Low cycle fatigue property of 1000N class steel and performances of H-section Column-to-Beam Welded Joints

- Investigation on Application of 1000N Class (950N/mm² Class) Ultra-high Strength Steel for Buildings -

Abstract

Recently, ultra high strength steel plate such as 1000N (950N/mm² Class) class strength is focused as material of various type of steel structure. 1000N class steel has already applied in hydropower plant in order to enjoy its effect on weight and cost reduction. However, in building construction field, high strength steel remains unfamiliar material. There are only a few example of application of 780N/mm² class strength steel in building field. Authors have already developed 1000N class steel plate and welding consumables for building. However, from viewpoint of actual application, structural performance under massive earthquake must be evaluated. Local area of column-to-beam connection seems be subject to large amount of strain when seismic event. So, in this report, low cycle fatigue properties of 1000N class steel and its weld was evaluated and structural experiments were conducted. As a result, it is revealed that Low fatigue property of 1000N class steel is equivalent to that of 780N class and can maintain the loading capacity under 26∼51 times of strain amplitude at _cδ_p. Furthermore, it is also shown that structural performance can be estimated by test results of small specimen with strain calculation by FE analysis and finishing of edge of beam is effective for extension of lifetime through decrease of strain.