Performance evaluation of strengthening options for institutional brick masonry buildings: A case study of Pulchowk Campus

Abstract

Four masonry classroom buildings of Pulchowk Campus constructed in 1970s were severely damaged during 2015 Gorkha Nepal earthquake and remained out of service. To replace these facilities with modern ones, Campus needed more than eight hundred million Nepali Rupees, which was not manageable at that time. Hence, strengthening of damaged classroom buildings via efficient, low cost and less time-consuming technique was developed and implemented. In these buildings, 7.45 m long prefabricated RC beams rest directly on one and half brick thick piers spaced at 3.7 m, over which prefabricated slab panels rest and on its top 5 cm thick RC overlay to provide monolithic action. During 2015 Gorkha Earthquake, bricks under these beam-piers crushed severely posing serious problem to retrofit. To arrive at the best technique, four possible options of strengthening were identified, simulated and obtained results were analyzed. RC jacketing was found the most effective method of retrofit for masonry structures; however, facade's appearance cannot be preserved. RC columns combined with brick piers via shear-keys, is the new option developed in this study, performed satisfactorily. This option, only at ground storey, improves performance slightly, however, it can be implemented incrementally phasewise when resources permit. Static pushover analyses were performed to evaluate capacities of the restored and four adopted options of retrofitting. The increase in the performance of masonry after application of different retrofitting options were evaluated. After a comprehensive analysis of the obtained results, keeping resource constraint in mind, retrofitting by using RC columns combined with brick piers at ground storey only was selected for final execution.