Browsing by Author "Chaulagain, Hemchandra"
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- Earthquake loss estimation for the Kathmandu ValleyPublication . Chaulagain, Hemchandra; Rodrigues, Hugo; Silva, Vitor; Spacone, Enrico; Varum, HumbertoKathmandu Valley is geologically located on lacustrine sediment basin, characterized by a long history of destructive earthquakes. The past events resulted in large structural damage, loss of human life’s and property, and interrupted the social development. In recent years, the earthquake risk in this area has significantly increased due to uncontrolled development, poor construction practices with no earthquake safety provisions, and lack of awareness amongst the general public and government authorities. In this context, this study explores the realistic situation of earthquake losses due to future earthquakes in Kathmandu Valley. To this end, three municipalities: (a) Kathmandu Metropolitan City, (b) Lalitpur Sub-Metropolitan City and (c) Bhaktapur Municipality are selected for a case study. The earthquake loss estimation in the selected municipalities is performed through the combination of seismic hazard, structural vulnerability, and exposure data. Regarding the seismic input, various earthquakes scenario considering four seismic sources in Nepal are adopted. For what concerns the exposure, existing literature describing the construction typologies and data from the recent national census survey of 2011 are employed to estimate ward level distribution of buildings. The economic losses due to the earthquake scenarios are determined using fragility functions. Finally, the ward level distribution of building damage and the corresponding economic losses for each earthquake scenario is obtained using the OpenQuake-engine. The distribution of building damage within the Kathmandu Valley is currently being employed in the development of a shelter model for the region, involving various local authorities and decision makers.
- Generation of spectrum-compatible acceleration time history for NepalPublication . Chaulagain, Hemchandra; Rodrigues, Hugo; Varum, Humberto; Silva, Vitor; Gautam, DipendraThe 25 April 2015 Gorkha earthquake in Nepal caused severe structural damage in central Nepal, including the capital city Kathmandu. Both seismic vulnerability analysis of affected buildings and nonlinear time history analysis need increasing time history. However, no adequate records are available in Nepal, thus structural engineering practices follow Indian guidelines. The Nepal building code allows time history analysis along with the seismic coefficient and response spectrum methods, so nonlinear time history analysis can be used to assure adequate seismic safety. To fulfill the gap of recorded accelerograms, we developed artificial acceleration time histories considering the seismic hazard model of Chaulagain et al. (2015). We compared the synthetic accelerograms developed in this study with the records of Gorkha earthquake; the recorded maximum peak ground acceleration during the Gorkha earthquake showed comparable acquaintance only to the peak amplitudes of synthetic accelerograms generated for 300- and 475-year return periods.
- Revisiting Major Historical Earthquakes in Nepal: Overview of 1833, 1934, 1980, 1988, 2011, and 2015 Seismic EventsPublication . Chaulagain, Hemchandra; Gautam, Dipendra; Rodrigues, HugoDue to its location in the region of interaction between the Indian and Eurasian plates, several earthquakes hit Nepal each year. These shaking events, from weak to strong, characterize Himalayan earthquakes, and major events in the past caused enormous losses in terms of casualties, injuries, biodiversity, and the country’s economy. Due to lack of proper accounts related to the occurrence, damage, and losses of past earthquakes, few accounts of the 20th century earthquakes can be found in existing literature; and comparative analysis of these earthquakes has not been done. To fill this hiatus of detailed accounts and interpretation of notable earthquakes in Nepal, this chapter offers classified damage statistics, losses, and the impact on the socioeconomic setting of the affected areas. In addition, it presents the damage to gender, rural, and urban populations along with brief details of known earthquakes since 19th century.
- Seismic safety assessment of existing masonry infill structures in NepalPublication . Chaulagain, Hemchandra; Rodrigues, Hugo; Spacone, Enrico; Varum, HumbertoThe main aim of this study is to identify the geographical seasonal mortality patterns in Portugal and, for the first time, to assess the relationship between seasonal and overall mortality. Monthly data from the Portuguese mortality database (2000-2009) by major cause of death were analysed and standardized to 30 days with adjustments for leap years. The chi-square goodness-of-fit test was used to compare the observed monthly deaths with deaths that could be expected if mortality were randomly distributed throughout the year. The seasonal burden was measured using the excess winter deaths (EWD) rate and the seasonal impact of winter on mortality was assessed through the EWD Index. The regions were clustered according to the overall mortality rate and the seasonal impact: 1-low seasonality and high values of overall mortality; 2-high seasonality and high values of overall mortality; 3-low values of seasonality and low overall mortality; 4-high seasonality and low overall mortality. Significant seasonal mortality increases were found in all causes of death. There were 86,000 EWDs, mostly through circulatory and respiratory diseases. 73% of the population lives in regions with high winter vulnerability to respiratory mortality and 60% in regions with high winter vulnerability to circulatory mortality. This study reinforces the idea that vulnerability to cold weather may play an important role in the public health in Portugal. This knowledge may be used to construct a set of regulations or policies designed to implement better health planning procedures and more effective warning systems.