权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Development of Expansive-High Strength Concrete and Systematic Evaluation of Structural Behavior of Reinforced Concrete Beams

膨胀高强混凝土的开发及钢筋混凝土梁结构性能的系统评价

基本信息

批准号：
16360220
负责人：
SATO Ryoichi
金额：
$ 8.83万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

Expansive-high strength concrete(E-LAS) with compressive strength over 100N/mm^2 and expansive strain reaching 200 X 10^<-8> at maximum was developed, which was made of low heat Portland cement, expansive additive and shrinkage reducing agent.Stress produced in E-LAS ranged from 0.5 to・.2 N/mm2, which was not strongly dependent on the strain.The ultimate and rate of creep strains of E-LAS and conventional HSC(N-HAS) obtained experimentally showed less difference between both concretes for the case of with water to binder ratios(W/B) of 0.3. Linear creep analysis based on step by step for reinforced HSC beams showed fairly good agreement with experimental results, while the former overestimated shrinkage stress and underestimate expansive stress of HSC with W/B of 0.15 with the increase of RB ratio. The reason for the overestimate of shrinkage stress was explained by the detection of micro cracking developed in the radial direction and the computed result was improved by incorporating t … More ension softening of concrete depending on the age.Effectiveness of E-LAS was verified by experiment for improving the serviceability performance of short-and long-term flexural crack width as well as curvature of reinforced concrete(RC) beams and a new concept was proposed for evaluating them based on the strain change in tension RB from the zero concrete stress condition at tension RB depth to the loaded condition and the change of stress related curvature before and after loading, respectively, whose validity was verified by comparing with results obtained by conventional method and experiment, while tension softening effect must be considered in case of small crack width.Shear strength at diagonal cracking of E-LAS beams, whose effective depth(d) is from 250-1000mm and strain in tension RB before loading is almost zero, was improved by 5% for d=250mm, 12% for d=500mm and 19% for d=1000mm, compared with that of N-HAS beams with remarkable shrinkage strain in the same RB. A concept of equivalent tension RB ratio considering RB strain due to early age deformation was proposed. The concept showed the linear relationship between shear strength at diagonal cracking and (effective depth)^<-1/3> independent of early age deformation, while previouisly proposed equations followed the law of (effective depth)^<-1/2> and (effective depth)^<-2/5> for RC beams made of N-HAS. A proposed equation formulated based on this concept showed high prediction accuracy independent of the magnitude of early age deformation in concrete.E-LAS was also effective in improving shear strength of RC beams which was 13% for shear RB ratio of 0.25% and 6% for 0.51% higher than that of corresponding N-HAS beam, respectively. The shear RB strains averaged along a primary shear crack of E-LAS beams were smaller than those of N-HAS beams which could be roughly predicted by the modified truss theory applied a proposed equation for evaluating concrete contribution for shear resistance. Less

采用低热波特兰水泥、膨胀剂和减缩剂配制了抗压强度大于100 N/mm ~ 2、膨胀应变最大可达200 × 10 ~ 4的膨胀高强混凝土（E-LAS），E-LAS产生的应力范围为0.5 ~ 0.2 N/mm ~ 2<-8>，E-LAS和常规HSC（N-HAS）的极限蠕变应变和蠕变速率在水胶比（W/B）的情况下差异较小。的0.3。采用逐步线性徐变分析方法对高强混凝土梁进行徐变分析，结果与试验结果吻合较好，但在W/B = 0.15时，随着配筋率的增加，逐步线性徐变分析高估了高强混凝土的收缩应力，低估了膨胀应力。通过对径向微裂纹的检测，解释了收缩应力高估的原因，并通过引入应力修正系数，改善了计算结果 ...更多信息通过试验验证了E-LAS对改善钢筋混凝土（RC）的短期和长期弯曲裂缝宽度和曲率的使用性能的有效性提出了一种新的概念来评估它们的基础上的应变变化的拉伸RB从零混凝土应力条件下的拉伸RB深度加载条件和应力的变化相关在裂缝宽度较小的情况下，必须考虑拉伸软化效应，当有效深度d为250- 1000 mm，加载前受拉应变RB几乎为零时，E-LAS梁斜裂缝处的抗剪强度在d= 250 mm时提高了5%，d= 1000 mm时为19%，而相同RB下具有显著收缩应变的N-HAS梁为12%。提出了考虑早期变形引起的RB应变的等效拉伸RB比的概念。该概念表明斜裂缝处的抗剪强度与（有效深度）^<-1/3>之间呈线性关系，与早期变形无关，而之前提出的N-HAS制成的RC梁的方程遵循（有效深度）^<-1/2>和（有效深度）^<-2/5>定律。E-LAS还能有效地提高RC梁的抗剪强度，当剪切RB比为0.25%时，其抗剪强度比相应的N-HAS梁提高13%;当剪切RB比为0.51%时，其抗剪强度比相应的N-HAS梁提高6%。E-LAS梁沿主剪切裂缝沿着平均的剪切RB应变小于N-HAS梁，这可以通过修正的桁架理论应用建议的公式来估算混凝土对剪切阻力的贡献来粗略预测。少