(a) Members that are continuously supported by soil or supported by other structural members capable of providing continuous vertical support
(b) Members for which arch action provides compression under all conditions of loading
- Structural plain concrete basement, foundation or other walls below the base as defined in ASCE 7 are permitted in detached one- and two-family dwellings three stories or less in height constructed with stud-bearing walls. In dwellings assigned to Seismic Design Category D or E, the height of the wall shall not exceed 8 feet (2438 mm), the thickness shall be not less than 71/2 inches (190 mm), and the wall shall retain no more than 4 feet (1219 mm) of unbalanced fill. Walls shall have reinforcement in accordance with 14.6.1.
- Isolated footings of plain concrete supporting pedestals or columns are permitted, provided the projection of the footing beyond the face of the supported member does not exceed the footing thickness.
Exception: In detached one- and two-family dwellings three stories or less in height, the projection of the footing beyond the face of the supported member is permitted to exceed the footing thickness.
- Plain concrete footings supporting walls are permitted, provided the footings have at least two continuous longitudinal reinforcing bars. Bars shall not be smaller than No. 4 and shall have a total area of not less than 0.002 times the gross cross-sectional area of the footing. For footings that exceed 8 inches (203 mm) in thickness, a minimum of one bar shall be provided at the top and bottom of the footing. Continuity of reinforcement shall be provided at corners and intersections.
- In Seismic Design Categories A, B and C, detached one- and two-family dwellings three stories or less in height constructed with stud-bearing walls are permitted to have plain concrete footings without longitudinal reinforcement.
- For foundation systems consisting of a plain concrete footing and a plain concrete stemwall, a minimum of one bar shall be provided at the top of the stemwall and at the bottom of the footing.
- Where a slab on ground is cast monolithically with the footing, one No. 5 bar is permitted to be located at either the top of the slab or bottom of the footing.
(a) Influence of climatic conditions
(b) Selection and proportioning of materials
(c) Mixing, placing, and curing of concrete
(d) Degree of restraint to movement
(e) Stresses due to loads to which an element is subjected
(f) Construction techniques
Table 18.104.22.168.1—Location of critical section for Mu
|Supported member||Location of critical section|
|Column or pedestal||Face of column or pedestal|
|Column with steel base plate||Halfway between face of column and edge of steel base plate|
|Concrete wall||Face of wall|
|Masonry wall||Halfway between center and face of masonry wall|
|Mn = 0.85f'cSm||(22.214.171.124b)|
where Sm is the corresponding elastic section modulus.
Table 126.96.36.199—Combined flexure and axial compression
Table 188.8.131.52—Nominal bearing strength
|Relative geometric conditions||Bn|
|Supporting surface is wider on all sides than the loaded area||Lesser of:||(a)|
Reinforcement shall be provided as follows:
- Vertical reinforcement of at least 0.20 square inch (129 mm2) in cross-sectional area shall be provided continuously from support to support at each corner, at each side of each opening and at the ends of walls. The continuous vertical bar required beside an opening is permitted to substitute for one of the two No. 5 bars required by 14.6.1.
Horizontal reinforcement at least 0.20 square inch (129 mm2) in cross-sectional area shall be provided:
- Continuously at structurally connected roof and floor levels and at the top of walls;
- At the bottom of load-bearing walls or in the top of foundations where doweled to the wall; and
- At a maximum spacing of 120 inches (3048 mm).