| = 18. CHAPTER 18 — EARTHQUAKE-RESISTANT STRUCTURES | |
| = 18.3 — Ordinary moment frames | |
| == 18.3.1 Scope | |
| === 18.3.1.1 This section shall apply to ordinary moment | |
| frames forming part of the seismic-force-resisting system. | |
| == 18.3.2 Beams shall have at least two continuous bars at | |
| both top and bottom faces. Continuous bottom bars shall | |
| have area not less than one-fourth the maximum area of | |
| bottom bars along the span. These bars shall be anchored to | |
| develop fy in tension at the face of support. | |
| == 18.3.3 Columns having unsupported length ℓu ≤ 5c1 shall | |
| have ϕVn at least the lesser of (a) and (b): | |
| (a) The shear associated with development of nominal | |
| moment strengths of the column at each restrained end of | |
| the unsupported length due to reverse curvature bending. | |
| Column flexural strength shall be calculated for the factored | |
| = R18.3 — Ordinary moment frames | |
| This section applies only to ordinary moment frames | |
| assigned to SDC B. The provisions for beam reinforcement | |
| are intended to improve continuity in the framing members | |
| and thereby improve lateral force resistance and structural | |
| integrity; these provisions do not apply to slab-column | |
| moment frames. The provisions for columns are intended to | |
| provide additional capacity to resist shear for columns with | |
| proportions that would otherwise make them more susceptible | |
| to shear failure under earthquake loading. | |
| American Concrete Institute – Copyrighted © Material – www.concrete.org | |
| PART 5: EARTHQUAKE RESISTANCE 291 | |
| 18 Seismic | |
| No further reproduction or distribution is permitted. | |
| CODE | |
| axial force, consistent with the direction of the lateral forces | |
| considered, resulting in the highest flexural strength. | |
| (b) The maximum shear obtained from design load combinations | |
| that include E, with ΩoE substituted for E. | |
| == 18.3.4 Beam-column joints shall satisfy Chapter 15 with | |
| joint shear Vu calculated on a plane at mid-height of the joint | |
| using tensile and compressive beam forces and column shear | |
| consistent with beam nominal moment strengths Mn. | |
| [ Lanjut Ke 18.4—Intermediate moment frames ... ] | |
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