Damage limitation and structural behaviour factor for masonry structures

Different codes provide a range of values for structural behaviour factor for various masonry building systems. High variation in structural behaviour factors in different codes arises mainly due to the lack of information from experimental studies. Thus, the present paper highlights investigation of behaviour of different masonry construction systems through full-scale tests on masonry buildings subjected to cyclic displacement. Six tests, out of which three on virgin masonry building systems, employing unreinforced masonry (URM), reinforced masonry (RM) and confined masonry (CM) having similar geometrical, material, constructional features and test procedures were conducted. The remaining three building models tested included repaired unreinforced masonry (URM-REP), retrofitted unreinforced masonry (URM-RET) and retrofitted reinforced masonry (RM-RET). Observations and data from the experiments have been co-related between damage index, grade of damage and displacement capacity, thereby estimation of structural behaviour factor for different masonry building typologies. The analysis shows that the ranges of structural behaviour factor mentioned in codes are adequate for URM and RM, while the same for CM is conservative, which can be relaxed. Also, it has been noticed that there is a substantial increase in structural behaviour factor for repaired and retrofitted masonry structures, thus proving the structural adequacy of retrofitting measures.