Knowledge factor, k, shall be applied on a component basis.
The following information is required, at a minimum, for a component strength assessment:
- Original construction records, including drawings and specifications.
- A set of "as-built" drawings and/or sketches, documenting both gravity and lateral systems (Section 3102F.1.5) and any postconstruction modification data.
- A visual condition survey, for structural components including identification of the size, location and connections of these components.
- In the absence of material properties, values from limited in-situ testing or conservative estimates of material properties (Tables 31F-7-1 and 31F-7-2).
- Assessment of component conditions, from an in-situ evaluation, including any observable deterioration.
- Detailed geotechnical information, based on recent test data, including risk of liquefaction, lateral spreading and slope stability.
The knowledge factor, k, is 1.0 when comprehensive knowledge as specified above is utilized. Otherwise, the knowledge factor shall be 0.75 (see Table 2-1 of FEMA 356 [7.3]).
|ASTM||STEEL TYPE||YEAR RANGE3||GRADE||STRUCTURAL1||INTERMEDIATE1||HARD1|
|Minimum Yield2 (psi)||33,000||40,000||50,000||60,000||70,000||75,000|
|Minimum Tensile2 (psi)||55,000||70,000||80,000||90,000||95,000||100,000|
- The terms structural, intermediate and hard became obsolete in 1968.
- Actual yield and tensile strengths may exceed minimum values.
- Untilabout 1920, a variety of proprietary reinforcing steels were used. Yield strengths are likely to be in the range from 33,000 psi to 55,000 psi, but higher values are possible. Plain and twisted square bars were sometimes used between 1900 and 1949.
- Rail bars should be marked with the letter "R. "
- ASTM steel is marked with the letter "W."