Model long-term concrete shortening for columns, walls, and girders with flexible inputs. Choose manual strains or estimate from humidity, strength, and size parameters easily.
Illustrative cases for quick comparison. Replace with project-specific values.
| Case | σ (MPa) | E (MPa) | L (m) | φ | εsh (με) | Estimated total shortening (mm) |
|---|---|---|---|---|---|---|
| A | 8 | 30000 | 3.0 | 1.6 | 350 | ≈ 0.98 |
| B | 10 | 28000 | 4.0 | 2.2 | 450 | ≈ 1.95 |
| C | 12 | 32000 | 3.5 | 1.8 | 500 | ≈ 1.53 |
| D | 6 | 30000 | 5.0 | 2.5 | 650 | ≈ 3.73 |
| E | 9 | 34000 | 2.8 | 1.4 | 300 | ≈ 0.82 |
This estimator combines sustained-load creep with drying shrinkage to approximate axial shortening. It reports each strain component and converts total strain into length change.
In “Estimate from environment” mode, φ and εsh are approximated using humidity, strength, size, and time factors for preliminary checks.
Creep and shrinkage create time-dependent axial shortening in concrete columns, walls, and girders. On multi-storey frames, a 1.0 mm shortening per storey can accumulate into centimetres, influencing floor levels, façade brackets, elevator rails, and partition gaps. Early quantification supports tolerance budgets and coordination drawings.
This calculator uses sustained stress σ (often 5–15 MPa in service), modulus E (commonly 20,000–40,000 MPa), member length L, creep coefficient φ, and shrinkage strain εsh in microstrain (typical 200–800 με). Values vary with mix design, curing, humidity, and element thickness.
Creep strain is computed as εc = φ·(σ/E). For example, with σ = 10 MPa, E = 30,000 MPa, and φ = 2.0, elastic strain is 3.33×10−4 and creep strain is 6.67×10−4. Over L = 3 m, creep shortening is about 2.0 mm.
Shrinkage strain is applied directly as εsh (microstrain × 10−6). A value of 400 με equals 4.00×10−4. Over 3 m, shrinkage shortening is about 1.2 mm. In lightly stressed members, shrinkage can be similar to or larger than creep shortening.
Long-term effects develop gradually. Coordination checks often use 90–180 days for early fit-out impacts and 365+ days for façade and permanent finishes. Earlier loading ages generally increase creep development; later loading reduces the effective creep contribution for the same sustained stress.
When φ and εsh are not available, the estimator mode approximates them from relative humidity, strength, notional size, and time factors. Lower humidity and smaller h0 increase drying potential, while higher mean strength tends to reduce both effects. Use this mode for preliminary coordination, not final certification.
Differential shortening between columns, core walls, and perimeter elements can introduce restraint forces and rotation demands in slabs and links. Run consistent assumptions across elements, then compare total shortening to identify where detailing, sequencing, or compensation measures may be needed.
Export the CSV or PDF to document assumptions: σ, E, L, φ, εsh, and whether immediate elastic shortening is included. For final design, confirm values using your governing standard’s creep–shrinkage model, specified curing regime, and project testing data.
Include it when you want total shortening from first loading. Exclude it when focusing only on long-term movements after initial construction and alignment adjustments are complete.
Use the sustained portion of service compressive stress, considering long-term dead load and a realistic sustained fraction of live load. Avoid short-term peak stresses for creep calculations.
Use the project’s expected elastic modulus at the relevant age, often based on mix design or testing. If unknown, select a typical value consistent with strength and aggregate type.
Many practical cases fall between 0.5 and 3.0, but it can be higher for early loading and dry conditions. Use your governing standard to confirm project-specific expectations.
Common coordination values are roughly 200–800 microstrain, depending on humidity, curing, cement content, and member thickness. Thin, exposed members can experience higher drying shrinkage.
Smaller members exchange moisture faster, increasing drying shrinkage and influencing creep development. Larger members dry more slowly, often reducing the effective long-term shortening over a given time horizon.
Yes, run consistent assumptions for each element and compare total shortening. Differences guide tolerance planning and detailing, but final decisions should follow your project’s specified creep-shrinkage model.
Use results wisely, and confirm with project standards always.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.