Design of one way ribbed slab pdf

Reinforced concrete design 1 design of slab examples. Guidelines for a oneway concrete flooring system brewer. A one way slab is simply a very wide beam that spans between supports. The service live load is 100 psf and 4000 psi concrete is specified for use with steel with a yield stress equal to 60000 psi. For 1m slab width, moment, shear force, one way continuous slab for continuous slab, moment and shear force can be obtained from table 3.

Bending will take place in the two directions in a dishlike fo. The ribs are tapered in crosssection in its lower part. Chapter 3 design of rectangular beams and oneway slabs. One way and two way slabs one way slabs transfer the imposed loads in one direction only. Distribute moments transverse at critical sections to column and middlestrip and if. For 1m slab width, moment, shear force, oneway continuous slab for continuous slab, moment and shear force can be obtained from table 3. In case of ribbed slab the blocks are not permanent. There are many methods that are used to analyze two way slabs and the precision of these methods vary depending.

In two way slab, the slabs are supported on all the four sides. 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. The domeshaped forms create a matrix of voids surrounded by orthogonal ribbing, producing a two way configuration very suitable for largespanning slabs. Ribbed slab design spreadsheets to eurocode engineering books. If the soil is unsuitable to hold the slab load design, pontex is used which in turn will create a one directional.

Get full capabiltiies with our free version of rcsolver once you signup for our newsletter. With the free version you will have to wait 30 seconds for. With accurate to temperature and shrinkage, minimum. 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. Ribbed slabs have been widely used in buildings due to their many advantages, especially the decrease of concrete below the neutral line. The general provisions for construction and design procedure are given in cop 20. A reinforced concrete slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so.

Ribbed slab design spreadsheets to eurocode engineering. Ultimate behavior of oneway spanning slab linear elastic analysis methods such as moment distribution are linear elastic methods. Optimum design of reinforced concrete waffle slabs alaa c. One way simplysupported and continuous solid slab free download as powerpoint presentation. Mathcad is an efficient learning environment for technical topics such as reinforced concrete design 1. Reinforced concrete ribbed slabs with widebeam lajes. 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. Slab slabs are an important structural component where prestressing is applied. Mention the parameters governing slab moment coefficients and explain their effects on moment. One way slab being supported on two opposite sides only leads to the structural action in single direction.

In one way slab, the loads are carried along one direction. The system was designed to decrease the weight of traditional fullconcrete slabs. Introduction hollow block and ribbed slabs are formed by placing blocks on the slab and concrete ribs. In addition, the scope of this study is to design oneway ribbed slab and twoway solid slab by using esteem software. Oct 27, 2016 difference between one way slab and two way slab. Oneway and twoway slabs oneway slabs transfer the imposed. Design of reinforced concrete structures ii twoway slabs. A slightly deeper section is required but these stiffer floors facilitate longer spans and provision of holes. In the one way ribbed slab where the ribs are in one direction, it is assumed. Design procedure steps for one way slab slab design steps. The two classifications are one way slab and two way slab.

Slabs are mostly used as roof coverings and floors in various shapes such as square, rectangular, circular and triangular in buildings, tanks, bridges etc. Chapter 3 design of rectangular beams and oneway slabs 12. Analysis and design of slabs one way civil engineers pk. Ribbed slabs oneway joists introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section. Ribbed and waffle slabs types, advantages, disadvantages. The model provides the actual behavior for ribbed slab by analyzing the structure as one unite in two dimensions. Deep ribs, the concrete and steel quantities are relative low expensive formwork expected. 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 basic design procedure of a two way slab system has five steps.

Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. Design of reinforced concrete structure one way slab presented by md. The moments and forces due to design ultimate loads on continuous slabs may be obtained by any of the methods given in 3. Allowable stress design or working stress design wsd 2. Analysis of two way ribbed and waffle slabs with hidden beams. One way slab oneway slabs are those slabs with an aspect ratio in plan of 2. Pontex is recycled polypropylene element that, combined with cupolex can be used to create beams so that aerated floors become selfbearing. The spacing between the ribs should be in general 2030 inch.

Jul 02, 2010 lecture series on design of reinforced concrete structures by prof. This form of construction is not very common because of the formwork costs and the low fire rating. If slab is supported on all four sides and r shorter side longer side one way slab. They are either one way spanning systems known as ribbed slab or a two way ribbed system known as a waffle slab. Oneway slabs notes edurev notes for is made by best teachers who have written some of the best books of. Comparison of one way and two way slab behavior economic choices one way slab on beams suitable span 3 to 6m with ll 35knm2. 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. Check the applicable joist dimensional limitations as follows. In this example, the latter option will be used to achieve better understanding for the design of two way joist slab often called two way ribbed slab or waffle slab. Pdf design calculation design of one way slab slab s1. One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. One way shear in slab structural engineering general. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. In reality, sandwich slabs are ribbed slabs with a slab placed both to their upper and lower surface.

Ribbed slab grid slab, solid slab, filler slab, folded plate 6 basis of spanning directions. Pdf analysis of two way ribbed and waffle slabs with. I am doing one way slabs and hope you can clean up my doubts about the one way shear in slab. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. Difference between one way slab and two way slab daily civil. Aug 22, 2018 one way ribbed slab part one civil team. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. 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. For those who do not know what are the des ign requirements of a slab.

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. The saving of materials tends to be offset by some. Here are the steps for the design procedure for one way slab in steps. Design of reinforced concrete structures ii two way slabs 1 1. Rectangular beams and one way slabs page 2 of 9 two methods. Oneway and two way slabs one way slabs transfer the imposed loads in one direction only.

As they are one way slabs i treat them as wide beams. One way spanning slabs should be treated as beams of unit width and chapter 2 should be followed except for minimum shear reinforcement. Here ratio of longer span of slab to the shorter span of slab is greater than 2. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. Teaching twoway ribbed slab analysis and design using. Lecture series on design of reinforced concrete structures by prof. In one way ribbed slab, loads are transferred in one direction, and the main reinforcement is distributed in the same direction of the load. The other half span rebars are formed with a straight length. A one way slab is supported on two opposite sides, so structural action is only ever in one direction. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. These conditions are set out in last section dealing with one way ribbed slabs. Step 2 design forces draw panel of slab and indicate maximum design moments, shears and in plane loads, if any, per unit width of slab. The waffle slab is also sometimes termed as ribbed slab system but you would find it interesting to know that ribbed and waffle slab are somehow two different things. Analysis and design of slabs, one way slabs, online free slab design, design of slabs one way, free slab design online, design procedure for one way slab.

This paper deals with the problem of optimum design of reinforced concrete two way ribbed waffle slabs using genetic algorithms. When one says ribbed slab it is actually a one way spanning system with ribs where as in waffle slab the joists form a two way system. To see their result for this slab we will find the load factor. One way slabs are such slabs in which the loads are shared only by the shorter direction of the slab. Whatever may be the width of the slabs it should always be designed for a width of equal to one metre and the same design should be adopted for the rest of the slab. Moments for design may be taken from table 3 for slabs simply supported on four sides. One way slab design procedure with example design of one. The design procedure for a uniformly loaded one way reinforced slab can be divided in the following steps. Free version of rcsolver concrete design with ec2, ec8, and aci 318. That is, the load factor at which the uls moment equals the moment capacity. 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. Bending will take place in the two directions in a dishlike form. Where the slabs are ribbed in two directions, they may be designed as two way spanning in accordance with 3. In one way slab, the slabs are supported by the beams on the two opposite sides.

Twoway joist waffle slab design approach and methodology. This paper focuses on analysis of two way ribbed and waffle slabs with hidden beams. The ribbed slab was analyzed exactly by finite element theory through sap 2000 program. Dhang, department of civil engineering, iit kharagpur. Figure 1 shows a rectangular slab, simply supported along its two opposite long edges and free of any support along the two. Ribbed slabs one way joists introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section.

Introduction in reinforced concrete construction, slabs are used to provide flat, useful surfaces. Analysis and design of twoway slabs page 1 chapter 3. A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. Jul 22, 2015 design of two way ribbed slab 18 x 25 m clear span 1. Slabs are plane structures whose thickness is quite small as compared to other dimensions. One way simplysupported and continuous solid slab bending. In case of hollow block slab voided blocks are placed to reduce the total weight of the slab. Reinforced concrete design 1 design of slab examples and. Egyptian code for design and construction of reinforcement concrete structures. Design of one way slabs the structural action of a one way slab may be visualized in terms of the deformed shape of the loaded surface. The blocks are considered as nonstructural element as they do not contribute to strength of. Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need.

Design of oneway slab free download as powerpoint presentation. Introcduction slab in which the deflected surface is predominantly cylindrical termed as oneway slabs spanning in the direction of curvature. Analysis and design of two way slabs page 1 chapter 3. Figure 1 shows a rectangular slab, simply supported along its two opposite long edges and free of any support along the two opposite short edges. Slabs are usually used in floor and roof construction. One way simply supported slab analysis and design of the slab similar to design of simply supported beam as indicate in the previous chapter. In this section, two types will be discussed, oneway solid slabs and oneway ribbed slabs. D mm d 105 mm loads on slab self weight of slab 3.

In oneway ribbed slab, loads are transferred in one direction, and the main reinforcement is distributed in the same direction of the load. Here ratio of longer span of slab to the shorter span of slab. This brief will provide guidance to architects and structural engineers during the concept phase of the design for selecting a suitable one way flooring system. Its computational and presentation capabilities not only. The minimum required reinforcement in the support areas is provided in two alternative ways.