Twoway slab analysis and design using equivalent frame method efm aci 318 states that a slab system shall be designed by any procedure satisfying. Slab design, bs 8110 slab design, how to determine ultimate load for slabs, how to check for deflection in slabs, how to calculate for dead load, how to calculate for lever arm, basics of slab design, how can i design a 2 way spanning slab, building. That is, the load factor at which the uls moment equals the moment capacity. Calculate factored moment and shear force by considering the onemeter width of the slab. Flat plate concrete floor system does not use beams between columns or. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. Design procedure steps for one way slab slab design steps. Two way slabs are such slabs in which the loads are shared by both the shorter and longer direction of the slab. There are several methods by which two way slabs can be designed. Fanella, which appeared in the october 2001 edition of structural engineer magazine. Design of concrete structure i bending will take place in the two directions in a dishlike form. Slabs are usually used in floor and roof construction. Analysis and design of two way slabs page 4 simple beam, uniformly loaded by its share of q.
Two way slab design by direct design method as per aci 31811. Basic steps in two way slab design choose layout and type of slab. Two way slabs prestressing tendons cgs at top 48 mm at bottom 48 mm nonprestressing reinforcement cover at top 25 mm at bottom 25 mm 143 design criteria 143. 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. I have developed a microssoft excel software for design of a two way rcc slab. This research introduces a new simple, efficient, and practical procedure to design the reinforced concrete rc circular slabs which have large diameters. Based on the stiffness requirement assume suitable depth and calculate the effective span. All methods are viable provided that the safety and serviceability of the elements are within the acceptable limits. In flatplate floors, slab column connections are subjected to high shear stresses produced by the transfer of axial loads and bending moments between slab and columns.
Bondy introduction two way posttensioned slabs have been an extremely popular floorframing system in american building construction. Example design of two way edgesupported solid slab. A six storey building for a commercial complex has plan dimensions as shown in figure 1. 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. The vast majority of posttensioning tendons used in these slabs have been unbonded. They may be supported on two opposite sides only fig. 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. Slab resting on walls or sufficiently deep and rigid beams on all sides. Design of one way slabs as per is 456 worked step by.
No redistribution is allowed when method 1 or method 2 of analysis in section 3. The lateral loads are independently resisted by shear walls. Accordingly, main reinforcement is required in the two directions. Oneway and twoway slabs university of asia pacific. Torsion steel must be provided at discontinuous edges as specified in code. Foreword the reinforced concrete design manual sp1711 is intended to provide guidance and assistance to professionals engaged in the design of castinplace reinforced concrete structures. So, main reinforcement is provided in both direction for two way slabs.
Analysis and design of slabs two way two way edge supported slabs twoway slabs. Flat slab analysis, design and detailing pdf civil. Determine moments at critical sections in each direction, normally the negative moments. The same is true for a two way slab or any other floor system. Ultimate behavior of one way spanning slab linear elastic analysis methods such as moment distribution are linear elastic methods. View test prep concrete 3 design of concrete beam and slab two way slab part 22 from engineerin 101 at royal melbourne institute of technology. A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. A rectangular reinforced concrete slab is simply supported on two masonry walls 250 mm thick and. One way slab design procedure with example design of one. Flat slab analysis, design and detailing pdf flat slab system is an important division of concrete floor system. Twoway slab design static equilibrium of twoway slabs analogy of twoway slab to plank and beam floor section aa. 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 slabs structural engineering forum of india, sefi.
A monolithic reinforced concrete floor is to be composed of rectangular bays measuring, as shown. The design bending moment of two way restrained slab can be calculated as follows. I am submitting it to you and i want students or professional engineers to download it and use it for their studies or projects. Aait, school of civil and environmental engineering reinforced concrete ii. 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. The following example illustrates the example building. A civil engineer must know all the aspects regarding the flat floor system. Twoway joist concrete slab floor waffle slab system. Allowable stress design or working stress design wsd 2. Middle strip is forming threefourth of slab width in width directions.
In two way slab, the ratio of longer span l to shorter span b is less than 2. Two way joist concrete slab floor waffle slab system analysis and design design the concrete floor slab system shown below for an intermediate floor with partition weight of 50 psf, and unfactored live load of 100 psf. The first reinforced concrete design manual formerly titled aci design handbook was developed in accordance with the design provisions of 1963 aci 318 building code by aci committee 340, design. Simply supported one way slab modification factor for span less than 7 m 1.
Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Twoway slabs have two way bending unlike oneway slab. Ppt design of one way slabs powerpoint presentation. In this video deisgn of two way slabs has been covered using is 456. Two way posttensioned slabs with bonded tendons by kenneth b. However, as in the one way slab, the depth of the two way slabs should also be checked for the shear stresses to avoid any reinforcement for shear. 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. 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. Chapter 3 design of rectangular beams and oneway slabs. A system where a two way slab is continuous with a one way slab or vice versa is called a mixed slab system. Design of reinforced concrete structures ii twoway slabs 1 1. Design of two way slabs is 456 limit state method youtube. This system consist of both one way and two way slabs. 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.
Design of a two way rcc slab structural engineering. Moreover, these slabs should have sufficient depth for the control deflection. The basic design procedure of a twoway slab system has five steps. 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 20 psf, and unfactored live load 40 psf. Reinforced concrete design 1 design of slab examples and. There are some basic differences between one way slabs and two way slabs. Figure 1 shows a rectangular slab, simply supported along its two opposite long edges and free of any support along the two. The following example illustrates the design methods presented in the pca book simplified design reinforced concrete buildings of moderate size and height third edition. The building is located in seismic zone iii on a site with medium soil.
Analysis and design of slabs one way civil engineers pk. Rooms two way slabs are continuous with verandah one way slab. It is anticipated that the design of largespan airsupported structures will increasingly rely on a two way system of reinforcing cables to provide the overall structural integrity. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. Concrete slabs are commonly divided into the following types. Beamless slabs beamless slabs are supported only on columns and are applied mostly in large industrial and public. To see their result for this slab we will find the load factor. Thus, strength and deflection are the requirements of design of two way slabs. Mention the parameters governing slab moment coefficients and explain their effects on moment. Analysis and design of slabs it may be supported by reinforced concrete beams and is usually cast monolithically with such beams, by masonry or by reinforced concrete walls, by steel structural members, directly by columns, or continuously by ground. Reinforced concrete design 1 design of slab examples. 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. Pdf design of reinforced concrete circular slabs by twoway. Bending will take place in the two directions in a dishlike form.
Two way concrete slabs with openings the static system and the design of reinforcement. Please read the lauses mentioned in the video while solving the problem. 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. This condition occur when the slabs are connected monolithically with support. Here the ratio of longer span of slab to the shorter span of slab is less or equals to 2.
Design of reinforced concrete structures ii twoway slabs. Concrete 3 design of concrete beam and slab twoway. Design of twoway slabs restrained two way slab is divided into middle strip and edge strips. Beams of width and depth are provided on all column lines. Redistribution of 10% may be allowed when method 3 or method 4 is adopted. 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. In two way slabs, load will be carried in both the directions. Oneway and twoway slabs oneway slabs transfer the imposed. The principal idea of this paper concerns to use the isotropic perpendicular rc straight. Unless otherwise noted, all referenced table, figure, and equation.
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