> ## Documentation Index
> Fetch the complete documentation index at: https://calcs.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Design a Concrete Beam to ACI 318-14

> Design rectangular concrete beams to ACI 318-14 across unlimited spans. An earlier code edition, kept for existing projects.

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    <div className="calc-details-head"><span className="calc-card-icon"><Icon icon="calculator" size={20} color="#0076d6" /></span><p className="calc-details-name">Concrete Beam (ACI 318-14)</p><a className="calc-details-run" href="https://app.calcs.com/new/sheet/concreteBeamRectangularUSA">Run the calc</a></div>
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  Design rectangular concrete beams to ACI 318-14 with customizable top and bottom reinforcement across unlimited spans. Checks include flexural strength, shear capacity, and short- and long-term deflection. Beam reactions link to connected column and footing calculations so changes propagate automatically.
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<Note>
  This calculator uses an earlier code edition (ACI 318-14). It stays available for existing projects. For new designs, check the [Calculator Library](/docs/calculators/us) for the current edition.
</Note>

## Method & scope

| Property         | Detail                                        |
| ---------------- | --------------------------------------------- |
| Design standards | ACI 318-14                                    |
| Regions          | United States                                 |
| What it checks   | Flexural capacity, Shear capacity, Deflection |

#### Calculation method

The Concrete Beam (ACI 318-14) calculator designs rectangular sections per ACI 318-14 using LRFD. The FEA solver envelopes ASCE 7 factored load combinations to find governing Mu+ (positive), Mu- (negative), and Vu.

##### Flexural capacity

Positive and negative moment capacities **φMn** are computed using the ACI rectangular stress block at ultimate concrete strain εcu = 0.003. The neutral axis depth c is solved from equilibrium between the concrete compression block and the total steel tension (or combined tension and compression steel for doubly reinforced sections):

**a = A\_s × fy / (0.85 × f'c × bw)**

The nominal moment capacity is:

**Mn = A\_s × fy × (d, a/2)** (for singly reinforced sections)

The strength reduction factor φ = 0.90 for tension-controlled sections (net tensile strain εt ≥ 0.005). A plain concrete section (no reinforcement) is flagged as unsupported.

##### Shear capacity

Shear capacity **φVn = φ(Vc + Vs)** where:

* **Vc** = concrete contribution per ACI 318-14 simplified formula, modified by λ for lightweight concrete
* **Vs** = stirrup contribution = Av × fy × d / s

**Utilization = Vu / φVn ≤ 1.0** where φ = 0.75 for shear.

##### Deflection

Deflection uses the effective moment of inertia **Ie = Ig × (Mcr/Ma)³ + Icr × \[1, (Mcr/Ma)³]** per ACI 318-14 Cl 24.2.3.5 to account for cracking. Three limit states are checked:

* **Short-term (δST):** under live/roof live service loads
* **Long-term (δLT):** total with creep and shrinkage multiplier
* **Simplified DL+(LL or SL):** combined dead plus governing transient load

**Deflection utilization = δ / Δmax ≤ 1.0** against user-defined L/n limits.

## How to use it

<Steps>
  <Step title="Open the calculator">
    Open it from **Run calc** in the About this calculator panel above.
  </Step>

  <Step title="Enter your inputs">
    Work through the input sections from top to bottom. Click any input label to see its reference explanation, clause, conditions and assumptions. See [Checks, References, Conditions and Assumptions](/docs/running-calculations/checking-results/checks-references-conditions-assumptions).
  </Step>

  <Step title="Review the results and export">
    Check the utilization of each governing check in the summary, then export a PDF report. See [Views and Export](/docs/running-calculations/exporting-reports/views-and-export).
  </Step>
</Steps>

## Common questions

<AccordionGroup>
  <Accordion title="What design method and standard does this calculator follow?">
    Strength Design Method (LRFD) per ACI 318-14. Factored loads from ASCE 7 LRFD combinations are compared to reduced nominal capacities using the appropriate ACI strength reduction factors.
  </Accordion>

  <Accordion title="What are the key inputs?">
    Cross-section dimensions (width bw and overall depth h, in inches), concrete compressive strength f'c (psi, minimum 2500 psi per ACI 318-14 Cl 19.2.1.1), concrete weight class (normalweight or lightweight, setting the λ factor), reinforcement yield strength fy (40-80 ksi), clear cover, positive and negative moment reinforcement (bar size and count, up to two rows), stirrup size and spacing, span geometry, supports, and factored loads by type.
  </Accordion>

  <Accordion title="What checks does it perform?">
    Positive flexural capacity φMn+ ≥ Mu+, negative flexural capacity φMn- ≥ Mu-, shear capacity φVn ≥ Vu (concrete plus stirrup contributions), short-term deflection, long-term deflection, and simplified DL+(LL or SL) deflection. All results show the demand-to-capacity ratio. Minimum cover and bar spacing requirements are also flagged.
  </Accordion>

  <Accordion title="Can it model multi-span continuous beams with different reinforcement in each region?">
    Yes, the FEA engine handles unlimited spans with configurable support conditions. Reinforcement is specified separately for positive moment regions (midspan) and negative moment regions (supports), reflecting real detailing practice.
  </Accordion>

  <Accordion title="Is this the current ACI edition?">
    This is the ACI 318-14 version. The current edition is ACI 318-19, use the Concrete Beam (ACI 318-19) calculator for new designs. ACI 318-14 remains valid for projects permitted under earlier IBC editions or jurisdictions that have not adopted the 2019 edition.
  </Accordion>

  <Accordion title="Does this calculator support load linking with column and footing calculations?">
    Yes, beam support reactions link directly to connected column and footing calculations in the same project. When any load or geometry changes in this beam, all linked downstream calculations update automatically.
  </Accordion>
</AccordionGroup>

## Next steps

<CardGroup cols={2}>
  <Card title="Calculator Library" icon="list" href="/docs/calculators/us">
    Complete list of Calcs.com design calculators available for United States projects (AISC, ACI, NDS, ASCE 7, IBC, and related standards).
  </Card>

  <Card title="Design a Rectangular Concrete Column to ACI 318-14" icon="calculator" href="/docs/calculators/us/columns/concreteColumnUSA">
    Design rectangular concrete columns to ACI 318-14. An earlier code edition, kept for existing projects.
  </Card>

  <Card title="Design a Concrete Beam to ACI 318-19" icon="calculator" href="/docs/calculators/us/beams/concreteBeamRectangularUSAACI318-19">
    Design rectangular concrete beams and T-beams to ACI 318-19 across unlimited spans. Checks flexure, shear, and short- and long-term deflection.
  </Card>

  <Card title="Concrete Column Calculator to ACI 318-19 - Overview" icon="calculator" href="/docs/calculators/us/columns/concreteColumnUSAACI318-19">
    Design rectangular concrete columns to ACI 318-19. Checks axial capacity, P-M interaction, biaxial bending and slender column moment magnification.
  </Card>
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