Confined masonry construction is very common in El Salvador. More than 60% of the houses were built from mixto, a type of confined masonry with closely spaced tie-beams and a small tie-column spacing.
Confined masonry buildings performed well in the El Salvador earthquakes of January 13 and February 13, 2001 (magnitudes of 7.7 and 6.6, respectively), which killed over 1,100 people. More than 160,000 houses collapsed, accounting for approximately 20% of the dwellings in the country (EERI, 2001).
The General Office of Statistics and Censuses in El Salvador published damage statistics data for concrete and confined masonry buildings affected by the 2001 earthquakes. Over 90% of the buildings of this type were undamaged. Only 5.9% of confined masonry or concrete buildings experienced repairable damage, while 2.4% of the buildings were damaged beyond repair (Dowling, 2004). Among the damaged buildings of this type, there were a few instances of wall shear failure, as well as out-of-plane wall failures (where the wall toppled outwards in spite of confining elements). It should be noted that most of the damaged or collapsed dwellings in the 2001 earthquake were of adobe construction (Dowling, 2004). As reported by Ascheim et al. (2006), mixto confined masonry construction was used in the post earthquake rehabilitation following the 2001 earthquakes.
- Preliminary Observations on the El Salvador Earthquakes of January 13 and February 13, 2001, EERI (2001), EERI Special Earthquake Report. Newsletter. Earthquake Engineering Research Institute, California, July 2001.
- Adobe Housing Reconstruction after the 2001 El Salvador Earthquakes, Dowling, D.M (2004), Lessons Learned Over Time – Learning From Earthquakes Series, Volume 5, Earthquake Engineering Research Institute (EERI), Oakland, California, 69 pp.
- Improving the Earthquake Resistance and Sustainability of Confined Masonry (Mixto) Dwellings in El Salvador, M. Aschheim, S. Flanagan, J. Harlander, C. Pitt, A. Alfaro, C. Rivas, and M. E. Rodriguez (2006), Proceedings of the 8th U.S. National Conference on Earthquake Engineering, San Francisco, USA, Paper No. 1462.