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. As they are oneway slabs i treat them as wide beams. 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. In two way slab, the ratio of longer span l to shorter span b is less than 2. The results of this analysis are compared with the results of the finite element method by sap program. 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. Slab are considered as oneway if the main reinforcement is designed only in one direction.
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. Analysis and parametric study of reinforced concrete twoway. One way slabs will not create a plate submeshed floor slab like the two way slab. Reinforced concrete design to bs8110 structural design 1. Table 5 showed that none of the slabs failed by punching shear. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Bending will take place in the two directions in a dishlike form.
This condition occur if the slab supported by two side of beam or walls. Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. Plan view of floor system assume partitions will not be damaged by deflections. The ribbed slab was analyzed exactly by finite element theory through sap 2000 program. There are many methods that are used to analyze twoway slabs and the precision of these methods vary depending. Design of concrete structures 14th edition, 2009, by arthur h. The two classifications are one way slab and two way slab. Teaching twoway ribbed slab analysis and design using the mathcad program mohammed s. Chapter 3 design of rectangular beams and oneway slabs 12 h a 12 strip in a simply supported one way sl ab. 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.
Composite beams can only be designed on one way slab floor. No redistribution is allowed when method 1 or method 2 of analysis in. 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. Parameters include support conditions nine cases, span ratios lalb 0. Oneway and twoway slabs university of asia pacific. 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. If you continue browsing the site, you agree to the use of cookies on this website. Analysis and design of slabs two way two way edge supported slabs twoway slabs. One way slabs are those supported continuously on the two opposite sides so that the load sare carried along one direction only.
Reinforced concrete, 2014, 9th edition, aci 31811 code edition, by jack c. Mathematical structural analysis of one way ribbed slabs was introduced in this paper. For those who do not know what are the des ign requirements of a slab. Design of reinforced concrete structures ii twoway slabs 1 1.
Teaching twoway ribbed slab analysis and design using. Chapter 3 design of rectangular beams and oneway slabs. Interior left, exterior right deflection analysis the final consideration in the design of the twoway slabs is deflection. Flat plate concrete floor system does not use beams between columns or. Design procedure steps for one way slab slab design steps. Floor slabs can range from a simple residential basement slab to a heavyduty industrial floor. The rib reinforcement follows the same rules with the beam reinforcement. Waffle slab plan view reinforcement detail faculdade. Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement. The medical office building malvern, pa 17 brendon burley structural option posttensioned twoway slab figure 23 details of the twoway slab. Slab resting on walls or sufficiently deep and rigid beams on all sides. Bridge approach slab analysis and design incorporating elastic soil support presented by. Sachpazis date 18012014 chkd by date appd by 1 flat slab design to bs8110. Analysis of two way ribbed and waffle slabs with hidden beams.
Here are the steps for the design procedure for one way slab in steps. 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. Ribbed slabs one way joists introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section. Reinforced concrete ribbed slabs with widebeam lajes. 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. Oneway and two way slabs one way slabs transfer the imposed loads in one direction only.
Analysis and design of slabs two way civil engineers pk. Ce 433, summer 20 slab design example 1 5 design a one. 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. One way shear in slab structural engineering general. They may be supported on two opposite sides only fig. Teaching twoway ribbed slab analysis and design using the. 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. The construction and design of concrete slabs on grade d. Reference 4 presented and discussed the optimum design problem of reinforced concrete two way. Introduction concrete slabs on grade are a very common type of concrete construction. Hello everyone, im trying to model a concrete building, and it has hollow block slabs. Reinforced concrete design to bs8110 structural design 1 lesson 5 1 lesson 5. Chajjas and verandahs are an practical example of one way slab. Assume partitions cannot be damaged by deflections.
Pdf ribbed slabs have been widely used in buildings due to their many advantages. Egyptian code for design and construction of reinforcement concrete structures. The direction in which the load is carried in one way slab is called the span. Design of reinforced concrete structure one way slab presented by md. 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 basic design procedure of a twoway slab system has five steps. They are either oneway spanning systems known as ribbed slab or a twoway ribbed system known as a waffle slab. Introcduction slab in which the deflected surface is predominantly cylindrical termed as oneway slabs spanning in the direction of curvature. Twoway flat plate concrete floor system analysis and design.
The construction and design of concrete slabs on grade. There are some basic steps which we generally do while designing theoretically some steps are rcc slab design guidelines. Twoway slabs have two way bending unlike oneway slab. 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. Oneway and twoway slabs oneway slabs transfer the imposed.
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. I am doing oneway slabs and hope you can clean up my doubts about the one way shear in slab. Two way slab design by direct design method as per aci 31811. 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. Analysis and design of slabs one way civil engineers pk. Slab slabs are an important structural component where prestressing is applied. For other conditions, the following modifications should be applied. Posttensioned twoway slab pennsylvania state university. 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. Sap2000, slab, twoway, ribbed, waffle, direct design method, beams. The tutorial consist of ribbed slab design throught etabs. A slightly deeper section is required but these stiffer floors facilitate longer spans and provision of holes.
The model provides the actual behavior for ribbed slab by analyzing the structure as oneunite in two dimensions. Procedures of two way slab design by direct design method. Asce, secb course content slab on grades construction. This paper focuses on analysis of twoway ribbed and waffle slabs with hidden beams. If none of the values satisfies, you need to change d. Ribbed slab floors are most economical for buildings such as hospitals, schools, hotels, and. Effective span of slab shall be lesser of the two 1. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. When choosing a oneway slab design, there is a default load attribution direction that must be. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. Effect of solid parts on nonlinear of one way ribbed slabs journal of. The basic design procedure of a two way slab system has five steps. The simplest routine structural element for illustration of design provisions in the code is the oneway slab. In this article, the author presents a parallel approach to the traditional teaching method of twoway ribbed slabs.
This form of construction is not very common because of the formwork costs and the low fire rating. 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. 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. They provide a very good form of construction where slab vibration is an issue, such as laboratories and hospitals. Design of reinforced concrete structures ii twoway slabs. Twoway joist waffle slab design approach and methodology. 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. The ratio for a twoway spanning slab should be based on the shorter span. Design of oneway slab free download as powerpoint presentation.
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