Study On Performance Based Seismic Evaluation And Strengthening For Vulnerable Buildings In Mandalay Region
This paper discusses study on performance based seismic evaluation and strengthening technique for existing brick-nogging buildings in Mandalay region. The main objective of this paper is to investigate their seismic performances, damage probabilities and to determine suitable strengthening technique of existing brick-nogging buildings under strong earthquake shaking. Myanmar is located in Alpide earthquake belt and quite earthquake prone region. There had been a lot of major earthquake (M7.0 – M7.9) and a strong earthquake (M8.0) in the past and some of which were quite destructive. Based on the observation of Thabeikkyin earthquake at 2012, the existing brick-nogging buildings reached the most vulnerable condition. Moreover, they were mostly constructed by local occupant. So, in this research, twelve case study buildings are selected to evaluate their seismic performances and damage probabilities for determining that they may or may not need further strengthening. As for the development of Performance based concept, nonlinear Static (Push-over) Analysis is used: to check performance levels of structure under minimum operational earthquake (MOE), design basic earthquake (DBE) and maximum considered earthquake (MCE) ground motions. Fragility curves were derived by using analytical approach with capacity spectrum method. The method of displacement control analysis was used. The 2% of total structure heights was used for displacement control value. Based on analysis results, it was needed to strengthen for resisting up to maximum considered earthquake shaking. Therefore, bracing was selected for upgrading them. After strengthening, the proposed buildings would be sustained MCE damage condition at almost the same probabilities of failure in existing condition. The study shows that the buildings were most vulnerable to slight damage and least vulnerable to complete damage. In this paper, design requirements were referenced from ATC-40, FEMA 356/273 and HAZUS MH and it was designed out by using Structural Analysis Program (SAP 2000) software.
Index Terms— Performance based seismic evaluation, Vulnerable buildings, Fragility curves, Push over analysis, Brick-nogging buildings, Strengthening technique