Codes
On initially entering Steel-Seismic Provision Mode, the engineer is presented a Seismic Design Code. This dialog can subsequently be displayed by selecting the command.
The choice of codes available to the engineer in this dialog is based on the steel design code specified in the standard provision mode. Strength seismic provision codes (AISC 341-16, AISC 341-10, AISC 341-05 LRFD, UBC 1997 – LRFD, AISC-1997, AISC-2002) will be available if LRFD is the steel design code selected in standard provision mode. Similarly AISC 341-16, AISC 341-10, AISC 341-05 ASD, UBC 1997 – ASD will be available if ASD is the steel design code selected in standard provision mode. This is because many of the checks performed in the seismic mode are dependent on the load combinations created in the standard provision mode.
Depending on the seismic code selected different options will be made available to the engineer. A description of all the options follows.
| Setting | Description |
|---|---|
| Apply One-and-Two Story Exceptions | This option typically applies to braced frame structures. Several of the design provisions provide exceptions if the structure is a low building (one-or two stories in height). Checking this option will indicate to the program that these exceptions are appropriate for this structure. If this option is selected then where applicable and necessary the exception will be attempted. For AISC 341 codes, this criteria is only applicable to the exception for the column-beam moment ratio. |
| Use Frame Nos. to Designate a Frame Line | This option applies to several of the braced frame types. While most of the seismic checks are performed on individual structural members, some are performed on complete frames. By applying unique frame numbers to members of individual braced frames, and checking this option, RAM Frame will perform these complete frame checks. |
| Perform FEMA 350 | This option applies only to special moment resisting frames. When checked, the AISC 1997 and UBC1997 panel-zone and strong-column-weak-beam checks will be superseded by the equivalent checks in the Federal Emergency Management publication 350. If reduced beam sections are applied to beams they will be considered. |
| Use AISC358-05/10/16 RBS Moment Connection | Applicable only when AISC 341-05/10/16 LRFD is selected. This option indicates the provisions of AISC 358-05/10/16 with respect to Beam Limitations, Column Limitations and Joint (Beam-Column Limitations) will be verified for SMF and where applicable IMF frame members and joints. Selection of this option provides the user the ability to designate. |
| Zone | The seismic zone of the structure. Affects which checks are performed for each frame type, as described in the associated building code. |
| Importance Factor | The importance factor assigned to the structure. Affects which checks are performed for each frame type, as described in the associated building code. |
| Over-Strength Factor / Cpr Factor | This factor is used where required by the code to increase the yield strength of beams to ultimate levels. Only where specifically required by the code will the over-strength factor be applied. For example UBC 1997 refers to the over-strength factor in section 2213.7.5. For the AISC 1997/2002/2005/2010/2016 provisions this value is calculated by the program (Ry) and is based on the yield strength of the base material (according to the specification). For AISC 341-05/10/16 if Use AISC358 is selected, this option is required to designate the factor to account for peak connection strength per 2.4.3 of AISC 358-05/10/16. The engineer may specify other Cpr Factors in the Other field for other connection types, such as QUF-W. SidePlate® and DuraFuse® connections assume Cpr factors of 1.21 and 1.0 respectively. |
| EBF-Cd Factor |
(AISC 1997/2002/2005/2010/2016 Only) This factor is used in accordance with AISC97/02 section 15.2g, AISC 341-05 15.2c, or AISC 341-10/16 F3.5b(3), where the design story drift is required. RAM Frame considers the design story drift as Cd times the elastic story drift. Refer to the technical section and the AISC commentary for additional information. Selecting the option Show this dialog when entering Seismic Provision Mode will automatically display the code dialog each time the seismic provision mode is entered. |
| EBF F3.3(1) Exceptions | (AISC 2010, AISC 2016 Only)
Selecting the check boxes applies Exception F3.3(1)a to EBF Beams Outside Link and Exception F3.3(1)b to all columns. The options are only available when the AISC 341-10 or AISC 341-16 code is selected |
| BRBF and SCBF - Required Strength of Columns |
(AISC 2005/2010/2016) The option to perform a BRBF and SCBF column strength check based on the Adjusted Brace Strength, Amplified Seismic Forces with Ω0 or the larger of the two may be made by selecting the option in the Seismic Provisions Code dialog. This option is only available for BRBFs when the AISC 341-05 code is selected. |