Concrete modulus of elasticity is calculated as follows:
For ASD, CSI Software uses the ACI equation.
- For LRFD, the value is input into the Material Property Data form.
Should cracking factors be applied to floor slabs?
Answer: Cracking factors need not be applied to floor slabs unless special conditions exist, such as when shear walls are close to one another and the shell object acts as a coupling/link beam. However, this is rarely the case in that floor slabs typically do not contribute to the lateral capacity of the system. In fact, ACI prohibits such behavior in high seismic areas because flexural contribution from floor slabs may increase lateral stiffness to an unconservative extent. Floor slabs should however behave as diaphragms to transfer in-plane forces.