Composite beams can only be designed on one way slab floor. The medical office building malvern, pa 17 brendon burley structural option posttensioned twoway slab figure 23 details of the twoway slab. No redistribution is allowed when method 1 or method 2 of analysis in. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns.
Assume partitions cannot be damaged by deflections. One way slabs are those supported continuously on the two opposite sides so that the load sare carried along one direction only. Analysis and design of slabs two way two way edge supported slabs twoway slabs. Pdf ribbed slabs have been widely used in buildings due to their many advantages. Chajjas and verandahs are an practical example of one way slab. Design of reinforced concrete structures ii twoway slabs. Ce 433, summer 20 slab design example 1 5 design a one. Slab is a common term used to describe the structural elements such as floors and roofs where the thickness of the element is very small compared to the length and. Analysis and parametric study of reinforced concrete twoway.
There are some basic steps which we generally do while designing theoretically some steps are rcc slab design guidelines. For other conditions, the following modifications should be applied. Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. The construction and design of concrete slabs on grade. Sap2000, slab, twoway, ribbed, waffle, direct design method, beams.
This condition occur if the slab supported by two side of beam or walls. They are either oneway spanning systems known as ribbed slab or a twoway ribbed system known as a waffle slab. As they are oneway slabs i treat them as wide beams. Minimum thickness of beams and oneway slabs values given in this table shall be used directly on members with normalweight concrete and grade 60 reinforcement. Introduction concrete slabs on grade are a very common type of concrete construction. 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. The construction and design of concrete slabs on grade d. Chapter 3 design of rectangular beams and oneway slabs. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems.
I am doing oneway slabs and hope you can clean up my doubts about the one way shear in slab. They may be supported on two opposite sides only fig. Teaching twoway ribbed slab analysis and design using the mathcad program mohammed s. The simplest routine structural element for illustration of design provisions in the code is the oneway slab. If none of the values satisfies, you need to change d. It is essentially a twodimensional reinforced or nonreinforced cement. 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. Mathematical structural analysis of one way ribbed slabs was introduced in this paper. If slab supported by four side of beams or walls, the slab is considered oneway if ratio of long span ly to short span lx greater than 2. They provide a very good form of construction where slab vibration is an issue, such as laboratories and hospitals. The results of this analysis are compared with the results of the finite element method by sap program. Ribbed slab floors are most economical for buildings such as hospitals, schools, hotels, and.
Reinforced concrete, 2014, 9th edition, aci 31811 code edition, by jack c. The massive buildings also shows different parts of the layout in a massive urban planning which shows a good way for architects to study the project. Sachpazis date 18012014 chkd by date appd by 1 flat slab design to bs8110. In this article, the author presents a parallel approach to the traditional teaching method of twoway ribbed slabs. Twoway joist waffle slab design approach and methodology. Parameters include support conditions nine cases, span ratios lalb 0. Analysis of two way ribbed and waffle slabs with hidden beams. Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement. Effective span of slab shall be lesser of the two 1. Design of reinforced concrete structure one way slab presented by md. This paper focuses on analysis of twoway ribbed and waffle slabs with hidden beams. Slab slabs are an important structural component where prestressing is applied. Plan view of floor system assume partitions will not be damaged by deflections. This form of construction is not very common because of the formwork costs and the low fire rating.
Teaching twoway ribbed slab analysis and design using. Bending will take place in the two directions in a dishlike form. Two way joist waffle slab design approach and methodology two way joist slab often called two way ribbed slab or waffle slab is an economical floor system when the spans are long andor loads are high. Bridge approach slab analysis and design incorporating elastic soil support presented by. The rib reinforcement follows the same rules with the beam reinforcement. Effect of solid parts on nonlinear of one way ribbed slabs journal of. Egyptian code for design and construction of reinforcement concrete structures. Waffle slab plan view reinforcement detail faculdade. Jul 5, 20 cad drawing detail with a plan view of a ribbed waffle slab that can be used as an example for other projects. Design of concrete structures 14th edition, 2009, by arthur h. Teaching twoway ribbed slab analysis and design using the. Hello everyone, im trying to model a concrete building, and it has hollow block slabs. One way slabs will not create a plate submeshed floor slab like the two way slab. The ratio for a twoway spanning slab should be based on the shorter span.
Master of science and hereby certify that, in their opinion, it is worthy of acceptance. 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. Interior left, exterior right deflection analysis the final consideration in the design of the twoway slabs is deflection. Chapter 3 design of rectangular beams and oneway slabs 12 h a 12 strip in a simply supported one way sl ab. Ce 433, fall 2006 slab design example 1 6 design a oneway slab for an exterior bay of a multistory office building using the information specified below. Floor slabs can range from a simple residential basement slab to a heavyduty industrial floor. However, mainly as far as the stirrups are concerned, the amount of placed rebars is not as large as it is in beams. Reinforced concrete design to bs8110 structural design 1. Analysis of two way ribbed and waffle slabs with hidden beams ibrahim mohammad arman international journal of civil and structural engineering volume 4 issue 3 2014 343 four slabs are taken in this study to show the moments distribution in two way ribbed slab.
Reinforced concrete design to bs8110 structural design 1 lesson 5 1 lesson 5. For those who do not know what are the des ign requirements of a slab. In two way slab, the ratio of longer span l to shorter span b is less than 2. Analysis and design of slabs one way civil engineers pk.
Design of oneway slab free download as powerpoint presentation. Ribbed slabs oneway joists introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section. Between the ribs, the slab is usually reinforced with a common wire mesh. 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. Here are the steps for the design procedure for one way slab in steps. Oneway and two way slabs one way slabs transfer the imposed loads in one direction only. The basic design procedure of a two way slab system has five steps. Design of reinforced concrete structures ii twoway slabs 1 1. One way slab design criteria with design example according to aci code slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Introcduction slab in which the deflected surface is predominantly cylindrical termed as oneway slabs spanning in the direction of curvature. In the one way ribbed slab where the ribs are in one direction, it is assumed that the loads are. Waffle slab analysis and design is similar to the procedure used with flat plates except that special considerations need.
The model provides the actual behavior for ribbed slab by analyzing the structure as oneunite in two dimensions. Twoway slabs have two way bending unlike oneway slab. The ribbed slab was analyzed exactly by finite element theory through sap 2000 program. The two classifications are one way slab and two way slab. Posttensioned twoway slab pennsylvania state university. Oneway and twoway slabs university of asia pacific. A slightly deeper section is required but these stiffer floors facilitate longer spans and provision of holes. Ribbed slabs one way joists introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section. If you continue browsing the site, you agree to the use of cookies on this website. Under the general provisions of the 1995 code, chapter, the twoway joist portion may be combined with a solid column head or with solid wide beam sections on the column centerlines for uniform depth construction. One way shear in slab structural engineering general. Design procedure steps for one way slab slab design steps. Twoway flat plate concrete floor system analysis and design.
When choosing a oneway slab design, there is a default load attribution direction that must be. 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. Table 5 showed that none of the slabs failed by punching shear. Reference 4 presented and discussed the optimum design problem of reinforced concrete two way. Reinforced concrete ribbed slabs with widebeam lajes. Procedures of two way slab design by direct design method. The direction in which the load is carried in one way slab is called the span. Slab are considered as oneway if the main reinforcement is designed only in one direction. The tutorial consist of ribbed slab design throught etabs. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Oneway and twoway slabs oneway slabs transfer the imposed. There are many methods that are used to analyze twoway slabs and the precision of these methods vary depending. In sap program, the model has been divided to frame elements to represent ribs and beams and shell elements to represent the slab and solid part.
Analysis and design of slabs two way civil engineers pk. Asce, secb course content slab on grades construction. 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. The basic design procedure of a twoway slab system has five steps. Direct design method, that could have been named the direct analysis method because it determines or prescribes moments for different parts of the slab panel without the need to conduct structural analysis, is explained in the following sections. Flat plate concrete floor system does not use beams between columns or. Slab resting on walls or sufficiently deep and rigid beams on all sides.
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