In 2010 I applied two rapid screening methods to Berkeley Town House, a 9-story residential apartment building in Berkeley, California. This month I learned of another screening method that had been validated in Turkey, Haiti, and China on mostly similar (i.e. reinforced concrete) buildings. Its validation was reported by Wei Zhou, Wenzhong Zheng, and Santiago Pujol in an article titled “Seismic vulnerability of reinforced concrete structures affected by the 2008 Wenchuan earthquake” in Bulletin of Earthquake Engineering, 11 (2013), 2079–2104. Here is a supplement, applying that method to Berkeley Town House.
The input data are:
- Total cross-sectional area of reinforced concrete columns on ground floor: 3.2 square meters
- Total cross-sectional area of north–south reinforced concrete walls on ground floor: 2 square meters
- Total cross-sectional area of east–west reinforced concrete walls on ground floor: 4.8 square meters
- Bounding rectangle area: 576 square meters
- Total areas above ground levels: 4608 square meters
- Total cross-sectional area of north–south infill masonry walls on ground floor: 1 square meter
- Total cross-sectional area of east–west infill masonry walls on ground floor: 3.4 square meters
The computations on these data are:
- Wall index (WI): (2 + 0.1)÷4608×100% = 0.046%
- Column index (CI): 0.5×3.2÷4608×100% = 0.035%
- Priority index: 0.046% + 0.035% = 0.081%
The larger the priority index, the more likely a building was to escape damage.
In their China validation, Zhou et al. used two different methods of damage classification and report that “no building was classified as having severe damage by either method for priority indices exceeding 0.3%”. Over all, they report that “Approximately 20 % (25 out of 116) of the surveyed buildings had damage involving the failure of at least one structural element.” Roughly half of the buildings with priority indices less than 0.1% (like Berkeley Town House) suffered moderate or severe damage. This result appears to me to suggest a more pessimistic prediction than the results produced in the above-cited previous report.
Few of the buildings on which this method was validated were as tall as Berkeley Town House. For this and other reasons mentioned in the above-cited previous report, this computation and any inferences from it have unknown value. I have performed these computations to satisfy my own curiosity, in the absence of a seismic assessment or screening performed by a competent professional.