The provisions of Section 502 of IEBC are adopted by reference with the following modifications:
1. Revise Section 502.2 to read:
"502.2 Disproportionate earthquake damage.
A building assigned to Seismic Design Category D that has sustained disproportionate earthquake damage shall be subject to the requirements for buildings with substantial structural damage to vertical elements of the lateral force-resisting system."
2. Delete Section 502.3.
3. Revise the exception to Section 502.4 to read:
"Exception: Buildings of Group R-5 occupancy where the existing building and the addition together comply with the conventional light-frame construction methods of the Chicago Building Code."
4. Revise Section 502.5 to read:
"502.5 Existing structural elements carrying lateral load.
Where the addition is structurally independent of the existing building, existing lateral load-carrying structural elements shall be permitted to remain unaltered. Where the addition is not structurally independent of the existing building, the existing building and its addition acting together as a single structure shall be shown to meet the requirements of Sections 1609 and 1613 of the Chicago Building Code using full seismic forces.
Exceptions:
1. Any existing lateral load-carrying structural element whose demand-capacity ratio with the addition considered is not more than 10 percent greater than its demand-capacity ratio with the addition ignored shall be permitted to remain unaltered. For purposes of calculating demand- capacity ratios, the demand shall consider applicable load combinations with design lateral loads or forces in accordance with Sections 1609 and 1613 of the Chicago Building Code. For purposes of this exception, comparisons of demand-capacity ratios and calculation of design lateral loads, forces and capacities shall account for the cumulative effects of additions and alterations since original construction.
2. Buildings of Group R-5 occupancy where the existing building and the addition together comply with the conventional light-frame construction methods of the Chicago Building Code."
5. Revise Section 502.6 to read:
"502.6 Smoke alarms in existing portions of a building.
Where an addition is made to a building or structure of a Group R or I-1 occupancy, the existing building shall be provided with smoke alarms in accordance with Section 504.8 of the Chicago Minimum Requirements for Existing Buildings or shown to be in compliance with these requirements."
6. Revise Section 502.7, including its exceptions, to read:
"502.7 Carbon monoxide alarms in existing portions of a building.
Where an addition is made to a building or structure of Group E, I-1, I-2, I-4 or R occupancy, the existing building shall be provided with carbon monoxide alarms in accordance with Section 504.9 of the Chicago Minimum Requirements for Existing Buildings or shown to be in compliance with these requirements."
7. Delete Section 502.8.
(Amend Coun. J. 2-19-20, p. 14473, Art. IV, § 9)