Optimum retrofitting methods for low rise masonry structures in Sri Lanka

Abstract

Floods can be considered as one of the natural hazards which cause destructive effects on the existence of mankind. Most of the mortalities have taken place due to damages in masonry walls of unreinforced masonry structures. These walls have failed due to its insufficient capacity to resist lateral forces exerted by floods. A field survey that was carried out in houses damaged due to flood revealed that, the outermost walls can play a major role in reducing flood induced damage, if they are strengthened to resist lateral forces applied by floods. Retrofitting of masonry walls has been recognized as a possible solution to strengthen the masonry structures against the aforementioned forces. Many researches have done in the past to strengthen the masonry walls by using different retrofitting types. Most of them are limited only to in plane behavior of walls with retrofitting. The study has focused on the out of plane loading exerted by flooding. The failure mechanism due to floods was identified as the flexure parallel to bed joint of the masonry based on the field study conducted in the flood affected areas of Sri Lanka. The experimental program was mainly focused on flexure parallel to bed joint. Fired Clay Bricks (FCB) and Cement Blocks (CB) were used as the walling material for panels, whereas geogrid and wire mesh were used as the retrofitting materials for the research. The FCB panels retrofitted with geogrid and rendering under saturated conditions have shown an increase of 9.2 times the flexural strength of the reference wall panel without any retrofitting which is subjected to saturated condition and 6.78 times for the wire mesh. For CB, it was 5.8 times and 4.5 times respectively. The results have indicated that the masonry houses can be retrofitted and deployed to protect the people from floods.