The concrete floor slab system shown below is for an intermediate floor to be designed considering partition weight 1 knm2, and unfactored live load 1. These shear walls transfer the lateral loads to the foundation by their shearing resistance and resistance to overturning. Pdf analysis of flat slab structures with outriggers. Types of economical floor systems for reinforced concrete. In the equivalent frame method, the flat slab system is modeled as an equivalent frame and an elastic analysis is performed. The best flat slab analysis, design and detailing related pdf and slides are. Liftslab system with walls prestressed slabcolumn system liftslab systems were introduced in the last decade of. There are many methods to incorporate lateral load resisting ability into a structure. Bookmark file pdf bubble deck voided flat slab solution bubble deck voided flat slab solution bubbledeck biaxial hollow precast slab system the bubbledeck system virtually eliminates dead weight concrete from the middle of a floor slab by incorporating recycled plastic. If a flat plate or flat slab is otherwise suitable for a particular structure, it will be found that there is the additional benefit of minimizing the story height. 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.
By definition, a flat slab structure consists of a slab built mono. Causal mechanisms and consequences of flat slab subduction causal mechanisms. 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 1 knm2, and unfactored live load 1. Seismic analysis of flat slab building with shear wall written by athira. In present work, a flat slab system is a significant advancement. The thickness of slab over columns is also increased to support heavy loads and the thickened part of the slab is called drop panel. Flat slab is defined as one sided or twosided support system with sheer load of the. However, the equivalent frame method is commonly used for the analysis of the flat slab structures subjected to lateral loads in practical engineering. While designing structure layout and during implementation using sub frame. Pdf effect of flat slab to progressive collapse on.
Dec, 2010 cven 444 structural concrete design structural system overview dr. Flatplate and flatslab roofs concrete construction magazine. You can consider it as beam with breadth more than 1m directly resting on column. Usually during design the middle strip or middle of the slab, critical deflection exists while designing the layout of the structure one must be sure about the anticipated deflection to be as accurate as possible. What is the maximum length of the span for a flat slab. The 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. Flat slab structure leads to economic saving, aesthetic view and yet allow the architect from great freedom of form works as compared to conventional slab structure. Department of mechanics, materials and structures english.
Total force of the slab is wl 2 where w is the load per unit area knm 2. Slab thickness having chosen a flat slab solution, the next key issue is to determine an appropriate slab thickness. The slab is outside buildings which subjected to 1 hr fire resistance and design for 50 years design life. Reinforced concrete flat plate system, eugene, usa s. Pdf in the construction industry, the need for flat slabs supported on columns in an irregular. Jul 28, 2014 the flat plate is a twoway reinforced concrete framing system utilizing a slab of uniform thickness, the simplest of structural shapes.
Blast design procedure for flat slab structures dtic. Flat slab construction can deeply reduce floorto floor. Design of reinforced concrete structures ii twoway slabs 1 1. Design considerations for reinforced concrete flat slab floor system harshal deshpande1, radhika joshi2. There are several working hypotheses for the initiation of flat slab subduction. Given the height, spans, and use of the structure, composite steel beam. Although there are multidimensional advantages of flat slab system but there are certain areas in which one must be watchful and cautious. Abhishek lakshman dhangar, a comparative study of flat slab structure and conventional structure. Advantages and disadvantages of flat slabs civil engineering. Design considerations for reinforced concrete flat slab. When the height of the building increases, the building should have a good lateral load resisting capacity. Chapter 18 concrete slab structures january 2019 183 18. Flat slab flat slab are also known as beamless slab, is a type of slab in which the flooring slab is directly supported on columns without the agency of beam or girders.
Windows can be extended up to the underside of the slab. I ultimately decided to break apart the spans and do a frame due to the large thickness of concrete required. Flat slabs are twoway slabs supported by pointlike supports. Design of reinforced concrete structures ii twoway slabs. In the present work, summarized the importance of flat slab construction and revealed the relevance of shear wall in a flat slab multistoried building. Reinforced concrete design 1 design of slab examples. A waffle slab is flat on top, while joists create a grid like surface on the bottom. The flat slab is a twoway reinforced structural system that includes either drop panels or column capitals at columns to resist heavier loads and thus permit longer spans.
The thickness of a floor slab must be determined early in design because the weight of the slab is an important part of the dead load of the structure. Hence the flat slabs 3 l2a l2b c of panel a c of panel b middle stripmiddle. Flat slab structure is more economical than that of conventional slab structure. Seismic analysis of flat slab building with shear wall ijert. A civil engineer should study these lectures and materials for structural engineering acumen. A flat slab is a oneway or twoway system with thickenings in the slab at the columns and load bearing walls called drop panels figure 9. The benefits of using flat slab construction are becoming increasingly recognised. Efficient analysis of flat slab structures subjected to. Jul 18, 2014 a flat slab is a oneway or twoway system with thickenings in the slab at the columns and load bearing walls called drop panels figure 9. Slabs and flat slabs lecture 5 19 th october 2016 contents lecture 5 designing for shear in slabs including punching shear detailing solid slabs flat slab design includes flexure worked example exercise punching shear.
Pdf irregular flat slabs designed according to the structural. Pdf comparison study for various structural slab systems. Flat slab subduction is an active area of research. This structure was designed to be more solid when used on longer spans and with heavier loads.
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. Where proprietary systems are used the control perimeter at which. Sandt summer 2003 semester slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Flat slab analysis, design and detailing pdf civil. Flat slab system is an important division of concrete floor system. The building is located in seismic zone iii on a site with medium soil. 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. Shear reinforcement is not required at the columns. Here, we have tried to gather various reading materials available in the web about flat slab floor system in one place. Flat slab with big shear wall in conventional outrigger sizes, location of outriggers, thickness of outriggers etc. A simplified drawing of a flat slab plate or waffle slab structure adapted from. The buoyant ridge hypothesis seems to be favored at the moment. This research aimed to analyse the influence of flat slab against progressive collapse at irregular building structures, and determine the type of collapse that occurred at irregular building.
The main objective of this report is to present different structural flooring that are intended to be considered by the structural designers in the design efforts during the different coming design development stages for the project of thakher city. 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. Cven 444 structural concrete design structural system overview dr. Shear strength of beamless slabs usually a controlling factor. Flat slabs are similar to flat plate apart from thickening of flat slabs around columns which are provided to improve shear capacity of this floor system. The minimum thickness can be determined by many factors. This flexibility results from the use of a square or nearsquare grid and the absence of beams, downstands or drops that complicate the routing of services and location of partitions. Punching of flat slabs design for shear at the column heads. By knowledge we know that flat slab is preferred as a floor system because of its architectural appearance, flexibility of flat slab rc structure, easy to construct and economic structure. Depth study flat plate concrete slab overview initial investigation of options for structural systems for this type of building revealed that the existing steel structure is typically the ideal selection.
The flat plate expansion device standard microstation drawings are combined into six drawing files. It is one of the most common forms of construction of floors in buildings. Twoway flat plate concrete floor system analysis and design. Bubbledeck behaves like a spatial structure as the only known hollow concrete floor structure. A flat plate is a one or twoway system usually supported directly on columns or load bearing walls. Hence the flat slabs 3 l2a l2b c of panel a c of panel b middle. Pdf in a developing country like india the benefits of posttensioning system are yet to be recognized.
Review paper on behavior of flat slab under dynamic loading. Advantages and disadvantages of flat slabs and standard. Flat slabs are economically viable for spans range from 6 to 9m and live loads range from 4 to 7 knm 2. Flat slab design structural analysis beam structure. Flat slab with big shear wall in conventional diagonal abdul karim mulla 2015. Bending will take place in the two directions in a dishlike form.
Flat slab analysis, design and detailing pdf civil engineering. Charleson, seismic design for architects, architectural press 2008, p. A civil engineer must know all the aspects regarding the flat floor system. Because of the threedimensional structure and the gentle graduated force flow, the hollow spheres will have no negative influence and cause no loss of strength. This method is used even today for the design of flat slabs and flat plates and is known as the direct design method.
Beside this, due to shear problems at column heads, the thickness of flat slab is greater. Flat slab sized for punching shear and deflection additional reinforcement added to span steel to reduce deflections typically 25% extra on a 7. Beams are not used therefore under floor services outside the drops are simple. Flat slabs are used by engineers in many building due to its advantages over other reinforced concrete floor system in different cases. Crosssectional areas of the floor beams and girders are 14. The materials to be used are grade c25 concrete and grade 500 reinforcement.
Design considerations for reinforced concrete flat slab floor. Flat slab flat slabs thin structure flat soffits no beams 80% of concrete framed buildings are flat slabs 4 million m2 built each year in uk. The drawings for left advanced, right advanced, and squared bridges are contained within two files each, one for cip slabs and one for pcp slabs. Diagram showing examples of flat plate and flat slabs. Also, speedy turnaround can be achieved using an arrangement using early striking and flying systems. Flat slab is a reinforced concrete slab supported directly by concrete columns without use beams. The flat plate is a twoway reinforced concrete framing system utilizing a slab of uniform thickness, the simplest of structural shapes. Using a drop panel and a column capital in flat slab. Flat slab is a reinforced concrete slab supported directly by concrete columns without the use of beams. Department of mechanics, materials and structures english courses reinforced concrete structures code. Pdf the structural performance of a common type of office buildings was examined.
These systems rely on shear walls to sustain lateral load effects, whereas the slabcolumn structure resists mainly gravity loads. Primarily used in hotels, multifamily residential buildings, and hospitals, this system has the advantages of simple con. Apr 18, 2018 flat slab is used when column and beam in the structure is undesirable like in cinema hall when you look around there will be no beams or column. Flat slab types, uses, advantages and disadvantages. The main hotel flatslab emulation could be constructed using four precast concrete components. I figured you would need atleast 2 edge beams in the long span, and if you are forming 2 beams, might as well form 5 for a stiffer structure. A six storey building for a commercial complex has plan dimensions as shown in figure 1.
The column tends to punch through the slab in flat slabs, which can be treated by three methods. Flat slab haunched slab a longitudinal slab is one of the least complex types of bridge superstructures. The effectiveness of its structural system to withstand. A flat slab can also become a major source of energy inefficiency, as structures tend to lose heat through the concrete. For lighter loads the column heads and drop panels are eliminated, such flat slab with constant thickness supported on prismatic columns are called flat plate. As manual calculation method the method of substitutive frames or. Flat slab is used when column and beam in the structure is undesirable like in cinema hall when you look around there will be no beams or column. Seismic analysis of flat slab by using etabs international journal. Design considerations for reinforced concrete flat slab floor system. Nancy debora assistant professor civil karunya university 2. Determine the floor loads on the floor beams, girders.
The grid is formed by the removal of molds after the concrete sets. Advantages and disadvantages of flat slabs and standard column beam slabs free download as word doc. Because of the absence of deep beams and shear walls, flatslab structural system is significantly more flexible for lateral loads then traditional rc frame system. Pdf flat slabs are highly versatile elements widely used in construction. The slab has to carry a distributed permanent action of 1. Design and construction of reinforced concrete flat slabs.
Mar 17, 2020 it can settle on uneven ground, allowing the structure to settle as well, for example, and during seismic activity, a slab foundation cannot hold up if the soils are subject to liquefaction. Common practice of design and construction is to support the slabs by beams and. Flat plate system a flat plate floor system is a twoway concrete slab supported directly on columns with reinforcement in two orthogonal directions figure 1a. Finally, an example of a flat slab floor system is presented to illustrate the practice. Is 4562000 recommends the analysis of flat slab and column structure as a. It can settle on uneven ground, allowing the structure to settle as well, for example, and during seismic activity, a slab foundation cannot hold up if the soils are subject to liquefaction.
Flat slabs system of construction is one in which the beams used in t he conventional methods. In areas of absolute height restrictions, this may enable one to have an additional floor for approximately each 10 floors, as compared. The floor system of a library consists of a 6in thick reinforced concrete slab resting on four floor steel beams, which in turn are supported by two steel girders. Flat plate concrete floor system does not use beams between columns or. Flat plate concrete floor system does not use beams between. Flat slab types of flat slab design and its advantages. A flat slab can also become a major source of energy inefficiency. Recently had a 4column concrete structure and contemplated a flat slab.
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