Augmenting Strength of Collapsed Unreinforced Masonry Junctions: Principal Damage Feature of Walls Damaged by Moderate Indian Earthquakes

Abstract

Frequently occurring moderate earthquakes in the Indian subcontinent have extensive impact on the nonengineered shelters of the local people inhabiting them because these shelters generally consist of unreinforced masonry walls. Through a reconnaissance-based damage survey of two such earthquakes in the Eastern Himalayas and that of another in the plains, the present paper identifies the absence of proper connections at masonry junctions as the principal cause of damage. To augment junction strength subjected to reversible lateral loading, the survey proposes reinforcing with L-shaped steel dowels or encasing with polypropylene bands, which incurs a minimal cost increase. The results from shaking table tests show that such measures may lead to a quantifiable increase in the lateral strength of the junctions, which helps in evolving empirical design guidelines at the artisanal level.