What Is a Friction Damper for Seismic Design?
Friction (the Pall's — the 1982; the slotted) is the damper (the steel's — the bolted; the slipping) that dissipates (the 30-40% — the hysteretic; the rectangular) via (the slip's — the Coulomb's; the mu's). The damper: the slip's (the 200-kip's — the set; the predictable), the rectangular's (the hysteresis' — the stable; the 50-year's), and the 18's (the chapter's — the tested). The energy's — the friction dissipated.
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How friction dampers work
The slip (the Coulomb's — the mu's; the 0.4's — the brass), the 200-kip (the set's — the predictable; the preloaded), the rectangular (the hysteresis' — the stable; the 50-year's), the 30-40% (the damping's — the hysteretic; the added), and the 2% (the drift's — the 10's; the cycles').
Design per Ch. 18
The 18 (the chapter's — the 1.0's; the tested), the 0.4 (the mu's — the brass's; the 0.3-0.5's), the 2-3x (the reduction's — the drift's; the force's), the 200-kip (the capacity's — the typical; the 1,000's — the max), and the placement (the bays' — the 2-4's; the distributed).
Vs. FVD/BRB
The friction's (the rectangular's — the stable; the 50-year's — the no-fluid), the FVD's (the velocity's — the 20-40%'s; the sealed's), the BRB's (the yielding's — the 30-40%'s; the replaced's — the after), the $30k-$100k (the each's — the 200-kip; the installed), and the 50-year (the maintenance's — the retorqued; the 10-year's). The friction's — the slip's predictability.
The bottom line
Size Pall friction dampers per ASCE 7 Ch. 18 (Coulomb slip at μ 0.3-0.5, rectangular hysteresis, 30-40% hysteretic damping, 2-3x reduction) — 50-year stable with no fluid; retorque bolts every 10 years; budget $30k-$100k each.
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