing of reinforced concrete to september 20 the code of practice for structural use of concrete 20 contents 1. Finally, since shear reinforcement is not used in one way slabs, the concrete must be able to resist the maximum shear force.
Rectangular beams and one way slabs page 5 of 9 maximum permissible steel ratio, max an over reinforced beam will fail in a brittle manner while an under reinforced beam will fail in a ductile manner. Manual for design and detailing of reinforced concrete to. Select reinforcing bars for the slab and concentrate bars near the column, if. However, the structural behavior of such slabs has not been adequately inspected, especially for one way slabs. Two way slabs are normally supported from four sides. These materials are originally located at different websites. A bentup bar called as crank bar is provided to make rcc slab safe from compressive stresses. Oneway and twoway slabs university of asia pacific. These slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs or other types of structures. Beamless slabs beamless slabs are supported only on columns and are applied mostly in large industrial and. Reinforced concrete design 1 design of slab examples. Two way concrete slabs with openings the static system and the design of reinforcement. Twoway joist concrete slab floor waffle slab system.
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