ACI-318 2019

The ACI 318-19 design code implementation in RAM Concrete Column utilizes the majority of the design logic contained in the ACI 318-14 code.

This section documents notable changes made for the implementation of ACI 318-19.

Maximum axial compressive strength, Pnmax

The value of f_y for obtaining the maximum axial compressive strength is now limited to 80,000 psi by Section 22.4.2.1.

Strength reduction factor for moment, axial force or combined moment and axial

The strength reduction factor, ϕ, is determined from Table 21.2.2 based on the net tensile strain, ε_ty.

Concrete Shear Capacity

Equation a of Table 22.5.5.1 has been implemented to calculate the concrete shear capacity:

V_{c} = [2 λ \sqrt{{f'}_{c}} + \frac{N_{u}}{6 A_{g}}] b_{w} d

ACI 318-19 (22.5.5.1.a)

Axial load, N_u, is positive for compression and negative for tension.

It is important to note that currently the λ modification factor considered by the program is always 1.00, corresponding to normal weight concrete.

The value of V_c is limited to a maximum of $5 λ \sqrt{{f'}_{c}} b_{w} d$ , according to Section 22.5.5.1.1, and is not taken less than zero.

The value of N_u/6A_g is limited to a maximum of 0.05f’c, according to Section 22.5.5.1.2.

Reinforced concrete members subjected to biaxial shear

Section 22.5.1.10 and 22.5.1.11 are not implemented in the program.

Reinforcement Detailing

Section 10.7.1.3 limits the transverse reinforcement along development and lap splice lengths of longitudinal bars with f_y ≥ 80,000 psi, stating that this reinforcement shall be provided such that K_tr shall not be smaller than 0.5 d_b.

Lightweight Concrete Factor

Lightweight concrete factors are not implemented in the determination of concrete column shear capacity. The design considers normal weight concrete and uses λ = 1 in all cases.