Kee hanyang university the equivalent frame method efm was developed for twoway slabs as a simple approximate method. Analytical study on effective width of equivalent frame. However, this method is only applicable in case of gravity loads and all general provisions for twoway slabs, except those of aci. I, method produces more realistic estimates of moment transfer than the simple frame analysis of c p.
It requires more accurate analysis methods that, depending on the size and geometry can prove to be long, tedious, and timeconsuming. Robot structural analysis 2016 equivalent frame method. The equivalent frame method efm was developed for twoway slabs as a simple approximate method. Pdf understanding to equivalent frame method adisorn. I would use yield line analysis to determine the requited slab thickness as well aa bar size, distribution, and placement.
On the other hand, finite element analysis using computer programs can be used. This method is used even today for the design of flat slabs and flat plates and is known as the direct design method. The direct design method is very limited in its scope. Beamcolumn frame system and flat plate slab system are analysed by semiempirical, direct design method ddm and approximate elastic method, equivalent frame method fem and the results of both methods are compared with computer software based on finite element method fem, taking into account the effect of changing the beam and column stiffness and the panel length ratio, for 3. Equivalent frame method equivalent frame method efm is described in aci. Flat slab analysis and design designs beamless concrete slab floors flat slab or waffle slab in accordance with aci 318.
Comparative study of reinforced concrete flat slabs with. How to design a flat slab, step by step explained in this video. This paper describes basic procedure of equivalent frame method for twoway slab analysis. Twoway slabs have two way bending unlike oneway slab. Bending will take place in the two directions in a dishlike form. Conclusions whilst some slightly unsafe results of moment transfer were produced by the a. It is related to peak value of bending moments over the columns as a results of point supports. The approach employs a parametric hysteretic model and is based on the effective slab width concept.
Analytical study on effective width of equivalent frame flat. Stucturepoints spslab software program solution utilizes the equivalent frame method to automate the process. The equivalent frame method efm does not have the limitations of direct design method. I am using a simple plane frame program to analyse the equivalent frame, however, my analysis gives moments that are too high. These are the direct design method presented in chap. Pdf a modified equivalent frame method for lateral load. This publication seeks to introduce fe methods, explain how concrete can be successfully modelled and how to interpret the results. This publication seeks to introduce fe methods, explain how concrete can be successfully modelled and how to. Powered by the equivalent frame method of analysis and design per latest american aci 31814 and canadian csa a23. Jul 12, 2018 how to design a flat slab, step by step explained in this video. This paper compares three equivalent frame analysis methods with experimental results obtained from scale models of flat slab exterior panels. Equivalent frame analysis methods for gravity loading in. Design considerations for reinforced concrete flat slab floor. Comparison of oneway and twoway slab behavior economic choices oneway slab on beams suitable span 3 to 6m with ll 35knm2.
Current design codes aci 31805, eurocode 2 and bs 8110 permit the efm for the analysis of twoway slab systems under gravity loads, as well as lateral loads such as seismic loads. Flat slab types of flat slab design and its advantages. The equivalent frame method efm is widely used for the design of twoway reinforced concrete slab structures, and current design codes of practice permit the application of the efm in analyzing. The equivalent frame method was for twoway slab as a simple approximate method. Hi i am trying to model a two way slab system on beams using the equivalent frame method since the direct design method wont work. The method of analysis is what you need to choose here, flat slab being the intended goal, not a type of design as you imply. How to design reinforced concrete flat slabs using finite. The equivalent frame method efm is widely used for the design of twoway reinforced concrete slab structures, and current design codes of practice permit the application of the efm in analyzing the flat plate slab structures under gravity and lateral loads.
Efficient analysis of flat slab structures subjected to. In the eurocodes, the analysis of flat slab is the same as that recommended in bs 8110. Robot structural analysis 2016 equivalent frame method 1. The objective of this paper is to present analysis and design of rc flat slab using two different methods and compare the superiority of the two methods over one another by various aspects. 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.
Structural analysis of the flat slab structure having irregular plan or slab with openings can be performed and stress distribution of floor slab can be easily represented the finite element method if the stiffness degradation in the slab could be consider. Structural engineers commonly use the equivalent frame method with equivalent beams such as the. In many projects, however, these requirements limit the usability of the direct design method significantly. For example the slab pannels should be at least 3 by 3, each pannel should be two way, the difference in length between conseqative panels shall not be gretter tha n 30 precent, a. Can be used for larger spans with relatively higher cost and higher deflections oneway joist system suitable span 6 to 9m with ll 46knm2. Flat slab analysis, design and detailing pdf civil. An equivalent frame approach is presented for nonlinear seismic anal ysis of reinforcedconcrete flat plate buildings. Must watch basics of flat slab for better understanding from the link given below. The efm defines an equivalent frame for use in structural analysis to determine the negative and positive moments acting on the slab system. Comparative study among direct design method, equivalent. Pdf unified equivalent frame method for flat plate slab. This type of structure can be analyzed with finite elements methods or with one of simplified method, as equivalent frame method or grillage method. Analysis and design of flat slab by aci code with matlab.
Dec, 2016 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. In the flatplate structure an analysis by using frame elements is generally carried out by the effective beamwidth model. The deflection of a uniformly loaded flat plate, flat slab, or twoway slab supported by beams on column lines can be calculated by an equivalent frame method that cor. Finite element fe analysis, is a popular powerful computer method of analysing flat slab concrete structures. Analysis and design of slabs two way civil engineers pk. Dimensions of cross sections used in proposed frame analysis 156 53. Flat slabs can be analysed using the frame equivalent method, or by using the simplified analysis method which involves the use of coefficients. It has been observed that to investigate the fragility of flat slab reinforced concrete systems. The unique experimental results were obtained by measuring strains in reinforcing bars at approximately 200 selected locations throughout a slab panel. Unlike in the previous equivalent frame approaches, the proposed method targets both the mo. Paper open access impact of the method of analysing. The unique experimental results were obtained by measuring strains in reinforcing bars at approximately 200 selected locations throughout a. Comparison of moments computed by proposed frame analysis with those by aci frame analysis and plate theory. Equivalent frame method most commonly used method the flat slab structure is divided longitudinally and transversely into frames consisting of columns and strips of slabs with.
Frame method example equivalent frame method design the. University of engineering and technology peshawar two way slab equivalent frame method efm introduction this 3d frame is converted to a 2d frame by taking effect of stiffness of laterally present members slabs and beams. However, the equivalent frame method is commonly used for the analysis of the flat slab structures subjected to lateral loads in practical engineering. Reinforced concrete flat slab structural engineering. For span from 5 to 9m thin flat slabs are the preferred solution for the construction of in situ concrete frame building, where a square or near square grid is used. Analyses are for a onebaywide strip using the equivalent frame analysis method of the aci code. In present work, a flat slab system is a significant advancement in the building technology. In this method, the plate is modeled as an equivalent beam with a certain effective width. University of engineering and technology peshawar two way slab equivalent frame method efm introduction ksb represents the combined stiffness of slab and. In the flat plate structure an analysis by using frame elements is generally carried out by the effective beamwidth model. Comparative study of equivalent static analysis and response. In the equivalent frame method, the flat slab system is modeled as an equivalent frame and an elastic analysis is performed. Equivalent frame method efm finite element method fem out of this, first 2 methods are recommended by the i. Equivalent frame analysis methods for gravity loading in flat.
Department of mechanics, materials and structures english. Analysis of flat sanalysis of flat sllab ab analysis of flat sanalysis of flat sllab ab. Current design codes aci 31805, eurocode 2 and bs 8110 permit the efm for the analysis of twoway slab systems. Comparative study of reinforced concrete flat slabs with and. What is the difference between direct design method and. To compare equivalent static analysis and response spectrum analysis method on flat slab for above parameters. Analysis and design of flat slab by aci code with matlab coding. Design of reinforced concrete structures ii twoway slabs 1 1. The approach employs a parametric hysteretic model and is based on the effective slabwidth concept.
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. The main objective of the paper is to study method of analysis. 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. A modified equivalent frame method for lateral load analysis. This pdf file contains a chapter of 23 pages with various aspects of flat slabs including four example of flat slab design. The strip may have up to 20 spans and may have cantilevers at the ends. 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. Design considerations for reinforced concrete flat slab.
There are two methods of analysis of rc flat slab viz. In twoway slabs shorter direction strip carry greater %age of load. The direct design method ddm is an approximate method and is applicable to flat plate concrete floor systems that meet the stringent requirements of aci 31814 8. Apr 12, 2016 modelling of a reinforced concrete 2d equivalent frame of a flat slab construction using autodesk robot structural analysis professional 2016. Punching of flat slabs design for shear at th e column heads 12. It is a general method for design of twoway column supported slab systems, without the restrictions of the direct design method. The slab is without drops and is supported internally and on the external long sides by square columns. Flat slab analysis and design free version download for pc.
A modified equivalent frame method for lateral load analysis y. The table below shows that both the direct design method and the equivalent frame method give similar results for this example. Behaviour of flat slabedge column joints sciencedirect. Flat slab, shear wall, linear dynamic analysis, base shear, time period, story drift, storey displacement 1 introduction from last two decades there is a high increase in the high rise buildings and modern trend is towards high rise. Flat slab analysis, design and detailing pdf civil engineering. Deep ribs, the concrete and steel quantities are relative low expensive formwork expected. This model is often preferred because simplicity and ease application.
The direct design method gives rules for the determination of the total static design moment and its distribution between negative and positive moment sections. In frames adjacent and parallel to an edge beam portion shall be equal to flat slab bounded by the edge and the centre line of. Both methods use the same procedure to divide the moments so found between the middle strip and column strips of the slab and the beams if any. Analyze and design flat slab or waffle slab floors. A floor slab in a building where stability is provided by shear walls in one direction ns. Flat slabs may have drop panels at columns and columns may have capitals. Current design codes aci 31805, eurocode 2 and bs 8110 permit the efm for the analysis of two. Structural design of flat slabs to eurocode 2 structville. Comparative study of equivalent static analysis and. Lecture 12 equivalent frame method linkedin slideshare. Accordingly, main reinforcement is required in the two directions. The methods of slabs analysis analysis of flat slabs presents many difficulties. Modelling of a reinforced concrete 2d equivalent frame of a flatslab construction using autodesk robot structural analysis professional 2016.
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