Slab are considered as oneway if the main reinforcement is designed only in one direction. In t h e category of slabs are interior floor slabs, e x t e r i o r sidewalks or a p r o n s, and p a t i o slabs. Waffle slabs are preferred for spans greater than 40 feet 12 m, as they are much stronger than flat slabs, flat slabs with drop panels, twoway slabs, oneway. A solid drop panel is required at the columns and loadbearing walls for shear. Design of waffle slab without beams by direct design method 32 32 32 c 1 c 2 c 3 c 4 2 c. Steelreinforced slabs, typically between 100 and 500 mm thick, are most often used to construct floors and ceilings, while thinner mud slabs may be used for exterior paving see below. Oct052018 twoway flat slab concrete floor with drop panels system analysis and design csa a23. This paper presents an experimental and computational study on ribbed slabs with wide beam, two oneway slabs and two twoway slabs, with variable depths were tested to evaluate their resistance. So a tbeam or an lbeam can be designed just as for a rectangular beam, except for the following considerations. Structural calculations for posttensioned beam and oneway. Different types of floor system used for steel structures include.
The reinforcing steel should be conforming to project specification and as per drawings. Previous accidental fires in multistorey buildings and large scale fire tests have shown composite floors with unprotected steel beams had large deformations but. In many domestic and industrial buildings, a thick concrete. Edge beam srt, triangular frame sdr 12 combihead sck a5 shuttering of columns 1 recessed panels 16 2 recessed panels 17 3 recessed panels 18 recessed main beams 19 a6 guardrails on open building edges 20 on casting segments 21 a7 striking 22 a8 maintenance and cleaning 24 a9 system dimensions 25 a10 site record 26 skydeck panel slab formwork. A building component develops cracks whenever stress in the component exceeds its strength. Twoway concrete slab with beams spanning between supports. If you continue browsing the site, you agree to the use of cookies on this website. Slabs are usually used in floor and roof construction. A slab is structural element whose thickness is small compared to its own length and width.
Beam and slab floor system this system consists of beams framing into columns and supporting slabs spanning between the beams. The beam is inside building subject to a 1 hour fire resistance and design for 50 years design life. Ribbed floors consisting of equally spaced ribs are usually supported directly by columns. Forms for beam soffits, slabs, and other parts requiring support will be removed as per specified standards. Advantages of rib clay pot slab over solid concrete slab published on january, 2017 january, 2017 25 likes 2 comments.
That is usually horizontal and has smaller thickness comparative of its span. The slab is the flange of the beam and the extended part is the web. Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extent of foundations. It is a square floor system, the edge beams support the same triangular load the area of the slab portion that is supported by a particular beam is called the tributary area. Jan, 2017 advantages of rib clay pot slab over solid concrete slab published on january, 2017 january, 2017 25 likes 2 comments. The lateral loads are independently resisted by shear walls. After proposing of effecting parameters in slabbeam interaction including of panel length and width, beam dimensions, and slab thickness, buckinghams theorem. Method statement for formwork, reinforcement and concrete. The quality assurance for formwork will be followed as per approved inspection and test plan. The name waffle comes from the grid pattern created by the reinforcing ribs. The three systems constitute the most attractive and commonly used floor systems, especially in highrise constructions. Direct design method ddm for slab systems with or without beams loaded only. Oneway and twoway slabs university of asia pacific. Types of concrete slabs covered are flat slab with reinforcement, slabs on steel.
A flat slab is a twoway reinforced concrete slab that usually does not have beams and girders, and the loads are transferred directly to the supporting concrete columns. Types of floors for multistorey steel structure construction. 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. Presentation to concrete structures beam structure concrete. Shortspan composite beams and composite slabs with metal decking. Structural calculations for posttensioned beam and oneway slab construction roya construction. The dbeam girder is a fabricated inverted tee assembly contained within the plane of the floor that eliminates issues associated with a standard wide flange beam sitting below the slab. The spacing between the ribs should be in general 2030 inch. The slab load dead and live, expressed in units of weight per area, is converted into weight per length of the beam. Types of floors systems used for multistorey steel structure construction. If the slab is thickened around the column, it is called a drop panel. In high seismicity regions, the declared nonductile flat slab system poses a significant risk.
Check the aci equations to determine if the slab thickness is satisfactory for an interior panel. Syllabus modulei properties of concrete and reinforcing steel, philosophy, concept and methods of reinforced concrete design, introduction to limit. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Design beams if any, using procedures you learned in civl. Aug 08, 2014 beam and slab floor system this system consists of beams framing into columns and supporting slabs spanning between the beams. 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. A concrete slab is a common structural element of modern buildings, consisting of a flat, horizontal surface made of cast concrete. They are either oneway spanning systems known as ribbed slab or a twoway ribbed system known as a waffle slab.
Twoway flat slab concrete floor with drop panels system analysis and design design the concrete floor slab system shown below for an intermediate floor considering partition weight 20 psf, and unfactored live load 60 psf. These two systems of concrete slabs are ductile, and balanced moments between slab and columns. A rectangular reinforced concrete beam simply supported on two mansory walls 200 mm thick and 6 m apart. Skydeck panelised slab formwork the proven aluminium. Presentation to concrete structures beam structure. Concrete beam design concrete design software that designs oneway flexural members, including beams, oneway slabs and. Posi ti ve beam moment in panel simplysupported on lib n. Select reinforcing bars for the slab and concentrate bars near the column, if necessary 5.
Pdf comparison study for various structural slab systems ismaiel. The twoway slab shown in figure below has been assumed to have a thickness of 7 in. Apr 04, 2012 title slide of 07 slabs 4 panelled beams. Concrete is cast between those spacing to make those ribs and in this way, the slab also cast and the slab becomes the flange of t beam. Advantages of rib clay pot slab over solid concrete slab. The first is the familiar beam type shear leading to diagonal tension failure.
The slab panel method spm covers design of steelconcrete composite floor systems for dependable inelastic response in severe fires, in which twoway action within a. With prophead ssk, main beam slt 150 150 x 150 cm, slab thickness max. I am looking at purchasing a home in dallas and i have come across several piered beam slab foundations. The grid is formed by the removal of molds after the concrete sets. Steel design steel design software that easily designs or checks steel beams, columns and single span beam columns using the asd and lrfd standards. Because there are joists in both directions, this floor system is the strongest and will have the least deflection. The load is transferred from slab to beams by distributing the load over the beam. Beam type roadwy width max span approx structure depth in 5sb12 24 40 18. They provide a very good form of construction where slab vibration is an issue, such as laboratories and hospitals. Effect of edge beam deformations on the slab panel method. Instead, the floor is heavily reinforced in both directions.
These three bridges meet national register eligibility criteria under criterion a, in the area of transportation. Advantages and disadvantages of flat slabs civil engineering. 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. This structure was designed to be more solid when used on longer spans and with heavier loads. Slab, more precisely concrete slab is a common structural element ofmodern building. Building construction, every floor generally has a beam slab arrangement and consists of fixed or continuous oneway slabs supported. With drophead sfk, main beam slt 225 230 x 150 cm, slab thickness max.
The slab panel method spm covers design of steelconcrete composite floor systems for dependable inelastic response in severe fires, in which twoway action within a deformed region of the floor. Oneway and twoway slabs oneway slabs transfer the imposed loads in one direction only. Twoway ribbed slab system waffle system the system was designed to decrease the weight of traditional fullconcrete slabs. Custom spread box beam spans beams can be placed plumb if addressed adequately in the plans, but not recommended for skews one pedestal width per beam width recommend a minimum clear distance between top beam corners of. Two kinds of shear may be critical in the design of flat slabs, flat plates, or footings. Design and construction of paneled beam system abdelrahman kotb. They were built as part of the us241431 section in madison county, the initial construction of the nations. From this standpoint, the choose of a system that provide rigid concrete slab than flat slab to resist lateral wind and seismic forces. The concept of the voided slab is simple in that concrete mass is removed from the areas in the slab where it is not needed to resist load and as a result of the reduced.
The relatively deep beams provide a stiff floor capable of long spans, and able to r. Long span composite beam and composite slab construction. Determine the area of steel required in the slab at critical sections for column and middle strips. For an interior panel surrounded by similar panels supporting the same distributed loads, the stiffness of the supporting beams, relative to slab stiffness is the controlling factor.
Flat slab is a reinforced concrete slab supported directly by concrete columns without the use of beams. They may be supported on two opposite sides only fig. Building construction, every floor generally has a beamslab arrangement and consists of fixed or continuous oneway slabs supported. From figure 7 and 8 it is clear that the quantity and cost of steel of beam and column for flat slab structure is 84. Slabs are used to furnish a flat and useful surface in reinforced concrete construct. Ribbed and waffle slabs types, advantages, disadvantages. In a flat plate, there are no beams, no drop panels or column capitals. The slab and beam connection over the walls at the two ends of the floor system are assume. Jan 10, 2018 design and construction of paneled beam system abdelrahman kotb. Chapter 6 slabs on expansive soils introduction slabonground c o n s t r u c t i o n, w h e n o n expansive soils, is a very difficult aspect t o c o n t r o l. The beam has to carry a distributed permanent action of 10 knm excluding beam selfweight and variable action of 8 knm. Twoway flat slab concrete floor with drop panels system. Materials used for this redesign is normal weight concrete with compressive strength of 4ksi and steel rebar with a yield stress of 60 ksi.
Applicable particularly to long narrow slabs or footings, this analysis considers the slab to act as a wide beam. Flat slab types of flat slab design and its advantages. Approximately 10% of the vertical member could be saved. Oneway and twoway slabs oneway slabs transfer the imposed. I know what a pier beam foundation and a slab foundation are but cant find the combination of the two anywhere. For this slab, panel a has two discontinuous exterior edges and.
National register of historic places national register. Dec, 2012 so a t beam or an l beam can be designed just as for a rectangular beam, except for the following considerations. Waffle slab twoway pan joist twoway joist slab, also called a waffle slab. A waffle slab is flat on top, while joists create a grid like surface on the bottom. Concrete beam design concrete design software that designs oneway flexural members, including beams, oneway slabs and continue reading. Skydeck panels and main beams have selfdraining edges as well as undercut panel edges. The distribution of total negative or positive moment between slab middle strip, column strip, and beams depends on. This form of construction is not very common because of the formwork costs and the low fire rating.
This system is chosen to be the ribbed slab, and the panelled beam slab. What is the basic difference between a slab and beam. This condition occur if the slab supported by two side of beam or walls. As a result, the side areas of the panels remain signifi. Different values of moment of inertia along the axis of slab beams should be taken into account where the gross moment of inertia at any cross section outside of joints or column capitals shall be taken, and the moment of. Section aa in the figure shows the beam cross section. As reinforcement detailing of flat slab is simple, it is easier to place.
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