Calculation of Immediate Deflections
Immediate Deflection is calculated automatically
Ec = modulus of elasticity of concrete, psi
fr = modulus of rupture of concrete, psi
fc' = specified compressive strength of concrete, psi
Icr = moment of inertia of cracked section transformed to concrete, in4
Ie = effective moment of inertia for calculation of deflection, in4
Ig = moment of inertia of gross concrete section about controidal axis, neglecting reinforcement, in4
Ma = maximum moment in member due to service loads at stage deflection is calculated, in.-lb
Mcr = cracking moment, in.-lb
yt = distance from centroidal axis of gross section, neglecting reinforcement, to tension surface, in.
wc = density, unit weight, of normalweight concrete, lb/ft3
According to ACI 220.127.116.11 Immediate deflections is calculated using eleastic deflection formulas, considering effects of cracking and reinforcement on member stiffness.
According to ACI 18.104.22.168 Modulüs of elasticity, Ec is calculated in accordance with following equation.
According to ACI 22.214.171.124 effective moment of inertia Ie is calculated in accordance with following equation and ACI Table 126.96.36.199.
According to ACI 188.8.131.52 for continuous one-way salbs and beams, Ie, can be taken as the average of values obtained from ACI Table 184.108.40.206. for the critical positive and negative moment sections.
According to ACI 220.127.116.11 for prismatic one-way salbs and beams, Ie, can be taken as the average of values obtained from ACI Table 18.104.22.168. at midspan for simple and continuous spans, and at support for cantilevers.