Design of one way and two way slab pdf

If a oneway slab is supported on more than two edges and its aspect ratio, i. Slab shear strength two way shear check the adequacy of slab thickness for punching shear two way shear at an interior column figure 4. Depending upon the building plan, or the arrangement of main beams andor secondary beams, the slab may have only one. Waffle slab twoway pan joist twoway joist slab, also called a waffle slab. Oneway and twoway slabs university of asia pacific. Generally, there are two types of slab which are one way and two way slabs.

Shear strength of twoway slabs shear failure occurs when inclined. If the length to breadth ratio of the room is less than 2, the slab is designed as a two way reinforced slab. The ratio lb which is less than 2 is known as two way slab. May 02, 2017 one way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. The simplest routine structural element for illustration of design provisions in the code is the oneway slab. Distribute moments transverse at critical sections to column and middlestrip and if. Bending will take place in the two directions in a dishlike fo. 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. The steel fixers formwork drawing of a twoway slab for reasons regarding behaviour, safety and economical design, the twoway slab is far more efficient than the equivalent oneway slab. Powered by the equivalent frame method of analysis and design per latest american aci 31814 and canadian csa a23. One way slab is the most basic and common type of slab. Buildinghow team integrates all earthquake resistant building technologies. Chapter 3 design of rectangular beams and oneway slabs 12.

Slabs are usually used in floor and roof construction. 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. One way slabs are such slabs in which the loads are shared only by the shorter direction of the slab. Reinforced concrete design 1 design of slab examples and. The same is true for a two way slab or any other floor system where. Experimental study of shear in reinforced concrete oneway. A rectangular reinforced concrete slab is simply supported on two masonry walls 250 mm thick and.

Rectangular beams and one way slabs page 2 of 9 two methods. A one way 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. 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. Based on the stiffness requirement assume suitable depth and calculate the effective span.

Allowable stress design or working stress design wsd 2. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. Slabs can be designed by direct design method known as ddm and another method for design is coefficient method which is the easier one. D mm d 105 mm loads on slab self weight of slab 3. They may be supported on two opposite sides only fig. In two way slab, the ratio of longer span l to shorter span b is less than 2. Jul112018 twoway flat plate concrete floor system analysis and design the concrete floor slab system shown below is for an intermediate floor to be designed considering partition weight. The program is developed around the robust computational core of two popular programs ptdata. Pdf cost optimum design of reinforced concrete simply.

According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. One way and two way slab design aspect online civilforum. 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. Distinction of twosystems from one way systems is given by aci 31814 r8. Oneway and twoway slabs oneway slabs transfer the imposed. If the length to breadth ratio of the room is less than 2, the slab is designed as a twoway reinforced slab. Difference between one way slab and two way slab system. Twoway flat plate concrete floor system analysis and design. The twoway slab will deflect in a dish or saucerlike form under the action of loads. In two way slab, the slabs are supported on all the four sides.

Mention the parameters governing slab moment coefficients and explain their effects on moment. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. Design examples look at example 7 design of a flat plate floor without spandrel beams direct design method look at example 9 design of a twoway slab with beams in both directions. Two way slabs have two way bending unlike one way slab. The twoway slab is designed for both the directions as it bends in both directions. Calculate hmin and round it to higher 10mm multiple. 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. A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. Analysis and design of slabs two way two way edge supported slabs twoway slabs. Analysis and design of slabs two way civil engineers pk. Find depth of slab using deflection control criteria.

In one way slab, the loads are carried along one direction. 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. In one way slab, the slabs are supported by the beams on the two opposite sides. 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. The one way and two way slab systems are the most commonly used floor system in the reinforced concrete structure. Oneway slabs are those supported on two opposite edges. Here ratio of longer span of slab to the shorter span of slab is greater than 2. Design of one way slabs as per is 456 worked step by step. In case of twoway slab main reinforcements are provided both along the length as well as along the width of the room. Application of one way slab provides useful flat surface one way slab may be used when there is architectural limitations it is the simplest form of slab design main reinforcement placing is one way, so there is a little congestion than two way slab 29. One way slab design procedure with example design of one. In general a slab which is not falling in the category of one way slab, considered as two way slab.

So how do you differentiate a oneway and twoway slab. Please read the lauses mentioned in the video while solving the problem. A reinforced concrete slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so. This condition occur when the slabs are connected monolithically with support. Net, which many engineers have come to trust over the years for its accuracy and flexibility. Design of reinforced concrete structures ii twoway slabs 1 1. When the ratio of long span to short span is less than 2, then the slab is known as a slab spanning in two directions or twoway slab.

Assume partitions cannot be damaged by deflections. When length width one way slab design go beyond effectiveness. Twoway slabs have two way bending unlike oneway slab. Introduction in reinforced concrete construction, slabs are used to provide flat, useful surfaces. Difference between one way slab and two way slab daily civil. Dec 20, 2017 in this video deisgn of two way slabs has been covered using is 456.

One way and two way slabs one way slabs transfer the imposed loads in one direction only. One way slab is supported by two parallel beams or walls. These slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs or other types of structures. Pdf this study focuses on the slabbeam interaction in oneway systems. 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. All methods are viable provided that the safety and serviceability of the elements are within the acceptable limits. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Here the ratio of longer span of slab to the shorter span of slab is less or equals to 2. One way slab being supported on two opposite sides only leads to the structural action in single direction. Pdf reinforced concrete oneway slabs subjected to concentrated loads are designed. Pdf historical perspective on the evolution of twoway slab design. Difference between one way slab and two way slab simple.

Depending upon the building plan, or the arrangement of main beams and or secondary beams, the slab may have only one. In two way slabs, load will be carried in both the directions. Design procedure steps for one way slab slab design steps. Design of reinforced concrete structures ii two way slabs 1 1. Jul112018 two way flat plate concrete floor system analysis and design the concrete floor slab system shown below is for an intermediate floor to be designed considering partition weight. Bending will take place in the two directions in a dishlike form. Analysis and design of slabs two way two way edge supported slabs two way slabs. The two way slab will deflect in a dish or saucerlike form under the action of loads. Slab positive moments have been considered as indicators on. Corners of the two way slab lift up if the slab is not cast monolithically with the supports wallsbeams. To see their result for this slab we will find the load factor. Oneway slab is the most basic and common type of slab.

Pt designer design of posttensioned concrete floors. In this video deisgn of two way slabs has been covered using is 456. 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. There are several methods by which two way slabs can be designed. 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 two way slab is designed for both the directions as it bends in both directions. Rectangular beams and oneway slabs page 2 of 9 two methods. Pt designer is a computer program for the design and analysis of linear posttensioned concrete floor systems. Its typically used when stiffness is important or if there are abnormally heavy loads. Strength design or ultimatestrength design usd strength design or ultimatestrength design usd with strength design method, the working dead load dl and live load ll are. So, main reinforcement is provided in both direction for two way slabs. When the ratio of long span to short span is less than 2, then the slab is known as a slab spanning in two directions or two way slab.

For those who do not know what are the des ign requirements of a slab. Pdf design calculation design of one way slab slab s1. Oneway slabs are typically divided into a series of. Analysis and design of slabs one way civil engineers pk. 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. Waffle slab two way pan joist two way joist slab, also called a waffle slab. If slab is supported on all four sides and r shorter side longer side one way slab. Pdf design calculation design of one way slab slab s1 span. 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. 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.

Slab resting on walls or sufficiently deep and rigid beams on all sides. That is, the load factor at which the uls moment equals the moment capacity. Design of reinforced concrete structures ii twoway slabs. Reinforced concrete design 1 design of slab examples. Corners of the twoway slab lift up if the slab is not cast monolithically with the supports wallsbeams. Because there are joists in both directions, this floor system is the strongest and will have the least deflection.

One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. 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. Comparison of oneway and twoway slab behavior economic choices oneway slab on beams suitable span 3 to 6m with ll 35knm2. Two way slabs are normally supported from four sides. 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. 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. The ratio of longer span l to shorter span b is equal or greater than 2, considered as one way slab because this s. Ultimate behavior of oneway spanning slab linear elastic analysis methods such as moment distribution are linear elastic methods. The two classifications are oneway slab and twoway slab. 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 slab design static equilibrium of two way slabs total moment in both beams full load was transferred eastwest by the planks and then was transferred northsouth by the beams.

The simplest routine structural element for illustration of design provisions in the code is the one way slab. The basic design procedure of a twoway slab system has five steps. Accordingly, main reinforcement is required in the two directions. Oct 27, 2016 difference between one way slab and two way slab. 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 here i solve a probleam based on the one way slab. Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement. Analysis and design of twoway slabs page 1 chapter 3.

Calculate factored moment and shear force by considering the onemeter width of the slab. Deep ribs, the concrete and steel quantities are relative low expensive formwork expected. 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. Chapter 3 design of rectangular beams and oneway slabs. Nov 15, 2014 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 the aspect ratio the type of slab. Pdf reinforced concrete twoway slabs have evolved in the past. The design bending moment of twoway restrained slab can be calculated as follows.