Hiroshi Komatsu

AN EXPERIMENTAL STUDY ON THE BOND PROPERTIES OF LAP SPLICES OF RECYCLED AGGREGATE CONCRETE HALF PRECAST BEAMS APPLIED ULTRA HIGH STRENGTH FIBER REINFORCED CONCRETE FORM

The bond properties of recycled aggregate concrete half precast beams using ultra high strength fiber reinforced concrete form were studied. This study aimed to increase the scope of application of recycled aggregate concrete. The high fluidity recycled aggregate concrete with a medium-quality recycled coarse aggregate used as site placed concrete. The four-point bending tests were conducted on recycled aggregate concrete half precast beams. The results showed that the load carrying capacity of the half precast beams using the ultra high strength fiber reinforced concrete form was higher than monolithic beams. Thus, high concrete strength of fiber reinforced form can be effectively used for the bond splitting strength of lap splices. Furthermore, the bond splitting strength of lap splices of recycled aggregate concrete half precast beams was estimated from the past bond splitting strength equation considering the strength difference of form and recycled aggregate concrete.

STUDY ON APPLICATION OF RECYCLED AGGREGATE CONCRETE TO THE COMPOSITE STRUCTURES

It is known that the axial strength of composite columns could be calculated by the strength superposing method due to the many experimental results of axial compression of composite columns. However, in case of the composite columns in which recycled concrete are used, the contribution of the confinement effect to the structural performance has not yet been clarified. Therefore, twenty-one composite columns were tested under axial compression loading to investigate the effects of concrete type, such as normal concrete, recycled aggregate concrete and fiber reinforced concrete. The application of recycled aggregate concrete to the composite structures are discussed in this paper based on test results.

Experimental Study on Buckling Strength of Angle Steel Compression Members with Built-up Bracing

1.はじめに アフリカあるいは中東の砂漠地帯では強風の影響 により通信用鉄塔の倒壊が問題となっている。これ に対し筆者らは主柱材に削孔・溶接等による損傷を 与えない,補強材である平鋼をボルトの締め付けに よる取付金物を用いた簡便な施工により山形鋼主柱 材への組立補剛方法を前報 1で提案した。その実験 内容は,一般化細長比0.8,1.0,1.2を対象として平 鋼補強材の主柱材に対する範囲を主としたもので, 無補強材に対して部分補強から全補強とすることに より座屈耐力の上昇が確認されるとともに,十分な 補強効果が示された。 本研究では前報 1の結果をもとに補強範囲を全補 強として,一般化細長比で0.6~1.6,細長比で50~ 130 の範囲を設定し,中心圧縮の曲げ座屈実験によ り細長比に対する補強効果を無補強材との比較によ り検討するものである。 2.試験体 本実験で使用する試験体形状を図-1 に,取付金 物を含む断面を図-2 示す。主柱材は山形鋼 L100×100×10(SS400),補強材は平鋼 PL-6×110 (SS400)である。実験因子は細長比と取付金物の 間隔で,一般化細長比(λc)は0.6,0.8,1.0,1.2, 1.3,1.4,1.5,1.6 の 8 種類とし同一細長比で各 2 体を設定している。また全補強とともに無補強材に ついても同様の細長比で 2 体ずつ実験を行っている。 試験体に用いた山形鋼および平鋼の機械的性質を表 -1に,また試験体の一覧を実験結果とともに表-2 に示す。 ここに試験体の補強範囲は,前報 1のエンドプレ L Lr