BRI Research Paper


BRI (Building Research Institute) Standard for Earthquake Resistant Properties of Existing Reinforced Concrete Buildings.

K.Nakano, M.Hirosawa; February, 1974. 21p.


Taking the opportunity that several buildings, designed according to existing regulations,suffered severe damages by the Tokachi-Oki earthquake, the demand for a review of earthquake resistant characteristics of existing buildings has been rising. This report presents the judgement standard prepared, in such a situation, for existing reinforced concrete buildings and an investigation result carried out using the standard.

Further, the main basic principles being considered in preparation for this standard are as follows.

a) Even if buildings suffer irreparable damages at a strong earthquake which rarely happens, human lives shall be kept safe.
b) In order to satisfy the above objective, buildings shall have a strength which corresponds to acceleration of 1.0g or shall be adequately ductile in addition to having a strength more than 0.25g, in case of the worst combination of structure-soil relationship.
c) In case of a better combination of structure-soil relationship, the limits for strength and ductility mentioned above may be decreased adequately.
d) In order to decrease the responsibilities of engineers on duty, a sieving system consisting of four steps from a simple first step to a more complicated fourth step is adopted to make the standard.

According to the standard, investigations were carried out for 436 governmental office buildings. The main results are as follows.

1) 143 buildings out of 436 were judged to have a strength of more than that correspond to horizontal accerelation of 1.0g.
2) 240 buildings were judged to have a strength between 1.0g and 0.4g. Shear capacity of columns in 197 buildings out of these were larger than flexure capacity.
3) 27 buildings were judged to have a strength less than 0.4g. Concerning 8 of these buildings, their shear strength was smaller than their flexure strength.
Furthermore, it is pointed out that some related research shall be carried forward, as

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