Provisions for Members not Designated as Part of the Seismic-Force-Resisting System
Section 21.13 specifies requirements for members not designated as part of the seismic-force-resisting system. The requirements apply only to structures assigned to seismic design categories D, E, or F. This requirement is not new to ACI 318. The '08 code is the first instance in which this provision has been implemented in RAM Concrete.
ACI 318-08 allows two approaches in fulfilling the requirements for members not designated as part of the seismic-force-resisting system. Section 21.13.3 involves the calculation of member forces and a comparison to a limit which, if exceeded, requires the fulfillment of 21.13.4.1, 21.13.4.2, and 21.13.4.3. Section 21.13.4 allows the engineer to fulfill Sections 21.13.4.1, 21.13.4.2, and 21.13.4.3 regardless of member forces.
RAM Concrete implements Section 21.13.4. That is, member forces are not checked to determine if the special detailing requirements are necessary for a given member. The requirements are implemented regardless. The following table provides a summary of the checks that are required by Section 21.13.4, and the checks that are implemented within RAM Concrete.
| Section | Referenced Section(s) | Implemented? | Description of Check |
|---|---|---|---|
| 21.13.4.1 | 21.1.4.2 | ✔ | Minimum f'c |
| 21.1.4.3 | ✔ | Maximum f'c for lightweight concrete | |
| 21.1.5.2 | X | Material requs. for reinforcing | |
| 21.1.5.4 | ✔ | Material requs. for confinement steel | |
| 21.1.5.5 | ✔ | Material requs. for shear reinforcing | |
| 21.1.6.1 | X | Mechanical splices | |
| 21.1.6.2 | X | Mechanical splices | |
| 21.1.7.1 | X | Welded splices | |
| 21.13.4.2 | 21.5.2.1 | ✔ | Reinforcing ratio limits |
| 21.5.4.1 | ✔ | Design shear force | |
| 21.5.4.2 | ✔ | Transverse reinforcement | |
| 21.13.4.3 | 21.6.3.1 | ✔ | Area of longitudinal reinforcement |
| 21.6.3.2 | X | Mechanical splices | |
| 21.6.4.1 | ✔ | Transverse reinforcement over lo | |
| 21.6.4.2 | X | Transverse reinforcement details | |
| 21.6.4.3 | ✔ | Spacing of transverse reinforcement | |
| 21.6.4.4 | ✔ | Minimum area of transverse reinforcement | |
| 21.6.4.5 | ✔ | Maximum tie spacing over lo | |
| 21.6.4.6 | X | Columns supporting discontinuous members | |
| 21.6.4.7 | X | Additional stirrups based on cover | |
| 21.6.5.1 | ✔ | Design shear force Ve | |
| 21.6.5.2 | ✔ | Transverse reinforcement over lo | |
| 21.7.3.1 | X | Joint transverse reinforcement |
RAM Concrete Column enforces the provisions listed in Table 8 for gravity columns when the ACI 318-08 design code is used, and the Seismic Design Category is set to D, E, or F.