報告書番号

383054

タイトル（和文）

低温下に置かれた鉄筋コンクリート曲げ部材の力学性状に関する解析的研究

タイトル（英文）

ANALYTICAL STUDY ON THE MECHANICAL BEHAVIORSOF REINFORCED CONCRETE FLEXURAL MEMBERS UNDER EXTREMELY LOW TEMPERATURES

概要 （図表や脚注は「報告書全文」に掲載しております）

鉄筋コンクリート製（以下ＲＣと略記）ＬＮＧ地下タンクは，約－５０度Ｃまでの極低温にさらされる。このような極低温下におけるＲＣ部材を構成する材料の諸性質は，コンクリート中の水分の凍結のため常温下での物性とは著しく相違することが明らかにされている。このため，ＲＣ部材のひびわれ性状ならびに剛性も，低温では常温下とは異なった特異な性質を示すが，既往の評価式は，常温下の条件で得られたものがほとんどであるため，実際の性状に即した解析を行なうことが困難であった。本研究は，ＲＣの基本的な特性である鉄筋とコンクリートの付着すべり関係に立脚し，構成材料の低温物性の変化を考慮した非線解析法を開発し，実験値との照合を行なうとともに，ＲＣ部材の極低温下における変形・ひびわれ等の解析手法の精度向上を図ったものである。これらの成果は，タンクの温度応力設計の合理化に資するものである。

概要 （英文）

THE WALL AS WELL AS THE BOTTOM SLAB OF A REINFORCED CONCRETE(RC) LNG IN GROUND TANK ARE COOLED DOWN TO A TEMPERATURE TO ABOUT -100DEGREES,ALTHOUGH INTERNAL FACES OF THE TANK ARE LINED WITH EFFECTIVE INSULATION MATERIALS.IT IS WELL KNOWN THROUGH THE EXPERIMENTS THAT THE MECHANICAL PROPERTIES OF RC MEMBERS UNDER SUCH A LOW TEMPERATURE,ESPECIALLY THE DEFORMATIONAL CHARACTERISTICS OF CONCRETE AND THEBOND PROPERTY BETWEEN STEEL AND CONCRETE,BECOME REMARKABLY DIFFERENT FROM THOSE UNDER ROOM TEMPERATURE,MAINLY DUE TO THE EFFECT OF FREEZING OF FREE WATER IN THE CAVITY OF CONCRETE.ACCORDINGLY,ALSO THE BEHAVIORS OF CRACKING AND RIGIDITY OF A RC MEMBER EXHIBIT PECULIAR CHARACTERISTICSCOMPARED WITH A MEMBER TESTED UNDER ROOM TEMPERATURE.IT HAS BEEN EXTREMELY DIFFICULT TO ESTIMATE THE BEHAVIORS OF RC MEMBERS IN THE FREEZING CONDITION,SINCE THE CONVENTIONAL EVALUATION FORMULAS ARE DEDUCTED CONSIDERING ONLY THE CONDITIONS OF ROOM TEMPERATURES. IN THE FRAME WORK OF THE PRESENT STUDY A NON-LINEAR ANALYTICAL METHOD WAS DEVELOPED BASED ON THE FUNDAMENTAL PROPERTY OF RC,THAT IS ,BOND STRESS-SLIP RELATIONSHIP OF A REINFORCING BAR,IN WHICH TEMPERATURE DEPENDENT MATERIAL PROPERTIES WERE TAKEN INTO CONSIDERATION.THE PURPOSE OF THE STUDY IS TO CONTRIBUTETO SOPHISTICATION AS WELL AS IMPROVEMENT OF ACCURACY FOR AN ANALYTICALAPPROACH TO EVALUATE THE DEFORMATIONS,CRACKING OF RC MEMBERS UNDER EXTREMELY LOW TEMPERATURES.THE VALIDITY OF THE PROPOSED ANALYTICAL METHOD WAS SUBSTANTIATED BY THE EXPERIMENTAL RESULTS PARTICULARLY CONDUCTED FOR THE PURPOSE.

報告者

キーワード