ACI 318-19

The ACI 318-19 design code implementation in RAM Foundation 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.

One-way Concrete Shear Strength

Equations to calculate the concrete shear capacity according to Table 22.5.5.1 have been implemented:

Criteria	V_c	ACI 318-19 Sec 22.5.5.1
A_v≥ A_{v, min}	$[2 λ \sqrt{{f'}_{c}} + \frac{N_{u}}{6 A_{g}}] b_{w} d$	(a)
A_v< A_{v, min}	$[8 λ_{s} λ {(ρ_{w})}^{\frac{1}{3}} \sqrt{{f^{'}}_{c}} + \frac{N_{u}}{6 A_{g}}] b_{w} d$	(c)

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.

The size effect factor is not applied, as permitted in Section 13.2.6.2.

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.

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.

Minimum Flexural Reinforcement

As specified in Section 8.6.1.1, minimum flexural reinforcement of 0.0018A_g is applied for all grades of reinforcement.

The minimum reinforcement requirement for high punching shear given by Eq. (8.6.1.2) in Section 8.6.1.2 has not been implemented.

Ductility Strain Limit

The requirement that two-way slabs be tension-controlled given in Section 8.3.3.1 has not been implemented.

Reinforcement Details, Modification Factor for Development of Reinforcement

Table 25.4.2.5 provides new modification factors for the development of deformed bars in tension based on reinforcement grade. These factors for Grade 80 and Grade 100 have not been implemented, a factor of 1.0 is always used as for Grade 40 and Grade 60.

Table 25.4.3.2 provides new modification factor values for the development of hooked bars in tension. These have not been implemented, the values given in Table 25.4.3.2 of ACI 318-14 are used.

Detailing Requirements for SDC D, E, or F

The detailing requirements for footings in Seismic Design Categories D, E, or F given in Section 18.13 have not be implemented.

Reduced ϕ factor for Foundations Supporting Seismic Frames or Walls

The requirement given in Section 21.2.4.3 to use a ϕ factor not exceeding that used in the design of those frames and walls has not been implemented.