D1.F.3 Design Parameters
The following outlines the parameters that are
available to control the design of members as beams or columns
per the ACI 318-14 code.
The commands that initiate the design of these is outlined in
TR.53.3
Concrete Design Command.
If any parameter is not specified and its value is required in the design, then
it will use that specified as the default value in the tables below.
Note: Not all the
parameters are used in all versions of the ACI 318 code. Ensure that all the
necessary parameters for the version of the code are properly specified. Where
practical, parameters used in earlier versions of the code will be supported in
the newer versions. Some old parameters are not supported in newer versions of
the code and new parameters have been added in newer versions of the code that
provide greater flexibility in the design.
| Parameter Name | Default Value | Description |
|---|---|---|
| BDY | 1.0 | Column stiffness reduction factor for bending about the local Y axis. |
| BDZ | 1.0 | Column stiffness reduction factor for bending about the local Z axis. |
| BRDO | 0 | Bottom Rebar Detail Options
|
| CLB |
1.5 in. (38 mm) for members* |
Minimum cover from the base of the section to the bottom longitudinal reinforcement. |
| CLS | 1.5 in. (38 mm)* | Minimum cover from the sides of the section to the side longitudinal reinforcement. |
| CLT |
1.5 in. (38 mm) for members* |
Minimum cover from the top of the section to the top longitudinal reinforcement. |
| CRDO | 0 | Design options for main
reinforcement in columns
|
| FC | 4,000 psi (28 N/mm2)* | Compressive strength of concrete. |
| FYMAIN | 60,000 psi (420 N/mm2)* | Yield stress for main longitudinal reinforcing steel. |
| FYSEC | 60,000 psi (420 N/mm2)* | Yield stress for transverse reinforcing steel. |
| LATR | 0 (No) | Is this member subject to lateral
loading?
|
| LWF | 0 | Specifies the aggregate
composition of the concrete.
|
| MAXMAIN | #18 (Imperial), 57M (Metric) |
Maximum size of reinforcing bar to be used for longitudinal reinforcement. |
| MIMB | #4 (Imperial), 13M (Metric) | Minimum main rebar number (size) at the bottom face |
| MIMS | #4 (Imperial), 13M(Metric) | Minimum main rebar number (size) at for skin (side) bars |
| MIMT | #4 (Imperial), 13M (Metric) | Minimum main rebar number (size) at the top face |
| MINMAIN | #4 (Imperial), 13M (Metric) |
Minimum size of reinforcing bar to be used for longitudinal reinforcement. |
| MINSEC | #4 (Imperial), 13M (Metric) | Minimum size of reinforcing bar to be used for transverse reinforcement. |
| MMAG | 1.0 | Factor to magnify the analysis moments used for column design. |
| MXMB | #18 (Imperial), 57M (Metric) | Maximum main rebar number (size) at the bottom face |
| MXMS | #18 (Imperial), 57M (Metric) | Maximum main rebar number (size) for skin (side faces) bars |
| MXMT | #18 (Imperial), 57M (Metric) | Maximum main rebar number (size) at the top face |
| RCOAT | 0 | Rebar coating type:
|
| REINF | 0 |
Column transverse reinforcement type.
|
| RHOMIN | 0.01 | Minimum reinforcement required in a concrete column. Enter a value between 0.0 and 0.08, where 0.08 = 8% reinforcement; the maximum allowed by the ACI code. |
| SKY | 1.0 | Effective length factor for moment magnification procedure calculations for columns, in the local Y direction. When the SWY parameter is 0 (i.e., not braced), then SKY ≥ 1.0. When SWY is 1 (i.e., braced), then 0.5 ≤ SKY ≤ 1.0. |
| SKZ | 1.0 | Effective length factor for moment magnification procedure calculations for columns, in the local Z direction. When the SWY parameter is 0 (i.e., not braced), then SKZ ≥ 1.0. When SWY is 1 (i.e., braced), then 0.5 ≤ SKZ ≤ 1.0. |
| SLY | n/a |
Number of the load case that applies sidesway load in the local Y axis for column design. The moments from this case are used to magnify the local Y axis moments for all design load cases as per the sway or non sway requirements. Calculations are dependent on the SWY parameter setting. |
| SLZ | n/a |
Number of the load case that applies sidesway load in the local z axis for column design. The moments from this case are used to magnify the local Z axis moments for all design load cases as per the sway or non sway requirements. Calculations are dependent on the SWY parameter setting. |
| SQY | 0.2 |
Stability index, Q, in the local Y axis as defined in ACI 318 section 6.6.4.3(b). |
| SQZ | 0.2 |
Stability index, Q, in the local Z axis as defined in ACI 318 section 6.6.4.3(b). |
| SWY | 0 |
Braced against sidesway:
|
| TRACK | 0.0 | |
| TRDO | 0 | Top Rebar Detail Options
|
| TRN | 0 | Specifies whether a member is
subject to transverse loads between supports. This parameter influences the
moment magnification calculations per CL 6.6.4.5.3.
|
Notes
- The value used when specifying the CLS parameter for column design is taken to be the clear cover for the longitudinal bars in a column. It is not taken as the clear cover for the tie bars. Therefore, the distance from the edge of the column to the centerline of the first row of longitudinal bars is CLS plus half the diameter of the main bar.
- The following parameters
are not applicable to the ACI 318-14 (only to ACI 318-11 and earlier):
- DEPTH
- EFACE
- RHOMAIN
- SFACE
- WIDTH
- NSECTION
- MAXMAIN and MINMAIN are now supplemented by new set of parameters like MXMB, MIMC etc. You can assign values either in the old parameters (like MAXMAIN) or in the new parameters (like MXMT, MXMB, MXMC). If you choose to use older parameters like MAXMAIN and MINMAIN, the program will store this input into newer parameters like MXMB, MIMC etc. internally. However, if you use both older and newer parameters, only the newer parameter values are accepted by the program.