Reply Delete. Slabs with Grade 40 or 50 deformed bars –> 0.0020, Slabs with Grade 60 deformed bars –> 0.0018, Slabs where reinforcement with yield strength Exceeding 60000 psi- ->( 0.0018 x 60000/fy), According to ACI Code 10.5.4, the minimum flexural reinforcement is not to be less than the shrinkage reinforcement, or 0.0018. EC2 Webinar - Autumn 2016 Lecture 5/2 Designing for shear in slabs • When shear reinforcement is not required –e.g. Step 2 Design forces Draw panel of slab and indicate maximum design moments, shears and in- plane loads, if any, per unit width of slab. As = (4.13 x 12)/(0.90 x 60 x 5.29) = 0.17 in², As = (2.41 x 12)/(0.90 x 60 x 5.29) = 0.10 in². • The ratio of characteristic imposed load to characteristic dead load does not exceed 1.25. In a one-way slab, the design shear force is calculated from the support reactions or end-shears at the support, while in a two-way slab, they can be obtained from the coefficients in Table 3.15 of BS 8110-1:1997. The method of checking the deflection of the slabs are similar to the checks of beam deflection. Section Civil & Geotechnical Engineering Sheet no./rev. 1.1: Load transfer in (a) One-way slab, (b) Two-way Slab (Nilson) Fig. The maximum area of steel provided should not exceed 0.04Ac. For a slab of a given shape and support conditions, the distribution of shear forces, bending, and twisting moments in the slab due to externally applied loads cannot be determined easily. Reinforced Concrete Design to BS8110 Structural Design 1 – Lesson 5 2 4.2 … Simply supported two-way slabsWhere the corners of slabs are free to lift and no provision is made to resist forces at the corners, the maximum moments per unit width are given by the following expressions:Msx = bending moment in strips with span lx = Msx = αsxqlx2Msy = bending moment in strips with span ly = Msy = αsyqlx2where lx is the shorter span of the panel, ly is the longer span of the panel and q is the design ultimate load per unit area. Minimum reinforcement for shrinkage and temperature is, How To Calculate Cement, Sand Quantity For Plastering. 1.1(a)], in which the structural action is essentially one-way, the loads being carried in direction perpendicular to the supporting beams or walls. Beam Design to BS (1.2). One-way slabs may be simply supported or continuous. This is actually an expensive operation (see cost of fixing reinforcement in Nigeria). Satisfying other requirements such as durability, fire resistance, etc are also necessary. Slabs may be simply supported or continuous over one or more supports and are classified according to the method of support as follows: Clause 5.3.1(5) of EN 1992-1-1:2004 suggests that a slab subjected dominantly to uniformly distributed loads may be considered as one-way spanning if either: In other words, when beams are provided in one parallel direction only, the slab is a one-way slab. A beam is similar to a slab in so many ways but there are fundamental differences in behaviour and stress distribution of the two elements. flat slabs and pad foundations Shear ... and is similar to BS 8110 methods Rating: 12 Description. (h) Check for deflectionThe check for deflection is a very important consideration in slab design and usually controls the slab depth. Foundations 43 7. The floor slab (PANEL 1) is spanning in two directions, since the ratio (k) of the longer side (ly) to the shorter side (lx) is less than 2. I do not know where to look for an example of a design of a simply supported slab per BS 8110. The loads used in the analysis are factored to represent the ultimate limit state condition. On the other hand, BS presents constant amount for shorter edge of span which means that shorter edge absorbs a greater amount of energy. The coefficients can be obtained from Table 3.14 of BS 8110-1:1997. Replies. Clear area for each slab is (13 × 19 ); therefore Span Ratio m = 13/19 = 0.68. A slab should not deflect excessively under service load. (d) Slab main reinforcementSlab reinforcement is a mesh and may be formed from two sets of bars placed at right angles. Due to the two-dimensional nature of a slab, it is subjected not only to bending moments Mxx and Myy and shear forces Vx and Vy but also to twisting moments Mxy on all the four faces. Select representative 1 m wide design strip/strips to span in the short direction, as shown in Figure 8.4.a. BS 8110, however, has an earlier withdrawal date of March 2008. The same as previous example, by using CCI provisions, obtained amounts show that the results would be close to the condition of one-way slab, when the spans ratio gets closer to 2.0. (b) Minimum tension steelThe main moment steel spans between supports and over the interior supports of a continuous slab. Design Two-Way Continuous Solid Slab. One-way simply supported slab • Analysis and design of the slab similar to design of simply supported beam as indicate in the previous chapter. Replies. Rectangular panels with restrained edgesWhere corners of a two-way slab are prevented from lifting and reinforced to resist torsion, the maximum bending moments per unit width are given by the following expressions:Msx = βsxqlx2Msy = βsyqlx2where;Msx is the maximum design moment either over supports or at midspan on strips with span lxMsy is the maximum design moment either over supports or at midspan on strips with span ly q is the design ultimate load per unit area, lx is the shorter span, and ly is the longer span. Ref. Reinforced concrete slabs are plate elements used to form the floors of buildings. April 14th, 2018 - Flat Slab Design Example Download As PDF File Pdf Text File Txt Or Read Online Flat Slab Design Example To BS 8110''Design and Analysis of Slabs Colin Caprani April 21st, 2018 - In a flat slab building you can Civil Engineering Design 1 11 Dr C Caprani 2 2 Example 1 Ultimate Behavior of One Way … –Refer Table 3.13 for bending moment coefficient. • Flat Slab Design –includes flexure worked example • Exercise -Punching shear. The main steel is placed nearest to the surface to give the greatest effective depth. Thus, the maximum reinforcement ratio corresponds to a net tensile strain in thereinforcement, €t of 0.004. In this article, I will discuss One way slab design procedure with example. RIBBED (JOIST), HOLLOW POT & WAFFLE SLAB DESIGN TO BS 8110 @Mr.Asish Seeboo 8 1.2 WAFFLE SLAB DESIGN 1.2.1 INTRODUCTION Similar to one-way slab, it is seen that the weight of a solid two-way slab can be appreciably reduced by eliminating portions of concrete from the tensile zones without affecting the structural integrity of the the slab. online slab design, Design of Two-way Slabs Example 1.2 Use (i) WSD, (ii) USD to design the two-way slab shown below, carrying floor finish = 30 psf, random wall = 50 psf and live load = 60 psf [Given: f c = 3 ksi, f y = 50 ksi]. This spreadsheet performs an analysis and design of two-way spanning reinforced concrete slab. Thanks. Thanks. Clause 9.3.1.1(2) states that in the case of one-way slabs, secondary reinforcement of not less than 20 percent of principal reinforcement should be provided. You will receive a link and will create a new password via email. Job No. It contains five spreadsheets for designing R.C. Project: Flat Slab Analysis & Design, In accordance with BS8110:PART 1:1997 Job Ref. 12.0 MOMENT AND SHEAR COEFFICIENT FOR SOLID SLAB 18 - Continuous One-way Slab - Table 3.12: Ultimate moment and shear coefficients in continuous one way slab (Ref. While a beam is generically a one-dimensional element, a plate is a two-dimensional element. For deemed to satisfy basic span/effective depth (limiting to depth/250);Actual L/d of the slab must be ≤ Limiting L/d × βsThe limiting basic span/ effective depth ratio is given by;L/d = K [11 + 1.5√(fck)ρ0/ρ + 3.2√(fck) (ρ0/ρ – 1)1.5] if ρ ≤ ρ0L/d = K [11 + 1.5√(fck) ρ0/(ρ – ρ’) + 1/12 √(fck) (ρ0/ρ)0.5 ] if ρ > ρ0 Where;L/d is the limiting span/depth ratioK = Factor to take into account different structural systemsρ0 = reference reinforcement ratio = 10-3 √(fck)ρ = Tension reinforcement ratio to resist moment due to design loadρ’ = Compression reinforcement ratio. Continuous beams may be provided in one direction or two orthogonal directions, to support slabs that may be solid or ribbed in cross-section. Linkedin. a) Classify all types of solid slab(CO1) b) Identify one way and two way solid slab (CO1) c) Use a relevant Clauses in code of practice (CO1) d) Design one-way slabs (CO2) e) Details the slabs(CO1). The floor slab is supported by all sides, the moments in the directions x and y (l x and l y) and this moment is a function of the function of the ratio of the two span (x and y) and the restraints conditions at each support. (100ρ1 fck)1/3, k = 1 + √(200/d) = 1 + √(200/119) = 2.296 > 2.0, therefore, k = 2, ρ1 = As/bd = 452/(1000 × 119) = 0.003798 < 0.02; K1 = 0.15. Fig. BS 8110 details how deflections and the accompanying crack widths may be calculated. CE 433, Fall 2006 Slab Design Example 1 / 6 Design a one-way slab for an exterior bay of a multi-story office building using the information specified below. Bending moments coefficiens have been taking from the BS code. R.C. Save my name, email, and website in this browser for the next time I comment. Excessive deflection of slabs can cause cracking to partitions and finishes. by Dr. C. Sachpazis Date 18/01/2014 Chk'd by Date App'd by 1 FLAT SLAB DESIGN TO BS8110:PART 1:1997 Slab geometry Span of slab in x-direction; Span x = 7200 mm Span of slab in y-direction; Span y = 7200 mm To check the shear capacity of slabs, the shear stress (vEd = VEd/bd) must be checked against the shear capacity of an unreinforced section (VRc,d). usually one and two-way spanning slabs • Punching shear –e.g. The above situation occurs in the case of simply supported slabs or the end support of a continuous slab cast integral with an L-beam which has been taken as a simple support for analysis but the end of the slab might not be permitted to rotate freely as assumed. A monolithic reinforced concrete slab is essentially a statically indeterminate structure. He is a member of the Nigerian Society of Engineers. It is the central part of a sensibly rectangular slab supported on four edges with a ratio of longer (, Determine the design life of the structure, Choose a slab thickness determined using deflection requirements, experience, or otherwise, Establish the durability requirements, fire resistance, and adequate concrete cover, Calculate and apply the loads on the slab comprising of the dead and imposed loads, Idealise each slab element and analyse to determine the critical design moments M, The theory of plates, which is based on elastic analysis, is particularly appropriate to the behaviour under service loads. –Slab only consist of one panel and the sides of the slab is not restrained against lifting. Structural Engineering. This should be a long post, but I am going to try and keep it as brief as possible. Difference between one-way and two-way slabs. Lost your password? They are; Generally, for rectangular slabs with standard edge conditions and subject to uniformly distributed loads, normally the bending moments are obtained using tabulated coefficients. Design of Slab (Examples and Tutorials) by Sharifah Maszura Syed Mohsin Example 1: Simply supported One way slab A rectangular reinforced concrete slab is simply-supported on two masonry walls 250 mm thick and 3.75 m apart. In design, a slab is considered to be two-way if the ratio of the longer side to the shorter side is less than two. Twitter. Choose a slab thickness to satisfy deflection control requirements. EXAMPLE ON THE ANALYSIS AND DESIGN OF CONTINUOUS SLAB AND BEAM FOOTING PER BS 8110-1:1997. Lorem ipsum dolor sit amet, consectetur adipiscing elit.Morbi adipiscing gravdio, sit amet suscipit risus ultrices eu.Fusce viverra neque at purus laoreet consequa.Vivamus vulputate posuere nisl quis consequat. The first stage of the design is finding the bending moment of the slab panels. Checking slab deflection is included in the beam design section of BS 8110 Part 01. VRd,c = [0.12 × 2 × (100 × 0.003798 × 25)1/3] × 1000 × 119 = 60476.947 N = 60.476 kN Since VRd,c (60.476 kN) > VEd (17.477 kN), no shear reinforcement is required.Note that shear reinforcements are rarely required in solid slabs supported by beams. Bending moments coefficiens have been taking from the BS code. One-way solid slabs are designed as rectangular sections subjected to shear and moment. Ref. Do you have any questions? Rev. Therefore, the main reinforcements will lie parallel to the short span, and that is where you check your deflections (see why short spans are critical in floor slabs). To control deflection, ACI Code 9.5.2.1 specifies minimum thickness values for one-way solid slabs. This will on the one hand, help the control of cracking, increase durability, while on the other assist placing and compaction. This spreadsheet performs an analysis and design of two-way spanning reinforced concrete slab. The provision of adequate reinforcement, slab thickness, and proper detailing to satisfy ultimate and serviceability limit state requirements forms the basis of the design of reinforced concrete slab. Let me know in the comments. 8.2.1 One-way Solid Slabs 8.2.1.1 Minimum Thickness 8.2.1.12 Summary of One-way Solid Slab Design Procedure Once design compressive strength of concrete and yield stress of reinforcement are specified, the next steps are followed: 1. This spreadsheet performs an analysis and design of two-way spanning reinforced concrete slab. Design is in accordance with BS 8110-1:1997. By purchasing this spreadsheet you agree to the disclaimer and terms & conditions. Ubani Obinna Uzodimma - April 10, 2016. Note that distribution steel is required at the top parallel to the supports of continuous slabs. CivilStructural Guru 23 August 2017 at 12:41. Design Example of a two-way slab. At Structville, we stop at nothing in giving you new dimensions to the profession of civil engineering. Table 1: Area of reinforcement per metre width of spacing. I do not know where to look for an example of a design of a simply supported slab per BS 8110. Floor slabs are usually subjected to uniformly distributed loads, partially distributed loads, line loads, or concentrated loads in the transverse direction. In clause 5.1.3 of Eurocode 2, the following two loading arrangements are recommended for buildings. Reference are to Eurocode 2 unless otherwise stated, all other references are to None Contradictory Complementary Information (NCCI) DESIGN OF TWO WAY SLAB Design Example of a two-way slab. By registering, you agree to the Terms of Service and Privacy Policy. Single-User or Company License, which one is the best for me? BS 8110 details how deflections and the accompanying crack widths may be calculated. Step 3 Cover to reinforcement Determine cover required to reinforcement as per Tables 11.6 and 11.7. 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. buildings, for example, design teams often say that wood-frame construction allows them to achieve • Slab-on-grade at freezer/cooler: 4" reinforced concrete, 15. In a typical reinforced concrete building, reinforcement bars arranged as mats are incorporated into a concrete plate of minimum thickness 125 mm to form a reinforced concrete solid slab. Moment coefficient for two adjacent edges discontinuous, Short Span Mid-span = 0.042 Continuous edge = 0.056, Long SpanMid-span = 0.034Continuous edge = 0.045, Design of short spanMid spanMEd = αnlx2 = 0.042 × 10.9575 × 3.6252 = 6.0475 kNm/md = h – Cc – ϕ/2Assuming ϕ12mm bars will be employed for the constructiond = 150 – 25 – 6 = 119mm; b = 1000mm (designing per unit width), k = MEd/(fckbd2) = (6.0475 × 106)/(25 × 1000 × 1192) = 0.0171, Since k < 0.167 No compression reinforcement requiredz = d[0.5 + √(0.25 – 0.882k)] z = d[0.5 + √(0.25 – 0.882 × 0.0273)] = 0.95d, As1 = MEd/(0.87fykz) = (6.0475 × 106)/(0.87 × 460 × 0.95 × 119) = 133.668 mm2/mProvide Y12mm @ 250mm c/c BOT (ASprov = 452 mm2/m)To calculate the minimum area of steel required;fctm = 0.3 × fck2⁄3 = 0.3 × 252⁄3 = 2.5649 N/mm2 (Table 3.1 EC2). However, in addition to self weight consisting of all permanent loads, live loads have to be added. usually one and two-way spanning slabs • Punching shear –e.g. Bending moments coefficiens have been taking from the BS code. In normal cases, a strip of slab 1 m wide is checked against span-to-effective depth ratios. It possesses two free (unsupported) and sensibly parallel edges. © (2020) Structville Integrated Services Limited. Design the floor slab below. Introduction to the design of reinforced concrete slabs. Support Conditions, b). BS 8110: Part 1: 1997) - Two-way Simply Supported Slab - Table 3.13: Bending moment coefficient for simply supported two-way slab (Ref. For slabs with irregular plan shapes and slabs subject to a combination of point loads and distributed loads, Johansen’s yield line analysis and the Hillerborg strip method provide powerful methods for strength calculations. The table below gives bar spacing data in the form of areas of steel per metre width for various bar diameters and spacings. –Refer Table 3.13 for bending moment coefficient. Design Slab(Two-way) Design of Isolated Footing Pile cap design_columns pile no. For a one-way slab to have a fire rating of one hour (REI 60), the minimum thickness should be 80 mm and the concrete cover (from the surface to the centre of bar) should be minimum of 20 mm. 2.1 Elevation of a one-way spanning slab (supported on 2 7 slabs) 2.2 One-way spanning slab (supported on 4 sides) 7 2.3 The Eurocodes 14 2.4 Alternate spans loaded 19 2.5 Adjacent spans loaded 20 2.6 All spans loaded 20 2.7 Basic span-to-effective-depth ratios 34 3.1 Slab Design Procedure 40 3.2 Procedure Shear checking 41 Plan View of Floor System Assume partitions will not be damaged by deflections. Therefore, approximate analyses are generally used. The deflection can be checked by two methods. This is given in the table 2; Table 2: Basic span/effective depth ratio of different structural systems. As ‘d’ is less than the effective depth of (6.50-1.00) = 5.50 in, the thickness of 6.50 in can be adopted. Plan View of Floor System Assume partitions will not be damaged by deflections. 66 inch-kips \⠀㄀─尩 if the concrete strength decreased from 3. voronoi urban design. Values of αsx and αsy are given in Table 3.13 of BS 8110-1:1997 for different ratios of ly and lx, where ly is the longer span. The equations for the analysis have been obtained from the Reinforced Concrete Designer's Handbook by Reynolds and Steedman. Member Design - RC One Way Spanning Slab Made by Date Chd.03-09-15 Drg. Hence negative moments may arise and cause cracking. Hence no further checks for shear will be done on the slab. Factored DL and LL should be ={(81×1.2)+(100×1.6)} =257 psf A reinforced concrete slab is built integrally with its supports and consists of equal span of 15 ft. For 1m slab width, • Moment, Shear Force, One-way Continuous slab • For continuous slab, moment and shear force can be obtained from Table 3.12: BS 8110 if the following conditions applied. For being both ends continuous minimum slab thickness =  L/28 =(15 x 120)/28= 6.43 in.Let a trial thickness of 6.50 in. Member/Location. Beam Section / Slab Section Design (BS 8110 -1997) Individual Footing Design (BS 8110 -1997) Post Tension analysis and Design to EC2 by The Concrete Center; Crack width calculation for (BS 8110 BS 8007) by The Concrete Center; Reinforced Concrete Retaining Wall Design to BS 8110 … Check for deflectionWe check for deflection at the short span of slabsk = 1.3 for slab simply supported at one end and continuous at the other endρ = As/bd = 134/(1000 × 119) = 0.001126 < 10-3√fck (0.005)Since ρ < ρ0 L/d = K [11 + 1.5√(fck ) ρ0/ρ + 3.2√(fck) (ρ0/ρ – 1)3⁄2]L/d = 1.3 [11 + 1.5√(25) × 0.005/0.001126 + 3.2√25 (0.005/0.001126 – 1)3⁄2] = 1.3(44.3 + 102.106) = 190.327. Structville is a media channel dedicated to civil engineering designs, tutorials, research, and general development. Moments and shear in slabs. Please tell me about the length of 152 feet in moment calculations. However, clause 9.3.1.2(1) requires that half the calculated span reinforcement must continue up to support. (g) Shear capacity of slabsUnder normal loads, shear stresses are not critical and shear reinforcement is not required in floor slabs. Reach him at ubani@structville.com. If you continue browsing the site, you agree to the use of cookies on this website. It also includes column chart generator. Hence, k = Ly/Lx = 3.825/3.625 = 1.055 (say 1.1, however it is more appropriate to interpolate from the table). Terms* CE 433, Fall 2006 Slab Design Example 1 / 6 Design a one-way slab for an exterior bay of a multi-story office building using the information specified below. Including steel fabric design. Where;CRd,c = 0.18/γck = 1 + √(200/d) < 0.02 (d in mm);ρ1 = As1/bd < 0.02 (In which As1 is the area of tensile reinforcement which extends ≥ (lbd + d) beyond the section considered)Vmin = 0.035k(3/2)fck0.5K1 = 0.15; σcp = NEd/Ac < 0.2fcd(Where NEd is the axial force at the section, Ac = cross sectional area of the concrete), fcd = design compressive strength of the concrete). The load on the slab is carried by the short span in one direction. However main reinforcement bar and distribution bar in transverse direction. Design the slab following the provisions of the ACI code. Eurocode 2 is one of the most globally recognized structural design authorities in the world today.The worked example below give detailed steps use in slab design to EC2. Charts are a very convenient and well used method for selecting column reinforcement depending on applied vertical load and moment. Can you identify the cause of failure of this building? Description: This is an R.C. If you know the maximum deflection for the relevant load case, we can check whether it is with in the limit.
What Does An Octopus Tattoo Symbolize, Cherry Vodka And Coke, Almond Date Balls, Lg Top Load Washer Smells Like Rotten Eggs, Organic Gold Potatoes,