DAMAGE TO CONCRETE STRUCTURES DUE TO THE JANUARY 17, 1995, HYOGO-KEN NANBU (KOBE) EARTHQUAKE

A brief history of the detailing changes following different Japanese earthquakes is presented. The design steps for reinforced concrete str uctures, as prescribed in the 1981 Japanese building code, are describ ed. Observations on the damage and the collapse of reinforced concrete structures caused by the 1995 Hyogo-ken Nanbu earthquake are reported . Failures occurred in older structures built before the improved 1981 code. Deficiencies observed include discontinuities due to the change between composite steel and reinforced concrete construction and rein forced concrete construction in columns, poor detailing of transverse reinforcement in columns, lack of transverse reinforcement in beam-col umn joints, insufficient amount of vertical and horizontal reinforceme nt in walls, presence of significant torsional eccentricities, abrupt changes in stiffness over the height of buildings, and the use of ''sh ort'' columns or ''short'' beams exhibiting high shear-to-moment ratio s. The excellent performance of structures designed using the 1981 Jap anese code is described.