Banda Aceh, Aceh, Indonesia
So the "Nameless NGO" (or should I refer to them as "the NGO we do not speak of"?) wants to retrofit the houses rather than demolishing them, even if it costs more to do so, which I believe will.
So how do you retrofit a poorly constructed confined masonry house? Let's start with listing what's wrong.
The connections in the reinforced columns to ring beams and the ring beams to each other at most, the rebar only hooks, and doesn't overlap. I have even seen where the rebar didn't even reach the column (see photo below), but I hope this is more uncommon than I think. Solution? I see two.
First, sandwich the beam/beam or beam/column/beam connections with steel plates on both sides and bolt through the concrete. Problem? It's going to cost a lot, steel and welders are not cheap, even out here, and this is also assuming the concrete is okay (many places you can break it away with your hands). Second, you'll have to remove a lot of masonry in order to get the plates connected to the columns and beams. And third, you got esthetics, it'd look horrible, like some Borg house and the home owners won't want to live in it.
Second solution, remove the concrete exposing the rebar at the connection and remove it as far back as needed in order to get a lap splice. We're using 50cm splices on 10mm diameter bars. So I envision removing the concrete at least 50cm from the joint along the beams and column, then place a 90degree bent bar so it'll lap with the longitudinal reinforcing bars in each perpendicular direction. You'll have to do this for each of the longitudinal bars. So you'll have four coming in from each of three directions. In a way it's "bridging the gap". I see this as the cheapest and esthetically the best solution, assuming we can fit all the bars in the given space, which it may.
By the way, if any of these ideas sound crazy or wrong, please let me know. That is why I'm posting this.
You have poorly built masonry infill. A number of bricks pop out with just the force of your hand. Also, many of the bricks are weak due to not being fully fired and the overall workmanship of the masonry is poor. Solutions? Again, I see two.
First, wrap the masonry wall with webbing or mesh of either carbon fiber or welded wire mesh embedded in plaster. At the ends of the walls, you'll have to wrap it around the columns. Questions? How do you wrap the webbing around the column when you have another masonry infill on the opposite or adjacent side of the column without removing that masonry? How do you wrap around the bottom, or the plinth beam? Do you need to? Carbon fiber is expensive, even in the States, so let's knock that one off the solutions. And lastly, what would prevent the mesh from "delaminating" from the masonry?
Second solution; build a stud wall on the internal face of the wall out of timber or light gage steel and fasten the stud wall to the masonry wall via bolts with plate washers spaced out on a grid pattern. Problems? You loose a lot of floor space on an already small house. It also requires a timber covering or drywall to cover up the stud framing. You want to stay away from timber if you can, because most likely it'd be coming from an illegal forest.
There are other issues with the houses, gable wall, terrace beams and foundation but we either have answers to those or require further research.
So I just got back from a meeting with the "nameless NGO" and they were very understanding and willing to do what is needed to get these houses seismically safer. They agreed the workmanship was very poor. What Elizabeth and I need to do is narrow down the options and come up with some details and procedures showing how to implement all of this. They, the "nameless NGO", will in turn give the same options to the contractor and tell them, retrofit it this way or tear it down and rebuild it, either way, you're not going to get paid until something is done.