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Repetitive But Not Quite

I’m on site today, reviewing masonry conditions at a project. It’s not new…as a matter of fact, I have our design drawings for repair that were created some time ago, and I’ll be using them as the basis for reviewing the conditions now. This is the third time I’ve reviewed the same conditions, at roughly 30-month intervals.

I think the reason why is fairly obvious. Conditions can change over time, and if we’re worried about distress changing to risky damage, we need to track the changes. The project was delayed for a while as the owner secured funding; it was delayed again by Covid.

In a recent conversation with an engineer at the beginning of his career, I amused him by saying that information found during a structural investigation has to be pinned down in four dimensions to be useful. The first reason for that is clear to everyone, I think: information is only meaningful if it is complete. The location, length, direction, and width of a masonry crack, combined with the date that geometry was noted comprises usable data.

The second reason is more esoteric, rooted in how engineering investigations move from data to conclusions. Qualitative analysis, which is part of nearly every investigation I’m involved with, depends on comparing the pattern of visible damage to the best model available of the load paths. Knowing that a new crack has appeared tells me nothing, but knowing its geometry relative to the pre-existing pattern and when it appeared relative to when other cracks appeared tells me a whole lot.

Four-dimensional information. Don’t leave a building without it.