This section (based on ACI 318-19 provisions) defines notation and terminology used in this design example:
a | = | depth of equivalent rectangular stress block, in. |
Ag | = | gross area of concrete section, in.2 For a hollow section, Ag is the area of the concrete only and does not include the area of the void(s) |
As | = | area of nonprestressed longitudinal tension reinforcement, in.2 |
c | = | distance from extreme compression fiber to neutral axis, in. |
d | = | distance from extreme compression fiber to centroid of longitudinal tension reinforcement, in. |
Ec | = | modulus of elasticity of concrete, psi |
Es | = | modulus of elasticity of reinforcement and structural steel, excluding prestressing reinforcement, psi |
fc' | = | specified compressive strength of concrete, psi |
fr | = | modulus of rupture of concrete, psi |
fy | = | specified yield strength for nonprestressed reinforcement, psi |
h | = | overall thickness, height, or depth of member, in. |
Icr | = | moment of inertia of cracked section transformed to concrete, in.4 |
Ig | = | moment of inertia of gross concrete section about centroidal axis, neglecting reinforcement, in.4 |
lc | = | length of compression member, measured center-to-center of the joints, in. |
lw | = | length of entire wall, or length of wall segment or wall pier considered in direction of shear force, in. |
Mcr | = | cracking moment, in.-lb |
Mn | = | nominal flexural strength at section, in.-lb |
Mu | = | factored moment at section, in.-lb |
Mua | = | moment at midheight of wall due to factored lateral and eccentric vertical loads, not including PΔ effects, in.-lb |
Pn | = | nominal axial compressive strength of member, lb |
Pum | = | factored applied gravity load + half the factored self-weight of the wall |
PΔ | = | secondary moment due to lateral deflection, in.-lb |
wc | = | density, unit weight, of normalweight concrete or equilibrium density of lightweight concrete, lb/ft3 |
yt | = | distance from centroidal axis of gross section, neglecting reinforcement, to tension face, in. |
β1 | = | factor relating depth of equivalent rectangular compressive stress block to depth of neutral axis |
Δu | = | calculated out-of-plane deflection at midheight of wall due to factored loads, in. |
εt | = | net tensile strain in extreme layer of longitudinal tension reinforcement at nominal strength, excluding strains due to effective prestress, creep, shrinkage, and temperature |
εty | = | value of net tensile strain in the extreme layer of longitudinal tension reinforcement used to define a compression-controlled section |
λ | = | modification factor to reflect the reduced mechanical properties of lightweight concrete relative to normalweight concrete of the same compressive strength |
ϕ | = | strength reduction factor |