INFLUENCE OF NONSTRUCTURAL MEMBERS ON NATURAL PERIOD OF STEEL STRUCTURES

The damage evaluation method was proposed, that natural period transition of a steel-frame building may be used to assume damage or maximum deformation after an earthquake. Nonstructural members which had not been evaluated as a proof stress, sometimes influence natural period of buildings. The unloaded horizontal stiffness after an earthquake was grasped by the frame experiment and the frame experiment with brace or nonstructural members. And the eigenvalue analysis was carried out to show natural period gets longer as seismic deformation becomes big. This depends on the data showing the unloaded horizontal stiffness of a frame is almost constant however that of a brace, an RC nonstructural wall or a PC wall falls fast. And it is confirmed that the natural period transitions of patterned steel- frame buildings of thermal power plants are effective to evaluate the damage after an earthquake.