The coefficient method may be the simplest, easiest and the quickest approach for the design of two way slab supported by edge beam on all slab sides. Two way slab being supported on four sides the load will be carried in both the directions. The basic design procedure of a twoway slab system has five steps. For those who do not know what are the des ign requirements of a slab. In two way slabs, load will be carried in both the directions. The design bending moment of two way restrained slab can be calculated as follows.
This strip is designed basically as if it were a 12inchwide beam, t inches thick. Reinforced concrete design 1 design of slab examples and. In two way slab, the ratio of longer span l to shorter span b is less than 2. Design procedure the basic design procedure of a twoway slab system has five steps. Twoway concrete slab with beams spanning between supports. In twoway slabs shorter direction strip carry greater %age of load. Alternate design method design procedure of twoway slabs. 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 18 concrete slab structures january 2019 188 18.
Design of a two way rcc slab structural engineering. Step 2 design forces draw panel of slab and indicate maximum design moments, shears and in. The program covers wide range of two way slab systems and can be used for more complex slab layouts. Twoway concrete slab on beams floor analysis and design.
Slab shear strength twoway shear check the adequacy of slab thickness for punching shear twoway shear at an interior column figure 4. The general provisions for construction and design procedure are given in cop 20. Here, we have tried to gather various reading materials available in the web about flat slab floor system in one place. The ratio lb which is less than 2 is known as two way slab. This method was provided in the american concrete institute aci in 1963 to design two way slabs carried by steel beams, deep beam, or walls. The load on the slab is carried by the short span in one direction. Here the ratio of longer span of slab to the shorter span of slab is less or equals to 2. Load transfer in a oneway slab, b twoway slab nilson fig. Two way slabs are normally supported from four sides. These conditions are set out in last section dealing with one way ribbed slabs. Reference 5 focused on analysis of two way ribbed slabs with. Aci 31811 code provides two methods for two way slab design one of which is direct design method. 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. Design of two way slabs is 456 limit state method youtube.
Reference 5 focused on analysis of twoway ribbed slabs with. Determine moments at critical sections in each direction, normally the negative moments at. This method was provided in the american concrete institute aci in 1963 to design twoway slabs carried by steel beams, deep beam, or walls. Procedures of two way slab design by direct design method. Design of reinforced concrete structures ii twoway slabs 1 1. May 15, 2020 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. Preliminary design of slab thickness thickness design depends on boundary conditions supports. Difference between one way slab and two way slab daily civil. Lecture series on design of reinforced concrete structures by prof. One way spanning slabs should be treated as beams of unit width and chapter 2 should be followed except for minimum shear reinforcement. Analysis and design of slabs two way civil engineers pk.
Aci 318 states that a slab system shall be designed by any procedure satisfying equilibrium and. I have developed a microssoft excel software for design of a two way rcc slab. Two way slabs have two way bending unlike one way slab. Determine the thickness of the slab panel using previous article. The slab has to carry a distributed permanent action of 1. 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. Types of one way slab one way slab may be solid hollow ribbed 6. Accordingly, main reinforcement is required in the two directions.
Oct 27, 2016 one way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. Design of reinforced concrete structures ii twoway slabs. Twoway slabs have two way bending unlike oneway slab. One way slab is supported by two parallel beams or walls. 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. Distribute moments transverse at critical sections to. An optimal plan geometry with all same supports is a square, based on load distribution into both directions. A combination of these values will determine the slab stresses at the time of stressing and at service loads. Lb2 is one way slab lb des ign requirements of a slab.
In one way slab, the ratio of longer span l to shorter span b is equal or greater than 2, i. Twoway slabs structural engineering forum of india, sefi. Slabs are usually used in floor and roof construction. The following example illustrates the example building. They may be supported on two opposite sides only fig. Design procedure the basic design procedure of a two way slab system has five steps. Assume partitions cannot be damaged by deflections.
The procedure of the design of twoway slabs will have all the six steps mentioned in sec. One way and twoway slabs one way slabs transfer the imposed loads in one direction only. Oneway spanning slabs should be treated as beams of unit width and chapter 2 should be followed except for minimum shear reinforcement. Use the aci 318 direct design method to design an interior bay of a flat plate slab system of multi bay building. A civil engineer must know all the aspects regarding the flat floor system. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. Distribute moments transverse at critical sections to column and middlestrip and if. Dhang, department of civil engineering, iit kharagpur.
The procedure of the design of two way slabs will have all the six steps mentioned in sec. In two way slabs shorter direction strip carry greater %age of load. Flat slab analysis, design and detailing pdf civil engineering. Bending will take place in the two directions in a dishlike form. Alternate design method design procedure of twoway slabs using aci moment coefficients and approved by bnbc 20 scope and limitations bnbc 6. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. The two classifications are one way slab and two way slab. I am submitting it to you and i want students or professional engineers to download it and use it for their studies or projects. Use i wsd, ii usd to design the twoway slab shown below, carrying floor finish 30 psf, random wall 50 psf and live load 60 psf given. Two way restrained slab if the slabs consist more than one panel or corner of the slab are prevent against lifting it is define as two way restrained slab. Twoway flat plate concrete floor system design structurepoint. Calculate aspect ratio aspect ratio 2 longer spanshorter span 2. A rectangular reinforced concrete slab is simply supported on two masonry walls 250 mm thick and.
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. Here are the steps for the design procedure for one way slab in steps. The design bending moment of twoway restrained slab can be calculated as follows. This condition occur when the slabs are connected monolithically with support. Application of lb ratio in first figure slab is supported on two opposite sides only. Load transfer in a one way slab, b two way slab nilson fig. Two way slab design by direct design method as per aci 31811. 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.
Verandah slab is a type of one way slab, where the slab is spanning in the shorter direction. 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 procedure steps for one way slab slab design steps. One way slab oneway slabs are those slabs with an aspect ratio in plan of 2. Analysis of two way ribbed and waffle slabs with hidden beams. Design procedure of two way slabs using aci moment coefficients. Difference between one way slab and two way slab simple. If frame analyses are performed to check the flexural resistance of a slab, the design moment, m ed transferred from the slab to a column and the design shear, v ed are obtained from the relevant analysis.
One way slab design how to design one way slab daily civil. Generally, there are two types of slab which are one way and two way slabs. The pca computer program pcaslab can be used to expedite the design of different slab systems. The dimensions of an interior bay are shown in figure 1. However main reinforcement bar and distribution bar in transverse direction. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. Oneway and twoway slabs university of asia pacific. Pdf this research introduces a new simple, efficient, and practical procedure to design the reinforced concrete rc circular slabs which have. Efm is the most comprehensive and detailed procedure provided by the aci 318 for the analysis and design of twoway slab systems where. Calculation of approximate depth from deflection criteria cl 23. Ce 403, fall 20 oneway slab design 2 4 aci 31811 referenced pp 2 4 typical concrete floor systems copied from ceco concrete construction pamphlet design procedure a oneway slab is designed by considering a onefootwide strip of slab. Pdf design of reinforced concrete circular slabs by twoway. In this video deisgn of two way slabs has been covered using is 456. Design procedure of twoway slabs using aci moment coefficients.
Please read the lauses mentioned in the video while solving the problem. The oneway slab is deflected in one way direction and primary reinforcement is placed in one direction whereas. The output of the program for the slab in the example is shown in the following pages. Dec 20, 2017 in this video deisgn of two way slabs has been covered using is 456. The one way slab is deflected in one way direction and primary reinforcement is placed in one direction whereas. Oneway and twoway slabs oneway slabs transfer the imposed. 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. Jul 02, 2010 lecture series on design of reinforced concrete structures by prof. Design of reinforced concrete structures ii two way slabs 1 1. Nov 27, 20 one way slab oneway slabs are those slabs with an aspect ratio in plan of 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.