Several equations for punching shear strength of the reinforced concrete slab have been proposed in the world. These equations have their own factors affecting the strength. There are numerous test data for punching shear strength of RC slabs, which have been obtained by numerous researchers. A database with approximately 300 specimens has been structured through the present study. In the present study seven equations for punching shear strength are evaluated based on the database. CCES equation is also evaluated from the present database.

Most investigations dealing with research on shear focus on concrete members such as reinforced concrete (RC) and prestressed concrete (PC) beams, columns, and slabs. It is difficult for such investigations, which include effects of reinforcing materials and so on, to evaluate shear cracking load in detail. Cracking caused by shear, however, may be a significant consideration for durability evaluation of concrete structures. Pure shear strength is an important property for estimation of cracking because shear failure is caused by fracture of the element. A simple test setup that employs only a universal testing machine has been found to be suitable for obtaining the pure shear cracking strength of concrete without reinforcement. The purpose of the study is to reevaluate the pure shear cracking strength property of plain concrete elements through testing. Based on laboratory testing, it is reconfirmed that reinforcement has little influence on the pure shear cracking strength. However, the shear cracking strength is strongly related to tensile strength and Poisson's ratio. DOI: 10.1061/(ASCE)MT.1943-5533.0000259. (C) 2011 American Society of Civil Engineers.

This paper presents the negative bending of reinforced concrete slabs strengthened with near-surface mounted (NSM) carbon fiber-reinforced polymer (CFRP) strips. Six slab specimens, three of which are strengthened with CFRP strips, are tested in static and fatigue loads. A wheel-running fatigue test machine is used to simulate vehicular loads on a bridge deck. The effectiveness of CFRP strengthening for bridge decks in cantilever and pseudonegative bending is examined based on moment-carrying capacity and cyclic behavior under the wheel-running fatigue loads, including crack patterns and damage accumulation. The moment-carrying capacity (static) of the cantilever slab strengthened with the NSM CFRP strips is improved by 68.4% when compared to that of an unstrengthened slab. The damage accumulation rate of the strengthened cantilever slab owing to the fatigue load is significantly lower than that of the unstrengthened slab. The damage accumulation of the strengthened slab gradually increases and is irreversible when the fatigue cycles increase. The fatigue-induced flexural cracks of the slabs develop along the wheel-running direction. A simple predictive model is presented to estimate the fatigue life of the test slabs.

A 63-year-old male was admitted to our hospital with diabetic ketoacidosis. He had flu-like symptoms 10 days before admission and developed thirst, polyuria and anorexia with 9 kg of body weight loss in a week. Plasma glucose level on admission was 983 mg/dL and HbA1c was 7.5%. Despite high levels of serum pancreatic enzymes, lack of severe abdominal pain and no morphological change of pancreas in the abdominal CT scan eliminated the complication of classical acute pancreatitis. These findings suggested the diagnosis of fulminant type 1 diabetes. However, urinary and plasma C-peptide levels showed that insulin secretion was not completely depleted at onset. Furthermore, an examination of islet-related antibodies revealed the presence of high titer anti-GAD antibody. His HLA typing showed that DRB1*0901-DQB1*0303 and A24 were present. He has been doing well with continuation of insulin therapy. Over two years after onset, his plasma C-peptide level was gradually lowered, and anti-GAD antibody was still positive. Taken together, this is a rare case of abrupt onset autoimmune type 1 diabetes with transient but apparent exocrine pancreatic impairment at onset. Similar cases should be accumulated to clarify pathophysiological similarities and/or differences between fulminant type 1 diabetes and abrupt onset autoimmune type 1 diabetes.

Although various studies related to the punching shear strength of slabs have been published, databases related to punching shear strength are small in size. A database of 313 specimens has been structured through the present study, compared to the 114-data compiled by Kakuta et al. (1974) and the 13 8 data compiled by Gardner et al. (1996).In this study, six equations for the punching shear strength prescribed in specifications were evaluated based on the database. This paper includes a discussion of the parameters of punching shear strength in JSCE and AIJ specifications. A simplified strength equation is also proposed from the database.

本研究は，道路橋のRC床版張出し部上面の負曲げ補強に適用することを主目的とし，CCFPの定着方法について実験的検討を試みたものである．先ず基礎実験として，各種方法でCCFP端部を定着補強したRCはり，およびコンクリート表面部を一部切削してCCFPを埋設定着させたRCはりを用いて曲げ実験を実施した．その結果，後者の方法によりRC床版上面の平滑性を確保できる上に高い定着性が得られることがわかった．さらに，RC床版張出し部を模擬した供試体を用いて輪荷重走行実験を行ったところ，直接輪荷重を受けたCCFP定着部においても，剥離破壊等は生じず，充分な定着性と疲労耐久性を有することが確認された．

本研究では,HVFAコンクリートの配合設計方法の構築に関する基礎的データを得る目的から,フライアッシュをセメント容積に対して50∼70%置換したHVFAコンクリートの圧縮強度発現性状について検討を試みた.その結果,フライアッシュ置換率50∼70%のHVFAコンクリートにおいても,フライアッシュのポゾラン反応による長期的な強度寄与がみられることを示した.さらに,材齢364日(52週)において,フライアッシュをセメント等価量として換算する係数が1.0以上になり,質量比でセメント等価の100%以上が強度寄与をもたらすことがわかった.

There is a large demand in consumption of fly ash due to current increase of coal power plants. Fly ash in concrete as admixture contributes to decrease heat of hydration. The larger amount of fly ash is in concrete, the lower heat of hydration is generated in the early age. This is caused by substitution of fly ash for cement, which implies that less cement is mixed in the concrete. Present paper describes adiabatic temperatures of the high volume fly ash concrete. The estimated adiabatic temperature in the concrete standard specification evaluates a little higher for amounts less than 200kg/m3 of cement in concrete, and an equation of adiabatic temperature for these amounts of cement is herein proposed.

Expansive concrete is often employed for prevention of cracks in early age. The present study focused on the tensile properties of the expansive concrete in early age. Especially, the influence of coarse aggregate on tensile strength was investigated in order to obtain an optimized mix-design for expansive concrete. The experimental results showed that expansive concrete in early age has higher tensile strength as the volume of the coarse aggregate increases. The present paper indicates such results are due to the confinement effect of the coarse aggregate in the expansive concrete. In addition, expansive strains of various kinds of concrete were investigated to confirm the confinement effect by the coarse aggregate.

This paper describes flexural fatigue strength of concrete with high volume fly ash (HVFA concrete). The number of coal-fired power plants has been increasing, and amount of coal ash will increase gradually in Japan. Proper use of coal ash is urgently needed. Long term increase of flexural strength of HVFA concrete is expected. From the life cycle cost performance, HVFA concrete suits for pavement concrete. Since Japanese normal pavement concrete design method requires the flexural fatigue strength, this study aims to investigate the flexural fatigue strength of HVFA pavement concrete. Fatigue test results have large scatter, and this scatter includes a scatter of concrete materials strength mixed in several batches. All test specimens were made from only 2 batches in order to exclude scatter of materials strength. From the flexural fatigue tests, the relation (P-S-N curve) between S-N curve and the life probability are obtained based on the normal and 3 parameter Weibull distributions. Based on the fatigue test results, the strength at 2 million repetitions are determined from these distributions. Resultantly, the S-N curve of HVFA pavement concrete is almost same as the normal pavement concrete. The P-S-N curve of HVFA concrete obtained from the normal distribution does not have a large difference to that obtained from 3 parameter Weibull distribution.

本研究は,フライアッシュの付加価値を高めた用途開発を目的に,フライアッシュを大量使用した舗装コンクリート(以下,HVFA舗装コンクリートと称す)の強度特性を調べたものである.さらに,HVFA舗装コンクリートを長寿命化舗装として位置づけ,長期にわたって強度が増加するフライアッシュコンクリートの特性を活かした舗装版厚の設計を行い,材料コストの試算を行った.本研究の範囲内から,フライアッシュ置換率が大きいほどフライアッシュのポゾラン反応による強度発現効果の程度は大きいこと,HVFAコンクリートの長期強度が増加する特性を踏まえて版厚を設計すれば,普通コンクリート舗装版よりもHVFAコンクリート舗装版の方が版厚を薄くできる可能性があることが明らかとなった.

本研究は，膨張コンクリート自身のひび割れ抵抗性におよぼす湿潤養生期間の影響を明らかにするため，膨張材量や湿布養生期間を主な実験パラメータとしたはりの曲げ実験を行い，その力学性状について検討した．その結果，膨張コンクリートでは，膨張材量が多くなるほど，また湿布養生期間が長いほど，曲げ強度およびみかけの伸び能力が大きくなった．特に標準添加量の2倍の膨張材量とした膨張コンクリートの曲げ強度は，湿布養生期間に大きく影響を受けることがわかった．

本研究は,初期ひび割れ(幅)予測などに活用できる,若材齢コンクリートと異形鉄筋の局部付着特性を求めたものである.その基礎実験として,鉄筋純かぶりの薄い実験供試体を用いて鉄筋周辺のモルタルに生じる損傷状況を観察し,若材齢であるほど鉄筋近傍の内部ひび割れが生じやすいことを確認した.また,既報の結果と対比するため充分に長い定着長を有する実験供試体を用いて両引き付着応力実験を行った.その結果,鉄筋ひずみとコンクリートの断面平均ひずみの差をもって定義したすべりを用いることで,鉄筋軸方向の任意の位置における局部付着特性が同程度であることを示した.さらに,コンクリートの圧縮強度の2/3乗で正規化した局部付着応力を用いることにより,充分に長い定着長を有する場合においても材齢2日以降で長期材齢の局部付着応力-すべり関係とほぼ同一になることを示した.

本研究の目的は,炭素繊維シートで補強されたコンクリート要素の純せん断力作用下における破壊挙動や補強効果を明らかとすることで,炭素繊維シートによるせん断補強効果に関する基礎的データを資することである.本研究では,簡易的に純せん断力を作用させることのできる中型純せん断実験装置を用いて,炭素繊維シートの種類や繊維軸角度をパラメータとした実験的検討を行った.その結果,炭素繊維シートによるせん断補強効果は,繊維軸角度に強く影響を受け,その破壊モードも異なることが確認できた.

本研究の目的は，純せん断力作用下にあるコンクリート要素の終局強度や破壊挙動を求めることで，部材レベルのせん断破壊の基礎的資料とすることである．特に本論文は，鉄筋のような補強材を含まないコンクリート要素における材料特性としての破壊挙動を示す．先ず，広範におよぶコンクリート要素の純せん断強度特性を示すとともに，純せん断応力下における応力－ひずみ関係を実験的に調べた．さらに，鋼繊維やエポキシ樹脂を用いることで，コンクリート要素のひび割れ前後の挙動を実験的に評価した．本研究の成果により，局所的なひび割れ発生以前では，圧縮・引張の主ひずみ成分の大きさはほぼ等しく，純せん断応力下にある要素レベルの挙動は極めて弾性的であることを実験的に確認した．

本研究は近年開発された低添加型膨張材による膨張コンクリートのひずみ特性を調べるため，若材齢期を中心とした長さ変化挙動を実験的に求めた．特に各ひずみ成分に分離を行うことを目的とし，配合条件や環境湿度を実験パラメータとしたコンクリートのひずみ計測を行った．そして，ひずみの重ね合わせ則に基づいて，若材齢期の膨張コンクリートの各ひずみ成分を求め，その特性について考察を加えた．その結果，標準添加量20kg/m3とする膨張コンクリートの(自由)ひずみ変化量は，ほぼ同じ配合構成で異なる環境下におけるコンクリートのひずみを用いることで，精度よく推定できることを確認できた．

This paper describes flexural strength characteristics of concrete with high volume fly ash. Coal-fired power plants have produce about 9,200,000tons coal ashes per year in Japan. The number of coal-fired power plants has been increasing, and amount of coal ash will increase gradually in future. About 90 percent of coal ashes is fly ash and the other bottom ash. Concrete with high volume fly ash may decrease the workability and strength. Short-term strength becomes low due to late reaction of fly ash. Slump as the pavement concrete with high volume is less than the half of the slump of the normal concrete. This results in a suitable pavement concrete. This study aims to investigate the feasibility of pavement concrete with high volume fly ash. Pavement concrete is designed based on the flexural strength. Flexural strength is determined by the failure at the weakest location in the tensile side of the specimen, and is determined by the amount of defects in the mortar and transition zone around aggregates. This may be verified by the distance of two loads over the flexural test specimen. Resultantly, high volume fly ash concrete is affected by the defect based on fly ash. In order to investigate variation of concrete strength, several tests have herein conducted. The strength variation is also analyzed by the Monte Carlo Simulation, which is based on the weakest-link-model. The numerical analysis agrees well with experimental results.