Repair Method of Damaged Steel Braced Structure and Restring ForceCharacteristics after Repair State

摘要

A lot of steel structures have experienced severe earthquake disasters in Japan, and its various kinds of failure mode have been reported. Especially on steel braced structure, the failure modes are generally categorized into two modes; buckling and fracture of brace member, and yielding of joints and fasteners. After a lot of earthquake disasters, the technical manual has been published to repair and recover the damaged building structures in Japan [1]. The manual suggests the actual repairing method for damaged steel braced structures; however, it is guessed that a few of these methods have some difficulties related to construction technique and estimation of recovery after repair. In this paper, new repairing method for joints on damaged steel brace structure has been proposed, and its applicability and feasibility are investigated experimentally. Herein, the horizontally loading test on diagonal steel brace are performed with parameters as follows; thickness of gusset plate, layout of bolts, slenderness ratio of brace and the method of joint. At first, the damaged state of gusset plate is reproduced by horizontally loading test. Next, the damaged gusset plate is repaired. Finally, the loading test is done to the repaired specimen again. From the test results, the strength is reinforced after repair, and the rigidity is almost same. The change of failure mode and slenderness ratio is presented, and which is related to eccentric distance and torsional parameters. Furthermore, the evaluation method of the failure mode and buckling strength are proposed, and this estimation method shows good utility.