How does ideCAD defines define the redundany redundancy factor, ρ, according to ASCE 7-16?
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Eh = Horizontal seismic load effect
hwall = height of shear wall
hwp = height of wall pier
Lwall = length of shear wall
Lwp = length of wall pier
ρ = Redundancy factor
QE = Effects of horizontal seismic forces from V or Fp
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Download ideCAD for ASCE 7-16 |
Redundancy is an important property for structures designed with the expectation that damage will occur. Redundant structures have alternative load paths so that if some elements are severely damaged and lose load-carrying capacity, other elements will be able to continue to provide a safe load path. Adequate redundancy is ensured when a large number of plastic hinges must form throughout the structure progressively before the formation of a mechanism and when no element is required to provide the full seismic resistance of the structure. The redundancy factor, ρ, is automatically obtained horizontal seismic forces according to ASCE 7-16 Section 12.3.4.
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Each story resisting more than 35% of the base shear in the direction of interest according to Table 12.3-3.
Structures are regular in plan at all levels provided that the seismic force-resisting systems consist of at least two bays of seismic force-resisting perimeter framing on each side of the structure in each orthogonal direction at each story resisting more than 35% of the base shear.
Lateral Force-Resisting Element | Requirement |
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Braced frames | Removal of an individual brace, or connection thereto, would not result in more than a 33% reduction in story strength, nor does the resulting system have an extreme torsional irregularity (horizontal structural irregularity Type 1b). |
Moment frames | Loss of moment resistance at the beam-to-column connections at both ends of a single beam would not result in more than a 33% reduction in story strength; nor does the resulting system have an extreme torsional irregularity (horizontal structural irregularity Type 1b). |
Shear walls or wall piers with a height-to-length ratio greater than 1.0 | Removal of a shear wall or wall pier with a height-to-length ratio greater than 1.0 within any story, or collector connections thereto, would not result in more than a 33% reduction in story strength; nor does the resulting system have an extreme torsional irregularity (horizontal structural irregularity Type 1b). The shear wall and wall pier height-to-length ratios are determined as shown in Figure. |
Cantilever columns | Loss of moment resistance at the base connections of any single cantilever column would not result in more than a 33% reduction in story strength; nor does the resulting system have an extreme torsional irregularity (horizontal structural irregularity Type 1b). |
Other | No requirements. |
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Download ideCAD for ASCE 7-16 |