Archive for April, 2014

Do-it-yourself seismic screening: an update

Thursday, April 17th, 2014

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.

Mass toilet extinction looms

Thursday, April 10th, 2014

Back in 2009, my wife and I replaced a 50-year-old wall-hung toilet in the Berkeley co-op apartment that we had just taken possession of. At the time, this replacement was optional. We thought it was smart, because the toilet leaked water and flushed more that 4 times as much water as a modern water-saving toilet. Also, repairing the old toilet had become difficult and expensive.

Well, what we did in 2009, and a few others in our building have likewise done, is now becoming mandatory, rather than optional. California is getting more serious about water conservation. Soon after we got our new toilet, the governor signed Senate Bill 407 into law. This new statute put the state on notice that old, water-guzzling fixtures would have to be replaced within 8 years in single-family or 10 years in multi-family residences. The provisions relevant to us remain in effect in Section 1101.5 of the Civil Code.

We who live in Berkeley Town House have 5 more years before the ax falls on our (by then 57-year-old) toilets on 1 January, 2019. And, starting this year, those of us who remodel our bathrooms can’t wait; we must include toilet replacements in our remodeling plans. These requirements would not apply to us if a licensed plumber were to certify that “installation of water-conserving plumbing fixtures is not technically feasible” in our building, but such a certification would, in my opinion, be a lie, because several members of our co-op have successfully made such replacements.

(The same law requires the replacement of water-wasting shower heads and faucets by the same deadlines.)

This mandate raises the question, on whom is this toilet-replacing obligation imposed? The answer isn’t obvious. Our co-op’s governing documents make each member responsible for the maintenance and repair of the toilet(s) in that member’s apartment. But the statute refers to the “owner” as having the duty to replace fixtures, and the owner of our entire property is Berkeley Town House Cooperative Corporation. Each co-op member is a tenant of the corporation. One could ask for an attorney’s opinion about this. Or one could decide that it’s simply stupid to expect every co-op member to undertake an individual toilet-replacement project, even if legally it’s an individual member’s responsibility. Why would it be smarter for the co-op to assume this obligation?

  1. The co-op could get the job done at less expense by competitively bidding it out as a large co-ordinated job.
  2. The co-op could get a single permit for all 70-odd toilet replacements, saving about $20,000 in permit fees.
  3. Given the rare toilet and wall types in this building, it’s difficult to get a plumber with relevant experience to take such a job at a reasonable fixed price. Even one bungled job could produce a flood causing hundreds of thousands of dollars in damage. The co-op could be more effective in assuring quality work.
  4. Doing the job collectively would eliminate the need to enforce the requirement against individual members.
  5. We pay for the water collectively, so it’s in our interest to get the replacements performed well, soon, and with fixtures that are highly water-saving.
  6. In many cases, replacement of a single toilet requires the shutoff of the entire building’s hot and cold water for several hours, at a cost of $300–400, with a lot of water wasted when it’s drained out of all the pipes, and with inconvenience to all residents. Coordinated replacements could minimize the shutoff days and times.

What should the co-op do about this? Since its money is flowing down the drain with every passing minute, one could argue that the co-op should get busy organizing compliance with this law early, rather than waiting until just before the deadline. What do you think? There’s a comment box below. Voice your opinion!