The provisions of Section 906 of IEBC are adopted by reference with the following modifications:
1. Revise Section 906.2 to read:
"906.2 Existing structural elements resisting lateral loads.
Where work involves a substantial structural alteration, the lateral load-resisting system of the altered building shall be shown to satisfy the requirements of Sections 1609 and 1613 of the Chicago Building Code. Reduced seismic forces shall be allowed.
Exceptions:
1. Buildings of Group R-5 occupancy that are altered based on the conventional light-frame construction methods of the Chicago Building Code.
2. Where the intended alteration involves only the lowest story above grade plane of a building, only the lateral load resisting components in and below that story need comply with this section."
2. Delete Section 906.3.
3. Revise Section 906.4 to read:
"906.4. Anchorage for concrete and masonry buildings.
For any building assigned to Seismic Design Category D with a structural system that includes concrete or reinforced masonry walls with a flexible roof diaphragm, the alteration work shall include installation of wall anchors at the roof line of all subject buildings and at the floor lines of unreinforced masonry buildings unless an evaluation demonstrates compliance of existing wall anchorage. Reduced seismic forces shall be allowed."
4. Revise Section 906.5 to read:
"906.5 Anchorage for unreinforced masonry walls.
For any building assigned to Seismic Design Category C or D with a structural system that includes unreinforced masonry bearing walls, the alteration work shall include installation of wall anchors at the roof line, unless an evaluation demonstrates compliance of existing wall anchorage. Reduced seismic forces shall be allowed."
5. Revise Section 906.6 to read:
"906.6 Bracing for unreinforced masonry parapets.
Parapets constructed of unreinforced masonry in buildings assigned to Seismic Design Category C or D shall have bracing installed as needed to resist the reduced seismic forces in accordance with Section 303.3, unless an evaluation demonstrates compliance of such items. Use of reduced seismic forces shall be allowed."
6. Revise Section 906.7 to read:
"906.7 Anchorage of unreinforced masonry partitions.
Where the building is assigned to Seismic Design Category C or D, unreinforced masonry partitions and nonstructural walls within the work area and adjacent to egress paths from the work area shall be anchored, removed, or altered to resist out-of-plane seismic forces, unless an evaluation demonstrates compliance of such items. Use of reduced seismic forces shall be allowed."