CHOURASIA AJAY1, BHATTACHARYYA, S.K.2, BHANDARI, N.M.3, and BHARGAVA PRADEEP4

1 Principal Scientist, CSIR-Central Building Research Institute (CBRI), Roorkee, India E-mail address:ajayc@cbri.res.in

2 Director, CSIR-Central Building Research Institute (CBRI), Roorkee, India E-mail address: sriman_bhattacharyya@yahoo.com

3 Emeritus Professor, Indian Institute of Technology Roorkee, Roorkee, India. E-mail address: nmbcefce@iitr.ac.in

4Professor, Indian Institute of Technology Roorkee, Roorkee, India E-mail address: bhpdpfce@iitr.ernet.in

To evaluate the behaviour of indigenously built masonry buildings during earthquake, full-scale tests on one room size masonry model 3.01×3.01m in plan and 3 m high, have been tested under quasi-static cyclic lateral displacements to study the relative performance of different types of construction practices prevalent. The three types of masonry buildings tested were in unreinforced masonry (URM), reinforced masonry (RM) and confined masonry (CM). Confined masonry is a structural system consisting of normal masonry walls strengthened by a framework of horizontal and vertical “confining” reinforced concrete members called bond beams and tie columns, embressing the masonry walls.

Further, to evaluate effectiveness of various repair and retrofitting measures, URM and RM models were repaired/retrofitted after first testing and then re-tested. The repair of masonry was carried out using concrete stitching across the cracks and plastering cracks with embedded galvanised iron (GI) welded wire mesh. The retrofitting of damaged URM model was performed with mild steel twin lintel belt and corner vertical reinforcement. This paper compares the performance of all the three types of masonry construction along with effectiveness of the repaired/retrofit schemes. The performance of CM over URM and RM in terms of strength showed about 3.42 and 2.63 times improvement and in terms of ductility around 4.29 and 1.39 folds increase respectively.

Keywords: Unreinforced masonry, Reinforced masonry, Confined masonry, strength, stiffness, ductility