Moment Resistance Calculator
Calculate the ultimate moment resistance (Mu) of a singly reinforced concrete slab using rebar diameter, count, concrete cover, and yield strength.
How to use Moment Resistance Calculator
- Select the rebar diameter (mm) and input the rebar count per meter width.
- Input the total slab thickness (cm) and the steel yield strength (N/mm²).
- Enter the concrete cover to the center of the rebar (mm).
- Click 'Calculate' to see the moment resistance and steel area results.
What is Moment Resistance Calculator?
A moment resistance calculator determines the bending moment capacity of a reinforced concrete slab section under ultimate limit state (ULS) loading. It uses standard flexural design formulas (such as in BS 8110 or Eurocode 2) where the moment capacity is calculated as a function of the reinforcement steel area ($A_s$), yield strength ($f_y$), and the lever arm ($z$).
This calculator is specifically calibrated for singly reinforced concrete slabs with a standard steel yield strength (e.g. grade 420 or 500 N/mm²) and assuming a standard lever arm limit of $0.95\cdot d$, offering quick structural estimation for engineers and designers.
FAQ
- What standard formulas are used here?
- We use the ultimate limit state (ULS) bending formula: Mu = 0.87 · fy · As · z, where z = 0.95 · d. This assumes the concrete compression zone is under-reinforced, which is typical for singly reinforced slabs.
- What is the concrete cover to the center of rebar?
- It is the distance from the bottom/top outer surface of the concrete slab to the center of the reinforcement bar. For example, if you have a 30mm clear concrete cover and a 20mm rebar, the cover to the center of the rebar is 30 + 20/2 = 40mm.
- Does this work for doubly reinforced slabs?
- No. This tool assumes singly reinforced slabs (tension reinforcement only), which is the standard design method for most ordinary floor slabs.
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