2202 Structural Steel and Composite Structural Steel and Concrete — 2025 California Building Code

The design, fabrication and erection of structural steel elements and composite structural steel and concrete elements in buildings, structures and portions thereof shall be in accordance with AISC 360.

Exceptions : [OSHPD 1R, 2 & 5] 1. For members designed based on tension, the slenderness ratio (L/r) shall not exceed 300, except for the design of hangers and bracing in accordance with NFPA 13 and for rod hangers in tension. 2. For members designed based on compression, the slenderness ratio (KL/r) shall not exceed 200, except for the design of hangers and bracing in accordance with NFPA 13.

Where required, the seismic design, fabrication and erection of buildings, structures and portions thereof shall be in accordance with Section 2202.2.1 or 2202.2.2, as applicable.

2202.2.1 Structural steel seismic force-resisting systems and composite structural steel and concrete seismic force-resist- ing systems. The design, detailing, fabrication and erection of structural steel seismic force-resisting systems and composite structural steel and concrete seismic force-resisting systems shall be in accordance with the provisions of Section 2202.2.1.1 or 2202.2.1.2, as applicable.

[ OSHPD 1R, 2 & 5 ] Seismic requirements for composite structural steel and concrete construction shall be considered as an alter- native system, except as permitted by Section 2202.4.1.

2202.2.1.1 Seismic Design Category B or C. Structures assigned to Seismic Design Category B or C shall be of any construction permitted in Section 2202. Where a response modification coefficient, R, in accordance with ASCE 7, Table 12.2-1, is used for the design of structures assigned to Seismic Design Category B or C, the structures shall be designed and detailed in accordance with the requirements of AISC 341. Beam-to-column moment connections in structural steel special moment frames and intermediate moment frames shall be prequalified in accordance with AISC 341, Section K1, qualified by testing in accordance with AISC 341, Section K2, or shall be prequalified in accordance with AISC 358.

Exception: The response modification coefficient, R, designated for “Steel systems not specifically detailed for seismic resistance, excluding cantilever column systems” in ASCE 7, Table 12.2-1, shall be permitted for structural steel systems designed and detailed in accordance with AISC 360, and need not be designed and detailed in accordance with AISC 341.

2202.2.1.2 Seismic Design Category D, E or F. Structures assigned to Seismic Design Category D, E or F shall be designed and detailed in accordance with AISC 341, except as permitted in ASCE 7, Table 15.4-1. Beam-to-column moment connections in structural steel special moment frames and intermediate moment frames shall be prequalified in accordance with AISC 341, Section K1, qualified by testing in accordance with AISC 341, Section K2, or shall be prequalified in accordance with AISC 358.

[OSHPD 1R, 2 & 5] All structural steel seismic force-resisting systems in ASCE 7 Table 15.4-1 shall be designed in accordance with AISC 341.

2202.2.2 Structural steel elements. The design, detailing, fabrication and erection of structural steel elements in seismic forceresisting systems other than those covered in Section 2202.2.1, including struts, collectors, chords and foundation elements, shall be in accordance with AISC 341 where either of the following applies:

1. The structure is assigned to Seismic Design Category D, E or F, except as permitted in ASCE 7, Table 15.4-1.
2. A response modification coefficient, R, greater than 3 in accordance with ASCE 7, Table 12.2-1, is used for the design of the structure assigned to Seismic Design Category B or C.

[OSHPD 1R, 2 & 5] All structural steel elements in seismic force-resisting systems shall satisfy the requirements in AISC 341.

2202.3.1 Section A4. Modify Section A4.1 Item (c) by adding the following:

(c) Locations and dimensions of protected zones. The fabricator shall permanently mark protected zones of structural elements in the seismic force-resisting system in the building that are designated on the construction documents. If these markings are obscured during construction, such as after the application of fire protection, the owner’s designated representative shall re-mark the protected zones as they are designated on the construction documents. Primers or paints used to mark protected zones on steel surfaces, which are to receive sprayed fire-resistance material, shall comply with California Building Code Section 704.13.3.2.

2202.3.2 Section I2. Replace Section I2.1 item (d) as follows:

(d) Decking attachments that penetrate the beam flange shall not be placed on beam flanges within the protected zone, except power-actuated fasteners up to 0.18 in. diameter are permitted, provided that the penetration is less than 85% of beam flange thickness.

2202.4.1 Modifications to AISC 358 Chapter 10. Steel and concrete ConXtech ConXL composite special moment frame connections shall be permitted, provided: a. Beams are provided with Reduced Beam Sections (RBS);

22-4 2025 CALIFORNIA BUILDING CODE

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b. Web extension to beam web two-sided fillet welds are sized to develop expected strength of the beam web and shall not be less than a 1/4 inch fillet weld; and c. The built-up box column wall thickness shall not be less than 1.25 inches and the HSS column wall thickness shall not be less than 1/2 inch.

2202.4.2 Modifications to AISC 358 Chapter 11 Welded Moment Connection. The welded sideplate steel moment connection shall be permitted, provided: 1. The beams shall consist of either rolled or built-up wide flange sections. 2. The biaxial dual-strong axis and column minor axis configurations of the moment connection shall be considered as an alternative system. 3. For SMF and IMF systems, U-shaped cover plates shall be used and the hinge-to-hinge span to beam depth, L h /d, shall be greater than or equal to 5. 4. The width-to-thickness ratios for beam flanges shall not be less than 3. 5. The spacing for lateral bracing of wide flange beams, L b , shall include the length of the side plate at beam ends. 6. The extension of the side plates beyond the face of the column shall be within the range of 0.77d to 1.0d. 7. The gap-to-side plate thickness ratio shall range from 2.1 to 2.3. Exception: The gap-to-side plate thickness ratio shall be permitted to be modified for moment connections with unequal beam sizes on opposite sides of the column or when orthogonal beams acting as drag connections frame into the side plate. 8. Demand critical fillet welds {2}, {5}, {5a} and {7} shall have Magnetic Particle Testing (MT) in accordance with AWS D1.1 for procedure, technique and acceptance. Inspect the beginning and end of these welds for a 6-inch length, plus any location along the length of the weld where a start and restart is visually noted for a distance of 6 inches on either side of the start/stop location.

2202.4.3 Modifications to AISC 358 Chapter 11 Bolted Moment Connection The bolted sideplate steel moment connection shall be permitted, provided: 1. The beams shall consist of either rolled or built-up wide flange sections. Columns shall consist of rolled or built-up wide flange sections or noncomposite built-up box or HSS with a minimum wall thickness of 3/4 inch (19 mm), or satisfy the requirements of width-to-thickness ratios of highly ductile members in AISC 341-16. 2. The biaxial dual-strong axis and column minor axis configurations of the moment connection shall be considered as an alternative system. 3. For SMF and IMF systems, on the sideplate standard or configuration A the U-shaped cover plates shall be used with the k dimension extension. The k dimension extension length is defined as beam depth d b /6, rounded to the nearest 1/2 inch (12.7 mm).

4. The hinge-to-hinge span to beam depth, L h /d, shall be greater than or equal to 4.5. 5. The width-to-thickness ratios for beam flanges shall not be less than 3.5. Exception: For width-to-thickness ratios less than 3.5 the C pr shall be calculated in accordance with that for welded side- plate connections but in no case shall the width-to-thickness ratio be less than 3.0. 6. The minimum bolt-to-bolt spacing shall not be less than 3 bolt diameters. 7. The extension of the side plates beyond the face of the column shall be within the range of 0.65d to 1.5d. 8. The gap-to-side plate thickness ratio shall range from 2.1 to 2.3.

Exception: The gap-to-side plate thickness ratio shall be permitted to be modified for moment connections with unequal beam sizes on opposite sides of the column or when orthogonal beams acting as drag connections frame into the side plate. 9. Demand Critical fillet welds {2}, {5}, {5a} and {8} shall have Magnetic Particle Testing (MT) in accordance with AWS D1.1 for procedure, technique and acceptance. Inspect the beginning and end of these welds for a 6-inch (152 mm) length, plus any location along the length of the weld where a start and restart is visually noted for a distance of 6 inches (152 mm) on either side of the start/stop location. 10. The connection specific factor to account for peak connection strength, C pr , shall be between 1.15 and 1.35. Calculations shall be submitted to OSHPD for review and approval. 11. For in-plane collectors transferring axial loads into the sideplate connection, coordination between sideplate and the regis- tered design professional in responsible charge will be required to confirm the collector connection is sufficient to transfer the load into the moment frame system. This requirement shall be satisfied by designing the sideplate connections in the first bay of a multi-bay sideplate moment frame or an end bay to have a minimum connection capacity, including combined shear (V u + V g ) and moment (M pr ) demands, of at least 1.2 times the M pr at the plastic hinge location when the axial load, as determined by ASCE 7, Section 12.10.2.1 without Ω o , exceeds 0.1 F y A g of the sideplate beam. 12. A complete frame analysis for gravity and design wind loading using LRFD load combinations in Section 1605.1 shall be performed including Demand/Capacity Ratios. Frame beam member nominal moment strengths (M n ) used for gravity and design wind loading for the bolted sideplate connection using Class A or Class B faying surfaces shall be taken as 0.80F y Z for frame beams up to 300 plf and 0.60F y Z for frame beams greater than 300 plf. 13. For moment frame beams with maximum beam shear greater than 90 percent of the vertical bolt shear capacity, a second- ary check is to be provided to confirm the vertical bolt shear capacities are sufficient.

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14. Bolted sideplate connections used on heavy-shallow frame beams for beams greater than 200 plf and shallower than 24 inches (610 mm) in depth shall be considered as an alternative system. 15. Skewed beams shall utilize the link-beam fabrication method with CJP welded splices for skew angles. The skew angle shall be less than 15 degrees. 16. For two-sided bolted sideplate connections sharing the same side plates at the same height and depth across the column, the vertical offset in the beams shall not exceed 10 inches (254 mm).

2202.4.4 Modifications to AISC 358 Chapter 12. The Simpson Strong-Tie (SST) Strong Frame bolted moment connection shall be permitted, provided: 1. Only T-stub yield links are permitted. End plate yield links are not permitted. 2. The biaxial dual-strong axis and column minor axis configurations of the moment connection shall be considered as an alternative system. 3. Beam flange width-to-thickness ratio shall satisfy AISC 341 Table D1.1b. 4. Yield-Link stem-to-beam flange connection bolts shall not slip under wind design demand loads. Yield-Link stem-to-beam flange connection shall be designed to prevent slip using AISC 360 Equation J3-4, where the slip resistance, μ , is taken to be 0.3.

5. Double shear plate connection is permitted to increase connection axial capacity for collector loads. A partial joint penetra- tion (PJP) groove weld for second shear plate is permissible due to space restrictions.

2202.4.5 Modifications to AISC 358 Chapter 15. The DuraFuse Frames (DFF) bolted moment connection shall be permitted, provided: 1. The biaxial dual-strong axis and column minor axis configurations of the moment connection shall be considered as an alternative system. 2. DFF connection bolts shall not slip under wind design demand loads. The connection shall be designed to prevent slip using AISC 360 Equation J3-4, where the slip resistance is taken to be 0.3. 3. Beam flange width-to-thickness ratio shall satisfy AISC 341 Table D1.1b. 4. The beam weight shall be limited to a maximum of 232 pounds per foot (345 kg/m).