報告書番号

380018

タイトル（和文）

低温領域で温度勾配を受ける鉄筋コンクリート部材の曲げ剛性とひびわれ性状

タイトル（英文）

FLEXURAL RIGIDITIES AND CRACKING BEHAVIOURS OF REINFORCED CONCRETE MEMBERS SUBJECTED TO THERMAL GRADIENTS IN THE LOW TEMPERATURE REGION

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ＬＮＧ地下タンクは，沸点が－１６２度のＬＮＧを貯蔵するため，タンク本体が－５０度程度の低温度にさられるとともに，タンク壁体の内外面間に温度勾配が生じ温度荷重が発生する。この温度荷重はＬＮＧタンクの設計荷重の中でも鉄筋量を支配する主要な荷重の一つであり，これを合理的に評価する方法の確立が急がれていた。本研究は，鉄筋コンクリートはり部材に実際のタンクと同じ温度条件を与え，実験的に温度荷重を把握し，部材剛性と温度荷重の関係を明らかにすることで，実際のタンクにおける温度荷重を評価するための剛性値について検討したものである。本研究の成果は，ＬＮＧタンクの温度荷重の合理的な評価に資するものである。

概要 （英文）

REINFORCED CONCRETE(RC)IN GROUND TANK FOR THE STRAGE OF LIQUEFIED NATURAL GAS(LNG)IS COOLED DOWN TO THE TEMPERATUREOF -60 DEGREES CENTIGRADE AND THE WALL AND THE BASE SLAB OF WHICH HAVETHE TEMPERATURE GRADIENT.THE TEMPERATURE STRESS DUE TO THE TEMPERATUREGRADIENT IS ONE OF THE MAIN DESIGN LOADS WHICH DOMINATE THE AMOUNT OF REINFOCEMENT. THIS STUDY HAD TWO PURPOSES,THAT IS,THE MEASUREMENT OF TEMPERATURE STRESS AND THE QUANTITATIVE EVALUATION OF AVERAGE FLEXURAL RIGIDITIES OF THE BEAMS WHICH IS NECESSIATED THE TEMPERATURE STRESS. THISPAPER DESCRIBES THE RESULTS OF THE TEST,IN WHICH THE FLEXURAL DEFORMATIONS OF THE BEAMS WERE RESTRAINED IN THE SIMILAR TEMPERATURE AND TEMPERATURE GRADIENT CONDITIONS AS ENCOUNTERED IN RC LNG TANKS,AND IN WHICH THE BEAMS WERE LOADED UP TO FAILURE AT THE MAXIMUM TEMPERATURE GRADIENT.THE MAIN CONCLUSIONS OBTAINED WITHIN THE LIMIT OF THE STUDY WERE AS FOLLOWS. (1)IT WAS CONFIRMED THAT IN THE DESIGN OF LNG TANKS,TWO THIRDS OF THE FULL SECTIONAL RIGIDITY OBTAINED BY THE YOUNG S MODULUS OF CONCRETE AT ROOM TEMPERATURE ARE APPLIED TO FLEXURAL RIGIDITY TO ESTIMATE THETEMPERATURE STRESS. (2)YIELD AND ULTIMATE CAPACITIES OF THE BEAMS WEREABLE TO BE CALCULATED CONSERVATIVELY WITH SUFFICIENT ACCURACY FOR PRACTICAL USE BY THE CONVENTIONAL METHOD WHEN THE INCREASE OF THE YIELD POINT OF REINFOROCMENT AT THE LOW TEMPERATURE WERE TAKEN INTO ACCOUNT. (3)CURVATURES OF THE BEAMS AT THE YIELD OF REINFORCEMENT UNDER TEMPERATUREGRADIENTS IN THE LOW TEMPERATURE REGION WERE MUCH REDUCED THAN THOSE UNDER ROOM TEMPERATURE,WHILE CURVATURES AT ULTIMATE STATE WERE HARDLY INFLUENCED BY THE DIFFERENCE OF TEMPERATURE CONDITIONS.

報告者

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