Theme

duryog nivaran

AUDMP - making cities safer

Bookmarks

WWW Sites

Dear Mr. Desai, I was pleased to read your article, "Retrofitting After or Before Disaster", in the Asian Disaster Management News, Vol. 6, No. 1, January-March 2000. Of the points you make, I would like to address these two excerpts: "A general feeling that prevailed among the communities was that the houses shaken up by the quake, and by the tens of small and big tremors that had preceded it, were simply unfit for any 'patching up'." "One of the most important lessons was that in order to make [retrofitting] workable and financially viable, the retrofitting scheme for each individual house can be planned in stages, around the availability of money, materials and time." On the first point, concern about the cost-effectiveness and reliability of retrofitting can cause fear and lack of faith among affected communities. How many experts can honestly say they are able to provide guidelines for an ordinary engineer to diagnose the nature, magnitude and mechanism of damage, and conceive a cost-effective, safety-guaranteed retrofitting scheme? As for the second point, one wonders about the wisdom of a step-by-step retrofitting approach. Partial remedy does not automatically lead to partial benefit. Moreover, it is not easy even for experts to confidently plan the stages under uncertain premises, even if such stages were conceivable. There is no denying that retrofitting is a powerful means of strengthening structures. However, this should not imply that retrofitting is always the answer. In many cases, economics may work in favor of demolishing and re-building. In others, economic concerns may demand investment for corrective action at the source of the problem. Investments in public awareness, instrumentation, monitoring and early warning may be given higher priority than retrofitting. Regards, R.K. Bhandari Head, International Science & Technology Affairs Directorate Council of Scientific and Industrial Research, India Dear Dr. R.K. Bhandari, With regards to the first point about the effectiveness of retrofitting in increasing occupant safety and building community confidence, I would like to say the following: Although no two houses are the same in terms of construction materials and quality, or building dimensions, one does not find major variability among the houses in the area. In both Latur and Garhwal, the only complication encountered is with the common walls which often cannot be touched. As a result, installation of a complete seismic band is a problem. Since there is uniformity among the houses and the damage patterns were studied, retrofitting measures were evolved to take care of the most commonly identified weaknesses. For the retrofitting of Latur houses, a field shake table test was conducted for the non-load bearing system, and later for the load bearing system. In both cases, it was evident that the retrofitting measures were effective in preventing house collapse. The videotape we made of the four test series has been effective in building people's confidence in retrofitting measures. Concerning the second point about a step-by-step retrofitting approach, I appreciate your concern that this approach may not mean additional safety. But it is necessary to look at the context and evolve a workable delivery system. When there are millions of vulnerable houses, people whose limited resources simply rule out new construction (let alone retrofitting in one go), masons as illiterate as the people, and serious accessibility and material transportation constraints, it is best to follow a simplified approach understandable by all. Our understanding of the grass-roots reality dictates our approach rather than our technical knowledge. Convincing house owners to invest in their own safety is itself a major task let alone the technical "mumbo jumbo", the demystification of which could ultimately result in large-scale, people-powered mitigation programs. Sincerely, Rajendra Desai