(A) Corbeling. Corbels may be built only into solid masonry walls 12 inches or more in thickness. The projection for each course in such corbel shall not exceed one inch, and the maximum projection shall not exceed one-third the total thickness of the wall when used to support structural members, and not more than six inches when used to support a chimney built into the wall. The top course of all corbels shall be a header course.
(B) Combined units. In walls or other structural members composed of different kinds or grades of units, materials or mortars, the maximum stress shall not exceed the allowable stress for the weakest of the combinations of units, materials and mortars of which the member is composed. The net thickness of any facing unit which is used to resist stress shall be not less than one and one-half inches.
(C) Piers. Every structural pier whose width is less than three times its thickness shall be designed and constructed as required for columns.
(D) Chases. Chases and recesses in masonry walls shall be designed and constructed so as not to reduce the required strength or required fire resistance of the wall.
(E) Stack bond. In unreinforced masonry where masonry units are laid in stack bond, longitudinal reinforcement consisting of not less than two continuous wires each with a minimum aggregate cross-sectional area of 0.017 square inch shall be provided in horizontal bed joints spaced not more than 16 inches on center vertically.
(F) Lintels. Masonry walls shall be reinforced over openings in accordance with the table below. The reinforcement shall be located in spaces fully grouted to a depth of not less than eight inches and shall extend not less than eight inches beyond the sides of the opening.
Allowable Span for Masonry and Steel Lintels Supporting Masonry Walls | ||||
Allowable Span in Feet and Inches | ||||
Number of 1/2 in. diameter or equivalent area, reinforcing bars | No Floor Above | One Floor Above | Two Floors Above | Structural Steel |
1 | 4 ft. 6 in. | 3 ft. 0 in. | 2 ft. 6 in. | 2-1/4 x 2-1/2 x 5/16 3 x 3 x 1/4 |
2 | 6 ft. 0 in. | 4 ft. 0 in. | 3 ft. 6 in. | 3-1/2 x 3-1/2 x 5/16 ST 5 I |
3 | 8 ft. 6 in | 5 ft. 0 in. | 4 ft. 0 in. | ST 5 ST 6 I |
4 | 10 ft. 0 in. | 6 ft. 0 in. | 5 ft. 0 in. | ST 6 ST 8 B |
(G) Anchorage. Floor and roof systems shall be firmly anchored to masonry walls. The typical drawing, § 150.190, may be used to graphically interpret anchorage requirements.
(H) Beam supports. Beam, girders or other concentrated loads supported by a wall or column shall have bearing of at least four inches in depth measured parallel to the beams and four inches in length upon solid masonry or upon a metal bearing plate of adequate design and dimensions to distribute the load safely.
(Prior Code, § 9-113) (Ord. 94-11B, passed 4-21-1994)