Abstract
The purpose of this study is to investigate the behavior of steel structures subjected to a strong earthquake and to evaluate the damage from a microscopic point of view. For this purpose, the authors have adopted two kinds of research techniques. The first is the "ON-LINE EARTHQUAKE RESPONSE SIMULATION SYSTEM (ON-LINE SIMULATION SYSTEM)", which is composed of an electro-hydrauric testing machine controled by a computer and a full scale specimen. Since a term of restoring force in the equation of motion is to be substituted by the actual reaction of a specimen under test, we can obtain the non-linear response of structure without any assumption about the hysteretic characteristics. Based on this method, the dynamic behavior of simple steel structures subjected to an intense earthquakes were simulated. The second technique is the "X-RAY DIFFRACTION METHOD". Although this method is usually regarded an experimental technique particular to the material science, we have realized the good applicability for the study of structural engineering, Because X-ray diffraction method is advantageous in investigating the microscopic behavior of steel member such as the plastic deformation and the low cycle fatigue. From the view point stated above, we have adopted this method for the evaluation of low cycle fatigue damage of steel member subjected to an earthquake. The experiment has been performed by radiating the X-ray at several stages of the ON-LINE SIMULATION. As has been expected, the X-ray diffraction patterns have changed in a regular manner depending on the degree of fatigue damge, and the results have shown a good possibility that the X-ray diffraction approach can offer a powerful tool for the detection of the earthquake damage of steel members.
