Nancy debora assistant professor civil karunya university 2. Sound transmission class guidance introduction the noise guidebook, pages 3337, provides an elementary discussion of stc, provides some stc ratings for common building materials and limited exterior and interior wall construction configurations, and describes a method to determine composite stc value of a wall containing a window or door. Coffered definition of coffered by the free dictionary. One way spanning slabs two way spanning slabs on linear. Adding corners also adds complexity and expense that is better. Behaviour and design examples xix chapter 20elevated water tanks 201. A waffle slab or twoway joist slab is a concrete slab made of reinforced concrete with concrete. A coffer or coffering in architecture is a series of sunken panels in the shape of a square, rectangle, or octagon in a ceiling, soffit or vault. Coffered slab, concentrated load, winklers model of styrodur, ultimate limit state 1. Flat slab types of flat slab design and its advantages. Twoway 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 crosssection of a cobiax slab has top and bottom flanges which accommodates compressive stresses for either sagging or hogging bending. The downsides of waffle slabs and cupolex slabs are the same its a slab constructed on top of the ground and its easy for water to get under the slab. Sep 03, 2011 reinforced concrete effective span centretocentre distance between supports longer dimension of a rectangular panel of slab for yield line calculations modular ratio esec design bending moment per unit width of slab modified to account for axial load moment per unit width about xaxis moment per unit width about yaxis. The williams coffer slab system consists of removable plastic coffer blocks suspended between a series of parallel ribs spanned across the area where a concrete slab is required. Feb 15, 2012 in this 3d animation, youll see six simple steps to build a wafflemat foundation, from clearing the pad to setting the individual waffleboxes, to pouring the concrete and removing the form boards. Manual for the design of reinforced concrete building. Ribbing beams reinforcement, slab top wire mesh, waffles dimensioning, voids width and depth, slab thickness. Flat slab is defined as one sided or twosided support system with sheer load of the slab being concentrated on the supporting columns and a square slab called drop panels. Depending on the application, the ribs will be either precast concrete lattice ribs or wooden purlins. Traditional slab spans in small residential buildings vary from 33. Concrete slab volume estimator calculator engineers edge.
The advantage of a coffered slab compared to traditional reinforced concrete slab is a possibility of bridging large spans. Introduction coffered slab consists of series of ribs on a small distance from each other and thin plate over them. At the planning stage, you can make your entire house cost less just by making it a little bit smaller. Flat slab analysis and design designs beamless concrete slab floors flat slab or waffle slab in accordance with aci 318. Waffle slabs are preferred for spans greater than 40 feet 12 m, as they are much stronger than flat slabs, flat slabs. The other issue for these slabs in cyclonic regions is the lack of concrete under the big truss reactions. Coffered vaulted slabs by creagh concrete products ltd. Analyze and design flat slab or waffle slab floors. Department of mechanics, materials and structures english. I have used the word flat slab and by that i mean the slab that has leveled surface from both top and soffit. Introductory design of elevated tanks examples xx chapter 21 intze tank 211. Coffered slab beam structure precast concrete scribd.
For span from 5 to 9m thin flat slabs are the preferred solution for the. A discreteelement method of analysis for orthogonal slab. One way spanning slabs two way spanning slabs on linear supports coffered slabs from structural 1 at indian institute of technology, roorkee. Determine v max v eff u od where u o is the length of column perimeter check v ma free is called as projected slab or cantilever slab. In the case of recessed or coffered slab which is made solid in the region of the columns, the stiffening effect may be ignored provided the solid part of the slab does not extend more than 0.
Coffers are sunken panels attached to a suspended drop grid to create a new ceiling with depth and architectural interest. Manual for the design of concrete and reinforced concrete structures of heavy concrete. Simply input the data required within the appropriate box and select update button located of the bottom. The lateral loads are independently resisted by shear walls. Late 16th century coffered ceiling of santa maria in aracoeli, rome coffering on. What is the maximum possible span between columns to support. The system is designed for heavy loads uniformly distributed superimposed analysis of waffle slab. Flat slab analysis and design free version download for pc. Its a series of geographical shapes created by beams in a square, rectangle or even triangle patterns. The kwikstrip system produces a coffer grid spacing of 0. Because of the ribs and double reinforcement, it is more stable and recommended for larger span slabs or foundations. Then rcc waffle slabs were built which resembled coffers and hence it is also called coffer slab.
This difference would cost a significant reduction in overall height of a construction of a multistorey building with appreciable saving in cost. Waffle slab or ribbed slab construction procedure and advantages. This form of construction is not very common because of the formwork costs and the low fire rating. Creagh concrete products ltd hasnt formatted technical specifications for coffered vaulted slabs yet.
Dec 01, 2016 features of the grid slab they are used on flat sites. Please check out the similar products section for alternatives. Introduction analysis and design example xxi chapter 22 elements. The name waffle comes from the grid pattern created by the reinforcing ribs. A discreteelement method of analysis for orthogonal slab and. Coffered slab free download as powerpoint presentation. In this 3d animation, youll see six simple steps to build a wafflemat foundation, from clearing the pad to setting the individual waffleboxes, to pouring the concrete and removing the form boards. Please practice handwashing and social distancing, and check out our resources for adapting to these times. To save on beam disruption, pt slabs are widely used instead of regular bed and columns. Pdf coffered slabs as a perspective type of the reinforced. A suspended ceiling is not needed as services are contained in the suspended floor above the. We recommend that beginners start with the easiest, simplest design to build, which is a small, square house. Some are bare wood beams while other types include crown molding.
The analysis and design follow the equivalent frame analysis method of the aci code, which considers a onebay wide strip of the floor system as a continuous frame. Now here i need to clarify that this article will not treat waffle slab foundation which is another building element used in high cyclonic and windy areas but that is out of the scope of this article. You have asked this question because waffle slab is not that common throughout the world. Although the crosssection is more complex when compared to a solid slab or coffer slab, flexural design poses no significant problem. A suspended ceiling is not needed as services are contained in the suspended floor. Tips for laying rcc slab roof on 12092014 9091 views 3 comments rcc slab laying is one of major step in any type of construction so it is mandatory to know all the points related to laying rcc slab. Waffle slab plan view reinforcement detail faculdade.
Gilded coffering on a barrel vault of the apsis in nazare, portugal giuliano da sangallos flat caisson ceiling, basilica di santa maria maggiore, rome decorative coffered slabs in historical structures coffering on the arch of septimius severus, rome a series of these sunken panels were used as decoration for a ceiling or a vault, also called. Coffers were used in historical buildings even before rcc structures came into being. These type of slabs are generally constructed in hotels, universities, function halls, etc. Determine v max v eff u od where u o is the length of column perimeter check v ma coffered system is quite suitable for medium size floors. Waffle slab dwg full project for autocad designs cad. The minimum slab thickness allowed for joist slabs is onetwelfth the clear rib spacing or 1. The developed computer program allows for the free variation of stiff nesses, supports, and loads. This calculator will estimate the require concrete volume to fill the width, height and depth given. The first floor of the twostorey office building consists of a series of coffered precast concrete slabs supported on precast columns. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. Nov 01, 2016 coffers were used in historical buildings even before rcc structures came into being. Features of the grid slab they are used on flat sites. Here is a detailed article with all the information regarding procedure of rcc slab roof laying. Inplane axial thrusts, if their distribution is known, are included and coupled with the stiffnesses of the structure.
Check out these 101 handselected coffered ceiling examples for all rooms of a house. How to build a log cabin the ultimate guide build log homes. To validate the results, selected cases are compared with. Here is a detailed article with all the information regarding procedure of. A series of these sunken panels was often used as decoration for a ceiling or a vault, also called caissons boxes, or lacunaria spaces, openings, so that a coffered ceiling can be called a. Minimum free edge distance for punching shear 4 times slab thickness. The underside of a waffle slab, showing the grid like structure. May 21, 2017 the slab which has one side fixed and the other side is free is called as projected slab or cantilever slab. No beam down drag from clay above ground slab occurs. Inputs to the program may be retained and used for a series of problems for the con venience of the user.
Coffered slabs as a perspective type of the reinforced concrete structures article pdf available in matec web of conferences 86. This is the compilation of the presentations available for grid slabs on slideshare. They provide a very good form where slab vibration is an issue, such as laboratories and hospitals. Coffered slabs as a perspective type of the reinforced concrete. Flat slabs may have drop panels at columns and columns may have capitals. Planning your log cabin is the most important stage of the build. The institution of structural engineers the institution of civil engineers march 2000 manual for the design of reinforced concrete building structures to ec2. Design of waffle slab without beams by direct design method 32 32 32 c 1 c 2 c 3 c 4 2 c 5 c 6 c 7 c 8 32 s ss 22 3 7 c 9 c 10 c 11 c 12 32 8 11 b 1210 bb c c 14 c 15 c 16 16.
Then rcc waffle slabs were built which resembled coffers and hence it. Precast was chosen for its energy efficiency the concrete mass provides thermal energy storage and to keep the overall height of the building as low as possible. See more ideas about waffle ceiling, architecture and ceiling design. Each lightweight rigid pvc plastic coffered panel is 24 x 24, available in either deep or shallow styles, and comes in white or black.
Shrinkage of slab is lower than stiffened rafts and footing slabs. So i am glad that you have asked me what a waffle slab system is. Analyses are for a onebaywide strip using the equivalent frame analysis method of the aci code. Flat slab types of flat slab design and its advantages flat slab is a reinforced concrete slab supported directly by concrete columns without the use of beams. Analysis and design of waff le slab with different boundary. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. Coffered slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extend of foundations. Twoway joist concrete slab floor waffle slab system. Twoway joist waffle slab design approach and methodology. They are either oneway spanning systems known as ribbed slab or a twoway ribbed system known as a waffle slab. Im commercial buildings to save on carpet space the span is kept is 1215m.
A coffered ceiling is created with coffered panels or coffers. We would be restricting ourselves to understand the waffle slab used as roof. Base slab examples xviii chapter 19 rectangular tanks 191. A waffle slab or twoway joist slab is a concrete slab made of reinforced concrete with concrete ribs running in two directions on its underside. The new formscaff coffers can support a slab thickness of 0.
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