General
Design Criteria is as follows:
1. OSSC
section 1613 is used to design for earthquake loads. Seismic design
category shall be “D” unless site specific conditions increase
design category to “E or F” (reference codes American Society of
Civil Engineers ASCE/SEI 7-05). Residential projects falling
under the ORSC shall use seismic zone D1.
2. OSSC
section 1609 is used for wind design. The design wind speed is 94.5
miles per hour (3-second gust). See section 1609.3.1 for additional
design information. Residential projects falling under the ORSC
shall use a design wind speed of 100 miles per hour (3-second
gust). See section R301.2.1.3 for additional design information.
Most
areas of Klamath County can be classified as wind exposure category
C. However, some areas may meet the criteria for exposure B
(typically within Urban Growth/ City Limits). The design
professional is responsible for justifying the exposure selected for
the specific area of construction.
3. Soils
bearing pressure is 1,500 pounds per square foot, unless justified
by a soils report. A lesser bearing pressure may be required in
specific locations.
4.
Ground snow loads are site specific and are published from the
Structural Engineers Association of Oregon “Snow Load Analysis
for Oregon” 3rd edition Dec 2007. However design
snow loads shall be a minimum of 25 pounds per square foot, with
factors: slope, exposure, thermal, importance, drifting, etc.
5.
Rainfall design is site specific and based on U.S. Weather Bureau
Technical paper #40: 100-year 60 minute storm. Klamath County has
four rainfall zones (3, 9, 10 & 13).
6. The
frost depth for foundation design is 24” below grade.
7. Flood
Loads section 1612 (if applicable)
