1 In slabs, beams and girders, splices in reinforcement at points of maximum stress shall be avoided wherever possible. 4. 3 Slabs Monolithic with Supports 24. 6. 3. 2—Flexural reinforcement spacing 8. C. ) = 200. 0104 Ai. If the maximum diameter for slab thickness is 75 mm, so the diameter of reinforcing bars should be 8 mm. bars should be arranged as distribution bars and are provided at 30 cm centres at the top of the. Distribution Bar. 5 bar is permitted to be located at either the top of the slab or bottom of the footing. spacing of bars should not be more than. Structural Design 1 - Design of Reinforced Concrete Structures REFERENCES/COURTESY 1) IS 456 : 2000 — Plain and reinforced concrete – Code of practice 2) S Unnikrishna pillai and. Step 4 – Extra Top Bar. Length of distribution bars = 6. bars at every 3 layers of chb finished surface corner wall detail 1 - 10mm Ø vert. Spacing should not exceed smaller these two values. Figure 3. purchase orders, drawings, or per diems shall be done at the risk of those making such references or quotation. These were developed for slabs of “ordinary” proportions supporting gravity loads, and they may not be sufficient to intercept potential punching shear cracks in thick transfer slabs, podium slabs, and mat foundations. 1. Distribution steel –5d or 450 mm whichever is smaller Where, ‘d’ is the effective depth of slab. They ensure that the load is not concentrated in one area, which could cause cracking or failure. 1 of IS 456:2000, the reinforcement in either direction ,in slabs shall not be less than 0. Given the radius of relative stiffness of 90 cm. According to ACI Code 7. 2, also includes guidance on achieving enhanced aggregate interlock by continuing a small percentage of deformed reinforcement (0. In conclusion, the efficient design of two-way slab demands following a step-by-step approach according to IS 456. (a) for a distance equal to the larger lateral dimension of the column above and below a beam or slab, andThe complete column design process as per IS code is determined by using below 3 basic formulas. 3 through the column, at least two post-tensioned tendons or two bonded bottom bars or wires in each direction shall pass through the lifting collar as close to the column as practicable. To firmly hold the main bars in their. 8. 3. 9 for flat slabs with drops. c) Slab reinforcement percentage less than 0. Inclined length = 0. For footings that exceed 8 inches (203 mm). Sawcut Joints A typical SOG includes three different types of joints, described in detail in ACI 360R Chapter 5. 6 For two‐way slabs, maximum spacing of bars shall not exceed two times the slab thickness h nor 450 mm. t 12mm stirrups at 150mm ctrs Two terminated bars A A Elevation Section A-A Lsy. The maximum spacing of reinforcement at critical design sections for positive and negative moments in both the middle and column strips shall not exceed two times the slab thickness (ACI Code Section 13. 8. Design ProcedureAllowable clear spacing of bars = 3d = 3(170) = 510 mm Actual clear spacing = 300 – 10 = 290 mm < 3d → ok Figure 3. 3. cb = smaller of (a) the distance from center of a bar or wire to nearest concrete surface, and (b) one-half the center-to-center spacing of bars or wires being developed, in. Design of slab. In this kind of. 5 inches (Singh & Saini, 2019). as per ACI 318. 8 ACI 318 , Section 17. Total Length of Distribution Bars = 786. Main Bars and Distribution Bars in Slab and Their Function. 3. anchorage to longitudinal bars and confinement of core concrete in resisting shear2. 3. 3. Here we have to calculate the number of main bar and distribution bar. The slab is not. Opposite length of bar = 2950. steel bar use Top Side +28 Nos Steel use. Ensure that the return bars at the edge of the slab are a minimum of ¼ (15%) of the length of the adjoining span. 3. 14 x r x r) = 3. If dowel placement deviates from the desired position, it is said to be misaligned. 26. Main Reinforcement Bars are used to transfer the bending moment developed at the bottom of the slab. 8. For interior Spans: According to the code, the moments can be distributed according to factores shown in the figure: II. The design of a one-way slab can be done by using the Indian standard code. 15=7no’s. 00mm Maximum Bar Spacing : 250. 54 * 1000 / 180 = 436. f yk = 460 Mpa. The distribution bars should not be under 8 mm in a diameter or not in excess of 1/8 of the thickness of the R. 4. 12% gross c/s of slab – for HYSD bars; Spacing of distribution bars. 2R-8 4. The distribution bars should be (2000- 2 x 25) /125 + 1. Reinforce concrete for a 5-inch thick concrete slab: For a 5-inch thick slab, #4 (1/2-inch diameter) rebar is commonly used. 2. f. Distribution bars typically have lesser dimension bars compared to main bars. Wall Load Per Running Meter. 7. 6 = 17 bars; The number of distribution. Distribution bars:-These bars are straight bars. 090 square inches per foot of slab width, required each way. 4 Water 5. 6. 1. 5] = 120 mm c/c. slab known as a joist system can be constructed without any shear reinforcement in the joist ribs. ,). 5, the lateral spacing of the. 1 Spacing s of longitudinal bars in cast-in-place walls shall not exceed the lesser of 3h and 18 inches. Bar crank. 2. Slab steel grid not less than Fe500. e. in. 3: Two-way slabs supported on four sides; Clause 6. 3. 2 For one-way shallow foundations, two-way isolated footings, or two-way combined. In Seismic Design Categories D 0, D 1 and D 2, slabs-on-ground cast monolithically with turned-down footings shall have not fewer than one No. (a) for a distance equal to the larger lateral dimension of the column above and below a beam or slab, andvii) Any other function assigned to the expansion joint as per the specific requirements of the structural systems. 2 Use Φ12 bar c/c 250mm 2. 25. Always main bar use in shorter span. Assume diameter of bars and calculate spacing of bars. M =. 0020. 1. 1—Reinforcement for shrinkage and temperature. Where a slab on ground is cast monolithically with the footing, one No. 67’ Weight of Distribution Bars = d 2 /52. The reinforcing bars must extend into the slab beyond the critical section for a required length. i,e. 3 For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall ‘be rounded off in accord-Table 5. This is also. 0018 times the slab's gross area, but the maximum spacing of the bars differs. 1. Check spacing of bars. The spacing or c/c distance of distribution bars shall not exceed the following. The Department of Civil Engineering at IIT Kanpur is producing since 1961, high quality technical manpower needed by industry, R&D organizations, and academic institutions. Clear Cover = 20 mm. 5. 5m . e. ACI 360R, Section 6. 5. 6 𝑀𝑃𝑎. 12. 5. C. 2. So No, of 8 mm Steel bar = 3. Step #1 – Bar Numbers. 1 of EC2, the recommended minimum spacing of reinforcing bars is 75 mm and 100 mm for laps. 7. 5. 715m long, and it is supporting a blockwork load at 1. Concrete cover = 25 mm. Spacing of bars = 180 mm c/c < 300 mm and 3d ok Distribution steel =. R4405. 1. 3. joint spacing greater than 50 ft (15. 3 Required Strength 4-2. Spacing = 150mm c/c as per given details = (2950/150) + 1 = 20. , addi-tional bonded shrinkage and temperature reinforcement conforming to 7. Step 1 – Find out the Total Number of Main Bars & Distribution Bars. Temperature distribution due to heat of hydration and internal stresses caused by outside cooling in a free standing concrete block. For longitudinal reinforcement in beams. 3 introduces a new requirement for bar 1) The maximum diameter of bar used in slab should not exceed 1/8 of the total thickness of slab. Refer to Section 5. 7. Dual degree in Civil Engineering, and M. Wood structural panels with a minimum thickness of 7 / 16 inch (11. The clear cover is 30 mm ( top to bottom ) and the thickness of the slab is 150 mm. (ii) The pitch of the bars provided to act as distribution bars or bars provided to guard against temperature and shrinkage in an R. 5 inches, and the transverse bars must be fully developed in grouted masonry at the point where they cross the lapped reinforcement. Current recommended. 2) For main bars, maximum spacing is restricted to 3 times effective depth or 300 mm whichever is smaller. Reinforcement Cover The minimum cover to outside of main bars shall not be less than the following: 15 mm and; Diameter of the main bar. 7. The diameter of the main bar is 12 mm in diameter with 100 mm c/c spacing and the diameter of the distribution bar is 8 mm with 130mm c/c spacing. 285+150. (c) Deep beams in accordance with 9. There are 51 nos of main bars are required for the slab. ([DPSOH ± 'HWHUPLQDWLRQ RI Seismic Forces: Diaphragms of %XLOGLQJ Chapter 4 One-way Slabs 4. Lower part bar will be worked by maintaining cover with spacer. vapor retarders - some times referred to as vapor barriers, insulation, etc. 4. 5, the lateral spacing of the. Basic considerations. STEP. 1. b) Slab depth does not exceed 200 mm when the steel grade is 460. 3(1) of EC2 for slabs not exceeding 200mm in overall depth and not subjected to significant axial tension the maximum limit on centre to centre bar spacing is governed by clause 9. Lapping is not allowed for the bars having diameters more than 36 mm. Design size and spacing of dowel bars at an expansion joint of concrete pavement of thickness 20 cm. 15%of gross cross-sectional area if plain bars are used and 0. The center of the dowel bar should be below the joint. What are the different functions of distribution bars in concrete . The main reinforcement of an RC slab consists of 10 mm bars at 10 cm spacing. 2and3 C. 1. (c) Distribution. The maximum clear spacing between parallel bars shall not be more than 1 N-6O. 5. 1,2 and 3 B. Plain bars———–10 mm Ø min dia Deformed bars—–8 mm Ø min dia; For Distribution bars: Plain bars———–6 mm Ø min dia Deformed bars—–6 mm Ø min dia; 4. 2, or >0. Number of bar =radius /spacing. The following details are obtained from the figure-2: Length of Footing = X = 2m. A cantilever slab 200 mm thick is 1. 3. Refer to "Determination of Bonded vs. In RC slabs and PT one-way slabs, the clear distance between bars is limited to the smaller of. Crack Control – when crack widths are not checked by calculations No Further Checked Required. Number of Required Bars Formula = (Length of slab / spacing) + 1. 7. The Distribution bars will be 8 mm in diameter with 125 mm c/c spacing. ACI 7. NOTATION All notations and definitions are the same as defined in Chapter 2 of the Code. What should be the diameter of chair bars used in construction? Typically, chair bars are made of reinforcement with a diameter of 12 mm and above. Spacing = 150mm c/c as per given details = (6000/150) + 1. 1. 1 Purchaser’s tests of steel reinforcing bars 28 Section 6 Methods of testing 32 6. 2 and 26. It is appropriate to design the slab per unit width, hence b = 1000mm. 67’ Weight of Distribution Bars = d 2 /52. 2. Provided spacings, therefore, satisfy the requirements. 7. Transverse joint spacing should not exceed 125% to 150% of the longitudinal joint spacing. For example let us consider a building which is having 120mm thickness of slab, for that particular structure we need to take maximum reinforcement bar diameter is (1/8) of 120mm which is 15mm. d = Effective depth. Spacing (feet) Deck Slab Thickness, T (inches) Transverse Bar Size and Maximum Bar Spacing, S (inches) F dimension (inches) #5 “D” Bars per Bay (quantity) #4 “G” Bars per Bay (quantity) Bar Size S 4. Total length = 3. 6 in the following cases; In sections within a distance equal to 4 × thickness of wall above or below a beam or slab. 11. The spacing between longitudinal reinforcement of the column should be the greatest of the following: 4 cm; 1. In this article I will explain you complete slab design as per IS 456 code by using manual method. 2. 3 Slenderness Limits for Columns 25. 33=16 no’s. as indicated in the table. The maximum spacing should be reduced by a factor of 0. Bar Spacing. Dia of Chair. Number of bar = 2150/150+1= 15. The slab is supported all around walls of width 300 mm. , 300 mm. 2 mm. A minimum of three bars evenly placed in the lap length is required. bars at 400 mm o. 6 𝑀𝑃𝑎. Instead, to comply with ACI minimum reinforcing ratio and bar spacing requirements, slabs from 4 to 7 inches thick should have at least #4 bars at 12 inches on centers; closer spacing or larger bar sizes are needed for thicker slabs. The shear resistance in a R. bar. 6. EXAMPLE: Suppose we have a one-way slab, which has a length of 5 m or a width of 2 m (clear span). So maximum diameter of reinforcement bar used in 5 inch (125mm) thick. 6. 2, The diameter of reinforcing bars shall not exceed one-eighth of the total thickness of the slab. (Main Bar & Distribution Bar Difference) Top and Bottom Clear Cover is 25 mm. Unit weight formula for kg per metre = (D2/163) × L kg/m. Main bar = 12mm@150mm c/c. A beam is similar to a slab in so many ways but there are fundamental differences in behaviour and stress distribution of the two. 2. 8 ACI 318 , Section 17. 53 Compute moments At support: ( - ) M1 = 3. 6. 3 Direct supply of steel reinforcing bars to site by QA Manufacturer 27 Section 5 Purchasers testing 28 5. Provide main reinforcement of 10 mm diameter bars at 120 mm c/c. 3. The maximum diameter of the reinforcement bars in R. 305. Minimum number of reinforcing bars. BS EN 1992–1–1 section 7. Continuously at structurally connected roof and floor levels and at the top of walls. c 0. 975 KN)/ (39. 3. The slab is. 3-Main bar Bottom Area Given data. to carry a uniform live load of 7500 Pa. 5 m as per IRC. dowel misalignment levels of less than 1 in. 10. 2. 10. 6—Reinforcement limits 8. Given, Length of longer span = 5000 mm. 0m from the fixed end. Total No’s of Distribution Bars = (Total layers of Dist Bars in Walls are 4) = 10 x 4 = 40 No’s Total Length of Distribution Bars = Cut Length x No’s of Bars. FAQ . iv) Detrmine Sapcing of bars at critical section based on designed value of Ast by selecting appropriate bar dia. (2× Spacing of distribution bar) + (2×25) = (2 x 150) + ( 2 x 25) = 350 mm . design wheel load. 2. 9) Prepare bar bending. As bar is placed in longer span which is 4m. 1: The prime functional requirement of a joint is to cater for movements with very low resistance or with no resistance at all. In Seismic Design Categories D 0, D 1 and D 2, slabs-on-ground cast monolithically with turned-down footings shall have not fewer than one No. 1. 4 Slabs Spanning in Two Directions at RightAngles 24. 2 Minimum Slab Thickness 4-1 4. What is the maximum spacing of a distribution reinforcement to be used in a one way slab as per IS 456? b. 15m. 3. Spacing of bar supports depends upon the size of the reinforcing bar being. Select the correct answer using the codes given below: A. per Section 6. (14) Step Find the load transfer capacities , , and of single dowel bar with the. Factor affecting spacing of chair bars. Figure 3:. 3. For eg. 7. Total Cutting Length Of Rod = 2nos x 1. Basically slab is the horizontal member which is rests on the beam section. 3. Step Assume load capacity of dowel bar is 40 percent wheel load, find the load capacity factor f as. 3(1) of IS 456, is the lesser of 3(135) and 300 mm. 3. Minimum reinforcement is ensured in slab (in both directions) to take care of shrinkage, thermal movements and. critical section of the slab is just outside the outside edge of the beam supporting the slab. D. Maximum spacing of bars for slabs • Main bars: 3h ≤ 400mm (in areas of concentrated loads 2h ≤ 250mm) • Secondary bars: 3. 4 mm. spacing of bar/prestressing strand etc. 66 < 2. Bar Spacing According to ACI Code 7. 2. 10mm Ø hor. Bars shall not be smaller than No. Note: The minimum clear spacing of bars is not kept less than 75 mm (Preferably 100 mm) though code do not recommend any value. 2) b = edge distane of bar for calculation of lap length (cl. 3. The spacing of distribution bar should not be greater than 5 times the effective thickness of slab or 450mm whichever is smaller. c) Spacing of bars: The maximum spacing of bars shall not exceed Main Steel – 3d or 300 mm whichever is smaller; Distribution steel –5d or 450 mm whichever is smaller Where, ‘d’ is the effective depth of slab. 2. For main bars, maximum spacing is restricted to 3 times effective depth or 300 mm whichever is smaller. Load Calculation: Live Load = 2 kN/m 2. Adopt a clear cover of 20 mm and 8 mm diameter bars. 7. cm. 25 kN/m 2. A minimum of three bars evenly placed in the lap length is required. The previous code that allowed up to Grade 520 was changed to Grade 550, and related regulations were modified. 2. 3 of the Eurocode or Chapter 2, originally published as. Distribution Reinforcement for Stairs. 3. 7. 3—Corner restraint in slabsColumn = Self Weight x Number of floors. 6H, and 0. Load Distribution. 2. . 7. According to direct design, the balanced load, W1, and the effective prestressing, F, in a one-way slab or the beam supports for one-way slabs can be computed as t _ 48kBW + 8k f (L (3) Wl — 1 + 48kB F, = 72BW L2 + 12 f t2 (4) t(1 + 48kB) where B is the moment coefficient, M = BWL2, depending on the slabDesign of 2 way slab as per IS code. The maximum spacing of reinforcement in slabs is 3d or 300mm(minimum of both). 3. Longitudinal reinforcement should not be less than 0. Minimum Bar Size : 16 mm Maximum Bar Size : 25 mm Top Footing Minimum Bar Size : 16 mm Top Footing Maximum Bar Size : 25 mm Pedestal Minimum Bar Size : 16 mm Pedestal Maximum Bar Size : 25 mm Minimum Bar Spacing : 100. This chapter shall apply to the design of nonprestressed and prestressed beams, including: (a) Composite beams of concrete elements constructed in separate placements but connected so that all elements resist loads as a unit. Concrete cover = 25 mm. 3. In slabs constructed with lift-slab methods where it is impractical to pass the tendons required by 8. it's a tool to maintain the spacing between two separate layers of slabs, footing etc. This portion is coming at the top of the bottom main bar. 2. 11. Cover block use 15 to 20mm. 2) For main bars, maximum spacing is restricted to 3 times effective depth or 300 mm whichever is smaller. Slabs - - - maximum spacing is 3*deff or 300mm whichever less side ) of the deformed bar ( see Note ) NOTE - In accordance with IS : 1139-1966. According to Clauses 8. Main Bar. 25 x 87 =34. Take à l/d as 32 for HYSD bars . Wood structural panels with a minimum thickness of 7 / 16 inch (11. , nonskewed) bridges only. 1. 667’ x 40.