PC Bridge Research Articles

지진을 경험한 형상비 2.5 RC 교각의 내진 변위 연성도 평가

1992년 내진규정 도입이전에 설계시공된 공용중의 철근콘크리트 교각은 대체로 소성힌지구간에 겹침이음 시공되었다. 본연구는 형상비 2.5의 철근콘크리트 교각실험체의 내진 연성도 평가를 위한 실험적 연구이다. 실험에 사용된 6기의 실험체는 횡방향 구속력, 주철근의 겹침이음 그리고 섬유보강을 변수로 가지고 있다. 이 실험체는 한국도로공사가 개발한 인공지진동을 사용하여 유사동적실험을 수행하여 지진이력을 주었으며, 유사동적실험 후에는 일정한 축력, P＝0.1 <TEX>$f_{ck}$</TEX> <TEX>$A_{g}$</TEX>을 유지하면서 변위제어방식으로 유사정적실험을 실시하여 잔류내진성능을 평가하였다. 실험 결과 소성힌지구간에 겹침이음 된 RC 교각이 낮은 연성에서 파괴에 도달하였다. 이는 주철근 겹침이음이 주철근의 충분한 연성발달을 저하시킨 결과라 할 수 있다. 또한, 섬유보강된 실험체는 ？강성과 변위연성도의 현저한 개선능력을 보였다.. For the construction of PC bridge piers the implementation of 1992 seismic provisions, longitudinal steels were practically lap-spliced in the plastic hinge region. Experimental investigation was conducted ductility of evaluate the seismic earthquake-experienced reinforced concrete columns with 2,5 aspect ratio. Six test specimens were mode with test parameters: confinement ratios, lap splices, and retrofitting FRP materials. They were damaged under series of artificial earthquakes that could be compatible in Korean peninsula. Directly after the pseudo-dynamic test, damaged columns were retested under inelastic reversal cyclic loading simultaneously under a constant axial load, P＝0.1f<TEX>$\_$</TEX>ck/A<TEX>$\_$</TEX>g/. Residual seismic performance of damaged columns was evaluated and compared to that of the corresponding original columns. Test results show that PC bridge piers with lap-spliced longitudinal steels appeared to fail at low ductility. This was due to the debonding of the lap splice, which resulted from insufficient development of the longitudinal steels. The specimens externally wrapped with composite FRP straps in the potential plastic hinge region indicated significant improvement both in flexural strength and displacement ductility.

海洋環境に位置するPC橋の劣化

海上に架橋され, 供用後22年の塩害による損傷の認められたPC橋である野甫大橋について, 劣化損傷状況の調査を実施した。その結果, 水セメント比が38%と小さい主げたコンクリートへの塩化物イオンの浸透が予測以上に早く, 塩害により激しい損傷を起こしていることが分かった。

PCグラウトの施工技術の現状と非破壊検査による点検

PC構造物の耐久性に大きく影響する, PCグラウトの充てんに関する施工技術の現状と, 既に供用中のPC橋に対する点検および補修方法の概要について述べる。混和剤では, 特に高粘性・ノンブリーディング型グラウトが, 各種混和剤の性能比較試験結果からも, 充てん性の向上に有効である。また, シースの空隙率の確保も重要であり, 空隙率の比較的小さいPC鋼棒は注入作業が難しいため, 欧米の基準を参考とすると50～60%は必要であると考えられる。既設PC橋りょうのグラウト充てん状況の点検には, 非破壊検査法の確立が必要であり, X線透過法と打音振動法についてその有効性と適用について考察する。

首都高速道路湾岸線における外ケーブル併用PC橋の設計

横浜市鶴見区扇島内にある首都高速湾岸線の3径間連続PC箱げたは外ケーブル併用方式で設計された。外ケーブル方式には多くの利点のあることは知られているが, 適切な技術基準等が整備されていないため, 新設橋りょうから使用された例はわが国ではまだ数橋にすぎない。そのため, 外ケーブル併用橋の設計にあたり, (1) 定着部のFEM解析と供試体による載荷実験, (2) 偏向部のFEM解析, (3) 終局曲げ耐力の評価, (4) 外ケーブルとして適切な材料の選定, (5) 外ケーブルの共振, (6) 外ケーブルの偏向部での疲労特性および摩擦特性の確認, (7) 実橋における外ケーブル緊張時の応力測定などの検討を行った。ここでは, それらの概要について報告する。

ChemInform Abstract: Persulfuration of Phosphinines: Synthesis and X‐Ray Crystal Structure Analysis of a P2S3 Derivative.

The reaction of 4,5-dimethyl-2-phenylphosphinine with sulfur in boiling benzene in the presence of N-methylimidazole as a catalyst first yields a P-sulfide. This monosulfide further reacts with sulfur to give a diphosphinine trisulfide and a diphosphinine tetrasulfide. The X-ray crystal structure analysis of the trisulfide has been carried out. The two head-to-tail 1,6-dihydrophosphinine rings are connected by PSC and PC links, thus forming a central 1,2,4-thiadiphospholane heterocycle. The PC bridge is weak [1.881(3) A] and sulfur can insert into it to give the symmetrical tetrasulfide with two PSC bridges.

Vibration of PC Bridge during Failure Process

A vibration measurement was carried out on an existing prestressed concrete bridge during its failure test. The vertical and horizontal vibrations were measured based on the ambient vibration method. The change of vibrational characteristics due to deterioration of the bridge during the failure test was obtained. Moreover, a measured mechanism on the change of vibrational characteristics is discussed compared with a numerical analysis.

Mixed-ligand rare earth complexes of phthalocyanine and β-diketones

Refluxing tris(β-diketonato) complexes of rare earth elements (Ln) with dilithium phthalocyaninate (Li 2Pc) in dried organic solvents resulted in mixed-ligand complexes of diverse composition depending on the β-diketones and solvents used. With dipivaloylmethane (dpmH) used as the β-diketone, two types of novel complexes, Ln 2Pc(dpm) 4 and [LnPc · (dpm) 2] 2, were obtained. By X-ray analysis the samarium complex of the former type was shown to have an axially symmetric Pc bridge binding two Sm atoms. The complexes of the latter type have an unpaired electron on the Pc ligand, as proved by the paramagnetism of the yttrium compound, and seem to be formed by atmospheric oxidation during the reflux. Other types of complexes obtained are: LnPc(dbm)(solv) 2, LnPcH(dbm) 2(solv) 2 and LnPcH(acac) 2 where dbmH = dibenzoylmethane and acacH = acetylacetone. The magnetic susceptibilities of the binuclear series Ln 2Pc(dpm) 4 conformed to the van Vleck-Frank formula down to 77 K, except that complexes with Ln ≡ Er, Tm and Yb gave somewhat large absolute values of the Curie-Weiss constants ( θ = 23, 20 and −50 K where χ = C (T − θ) ). A comparative study disclosed that Yb(dpm) 3 and even YbCl 3 · 6H 2O gave θ also in the neighborhood of −50 K, although Tm(dpm) 3 and Er(dpm) 3 showed θ values close to 0.