Final Behavior of Structures Suffered by Big Earthquake.

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The social needs for large span structures, such as atria attached to tall building or baseball stadium roofs, are increasing. Such structures include shell structures using reinforced concrete and air-inflated membrane structures, but steel trusses are the most common. In japan, a seismically active land, it is very important to ensure safety against earthquakes for steel truss structures as well as for general buildings.In the seismic design of general buildings, plastic deformations are permitted for some structural members in order to absorb the large earthquake input energy. However, in steel truss structures, it is quite difficult to perform seismic design by allowing plastic deformation of members because of the brittle buckling behavior of compressive members. If stable plastic deformation could be allowed for steel truss structures, a more rational seismic design method could be used.In this paper, the following studies area accomplished;1.Elasto-plastic response analysis is carried out for double-layer cylindrical truss structures and the collapse behavior of the large-span truss structure is investigated. The analysis method takes into account buckling in the relationship between the member's axial force and axial deformation.2. To prevent truss structure from the collapse, experiments are performed on three types of 6 grids statically determinate plane truss structures;normal truss structure, truss structure with one non-buckling member installed in the central upper chord and truss structure with five non-buckling members installed in all upper chords. Non-buckling member is duckling pipe member inserted an inner pipe. As a result, the stable plastic deformation can be obtained for the truss structure.3. Elasto-plastic response analysis is carried out for double-layer cylindrical truss structures with non-buckling members and it is shown that plastic deformation can be allowed for large earthquake.