Slab beam design

It provides solutions to all problems pertaining to houses right from concept to completion. The load is transferred directly from slab to column in the flat slab. In conventional slab-beam system, the load is transferred from slab to beam and ultimately beam to the column.

Skip to content. House Construction Sep 03, Gharpedia. Flat Slab System. Slab Beam System.

Design of Slab and Girder Bridges (With Diagram)

In flat slab system, the thickness of slab is large. In slab beam system, the thickness of slab is small while depth of beam is large. It provides greater clear ceiling heights.

It provides lesser clear ceiling heights. Here load from slab is directly transferred to column. Here load from slab is transferred to beam and from beam to column. In flat slab system, less formwork is needed. In slab beam system, more formwork is needed. Form work is simple and hence not costly. Form work is complicated and hence costly.

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Drop panel is provided above column. Drop panel is not needed above column.

Difference Between Flat Slab & Conventional Slab-Beam System

Floor system requires lesser depth and hence there will be reduction in storey height. Floor system requires more depth and hence there will be increase in storey height as compared to flat slab. Dead load of structure is less. Dead load of structure is more. In flat slab system, It is easy to install sprinkler and piping and other utilities as beams are absent. In slab beam system, It is tricky to install sprinkler, piping and other utilities as beams are present.

Flat ceiling is available which gives attractive appearance.

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Flat ceiling is not available for flat attractive appearance, you may have to do false ceiling. Illumination is better as beams are absent. Illumination is not as effective as in flat slab as beam are present.

It is easier to provide acoustical treatment underside of slab. It is difficult to provide acoustical treatment underside of slab. At least three continuous spans in each direction are needed for construction. Construction of Single slab is possible. Ratio of Longer span to shorter span should not be more than 2. Ratio of Longer span to shorter span has no limitation.

Live load shall not exceed three times the design dead load. Live load has no relation with design dead load. In flat slab system, minimum thickness of slab is mm.After analysis and design of the superstructure see a section of the stadium in the picture belowI realized I had a very large magnitude of axial loads and moments at the foundation.

Foundations must be designed to resist geotechnical and structural failure, and at the same time should be economical.

slab beam design

The ultimate bearing capacity of the supporting soil at 2. However, adopting a pad footing proved very uneconomical given the large area of excavation required columns are spaced at 6. Raft foundation proved to be too expensive for a soil with such a good bearing capacity. After much consideration, I realized that chaining the columns continuously will do the trick, but at the same time, I could combine the slab with upstand beams running continuously along the axis of the column. My whole aim was to reduce the great quantity of concrete that would have been required to control diagonal shear by using shear reinforcements stirrups in the beams.

This eventually proved to be much cheaper. From the symmetrical arrangement of the loads, it is quite obvious that the centroid will pass through the middle column, hence, soil pressure can be assumed to be uniform under the whole length of the footing. Taking a Design of the footing cantilever slab portion per meter strip Note that the bending moment in the slab is maximum at the face of the column in this case at the face of the upstand beams. Hence design is ok.

Design of ground longitudinal upstand beam. See detailed drawings. Thanks for sharing nice content. I came across a good example of this problem. I actually try to design this foundation type.

Could you let me know of any book illustrating solutions for the same footing type? The analysis to obtain shear and moment is misleading. It is tempting to analyze continuous footing as if it were tee beam at upper floors, where we will normally have UDL applied on the beam and we go ahead with determining the axial forces, shear and bending moments. For footing, however, the soil reaction acts as UDL upward if uniform pressure and the column loads are already the reactions.

In this case, larger bending moment is often around the mid-span; requiring more reinforcement compared to locations of column. Another thing is when the exterior axial loads are not significantly smaller than interior column axial loads, the interior columns may experience uplifting as the exterior loads pressuring downward.

This is mechanically and geometrically possible due to continuity provided by the footing slab and girder. I would love to hear other views. Save my name, email, and website in this browser for the next time I comment. Structville is a media channel dedicated to civil engineering designs, tutorials, research, and general development. At Structville, we stop at nothing in giving you new dimensions to the profession of civil engineering.In the design of reinforced concrete structures, floor loads are usually transferred from slabs to beams, and from the beams, the loads are transferred to the columns, and finally to the foundation.

One Way Slab Design – How To Design One Way Slab

Load transfer from slab to beams is one of the most intriguing aspects of design, especially for beginners in the design of reinforced concrete structures. In the manual design of structures, some formulas can be used to represent slab loads on beams as uniformly distributed loads.

The main essence of this is to simply analysis and the formula can be obtained from Reynolds and Steedman for transfer of load from two-way slab to beams. In this article, we are going to review load transfer from slab to beams using three approaches; 1 Full finite element analysis of beams and slabs using Staad Pro 2 Yield line method of load transfer using Staad Pro 3 Manual method using formula. Manual analysis overestimated the load transferred. Manual analysis gave close result to finite element analysis.

Manual analysis using formula underestimated the load transferred. The shear force and bending moment in the short span beam were underestimated when formula was used.

There is always a two way action even though it is greater in the long span. I just went through the write up, it was great. But the comparison is not proper until u make the boundary conditions the same. So hinge the two ends of the beams in the model and run the analysis again. Then you can now compare Apple for Apple. Thanks for doing a good work.

Yes… I clearly understand what you mean. But since we usually assume pinned support for manual designs, I decided to present the result the way it will likely be encountered and used in practice.

I was tempted to transfer the manual load to subframe models, but decided to leave that for another time since it is rarely done due to the computational effort required. Hello sir, great share! How did you get the different result sets for the Yield line and FE analysis of the concrete plate slab? Save my name, email, and website in this browser for the next time I comment. Structville is a media channel dedicated to civil engineering designs, tutorials, research, and general development.Lost your password?

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slab beam design

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Vivamus vulputate posuere nisl quis consequat. In this article, I will discuss One way slab design procedure with example. When a slab is supported on all four sides and the ratio of long span to short span is equal or greater than two, it will be considered as one way slab. However main reinforcement bar and distribution bar in transverse direction. To control deflection, ACI Code 9. According to ACI code 8. The lateral spacing of the flexural bars should not exceed 3 times the thickness h or 18 inch according to ACI code 7.

Reinforcement ratio is the ratio of reinforcement area to gross concrete area based on total depth of slab. One-way solid slabs are designed as rectangular sections subjected to shear and moment.

According to ACI Code A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. The service live load is psf and psi concrete is specified for use with steel with a yield stress equal to psi.

Design the slab following the provisions of the ACI code. Let a trial thickness of 6. Minimum reinforcement for shrinkage and temperature is. I am understanding all things ,but one thing is left for me pls show me how can I derive the calculation ratio for the long span to short span is greater or equal two. Previous post. Next post. Register Now.Directions: Enter values for design factored moment, beam "stem" width, b weffective depth, d, span, spacing, and slab thickness not all parameters are used for all calculations.

Note that design moment for slabs is calculated on a typical 1-ft wide section of the slab. Press "update" button. The required reinforcement area, A swill be calculated for slabs, the required spacing of a selected bar size is calculated. More detailed explanations and examples of reinforced concrete beam and slab design can be found in my text. Note that the strength design method is used; moments must be computed based on factored loads. Calculator works for rectangular beams, positive-moment and negative-moment T-beams, and 1-way slabs, as shown in the sections below:.

Disclaimer: This calculator is not intended to be used for the design of actual structures, but only for schematic preliminary understanding of structural design principles. For the design of an actual structure, a competent professional should be consulted. First posted Sept. Reinforced concrete beam sections: a positive-moment rectangular beam; b negative-moment rectangular beam; c negative-moment T-beam; and d positive-moment T-beam.

Mu units d in.The lateral loads are resisted by shear walls. Preliminary Slab Thickness Sizing. Equivalent frame method limitations. Frame members of equivalent frame. Equivalent frame analysis. Design moments.

Distribution of design moments. Flexural reinforcement requirements.

slab beam design

Column design moments. Design of Interior, Edge, and Corner Columns. Two-Way Slab Shear Strength. One-Way Beam action Shear Strength. Two-Way Punching Shear Strength. Immediate Instantaneous Deflections. Summary and Comparison of Design Results. Kamara and Lawrence C. Design Data. Control of deflections. ACI 8. In lieu of detailed calculation for deflections, ACI Code gives minimum thickness for two-way slab with beams spanning between supports on all sides in Table 8.

The moment of inertia for the effective beam and slab sections can be calculated as follows:. For Edge Beams:. The effective beam and slab sections for the computation of stiffness ratio for edge beam is shown in Figure 2.

For North-South Edge Beam:. For East-West Edge Beam:. For interior Beams:.Spacing 3 t 45 cm 17in. Shear Strength of Slabs In two-way floor systems, the slab must have adequate thickness to resist both bending moments and shear forces at critical section. There are three cases to look at for shear. Two-way Slabs supported on beams 2.

Two-Way Slabs without beams 3. Shear Reinforcement in two-way slabs without beams. Shear Strength of Slabs Two-way slabs supported on beams The critical location is found at d distance from the column, where. The supporting beams are stiff and are capable of transmitting floor loads to the columns.

Design and Analysis of Sturctures in SAP2000; modeling slabs, beams and columns

Shear Strength of Slabs The shear force is calculated using the triangular and trapezoidal areas. If no shear reinforcement is provided, the shear force at a distance d from the beam must equal. One-way shear or beam shear at distance d from the column 2. Two-way or punch out shear which occurs along a truncated cone.

One-way shear considers critical section a distance d from the column and the slab is considered as a wide beam spanning between supports. Shear Strength of Slabs Two-way shear fails along a a truncated cone or pyramid around the column. Shear Strength of Slabs If shear reinforcement is not provided, the shear strength of concrete is the smaller of:.

Shear Strength of Slabs Shear Reinforcement in two-way slabs without beams. For plates and flat slabs, which do not meet the condition for shear, one can either - Increase slab thickness - Add reinforcement Reinforcement can be done by shearheads, anchor bars, conventional stirrup cages and studded steel strips. Shear Strength of Slabs Shearhead consists of steel I-beams or channel welded into four cross arms to be placed in slab above a column.

Does not apply to external columns due to lateral loads and torsion. Shear Strength of Slabs Anchor bars consists of steel reinforcement rods or bent bar reinforcement. Shear Strength of Slabs The reinforced slab follows section The total distance is 15 3.

Example Problem The final result: 15 stirrups at total distance of Limitations on use of Direct Design method 1. Minimum of 3 continuous spans in each direction.

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Columns may be offset from the basic rectangular grid of the building by up to 0. Service unfactored live load 2 service dead load. For panels with beams between supports on all sides, relative stiffness of the beams in the 2 perpendicular directions. Definition of Beam-to-Slab Stiffness Ratio, Accounts for stiffness effect of beams located along slab edge reduces deflections of panel adjacent to beams.

E cb Modulus of elasticity of beam concrete E sb Modulus of elasticity of slab concrete I b Moment of inertia of uncracked beam Is Moment of inertia of uncracked slab With width bounded laterally by centerline of adjacent panels on each side of the beam. Analogy of two-way slab to plank and beam floor Uniform load on each beam Moment in one beam Sec: B-B. Full load was transferred east-west by the planks and then was transferred north-south by the beams; The same is true for a two-way slab or any other floor system.

Choose layout and type of slab. Choose slab thickness to control deflection. Also, check if thickness is adequate for shear. Choose Design method Equivalent Frame Method- use elastic frame analysis to compute positive and negative moments Direct Design Method - uses coefficients to compute positive and negative slab moments. Basic Steps in Two-way Slab Design 4. Calculate positive and negative moments in the slab. Determine distribution of moments across the width of the slab.

Assign a portion of moment to beams, if present.

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