This paper presen 窰 s an experimental s加 dy on new moment frame cDmections designed to restrict damage to specific connection elemcnts placed at the bottem flange of the beam ． Composite effects and damage to the concrete slab were addressed in these tests ． Composite action Ied to a roughly 98 ％ increase in initial elastic stiffness and 20％ increase in yield strength ． Mcanwhile ， the plastic strain at the specific connection elements was increas巳 d by only 20％ ， indicating thaUhe plastic rotation capacity of the connections was hardly affected by tho presence of the concrete slab ． And the feature ofthe design forcing the connection Io rotate about the top fiange was beneficial in reducing damage to Ihc ooncrete slab ．

Many steel ・風 。雌 ・・ s ・ffe ・ ed ・ ・ g ・ a 【b ・ 跚姻 ・ 1 ・。 ・・ti … 雌 ・ 伽・ N・ 貢 dg・ ang Hy・gQ −k・・ N 跏 b・ E ・・ thq・ak・・ m 。 ・ e 岫 8y ・ar ・ ・ g ・ ・ 撫 th … earthquakes ． aremarkab 【 c numb 巳r ofs 唄 ieshave been made on bea 一 to − Oolu【 。o lions血 U ． S、 and Japan． Neve曲 eless ， i飢 hose s 加 dies， 【 ittte attention has bee晶 paid to the po 重ofrepa 庄 r血g ． The purpose ofthis sIudy is to proposc new duc【ile steel sロuc 眦 e frame system ， which real 皀 es no ！on ］ y structura ］pcr 兪 ) m 瀏 aces b山 a且 so easy repairing after heaVy eatthquake ． ］ hs syst ¢ m is based Qn bolted conncctb 皿 s With sp ］ iF ・ 【 ee ． Main fea 眦 of 出is system is【o limiI p且 astic defbma【ion to the split − 【 ee al bot重om fiange ． τ b dhe contr町 ， 山e sp ［ i重 ・ tee a ロ op fiange can be kept血 elasdc ， becaus ピ血e cent ¢ r ofrotation slays at lhe top flange orbeam end ． Consequen 霍 1) when 出 e stmctUfe using this system suffers compulsory defomation under the earthq 凵ake ， the deformation concen 【 rates on the Sptit − tee at bottom flange ． Finally ． two ． series ofstaIic tesls were conduc 吐 巳 d ． First series are axia 宦10ad洫 g に es ε s of 山e weak − we 卜 spli 巴 ・ 【 ee e ］ ements ， and second sehes are be"d血 g tests ofbeam −to −colum 囗 cennections haVing weak −web − spli 【 − teo． From 止e resUlt ofthese tests ， we verified that this sys 【 em had e 伍 ciem d 巳 formation capacity． In addi監 ion， 【 he damaged part ef this sys 【 em would ． be easy に o repair or change 10 " ew on 巳． ・ Keywords i beam − to − colurpn cOnnection ・ bolted cOnnecti ・ π ， 卿 'θ 一 tee， hysteretic dam ρ er ， damage −C ・ ntroUed − structure

Evaluation of bi-directional characteristics of base-isolation devices is a very important issue for base-isolated structures. This paper describes a bi-directional loading test of U-shaped steel dampers widely-used for energy dissipation in base-isolated structures. The major findings obtained from the test are as follows: (1) torsion-induced residual deformation leads to contact with damper connections; (2) evaluation method of cyclic deformation capacity, which divides bi-directional orbit into deformations in 0 and 90 degree, is proposed and the validity is verified; (3) cyclic deformation capacity is reduced by cumulative torsion; (4) two indices J c and J f proposed in this paper can evaluate the limitation of cumulative torsion until contact with connections and the tendency of torsioninduced reduction of cyclic deformation capacity.

This paper focuses on the seismic repair by retightening turnbuckle. In order to investigate performance recovery, internal forces and workability when the turnbuckle is retightened, the loading test was conducted. The findings obtained from the test are summarized as follows: (1)The performance of the brace is recovered by retightening the turnbuckle. Multiple seismic repairs reduce elastic stiffness, but restore yield strength and maximum strength. (2)Internal forces in tension can be grasped by using the structural model proposed in this paper. (3)Repairing deformation is easier than introducing axial force. In addition, the workability does not change even after multiple retightening turnbuckle. 1967