**Related Resources: civil engineering**

### Concrete Long Term Creep Deflections per. ACI 318 Equations

Civil Engineering and Design

Strength of Materials Basics and Equations | Mechanics of Materials

Concrete Long Term Creep Deflections per. ACI 318 Equations

Long-term deflection is caused by creep and shrinkage of
the concrete. The long-term deformation develops
rapidly at first and then slows down, being largely complete
after approximately five years. As specified by
ACI 318 Sec. 9.5.2.5, the long-term deformation, *Δ _{a}*, is
obtained by multiplying the immediate deflection produced
by the portion of the load that is sustained by an
amplification factor, %. In computing the sustained part
of the immediate deflection, judgment is required to
decide what fraction of the prescribed service live load
can be assumed to be acting continuously. The longterm
deflection is taken as

The longterm deflection is taken as

Eq. 1

*Δ _{a}*

*= λ · Δ*

_{i}Eq. 2

λ = i / ( 1 + 50 ρ' )

Eq. 3, compression steel ratio at midspan

ρ' = A'_{s} / ( b · d )

*ρ'* is the compression steel ratio at midspan for
simply supported and continuous beams, and at supports
for cantilevers. *i* is an empirical factor that
accounts for the rate of the additional deflection. *i* is
1.0 at three months, 1.2 at six months, 1.4 at one year,
and 2 at five years or more.

The total deflection is the sum of the instantaneous plus the long-term deflections.

Reference

- ACI 318 Building Code Requirements for Structural Steel, paragraph 10.5 Minimum reinforcement of flexural members
- Civil Engineering Reference Manual, Fifteenth Edition, Chapter 48, p. 50.7, Paragraph 16 (Long-Term Deflections), Michael R. Lindeburg, PE

Related

- Minimum Reinforcement Steel Area Calculator
- Rebar Two Parallel Legs One Angled Leg Center Line Length Equation and Calculator
- Standard ReBar Shapes Formula and Calculator
- Concrete Splitting Tensile Strength Test Equations and Calculator
- Tensile Thread Stress Area Equation and Calculator - 180 ksi and More
- Material Tensile Shear and Yield Strength of Engineering Materials Table
- Concrete Modulus of Elasticity Equations and Calculator
- Modulus of Elasticity, Youngs Modulus Table and Calculator
- Bulk Modulus for Materials Metals and Liquids
- Circular Formed Rebar Center Line Length Equation and Calculator
- Young's Modulus (Elastic Modulus ) Equation
- Ultimate Strength, Modulus of Elasticity , Yield Point of Metals Table Chart
- Concrete Foundation Anchor Bolts Design
- Manual of Concrete Design ACI
- Reinforced Concrete Beam Design to BS8110 Calculator
- Reinforced Concrete Beam Design per. ACI 318-08 Calculator Spreadsheet
- Concrete Pad Foundation Design Spreadsheet Calculator
- Concrete Structural Designers Guide