|Session 8.3 - Society I|
Recent earthquakes in Turkey and India have caused human loss and destruction of buildings on a large scale. The economic and human losses have opened a Pandora’s box of problems in the implementation of seismic protection in these countries and placed blame on many of the stakeholders in the construction industry. Affordability, lack of awareness, weak human memory (caused by large time gaps between seismic events) and lack of legal control are generally considered major hurdles to the implementation of seismic protection. However, the losses to middle-class housing in Ahmedabad in the 2001 Bhuj (India) earthquake highlighted how increased affluence does not necessarily result in safer buildings. Similarly, the extraordinary losses in the 1999 Marmara Sea (Turkey) earthquake happened despite the awareness of the hazard. There, despite the inevitability of this earthquake, shoddy structures continued to be built. Both these countries have some sort of legal system to control bad construction, but it could not be turned into safer buildings. These examples raise concern that affordability, lack of awareness, and the legal system are not the only issues. The difficulty in providing seismic protection is more of a socio-economic, legal and human issue than merely a technical one. Unfortunately, there remain fatal gaps between the socio-economy, the legal system, implementation processes, building codes and local needs and practices. Until these issues are addressed, seismic protection in these countries will remain essentially a mirage. This paper describes these gaps, taking examples from Nepal, India and Turkey, and examines how these gaps could be mended.
Keywords: seismic safety, informal construction, developing countries, legal issue, gaps in approach
Strengthening Existing New Zealand Buildings for Earthquakes: An Analysis of Cost Benefit using Annual Probabilities
This paper describes the cost benefit analysis of improving the performance of existing buildings for earthquakes. This involved the development of a custom-made mathematical model to deal with wide range of data and variables involved, including time.
Four groups of commercial and large residential buildings (Pre-1935, 1935-65, 1965-76 and post-1976) were examined in 32 cities and towns in New Zealand. Specially derived values were obtained for the seismicity at each location and for the floor areas of each building type. Relationships between shaking intensity and damage were used to estimate the benefit of improving structural performance. Corresponding relationships for injuries and fatalities were used. Business interruption and social disruption were also taken into account.
Estimates were made for each of four possible legislation regimes: the status quo, and regimes requiring existing buildings to comply with 33%, 67% and 100% of new building standards, respectively.
For the base values used in the analysis, benefit cost ratios varied considerably, reflecting the wide variation in seismicity within New Zealand. The results obtained underline the need to deal with existing buildings, and particularly high risk buildings in those towns and cities in New Zealand that are subject to moderate to high seismicity.
Paper 072: [Read]
Keywords: buildings, retrofit, cost-benefit analysis, New Zealand Earthquake Codes