7

Columns with architectural flares — with or without an isolation gap

OANR: Remove flare Note: OANR means a design alternate where owners approval is not required and a higher level of analysis (pushover in SDAP E) can be avoided.

FIGURE 20.9 Permissible earthquake resisting elements that require owner's approval [37].

curved superstructures, varying structure types, outriggers, unbalanced mass and stiffness, high skew) and unusual geologic conditions (soft soil, moderate to high liquefaction potential and proximity to an earthquake fault). In this case, project-specific criteria need to be developed to address their nonstandard features.

For important bridges such as the San Francisco-Oakland Bay Bridge and the Benicia-Martinez Bridge or structures in a designated lifeline route, performance-based project-specific two-level seismic design criteria [28-30] are required.

Plastic hinges in superstructure

Bearing systems that do not provide for the expected displacements and/or forces (e.g., rocker bearings)

Plastic hinges in superstructure

Bearing systems that do not provide for the expected displacements and/or forces (e.g., rocker bearings)

Battered-pile systems that are not designed to fuse geotechnically or structurally by elements with adequate ductility capacity

Cap beam plastic hinging (particularly hinging that leads to vertical girder movement) also includes eccentric braced frames with girders supported by cap beam

Battered-pile systems that are not designed to fuse geotechnically or structurally by elements with adequate ductility capacity

FIGURE 20.10 Earthquake resisting elements that are not recommended for new bridges (ATC/MCEER Joint Venture, 2001).

- Knock-off curb

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