Slabs are usually used in floor and roof construction. In 1914 nichols used statics to compute the total moment in a slab panel. The design bending moment of twoway restrained slab can be calculated as follows. 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. This paper focuses on analysis of twoway ribbed and waffle slabs with hidden beams. Member design reinforced concrete two way spanning. A six storey building for a commercial complex has plan dimensions as shown in figure 1. Design of a two way slabs for punching shear resistance. Distribute moments transverse at critical sections to column and middlestrip and if. Download two way slab design excel sheet template for free.
The slab has to carry a distributed permanent action of 1. I am submitting it to you and i want students or professional engineers to download it and use it for their studies or projects. Reinforced concrete design 1 design of slab examples and. Flat plate concrete floor system does not use beams between columns or. The coefficient method may be the simplest, easiest and the quickest approach for the design of twoway slab supported by edge beam on all slab sides. The building is located in seismic zone iii on a site with medium soil. Two way slabs are such slabs in which the loads are shared by both the shorter and longer direction of the slab. In case of one ways slabs, the aci approximate analysis is applicable to one way slab system where a one way slab is continuous with a one way slab. These materials are originally located at different websites. The slab is supported on beams of size 225 x 500 mm spaced at 4. Introduction in reinforced concrete construction, slabs are used to provide flat, useful surfaces.
The slab may be supported by walls, by reinforced concrete beams usually cast monolithically with the slab, by s. They may be supported on two opposite sides only fig. There are many methods that are used to analyze twoway slabs and the precision of these methods vary depending. Twoway slabs structural engineering forum of india, sefi. For the design of columns and beams frame analysis is done by limit state method to know the moments they are acted upon. 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. Find depth of slab using deflection control criteria. Bending will take place in the two directions in a dishlike form. Reinforced concrete design reinforced concrete design twoway slabs design of twoway slab moment coefficient method load transfer from twoway slab bar. Slab resting on walls or sufficiently deep and rigid beams on all sides. Slabs can be designed by direct design method known as ddm and another method for design is coefficient method which is the easier one. The following example illustrates the design methods presented in the pca book simplified design reinforced concrete buildings of moderate size and height third edition.
Two way slab being supported on four sides the load will be carried in both the directions. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. Analysis of two way ribbed and waffle slabs with hidden beams. 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. Basic steps in twoway slab design choose layout and type of slab. Continuous one way slab figure 1 shows a clear area of 12 m x 8.
A rectangular reinforced concrete slab is simply supported on two masonry walls 250 mm thick and. Design the slab, following the provisions of the ack code. For those who do not know what are the des ign requirements of a slab. The following example illustrates the design methods presented in the pca book simplified designreinforced concrete buildings of moderate size and height third edition.
Oneway and twoway slabs oneway slabs transfer the imposed. Two way slab being supported on four sides the load will be carried in both the. 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. Design procedure steps for one way slab slab design steps. In this article, it is assumed that slab thickness is determine but calculation of column and middle strips is explained in the following section. Redistribution of 10% may be allowed when method 3 or method 4 is adopted. There are several methods by which twoway slabs can be designed. Slab is one of the most famous part of a construction project. I have developed a microssoft excel software for design of a two way rcc slab. Design of reinforced concrete structures ii twoway slabs. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. Here, we have tried to gather various reading materials available in the web about flat slab floor system in one place. 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. A 2 2area 2 a c 2 2 posttensioned concrete design table 11 list of symbols used in the aci 31808 code cp area enclosed by the outside perimeter of the section, in a g gross area of concrete, in a 2 l total area of longitudinal reinforcement to resist torsion, in a o area enclosed by the shear flow path, sqin a oh area enclosed by the centerline of the outermost closed.
Alternate design method design procedure of twoway slabs. History of twoway slabs the feeling at start that only part of the load to be carried in each direction, so that statics somehow did not apply to slab construction. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. Chapter 3 design of rectangular beams and oneway slabs. Member design reinforced concrete two way spanning slab bs8110 v2015.
Twoway concrete slab on beams floor analysis and design. Design of two way slabs is 456 limit state method youtube. Lecture series on design of reinforced concrete structures by prof. Twoway concrete floor slab with beams design and detailing. Design procedure of twoway slabs using aci moment coefficients. In this video deisgn of two way slabs has been covered using is 456. Slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs, bridges, and other types of structures.
M before discussion of this method, we have to study some concepts. Direct design method ddm for slab systems with or without beams loaded only. Beamless slabs beamless slabs are supported only on columns and are applied mostly in large industrial and public. 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. Twoway concrete slabs with openings the static system and the design of reinforcement. Twoway flat plate concrete floor system design structurepoint. Rectangular beams and oneway slabs page 2 of 9 two methods. This condition occur when the slabs are connected monolithically with support. Here are the steps for the design procedure for one way slab in steps. Distinction of twosystems from oneway systems is given by aci 31814 r 8. Analysis and design of twoway slabs page 1 chapter 3.
Mention the parameters governing slab moment coefficients and explain their effects on moment. Twoway concrete slab with beams spanning between supports. 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. Concrete slabs are commonly divided into the following types. Design of a two way rcc slab structural engineering. How to design a twoway slab free download as powerpoint presentation. A potential diagonal crack extends in a plane across the entire width l2 of the slab. The basic design procedure of a twoway slab system has five steps. According to the way loads are transferred to supporting beams and columns, slabs are classified into two types. Slab designing is done depending upon the type of slab one way or two way, end conditions and the loading.
Design of slab examples and tutorials by sharifah maszura syed mohsin example 2. 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 contractor secrets secrets you should know as. Two way slab design by direct design method as per aci 31811. No redistribution is allowed when method 1 or method 2 of analysis in section 3. All methods are viable provided that the safety and serviceability of the elements are within the acceptable limits. Please read the lauses mentioned in the video while solving the problem. 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. Two types of shear may be critical in the design of the flat slabs. Analysis and design of slabs two way two way edge supported slabs twoway slabs. His analysis suggested that the current slab design. 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. Critical section a distance d from the face of column or capital.
A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. 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 of reinforced concrete structures ii twoway slabs 1 1. 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.
The two classifications are oneway slab and twoway slab. A reinforced concrete slab is a broad, flat plate, usually horizontal, with top and bottom surfaces parallel or nearly so. Allowable stress design or working stress design wsd 2. Static equilibrium of twoway slabs total moment in both beams full load was transferred eastwest by the planks and then was transferred northsouth by the beams. Design the slab system shown in figure 1 for an intermediate floor where the story height 12 ft, column cross sectional dimensions 18 in. Please enter the support width along the shorter span of slab panel. Two way slab design by direct design method as per aci 318 11, step by step procedure and limitations of direct design method for two way. Unless otherwise noted, all referenced table, figure, and equation. Analysis and design of slabs two way civil engineers pk. Flat slab analysis, design and detailing pdf civil. Dhang, department of civil engineering, iit kharagpur. Home structural engineering slab design two way slab design by direct design method as per aci 31811. Twoway slabs have two way bending unlike oneway slab.
Powered by the equivalent frame method of analysis and design per latest american aci 31814 and canadian csa a23. The same is true for a twoway slab or any other floor system. A monolithic reinforced concrete floor is to be composed of rectangular bays measuring, as shown. 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 60,000 psi. One way slab design procedure with example design of one. Beams of width and depth are provided on all column lines. Contains all design checks required by the american concrete institute code and all the conditions that must be met during the design process. Here the ratio of longer span of slab to the shorter span of slab is less or equals to 2. A reinforced concrete slab is built integrally with its supports and consists of two equal spans, each with a clear span of 15 ft. A civil engineer should study these lectures and materials for structural engineering acumen.
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