30 September 1999
-1.0 for poor details in high seismic regions; from +0.8 to -0.8 for moderate seismic regions; and
from +0.6 to -0.6 for low seismic regions. A detail modifier of 0.0 denotes average details. The
reviewer should determine the details for each building type (e.g., wall openings, connections,
or foundations) that will have a significant impact on the capability of the structural system to
protect the life safety of the occupants. The reviewer should then assign an approximate
judgmental weighting factor to each detail, based on its importance, so that the cumulative
modifier falls within the -1.0/-0.8/-0.6 to +1.0/+0.8/+0.6 range (high/moderate/low regions of
seismicity). It should also be noted that some detailing features might preempt an otherwise
good rating of other details. For example, a shear wall building, with minimal wall openings (i.e.,
reduced not more than 25 percent by wall openings, and acceptable foundation details) may
have minimal connections to floor and roof diaphragms, and in the judgment of the reviewer,
should therefore be assigned a cumulative modifier of -0.7/-0.6/-0.4 (high/moderate/low regions
of seismicity). The following are examples of qualitatively evaluated details. The values in the
parentheses (e.g., +1.0/+0.8/+0.6) are intended to provide a relative range of the modifier for
each specific detail in the (high/moderate/low) regions of seismicity.
Concrete or masonry shear walls with the gross cross-sectional area at any
story reduced not more than 25 percent by window or door openings (e.g., +1.0/+0.8/+0.6). If
reduced by openings more than 75 percent (e.g., -1.0/-0.8/-0.6).
Positive ties at floor and roof diaphragms to resist out-of-plane forces on
exterior walls (e.g., +0.5/+0.4/+0.3). If no indication of ties (e.g., -1.0/-0.8/-0.6).
Positive connections to transfer diaphragm shears to vertical resisting
elements (e.g., +0.5/+0.4/+0.3). If no indication of connections (e.g., -0.5/-0.4/-0.3).
Anchorage of wood framed buildings to foundation to prevent sliding or uplift
(e.g., +0.5/+0.4/+0.3). If no indication of anchorage (e.g., -0.5/-0.4/-0.3)
Diagonal trim bars at openings in concrete walls are desirable to restrain
corner cracking under in-plane lateral forces. If trim bars are provided when window or door
openings constitute 20% or more of the gross horizontal cross-section of the wall (e.g.,
+0.3/+0.2/+0.2). If no indication of trim bars (e.g., -0.3/-0.2/-0.2), no modifier is required (0.0)
when openings constitute less than 20% of the gross cross-section.