An Interview with
Prof. R N Iyengar
Director
The Central Building Research Institute (CBRI), Roorkee http://sunsite.sut.ac.jp/asia/india/jitnet/india/csir/cbri.html
E-Mail Address :Dr. R.N. Iyengar 




The Central Building Research Institute (CBRI), in  Roorkee, 

is  known  for designing  and  development  earthquake-proof 

buildings.  The institute, a constituent laboratory  of  the Council 

of Scientific & Industrial Research (CSIR) has  made tremendous

contributions  in  the  field   of   earthquake engineering.  

COM  COM  spoke to its  director,  Prof.  R  N Iyengar. 












Com  Com: CBRI is one of the premier laboratories under  the 

aegis  of the Council of Scientific and Industrial  Research 

(CSIR).  Could  you briefly tell us about the  major  thrust 

areas identified by the institute?

Prof. Iyengar: The main mandate given to the CBRI, one of the oldest CSIR institutes, was to give scientific inputs to construction and housing sectors. Accordingly, we identified Shelter Planning, New Materials, Structures and Foundation Engineering, Disaster Mitigation and Process Development as major thrust areas.

Com Com: Your institute which celebrated its golden jubilee a year and a half ago has done pioneering work in the area of designing tremor-proof buildings for major seismic zones in the country. Will you please give an account of the achievements of CBRI in this field?

Prof. Iyengar: In the aftermath of various tremors that shook different parts of India in the Nineties, CBRI worked very closely with aggrieved parties and government institutions in developing new housing designs for various tremor-prone areas. For instance, during the 1991 Uttarkashi earthquake, which claimed more than 2,000 lives, we collaborated on a national mission to rehabilitate the large number of educational and health buildings, which were damaged in the region.

A survey of 500 buildings conducted by us revealed that most of the damaged buildings were non-engineered constructions, with random rubble masonry in mud mortar. The construction was found to be of very poor quality. Masonry walls were heavily damaged and partially collapsed in the majority of the buildings.

For instant rehabilitation of the victims, CBRI developed instant shelters. It also organised a one-day national level seminar on rehabilitation of earthquake affected people in which state government officials, representatives of agencies involved in rehabilitation work, contractors, builders and engineers participated. As a fall-out of this seminar, it was proposed to construct pre-fabricated instant shelters throughout these affected areas. The fabrication of these kutirs was done by state public works department and UP Bridge Corporation at Hardwar, Lucknow, Roorkee, Ghaziabad and Meerut.

A mathematical model for seismic stability analysis has been developed at CBRI, which can be used by engineers to analyse rock wedge stability under seismicity.

A CBRI study on behaviour of masonry buildings under earthquake conditions is in progress. Experimental studies on masonry walls built with irregular or round shaped stones and mud mortar show that the lateral strength of these walls is poor. Strengthening of these walls by fixing chicken wire mesh on both faces and plastering with cement and sand mortar in a 1:6 ratio, resulted in considerable increase in lateral strength. This could be one of the strengthening measures that could be adopted for buildings, which are not severely damaged.

After the earthquake of September 30, 1993 in Latur, Maharashtra, the Institute has been closely associated with the government of Maharashtra and donor agencies which are engaged in rehabilitation works and also designing and constructing earthquake resistant buildings. At the request of the government of Maharashtra, the CBRI scrutinised a number of designs received from donor agencies and gave comments and suggestions. It has also undertaken a damage survey and catagorisation of damaged houses and other buildings in the districts of Latur, Osmanabad, Sholapur, and Satara. CBRI has trained about 1000 engineers to carry out survey, damage categorisation, repair and strengthening of damaged houses.

Com Com: What is the maximum intensity of earthquake that could be withstood by such designs?

Prof. Iyengar: The intensity is a measure of damage at a place. Generally, the modified Merculi Scale is used for this purpose. We can economically design structures to withstand intensities of the order of IX-X, obviously the cost increases with intensities.

Com Com: What are the major parameters that you take into account while designing houses for a particular seismic zone? Do these parameters vary from place to place? Can there be standard designs for all seismic zones in the country?

Prof. Iyengar: The parameters are the soil condition, foundation type, building dimensions etc. Also design of masonry buildings and RC frame buildings will be different. Apart from seismicity, other geoclimatic conditions are to be considered while designing the buildings. A standard design for all zones, however, is not possible.

Com Com: You had earlier expressed an opinion that it was high time India had redefined its seismic zones and moved away from macro level classification of seismic zones to micro level. Would you like to elaborate on that?

Prof. Iyengar: Macro zones are alright for broad specification and design of very routine buildings. Micro zonation is particularly needed for big cities. The local ground vibration varies depending on the local soil conditions. What a building senses is the movement at the basement. This can be spectacularly different between hard rock and soft soil. For example, in Delhi the northern part is overlain with deep alluvium in contrast with the southern part that has rock sediments. Micro zonation would incorporate these small-scale variations also. In micro zonation one can incorporate conditions of existing buildings on seismic hazard to arrive at final seismic risk status of the built environment upto block level or apartment level or street level. This is of great help in minimising damage through strengthening measures or insurance approaches.

Com Com: Has science reached a stage that earthquakes can be predicted well in advance so that casualties due to such natural calamities can be controlled?

Prof. Iyengar: No.

Com Com: Right from your IISc days you have been working on indigenous devices that can be used for measure the tolerance of structures and buildings to earthquakes. For example, the innovatively designed shaking table. What progress you have achieved on that count?

Prof. Iyengar: Innovative approach for seismic testing of equipment by carrying them in railway wagons on unmanned railway tracks was suggested to Bhabha Atomic Research Centre (BARC), in Mumbai. They have successfully adopted this for qualifying their heavy diesel generation sets for earthquakes.