Takashi Fujinaga

Experimental Study on Seismic Retrofitting for Existing R/C Buildings Using Steel Columns

The authors proposed a new retrofitting element to externally retrofit existing concrete buildings. The proposed element consists of a monolithic steel column and steel beams at each story level, and looks like a tree. The tree-shaped element is connected to the exterior of the building through studs and anchors distributed only along the length of the beams, and the steel column is free from the existing building. Three retrofitted column specimens and four indirect connection specimens were tested. The effectiveness of the proposed retrofitting element and the mechanical properties of the indirect connection were discussed and investigated.ブレースを用いない耐震補強工法へのニーズの高まりを背景に，新しい外付け耐震補強法を提案した。本工法は鋼製柱によりRC柱の外付け補強を行おうとするもので，既存躯体とは梁部分のみを間接接合部で接合しており，既存躯体から独立した鋼製柱の曲げに対して間接接合部が回転抵抗する抵抗機構である。3体5種類の柱の逆対称加力実験を行い，本補強工法の補強効果を確認した。柱実験に加えて4体の接合部実験を行った。梁部間接接合部の性能を把握するとともに，簡易モデルによる挙動予測を行い，同工法の接合部の設計法の提案を行った。

Damage to Steel Reinforced Concrete Buildings

Steering Committee on Steel-Concrete Composite Structure (SCCS), Architectural Institute of Japan, conducted a survey on the damage of Steel Reinforced Concrete (SRC) buildings in Sendai City. The SRC buildings suffered damage to nonstructural members in principle and little damage was observed in structural members. However, some buildings designed by old seismic design codes suffered severe damage to structural members. But they are not such serious damage as story collapse at the middle story of SRC buildings, which were found after the 1995 Great Hanshin earthquake. This chapter briefly describes damage to four SRC buildings which showed distinct types of damage.

Stress Transmission Mechanism in RC Footing Beam Supporting Exposed-type Corn Base with Unbonded Anchor Bolts

Experimental study was carried out to examine the effectiveness of arrangement of reinforcement in a footing beam for an exposed-type steel column base. In the study, location of horizontal anchor and amount of vertical reinforcement are selected as experimental parameters to investigate suitable arrangement of reinforcement. In the tests, a column base is loaded through a column subjected to horizontal and vertical loads at the top. Test results show that the column base reinforced by horizontal anchors, which are placed at the upper side of anchor plates, and by a few amount of vertical reinforcement does perform as well as that fully reinforced by vertical reinforcement.