For column = 2. 2655 = 0. 3 of ACI 318-11 or older. The Rebar Calculator also has concrete functions to help you compute: Surface Areas of slabs in square feet, yards and meters. 0⋅ Φ , where Φ is the diameter of the reinforcement bar (or equivalent diameter of. ( W) Width of the slab. The columns are modeled as elastic nodal supports by determining the spring stiffness. 78. Nonstructural concrete shall have a minimum specified compressive strength, f´c, of 2,500 psi (17. Introduction. 3. In order to calculate this, you need to input the length and width of your slab. The Rebar calculator for slab help to estimate the dimension. Ensuring that the concrete is damp can increase the strength of the concrete during the early stages of curing. Equate the balanced moment of resistance to the maximum bending moment; Find the effective depth ‘d’ from the above equation. Start simply by entering "Add/edit Section" to add the main beam section. When you swing on a rope swing and jump into a swimming hole, you exert tensile stress on the rope. Thumb Rules For Shuttering Work. INSTRUCTIONS: Choose units and enter the following: ( L) Length of the slab. utilizing FRC include ground supported slabs, composite metal deck, pile supported slabs, mat slabs, pavements, bridge decks, tunnel segments, shotcrete, and various precast applications. The volume is simply the area (A = L*W) times the depth (D). 5m and loading class is <3. Generally speaking, rebar should be placed in the slab at a rate of one bar (1/2” round) per every 16” along all edges and the center of the slab. The formulas calculate materials needed for rectangular, circular and irregular shaped slabs. The user must enter the strengths of the concrete and the reinforcement, the unit weight of concrete, strength reduction factor for lightweight concrete, beam dimensions and slab. This calculator is to be used as an estimating tool only. of Wall = the # of concrete blockThe appropriate rebar size depends on the project, with #3 and #4 being common choices. How to calculate Reinforcement Ratio in Concrete || Percentage of Steel in Structural Member by CE&TSubscribe this channel for latest and update videosPlzHel. (default is one). Retaining Walls: The most commonly used rebars in retaining walls are #3, #4 and #5. So, a #4 rebar weighs approximately 0. ©2023 PJ's Rebar | 45055 Fremont Blvd | Fremont CA 94538. imperial dimensions of rebar; Rebars - Weights Weights of rebar rods - size ranging 1/4. An older reinforced concrete design calculator that computes required steel area for T-beams and 1-way slabs can be found here. #3 rebar is ⅜” in diameter, #4 is ½” in diameter, and so on. 2) Development of the bar does NOT ensure that a concrete breakout failure will not occur. This is the formula: mesh needed = slab area ÷ mesh area. Based on the ACI 318-99 version "REBARS. Find the number of concrete bags in the most popular sizes in the chart below: Bag Size. e. 4 = 188. Rebar Development Length Calculator is a web application that supports the design of post-installed rebar in concrete applications by calculating the necessary tension and compression development lengths required in accordance with ACI 318-19 / ACI 318-14. 125 x Sq. It is the number of slots for reinforcement across your foundation. Now the maximum quantity of steel in slab is 2% of the volume. 43/30 = 0. The load capacity of. In the two-way slab, the same practice as mentioned above should be followed for both directions. I have added the capability to use Chapter 21 for high seismic. Initially, they mostly used in masonry structures to enhance their capacity. 19 c rc c c ' c '. ( para español, HAGA CLIC AQUÍ) . 4 wire mesh in a 4-inch slab, P = 8. justcalc. Hello ACE, In order to determine the load-carrying capacity of your existing roof slab you are going to need to determine several more items, such as: 1) Concrete compressive strength in Pounds per Square Inch (PSI) as determined by the Windsor Probe method. 6 rebar spaced 4 inches on center is P = 8. 2. Click the button to calculate the volume of concrete and man-hours (not including mixing) needed for this. Pour concrete sand to fill the gaps in the gravel base. 2, see D. 0 % of concrete volume. . 01942 pounds per linear foot. Convert your longitude estimation into inches: 15 x 12 = 180. U. The total quantity of steel required in the given slab is 565. Step 1. 3. A slab layout plan is a drawing that you’ll get in the structural drawing book. The next thing that you need to consider is that every four feet of the foundation wall will require concrete and rebar. 8 kg . If you prefer to calculate the number of bags of concrete needed, you can use the weight of the bags as a reference. Hand calculation according to AS3600 Standard. How much rebar do you need? How to calculate the quantity and size of steel reinforcement in a concrete suspended slab the easy way! Work out loads, then ben. For example, let’s find the number of 5′ x 50′ rolls of mesh required to reinforce a slab that is 25′ by 25′. 1 provides expressions for determining. Required thickness of concrete slabs. Calculate the volume of cubic yards needed to fill in a square or rectangular slab pour for flooring, walls & similar structures. For slabs = 1. The article presents detailed results of the experiment made and advanced numerical modelling based on nonlinear analysis and. slab and foundation contractors to help with your footings. On average are required, for 100 square feet with 5 inches thick slab, 19 strips of 3/8” rods (30 ft each one), are 570 ft. Slabs are defined as two-way slabs when the ratio of long-to-short sides is less than 2. Total rebar weight 53. 7 MPa) for Class F1; and 3,500 psi. Width. For live loads of about 50 psf (2. See full list on inchcalculator. 4 shows the thickness of concrete needed for various axle loads. Concrete calculators that estimate the amount of concrete and rebar you need for footings, concrete walls, concrete stairs, slabs, patios and driveways. of Main bars = (3000)/150 + 1. 3 cu. It also checks for minimum steel for crack control as well as steel for balanced section. Multiply the length (10 ft. Calculate the Moment Capacity. Therefore, #2 rebar is ⅛” + ⅛” = ¼” in diameter. For example in a slab of 6-inch depth, a rebar of 6/8 inch will be used. NOTE: this calculator was updated on 16 Feb 2022 to accommodate the inset of rebar placement from the edge of the slab. Rebar - Slab, Driveway or Patio. Spread 3-4 inches of gravel aggregate within the formwork. Concrete slab resting o n grade containing minimal distributed st eel, usually of weld ed wire fabric (WWF), for the purpose of limiti ng crack width due to shrinkage and tempera-ture change. 3 cubic feet of concrete for this slab. 4 Shear strength of two-way slabs Loads applied to a relatively small area of slabs create shear stress perpendicular to the edge(s) of the area of load application. Note – it is found that for 1000 kg of steel (1000 kg = 1. Volume of the slab = Length of the slab X Width of the slab X Thickness of the slab. Step 4: Place all of the step-up rebar you’ll. 5 allows for sufficient clearance for fitting the rebar within the slab. For instance, if the area of reinforcement required (A s,req) from calculation is 523 mm 2 /m, you can provide H12@200 c/c (Area of steel provided A s,prov = 565 mm 2 /m). INSTRUCTIONS: Choose units and enter the following: (r) Radius of Circular Slab (e. xls" also included in this repository. 3. Here’s what you’ll need to do before you pour any concrete: 1. Some regulations specify how much rebar is required to be poured into concrete. Using the above equations, when lb la = 2 l b l a. Calculate how much rebar you need to reinforce a concrete slab. a car weight about 5000lb. L = Depth – 2 times cover. 2, see D. Cost of Rebar: Provides the cost of rebar on a project. Weight (lbs/ft) = (0. Feet. INSTRUCTIONS: Choose units and enter the following: Rebar Grid - One Mat (L) Length of Slab (W) Width of Slab (D) Depth of Slab (rS) Size of Rebar (none, 2-11,14,18) (i) Rebar Inset from the edge of the slab. Rebar is a key part of reinforcing concrete and ensuring a strong and durable structure. First, add up the total length of rebar you need. Quantity Estimate for Reinforcement in Kg: Quantity Estimation of Reinforcement in Kg. No. . = 565. Set Project Zip Code Enter the Zip Code for the location where labor is hired and. By: Olin Wade (Remodel or Move Stuff) Calculating the amount of rebar needed for a concrete slab involves many steps. (default is one). Length (feet) length x12. Choose Round Column (or Round Slab) on the calculator. 2. By using the simplified calculation method of CCD in Section 2 and the analytical formulae in Section 3, systematic parametric analyses can be conducted to. Concrete volume calculator plan view diagram. Chapter 19 relies primarily on the reference to American Concrete Institute (ACI) 318, Building Code Requirements for Structural Concrete. To. The minimum shear reinforcement (A v,min) in beams should be the greater of the following: Av,min=0. The rebar is built in a grid structure and costs $2 to $3 per square foot. . 5 feet. However, no matter how basic or complex the floor is, the construction method is similar and includes; preparing the sub-grade and sub-base, placing the reinforcement and. (Imagine you are walking around the slab) Hit Undo Last to Undo last side. Calculate the amount of Rebar needed for reinforcing a wall. On average are required, for 10 square meter with 12cm thick slab, 19 strips of 3/8” rods (9ml each one), are 171 ml. 2. The term units refers to the same units as the slab length. The string will act as a guide to keep the form boards straight. They seem to have that. 35 ft. REINFORCEMENT Estimate Calculator. 1100 at 12” on center, therefore, . As one cubic yard is equal as 27 cubic feet and weight of 1 cubic foot rebar is around 490 pounds, so wt of rebar per cubic yard = 490 × 27=13232 pounds, regarding this, weight of rebar per cubic yard, generally, it will be 13232 pounds. ( i) Inset distance from the side of the slab to the rebar grid (default of 3″). Step-2: Get The Slab Reinforcement Details. Concrete and rebar must be used for every four feet of the foundation wall. After that, the following steps will be taken to compute steel quantity. Input all the dimensions in the input section of the above calculator. First, enter the concrete slab sizes: length = 6 m, width = 4 m. 10 of ACI 318-05, and also illustrated in Flexure. Concrete Slabs Calculator. The gauge, or diameter, of the rebar is selected based on the purpose and the load-bearing requirements of the structure: For standard residential concrete slabs, #3 (3/8 inch diameter) to #5 (5/8 inch diameter) rebar is typically used. Slab concrete properties definition before design optimization. = 7. #3 rebar is ⅜” in diameter, #4 is ½” in diameter, and so on. Width (feet) width x12. 3. If the slab has hydronic tubing, the minimum R-value of this insulation increases to R-15. (feet + inches) Enter the width. How do you calculate rebar spacing? Find the rebar-to-spacing multiplier with the formula M = 0. The calculation is very easy for circular areas. Using the Plate Design. After finding the overall thickness of the slab, compute the volume to determine how many bags of concrete you need for a given slab. Our calculator will instantly calculate the quantity of rebar required. Use a tamper or plate compactor to flatten the gravel base. The Weight of a Slab with Rebar Calculator computes the weight of rebar in the rectangular slab, and removes the weight of the displaced concrete to provide the best estimate. The Calculation. ( rS) Rebar Size (2,3,4,5,6,7,8,9,10,11,12,14,16,18,20) Use Size "0" for. ACI code 7. Fill in the price and single rebar length that you will buy at your supplier: rebar price = €2/m single rebar length = 6 m. (inches) Enter the required splice (overlap) of your bars. All this procedure is totally automated in SkyCiv Reinforced. Provide the diameter or cross-sectional dimensions of your concrete column, as well as. To estimate costs for your project: 1. Generally, the minimum amount of rebar recommended by the American Concrete Institute (ACI) is at least one vertical bar per cubic yard of concrete and two horizontal bars, either laid flat or tied together with wire. . The minimum compression development length shall not be less than 8 inches. If you can get 20' long bars the total length of your slab can be 20'. First, enter the concrete slab sizes: length = 6 m, width = 4 m. 5 to determine you will need 120 feet of rebar. Our rebar weight calculator is a handy tool that allows you to efficiently calculate the weight of rebar for your projects. 1R-04. For driveways and patios, #4 (1/2 inch diameter) rebar is a common choice. After finding the overall thickness of the slab, compute the volume to determine how many bags of concrete you need for a given slab. = 7. NOTE: this calculator was updated on 16 Feb 2022 to accommodate the inset of rebar placement from the edge of the slab. Any suggestions/comments are appreciated. I am looking for information to calculate what is my required dowel rebar size and embedment length to dowel into a reinforced concrete slab? I know ACI has provisions for doweling a concrete column/pedestal into a footing, but I am trying to find something regarding doweling CMU rebar into a concrete slab. Check it against the factored shear load on the slab, 0. The type of. Self-consolidating concrete (SCC) often requires larger-sized rebar to enhance its strength, such as #11 or larger. The weight of a concrete slab can be estimated by computing the volume of the slab and multiplying the volume (V) by the density of the concrete. Fill in the price and single rebar length that you will buy at your supplier: rebar price = €2/m single rebar. (inches). The resulting one-way structural system has a T-section. That way you can use the forms themselves as a guide for the final base height. of Main bars = 20 + 1 = 21 Nos. Less concrete, i. For example, if you are using ½ inch rebar, divide 60 feet by 0. Eliminate the need for thickened slabs at joints and e d g e s . 37 cubic yards of concrete for a 4×4 slab that is 4 inches thick. The plate is 24 cm thick and is supported by 45/45/300 cm columns at distances of 6. Calculate rebar length for the slab — RL — using the formula: RL = SL – 0. Like our other calculators, this reinforced concrete Beam Capacity Calculator is very easy to use. 33_6_0. Column strip includes beams if any. Fa b r ic may also be supported at the center of the slab, or it may be installed in two flat layers with the top layer (nega-t i v e steel) extending on either side of the support for one-quarter of theFibre-reinforced polymer (FRP) rebars are being increasingly used to reinforce concrete structures that require long-term resistance to a corrosive environment. Fa b r ic may also be supported at the center of the slab, or it may be installed in two flat layers with the top layer (nega-t i v e steel) extending on either side of the support for one-quarter of theSteps to Calculate Steel Quantity · Enter the Length and Width of your slab in ft in Excel Sheet. Reinforcing beam and slab with correct steel bar. After that, the following steps will be taken to compute steel quantity. This weight is used to estimate the. ACI 347-04 "Guide to Formwork for Concrete" lists three modified hydrostatic pressure equations: pmax=CwCc [150+9000R/T] for columns. Concrete grade and. 5KN/m 2. Rebar Lapping Length: Computes the length overlap needed at rebar joints based on the size of the rebar. Calculate Rebar Quantity From Total Slab Area and Perimeter. Minimum dimensions and axis distances for reinforced concrete slabs. . 3. Rebar Development Length Calculator. INSTRUCTIONS: Choose units and enter the following: ( L) Length of the slab. 2 kg. For slabs = 1. In other words, post-tensioning pre-compresses the concrete to help prevent cracking from occurring rather thanA minimum area of shear reinforcement should be provided in all regions of a beam where applied shear is greater than half the designed shear strength of concrete. Click the button to calculate the volume of concrete and man-hours (not including mixing) needed for this job. 2 MPa) for Class F0; 3,000 psi (20. Once this is complete, you will need to add the steel reinforcement bars (or similar) by clicking the "Add/Edit Steel Reinforcement. Then, find the length of one bar. As you. 05 percent of steel ireinforced concrete pavement, and the minimun m directions normal to each other for a distance of 3 allowable length of the slabs. Input the number of mesh in slab rebar. 2—Design considerations Chapter 13—Design of slabs for refrigerated facilities. In climate zones 4 and 5, the code requires certain slabs (below-grade slabs that are less than 12 in. Calculate Rebar Quantity From Total Slab Area and Perimeter. I am looking for information to calculate what is my required dowel rebar size and embedment length to dowel into a reinforced concrete slab? I know ACI has provisions for doweling a concrete column/pedestal into a footing, but I am trying to find something regarding doweling CMU rebar into a concrete slab. The Rebar for an Irregular Shaped Slab calculator estimates the total length and weight of reinforcement bars (rebar) needed for an irregular shaped concrete slab. ) Where, L = development length. 9. Therefore, you will need approximately 2. The registered design professional shall assign nonstructural concrete a freeze-thaw exposure class, as defined in ACI 318, based on the anticipated exposure of nonstructural concrete. Mark your project plans with a highlighter wherever the psi amount you calculated in Step 3 is found. compensating concrete demands the use of reinforcing steel so the concrete can expand and con-tract as planned. 01. yds. 28084 feet Rebar calculator for slab helps you find the total weight of steel rod required to construct the. 1. To truly reinforce concrete, the percentage has to. INSTRUCTIONS:. Structural concrete must be designed and constructed to comply with this code and all listed standards. Side walks, barn and granny floors : 5 - 6 inches (0. For compatibility with older ACI codes, Ψr is taken as 1. This calculator is to be used as an estimating tool only. This concrete calculator also calculates cubic meters. Products. Columns that support flat plate slabs and columns that are supported by footings are the most common examples. Calculating the concrete volume required for an operation. This calculator finds rebar sizes and spacing for beams, girders, and 1-way slabs for a particular type of reinforced concrete floor system consisting of a regular grid of columns supporting a hierarchical. This will allow you to calculate the square footage of the slab. ACI 318M-14 Equation 25. 037 to get cubic yards of concrete. 2-inch slab; 2-inch chairs for a 4-inch slab; 21⁄ 2- i n c h chairs for a 41⁄ 2-inch slab and 3-inch chairs for a 5-inch slab. Rebar Weights: The table below is based on a 10 % lap and works with any diameter rebar. 1. 2. ( M) Number of mats. Convert your longitude measurement into inches: 15 feet x 12 inches per foot = 180 inches. The Rebar and Concrete in a Slab calculator computes the total length and weight of rebar and the volume of concrete needed for a slab. The calculator estimates the number of rebar pieces needed for the slab. The Total Grid Rebar Length calculator computes the total length of rebar needed for one or more mats of rebar in a concrete slab. 2m3 x 7850 kg/m3 x 0. 78. Divide the area number calculated in Step 3 by 5, as wire mesh in most commonly. coverage = 250 sq ft. Where; A c is the area of the cross-section Shear Reinforcements (links and stirrups) The minimum area of shear reinforcement in beams should be calculated from; A sw. 5 CY for Site A and 21. Values of α 1, α 2, α 3 and α 5 may be taken as for the calculation of anchorage length but for the calculation of α 3, ΣA st,min should be taken as 1. 43/30 = 0. Calculate the number of rebar lengths needed for concrete reinforcement. 2: Repeat and continue to draw complete (closed) shape. 2 to 0. Concrete foundations are the cheapest type of home foundation and are the easiest to install and maintain. Example Calculation: Suppose you have a concrete slab with dimensions of 10 feet by. The experimental program was designed to evaluate how flexural performance at service and ultimate limit states are affected by a one-to-one replacement of Grade 60 with CRR bars, a reduction of concrete clear cover, and a reduction in rebarThe use of the rebar bar in construction extends up to the 15 century for masonry structures. A: A rebar spacer is a piece of concrete block (usually 25 to 50mm cube or 50mm dia cylindrical) intended to provide spacing between the outer surface of the finished concrete and the reinforcement inside. 3. For the day to day calculations of engineers, fischer offers an efficient way to design post. The formulas calculate materials needed. It ensures that you. 3 of ACI 318. Assume your longitude is 15 feet and there will be 14 inches between latitude rebar. In this topic, we find how to calculate Rebar for your project, so you can protect your assets. These are known as rebar sticks. Concrete - Water to Cement Ratios. 2 kg. the Android app here: the iPhone app here: The maximum bending moment per meter width of slab, Where, w = total load intensity per square meter of the slab. REINFORCEMENT. In order to calculate this, you need to input the length and width. 10m= 3m3:- here we have slab of 6 meter length, 5 meters width and 100mm or 4″ thick, so volume of concrete of slab = 6m × 5m × 0. "Specification for Tolerances for Concrete Construction and Materials" ACI 302. = 565. **Unit weight in kg/m is calculated using the formula = D2/162 For 8mm bar = 8 2 /162 = 64/162 = 0. " Multiply the measurements from Step 1 and Step 2 together. pmax=CwCc [150+9000R/T] for walls with a rate of placement of. Commonly called “rebar,” these 1/2-inch-diameter steel rods are embedded in the center of the slab to create a grid that extends lengthwise and crosswise to help the concrete better resist pulling and bending forces. Rebar one rod weight is 5. The gauge, or diameter, of the rebar is selected based on the purpose and the load-bearing requirements of the structure: For standard residential concrete slabs, #3 (3/8 inch diameter) to #5 (5/8 inch diameter) rebar is typically used. The average cost to install a concrete slab is $6 – $20 per square foot. splices) or global compression struts to avoid brittle. For one layer of 6x6 W1. ls = (0. 500 kg/m2 is. 0 % of concrete volume. Concrete is very strong under compressive stress and shear stress, but it performs poorly under tensile strength. Mass / Volume Conversion. Assuming that you are referring to the number of steel bars needed for reinforcing a concrete slab, the calculation depends on several factors, such as the steel type, grade, size, spacing, and the dimensions of the slab. For driveways and patios, #4 (1/2 inch diameter) rebar is a common. Choose the unit of all the dimension like, length, width, and thickness of slab in different unit like mm, cm, inch, meter, foot etc. According to this method, you will need two rebars for a footing width of 16 inches, four rebars for a footing width of 24 inches, and so on. This allows the de-signer to maintain a constant slab depth without thickening at joints or edges. Determine the Pad's Area. In this article, a method is proposed for calculating the reinforcement of concrete ceiling slabs with carbon composite materials based on the finite element model in the computer program SCAD. The type of and intended use of concrete impacts the need for rebar reinforcement. Running Bar Points (Length - Left to Right): Running Bar Points (Width - Top to Bottom): Calculate Rebar Quantity and Mesh From Total Slab Area and Perimeter. The Length and Weight of Rebar in Concrete Slab calculator computes the total length and weight of rebar needed for one or more mats of rebar in a concrete slab. It requires careful attention to detail and an understanding of the various factors that can affect the outcome. Every concrete slab should have a minimum. 56%. Simply input the dimensions and spacing of the rebar, and our calculator will provide you with the total weight. Slabs are defined as two-way slabs when the ratio of long-to-short sides is less than 2. Concrete calculators that estimate the amount of concrete and rebar you need for footings, concrete walls, concrete stairs, slabs, patios and driveways. 075kN m. Thumb rule to estimate Steel quantity of above slab = Volume of Concrete x Density of Steel x % of Steel of Member. cracked section transformed to concrete, and effective moment of inertia for T-beams, rectangular beams, or slabs, in accordance with Section 9. Reinforced concrete for a 6-inch thick concrete slab: For a 6-inch thick slab, #4 (1/2-inch diameter) or #5 (5/8-inch diameter) thicker rebar is often used. 1,IS 456 provided short span is <3. You will get 1,280 inches or 106. Radiant heat tubing in a concrete slab needs to be closer to the top of the slab than its bottom, normally in the top 2-inches of concrete. Per ACI 318 13. 2. The Distribution bars will be 8 mm in diameter with 125 mm c/c spacing. 08 cubic yards for one concrete tube. area = 25′ × 25′. All of these. (b) A flat slab which is the same as a flat plate except the areas around the columns have increased thicknesses, called. 00 per hundred pounds or $80 per ton more than for #4 bars. This is the formula: mesh needed = slab area ÷ mesh area. 817. This section provides a calculator to estimate the strength of rectangular section of a reinforced concrete beam (singly or doubly reinforced). The weight of a concrete slab can be estimated by computing the volume of the slab and multiplying the volume (V) by the density of the concrete. (Rebar Calculation Formula) No. ACI 318-08 Calculator Spreadsheet; Reinforcing Rebar Engineering Data Rebar (short for reinforcing bar ),. Chapter 11—Fiber-reinforced concrete slabs-on-ground, p. 45 cubic feet. To find the Bar Bending Schedule for Slab we use the following formula, No. 6 rebar spaced 4 inches on center is P = 8. The weight of the concrete slab would then cause the cambered beam to deflect to a level plane at the speci-fied eleva t i o n . 5^2 / 162. This study presents structural performance of large scale two-way concrete slabs reinforced with FRP rebars, and their performances were compared against conventional steel reinforced. Square Column: $$ Volumeleft(ft^{3} ight) = Height * Length * Width $$. Inches. The rebar needs to sit within the slab and away from the edge of the slab. Tensile stress. If needed, add more gravel and compact until you have a 4-inch base. With our rebar calculator, you can eliminate. cracked section transformed to concrete, and effective moment of inertia for T-beams, rectangular beams, or slabs, in accordance with Section 9. How to calculate Reinforcement Ratio in Concrete || Percentage of Steel in Structural Member by CE&TSubscribe this channel for latest and update videosPlzHel. A concrete slab of uniform thick-ness can be placed by positioning the screeds at the high and low points of the cambered beam. The Clear cover will be 25 mm (Top or Bottom) and the thickness of the slab will be 150 mm. 5% of concrete volume, weight of steel required will be: =196. Re-Bar Calculator for a Slab using Custom Cut Lengths. 3. Put this value of nominal cover in. 4 Shear strength of two-way slabs Loads applied to a relatively small area of slabs create shear stress perpendicular to the edge(s) of the area of load application. Bar chairs. of Main bars = (Width of Slab/Spacing) + 1. This process is called lapping, and the. To truly reinforce concrete, the percentage. Note that the size extra for #3 bars is $4. "Guide for Concrete Floor and Slab Construction" ACI 360R-06. INSTRUCTIONS: Choose units and enter the following: (r) Radius of Circular Slab (e. Steps to Calculate Steel Quantity · Enter the Length and Width of your slab in ft in Excel Sheet.