Average foundation cost - chart. 11. As per thumb Rule, the amount of steel quantity required for an RCC roof slab should be 1% of total volume of concrete slab. 03 lb/ft³) – a composite material most commonly used. The rebar within the concrete takes in some of the force applied to the concrete matrix. By using our product, rebar snaps into the proper position saving time and labor. 9 of ACI 318-14 or Section 12. 04A c —- (3). 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. (b) A flat slab which is the same as a flat plate except the areas around the columns have increased thicknesses, called. 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. Dead load, g = (3. Besides the cost of concrete and materials, there are also labor costs. 6 rebar spaced 4 inches on center is P = 8. The ratio of the longer span to the shorter span in a two-way slab, known as the span ratio, can vary but is typically around 2:1 in many design scenarios. As you. are needed for a slab or concrete cores, and a quick and easy connection to get a quote on rebar, mesh, or other concrete supplies. This resulting number is the area ("A") in square feet of the concrete pad: A = L1*L2. 19 c rc c c ' c '. For example, if you have a slab with a single mat. 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. D. coverage = 5′ × 50′. ( D) Depth of slab. How do you calculate rebar spacing? Find the rebar-to-spacing multiplier with the formula M = 0. See full list on inchcalculator. Feet. Divide your result by the spacing measurement: 180 in / 14 in = 12. 28084 feet Rebar calculator for slab helps you find the total weight of steel rod required to construct the. The proposed method of calculating reinforced-concrete slabs of slope protection for wave loads is simple and sufficiently accurate. Wall, internal element (for instance 180 mm): 35 kg of normal rebar steel. 0 + 6. 75 m in both the X and Y directions (Image 1). 3 cu. To calculate concrete for slabs, add ¼ of an inch to the slab thickness, assuming that the job is evenly graded to the proper depth. 2. Divide 27 cubic feet of concrete in a cubic yard by the volume of the concrete bag. First, add up the total length of rebar you need. The Distribution bars will be 8 mm in diameter with 125 mm c/c spacing. area = 25′ × 25′. Concrete grade and. 2. For driveways and patios, #4 (1/2 inch diameter) rebar is a common. of Main bars = 20 + 1 = 21 Nos. Most residential slabs use #3 which is 3/8” diameter (3/8in² cross-section) or #4 which is 1/2″ diameter (1/2in² cross-section). 1 meter = 3. Step-3: Study The Drawing. The Concrete Weight formula computes the weight of a volume (V) of concrete. Steel- reinforced slabs, typically between 100 and 500 mm thick, are most often used to construct floors and ceilings, while thinner mud slabs. The calculation is very easy for circular areas. g. The calculator estimates the number of rebar pieces needed for the slab. (a) A flat plate which is a two-way slab supported on a column grid without the use of beams. 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. Calculate the number of rebar lengths needed for concrete reinforcement. I have added the capability to use Chapter 21 for high seismic. The Area of a Concrete Slab calculator computes the surface area of a rectangular slab. 058 percent, which is only enough for crack containment. 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. The slab reinforcement details are separate drawing sheets where the details. In the two-way slab, the same practice as mentioned above should be followed for both directions. 2) Development of the bar does NOT ensure that a concrete breakout failure will not occur. 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. The total quantity of steel required in the given slab is 565. Column: 100 kg of normal rebar steel. 4 = 188. Similar comparisons could be made for other size s . A 4” concrete slab can easily support 125 lbs. The most common lengths of pre-cut rebar in the United States are 20`, 40' and 60'. Therefore, for most concrete projects, rebar is required to help the slab, footer, or foundation maintain its structural integrity. Placing tubing deeper in the slab means, simply-put, that more heat will transfer into the slab and ultimately into the soil below than will be transferred up to the top of the slab and into the occupied space. It’s because of non-contact lapping has a full surface area to transfer force to the concrete. · Enter the Thickness of the slab in mm only. If your wall is over 20 feet long it will add the amount of overlap required. INSTRUCTIONS: Choose units and enter the following: (r) Radius of Circular Slab (e. You get 1. The formula for the weight of a slab used in this calculator is: Wt = L•W•D•mD. The weight of rebar can be easily calculated by using this standard formula mentioned below: W= (D2/162. 10m= 3m3. The formula for the weight of a slab used in this calculator is: Wt = L•W•D•mD. Estimation of steel reinforcement quantity is a necessary step in calculating cost of RCC structure along with other building materials as per. Placement and bar diameter are important to the structural strength of the concrete. 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. The PT Calculator is ideal for owners, developers, contractors, architects, and engineers who need to quickly estimate quantities and concrete sizes. 10m = 2. A 30-by-30-foot slab of concrete for a driveway, garage floor, or large patio costs $3,600–$7,200 on average. Next, divide the total square footage by the size of the rebar. A 4” concrete slab can easily support 125 lbs. 60 per square foot, including materials and labor. We first obtain the total factored bending moment to be carried out by the slab’s unitary width strip. Gap your outcome by the dispersing estimation: 180/14 = 12. A rebar slab calculator is a tool used to determine the quantity and spacing of reinforcing bars (rebars) needed in a concrete slab. For example, if SL is 50 feet, RL = 50 feet – 0. This gives you the weight required. The process of calculating rebar spacing for a concrete slab is like solving a puzzle. ( D) Depth of slab. area = 625 sq ft. #3 rebar is ⅜” in diameter, #4 is ½” in diameter, and so on. Example Calculation: Suppose you have a concrete slab with dimensions of 10 feet by. The changing point in the use of the rebar in construction is the 19th century with enhancing its strength by embedding it in the concrete. It is generally accepted that rebar should have minimum 6″ clear cover from all edges, corners, and other forms of reinforcement. 2. Step 3: Determine the thickness: Measure. If you want to combine rods of two diameters, there would. 125 - 0. The formula for the weight of a slab used in this calculator is: Wt = L•W•D•mD. I'm casting a 4m long triangular-profile reinforced gravity retaining wall against soil movement due to a 1 metre jump in ground level. 4. 12. 00679 cubic m. Once this is complete, you will need to add the steel reinforcement bars (or similar) by clicking the "Add/Edit Steel Reinforcement. 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. Overlap joint for rebar connections of slabs and beams and overlap joint at a . Layout of Rebar for Concrete Slabs to Estimate the Quantity of Rebar in Slab. The amount of rebar needed for a slab will depend on the size of the slab and the particular requirements of the project. 4 wire mesh in a 4-inch slab, P = 8. Calculate how much rebar you need to reinforce a concrete slab. calculate the required number of bars for both directions. 4. The research is focused on punching shear failure of reinforced ground supported slab. The quantities for Removal of Concrete and Class B Concrete are 21. To calculate Total Area of a multi sided slab, first divide the shape into rectangles or squares. ( i) Inset distance from the side of the slab to the rebar grid (default of 3″). Reinforced slab. j. 8) * 12. So you will want to take note of the slab length and width. Our rebar weight calculator is a handy tool that allows you to efficiently calculate the weight of rebar for your projects. 56%. Lets take example of RCC Column, where reinforcement. The most commonly used rebar sizes for slabs up to six inches thick are #5 and #6. Input length, width and depth of the area. g. Calculating The Rebar Spacing For A Concrete Slab. Determine the rebar gauge. Weight (lbs/ft) = (Diameter^2 / 162. cracked section transformed to concrete, and effective moment of inertia for T-beams, rectangular beams, or slabs, in accordance with Section 9. The first step is to determine how much rebar is required to support your foundation. The Rebar Weight calculator computes the total weight(w) of rebar based on the length (l) and size (s) of rebar. The pavement slab directldesign method consists of determining thy e opposite the mismatched joint should be reinforced percentage of steel required, the thickness of the with a minimum of 0. "Deign of Slabs-on-ground" ASCC Position. Enter your length, width, and thickness then hit calculate and you'll see how many cubic yards you need. In this example, you'd need 18 lengths at 20 feet for a total of 360 linear feet. NOTE: this calculator was updated on 16 Feb 2022 to accommodate the inset of rebar placement from the edge of the slab. 2, two-way slabs are designed based on "column strips" and "middle strips". Concrete Walls - Volume Estimate concrete wall volume. Next, find the coverage of the roll. 33_2_0. The volume is simply the area (A = L*W) times the depth (D). 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 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. A slab layout plan is a drawing that you’ll get in the structural drawing book. Using the above equations, when lb la = 2 l b l a. This is the formula: mesh needed = slab area ÷ mesh area. The Total Grid Rebar Length calculator computes the total length of rebar needed for one or more mats of rebar in a concrete slab. Input length, width and depth of the area. 6m × 5m × 0. It requires careful attention to detail and an understanding of the various factors that can affect the outcome. The term units refers to the same units as the slab length. Concrete - Water to Cement Ratios. This calculator assumes that you are using 20 foot long lengths of Rebar. 125 x Sq. If the shear strength is insufficient increase slab thickness until 0. or ACI 318M-11 Equation 12-1. 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. Fill in the price and single rebar length that you will buy at your supplier: rebar price = €2/m single rebar. Then determine the space needed between the rebar and slab edge. FIrst, find number of rods required for main reinforcement and distribution. Calculate. . 4. 5. 5% of concrete volume, weight of steel required will be: =196. This allows the de-signer to maintain a constant slab depth without thickening at joints or edges. below grade) to have R-10 vertical insulation at the slab perimeter, extending downward from the top of the slab to a depth of at least 2 ft. Concrete slabs thicker than 4” will often need rebar, especially for heavy-vehicle parking areas. When reinforcement bars of different sizes are bundled as compression bars, the lap length chosen must be larger of the following cases: Compression splice length of the least diameter bar or. For heavy-duty purposes. Concrete Slabs Calculator. The next thing that you need to consider is that every four feet of the foundation wall will require concrete and rebar. 6″)(i) Inset from the edge of the circular slab (e. Lets take example of RCC Column, where reinforcement required is 2. 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. There are four types of two-way slabs. The formula is in feet and is L x W x H (/27). 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. Equate the balanced moment of resistance to the maximum bending moment; Find the effective depth ‘d’ from the above equation. For RCC Roads, 0. utilizing FRC include ground supported slabs, composite metal deck, pile supported slabs, mat slabs, pavements, bridge decks, tunnel segments, shotcrete, and various precast applications. 28)* L. A typical 1,200-square-foot house foundation costs $6,900 to $16,200 for a concrete slab, or about $40,000 for a full unfinished basement. yds. Weight of one m of rebar is 0. The Rebar in a Circular Shaped Slab calculator estimates the total length and weight of reinforcement bars (rebar) needed for a circular shaped concrete slab. By special permission of the publishers, Co n c re t eproject has two structures, both of them have removal of concrete, class B concrete, and new strip seal expansion devices. Steps to Calculate Steel Quantity · Enter the Length and Width of your slab in ft in Excel Sheet. There is one new addition to the calculation worksheet of the new "REBARS (318-05). 2, see D. • A cubic yard of. A 30-by-30-foot slab of concrete for a driveway, garage floor, or large patio costs $3,600–$7,200 on average. · Enter the Thickness of the slab in mm only. Once this is complete, you will need to add the steel reinforcement bars (or similar) by clicking the "Add/Edit Steel Reinforcement. . For direct tension, Lap length = 2 x L x d or 30 x d (The greater value among the two values calculated is taken. We typically ask our structural engineer for the weight of rebar is per sf (slabs) or volume of concrete for each mix/use. Input length, width and depth of the area. Rebar one rod weight is 5. You'll also need 26 at 30 feet for a total of 780 linear feet. Standard Data Taken The density of Steel Rod = 7850 Kg/m 3 1 meter = 3. Building a concrete slab foundation costs $5 to $14 per square foot or $4,000 to $33,600 total on average. Note that this calculation is the volume of your tubes only and does not account for any overflow. Depth. For each additional 20 foot increase of the wall. Supporting the rebar during the concrete pour is. Enhancement of the strength of the. Any suggestions/comments are. 075)kN m2 × 1m = 9. Length. Step 2: Calculate the area: Multiply the length by the width to find the area of the slab in square feet. The Rebar in a Circular Shaped Slab calculator estimates the total length and weight of reinforcement bars (rebar) needed for a circular shaped concrete slab. Imposed loads varies from approximately 1. It’s a time-saving solution that eliminates the need. 85Vc > Vu. Our calculator will instantly calculate the quantity of rebar required. 7 MPa) for Class F1; and 3,500 psi. 40 to $1. 075kN m. Chapter 19 relies primarily on the reference to American Concrete Institute (ACI) 318, Building Code Requirements for Structural Concrete. L 1 and L 1 are the span lengths in the two slab directions. . 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. If you want to increase the strength of the concrete without using rebar, try using wire mesh that is not only cheap enough but also makes the concrete too stiff like a rock. 2) Development of the bar does NOT ensure that a concrete breakout failure will not occur. 2655 = 0. When the dimensions of a slab, wall or other form exceed the length of a single stick of rebar, it is required to overlap and tie rebar pieces to create the added length. 78. 01. 56% results in the greater concrete shear resistance. Reinforced concrete beam: 100 kg of normal rebar steel. When reinforcement bars of different sizes are bundled as compression bars, the lap length chosen must be larger of the following cases: Compression splice length of the least diameter bar or. 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. CRSI’s Reinforced Concrete Concept is an online tool for preliminary slab design that provides design and construction teams with comparative evaluations and estimates for the most. Most concrete slabs are cast monolithically with supporting beams, with portions of the slab participating in flexural resistance of the beams. Quantity Estimate for Reinforcement in Kg: Quantity Estimation of Reinforcement in Kg. . For compatibility with older ACI codes, Ψr is taken as 1. 5 kN/m2 (153 kg/m2) in domestic buildings to approximately 1 0 kN/m2 (1053 kg/m2) in heavy industrial areas. 2: Repeat and continue to draw complete (closed) shape. In simple, it is a concrete block provided to create the cover between the reinforcement bar and the concrete surface. Columns that support flat plate slabs and columns that are supported by footings are the most common examples. xls" also included in this repository. For instance, try using a free online concrete slab calculator for most accurate results. 2. To compute the weigh of a slab with rebar, see the Weight of a Slab with Rebar Calculator. The average cost of a concrete slab is $8. Therefore, #2 rebar is ⅛” + ⅛” = ¼” in diameter. (as in example. Enter Height 4 ft (or 48 in) Enter Diameter 10 in. Add 5%-10% additional material for some waste or spills. Inputs can be either imperial or metric with results shown to. 01 x 7850 x 2. of Main bars = (3000)/150 + 1. Rebar and Slab Calculators: Find how much concrete weighs by entering the. 72 percent. Concrete is very strong under compressive stress and shear stress, but it performs poorly under tensile strength. xls" workbook. With our rebar calculator, you can eliminate. 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. If your footings are 16 inches thick, multiply 16 by 80. 3. Finally, take a look at the calculation results: grid length = 5. Fill in the price and single rebar length that you will buy at your supplier: rebar price = €2/m single rebar length = 6 m. Steel weight required for above slab = 3 x 7850 x 0. 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. The Rebar Calculator contains equations and data used in working with reinforcement bars (rebar) in concrete slabs. OR, you can add reinforcing steel. 2 kg. Re-Bar Calculator for a Slab using Custom Cut Lengths. Once you know how much rebar you need, place an order or request an estimate. 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. Mass / Volume Conversion. Calculate Lap Length in Column Beam & Slab formula. Products. Compute the cost per bag, cost per unit area, and the overall material costs. ) Where, L = development length. For example, the percentage of reinforcement of a 30-inch slab with two layers of No. For example, if the length is 10 feet and the width is 8 feet, the area would be 10 x 8 = 80 square feet. It has a foot print of four tires about 10 inches by 10 inches time 4. 40X13. The compression development length is calculated using Section 25. To. Av,min=0. 4m mesh is required. of Main bars = (Width of Slab/Spacing) + 1. 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. 037 to get cubic yards of concrete. Reinforcement for shrinkage and temperature stresses normal to the principal reinforcement should be provided in a structural slab which the principal reinforcement extends in one direction only. Column — 6% of cross-section area. Some regulations specify how much rebar is required to be poured into concrete. Number of Main Bars = Ly / spacing + 1 = (4000/150) + 1 = 27 nos. Then, find the length of one bar. g. For example, if the length is 10 feet and the width is 8 feet, the area would be 10 x 8 = 80 square feet. At the net tensile strain limit of 0. REINFORCEMENT Estimate Calculator. For example, the length is 20 inches and the width is 15 inches, the area is. Post-Installed Reinforcing Bar Guide. Width. When you swing on a rope swing and jump into a swimming hole, you exert tensile stress on the rope. Therefore, #2 rebar is ⅛” + ⅛” = ¼” in diameter. or ACI 318M-11 Equation 12-1. Concrete volume calculator plan view diagram. Note – it is found that for 1000 kg of steel (1000 kg = 1. 6% concrete volume. Concrete. 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. Measure the side that is the directly next to and perpendicular to the side measured in Step 1. Input the number of mesh in slab rebar. (D) Depth of Slab (e. Enter the length. 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. 0, 8 λ (ρ w) 1/3 becomes equal to the value 2 λ for a longitudinal reinforcement ratio ρ w = 1. "Specification for Tolerances for Concrete Construction and Materials" ACI 302. 2 kg. In this method, forces transfer from one bar to the other through concrete. 3. 2). calculate the required number of bars for both directions. 28084 feet. 5(alternate) and 5. Once you input these values, you. Structural concrete must be designed and constructed to comply with this code and all listed standards. Note that this calculator does not account for rebar and gravel that may be part of your project. Tensile stress. 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 net result is a more accurate and less. Concrete slabs that will hold a heavy load or be built on soil in poor condition could require steel rebar reinforcements. 43/30 = 0. 6 rebar spaced 4 inches on center is P = 8. Rebar Calculation For Slab Step-1: Get The Slab Layout Plan. com ©. Measure the length and width of the top surface of the concrete pad in inches and then multiply them to get the pad's area in square inches. Initially, they mostly used in masonry structures to enhance their capacity. Click the button to calculate the volume of concrete and man-hours (not including mixing) needed for this job. Nc = projected concrete failure area of a single anchor or group of anchors, for calculation of strength in tension (A Nc shall not be taken greater than nA Nco), in. 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. The Weight of a Slab with Rebar calculator estimates the weight of a rectangular slab including rebar (if used). Similarly for other structural components, the quantity of steel can be worked out. 24. Calculate the volume of cubic yards needed to fill in a square or rectangular slab pour for flooring, walls & similar structures. Calculate rebar length for the slab — RL — using the formula: RL = SL – 0. To calculate Total Area of a multi sided slab, first divide the shape into rectangles or squares. The appropriate rebar size depends on the project, with #3 and #4 being common choices. The Rebar in a Circular Shaped Slab calculator estimates the total length and weight of reinforcement bars (rebar) needed for a circular shaped concrete slab. 1 ABefore calculating the steel rebar reinforcement, it is recommended to check the shear capacity of the slab, one for direct shear in the connection and the other for the punching shear capacity on the connection slab column. Convert Cubic Feet to Cubic Yards and Metres. Click the button to calculate the volume of concrete and man-hours (not including mixing) needed for this job. That is Ce = Cn + dia/2. First, grab a few 2 x 4’s and use the lumber to measure out and frame the area to your desired slab size (whatever best fits your space and needs). 5 to 7. Common rebar sizes range from #3 to #6 for slab footings, with #4 being the most commonly used. The steel working stress must be great enough to. For example, let’s find the number of 5′ x 50′ rolls of mesh required to reinforce a slab that is 25′ by 25′. Set Project Zip Code Enter the Zip Code for the location where labor is hired and. The current design codes discuss the effective compressive strengths of columns, which reflect a decrease in load transfer performance that can occur when columns and slabs have different concrete compressive strengths. 45 cubic feet. Then add 10 percent to allow for spillage and slab depth variations to help determine the concrete cost per yard. 6")The Total Grid Rebar Length calculator computes the total length of rebar needed for one or more mats of rebar in a concrete slab. 8 kg . of Main bars = 20 + 1 = 21 Nos. After that, the following steps will be taken to compute steel quantity. So, if you have a foundation wall that is 140 feet in total, you would divide that by four, to get a total of 35, which is the number of block cells. The simplest type of two-way slab to construct is known as a flat plate. Where; A c is the area of the cross. 5^2 / 162. 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. Every concrete slab should have a minimum. No. Rebar must be placed at the center of or slightly above the center of the concrete slab —hence why it should be a certain thickness for best results. Step 1: – Calculate numbers of distribution rods. Rebar, or reinforcing bar, is used in many masonry and concrete projects to reinforce slabs and structures. 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. (Rebar Calculation Formula) No. Rebar Development Length Calculator. 2], even though the code permits. Since we do not typically model rebar or have access to the rebar shop drawings at the time of the LCA calculation, we need to come up with the rebar quantities in a different manner. The lateral forces and moments on the formwork have been easy to handle, but I'm trying to find a good approach to the vertical uplift hydrostatic force on small-scale/DIY formwork while concrete is poured, which is a. For example, if you are using ½ inch rebar, divide 60 feet by 0. Effective depth d= Span / ( (L/d) Basic x modification factor) For obtaining modification factor, the percentage of steel for slab can be assumed from 0. per square foot without rebar, but you’ll need “control joints” or the slab will crack. The minimum shear reinforcement (A v,min) in beams should be the greater of the following: Av,min=0.