35 溶接を用いない高力ボルト接合構造の耐震性能に対する方杖ダンパー初期応力の影響

概要

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An innovative structural system, named weld-free system was developed to overcome the difficulty in the quality assurance encountered in the construction of steel moment resisting frames with conventional welded connections. In this system, beam-to-column connections are equipped with knee brace dampers (KBDs), which can be classified as a kind of buckling-restrained brace. To avoid initial stress on KBDs due to vertical load, complex installation procedures are required in construction. To simplify this procedure, a strategy to allow the initial stresses on KBDs is suggested. Effects of KBDs initial stress on seismic performance of weld-free steel frames are investigated using time history analysis. The major findings are: (1) KBDs initial stress is larger in low-rise structures than in mid-rise and higher structures; (2) the KBDs maximal strain is enlarged significantly due to initial stress and some KBDs even yield under level-1 ground motions but compared with previous test results, there is still sufficient safety margin; (3) effects of KBDs initial stress on structure maximal story drift as well as on energy dissipation capacity of this weld-free system is minimal. An alternative design method is suggested that enlarge the sections of KBDs according to the initial stress to retain the KBDs in elastic range under level-1 earthquake force.
一般社団法人日本建築学会の論文
2005-03-20