Laserfiche WebLink
4 <br /> <br />22.10.1- Structures assigned to Seismic Design Category C, D, E or F shall not have <br />elements of structural plain concrete, except as follows: <br /> <br />a. Isolated footings of plain concrete supporting pedestals or columns are permitted, <br />provided the projection of the footing beyond the face of the supported member <br />does not exceed the footing thickness. <br />Exception: In detached one- and two-family dwelling three stories or less in <br />height, the projection of the footing beyond the face of the supported member is <br />permitted to exceed the footing thickness. <br />b. Plain concrete footing supporting walls are permitted, provided the footings have <br />at least two continuous longitudinal reinforcing bars. Bars shall not be smaller <br />than No. 4 and shall have a total area of not less than 0.002 times the gross cross- <br />sectional area of the footing. A minimum of one bar shall be provided at the top <br />and bottom of the footing. Continuity of reinforcement shall be provided at <br />corners and intersections. <br />Exception: In detached one- and two-family dwellings three stories or less in <br />height and constructed with stud bearing walls, with at least two continuous <br />longitudinal reinforcing bars not smaller than No. 4 are permitted to have a total <br />area of less than 0.002 times the gross cross–sectional area of the footing <br />. <br /> Sections 1905.1.10 through 1905.1.12 are added as follows: <br /> <br />1905.1.10 ACI 318, Section 21.6.4. Modify ACI 318, Section 21.6.4, by adding Section <br />21.6.4.8 and 12.6.4.9 as follows: <br /> <br />21.6.4.8 Where the calculated point of contraflexure is not within the middle half of the <br />member clear height, provide transverse reinforcement as specified in ACI 318 Sections <br />21.6.4.1, Items (a) through (c), over the full height of the member. <br /> <br />21.6.4.9 – At any section where the design strength, ϕP n , of the column is less than the sum <br />of the shears V e computed in accordance with ACI 318 Sections 21.5.4.1 and 21.6.5.1 for all <br />the beams framing into the column above the level under consideration, transverse <br />reinforcement as specified in ACI 318 Sections 21.6.4.1 through 21.6.4.3 shall be provided. <br />For beams framing into opposite sides of the column, the moment components are permitted <br />to be assumed to be of opposite sign. For the determination of the design strength, ϕP n , of the <br />column, these moments are permitted to be assumed to result from the deformation of the <br />frame in any one principal axis. <br /> <br />1905.1.11 ACI 318, Section 21.9.4. Modify ACI 318, Section 21.9.4, by adding Section 21.9.4.6 <br />to read as follows: <br /> <br />21.9.4.6 – Walls and portions of walls with P u > 0.35P o shall not be considered to contribute <br />to the calculated shear strength of the structure for resisting earthquake-induced forces. Such <br />walls shall conform to the requirements of ACI 318 Section 21.13.