本文对8根大比例的FRP加固钢筋混凝土桥柱模型在轴压比为0.2的恒定轴压力下进行拟静力试验,再对其中5根试验柱在经历有限的地震作用后进行长期荷载作用下的轴压试验。试验表明,FRP加固柱的徐变变形远小于对比柱的徐变变形;带损伤的加固...本文对8根大比例的FRP加固钢筋混凝土桥柱模型在轴压比为0.2的恒定轴压力下进行拟静力试验,再对其中5根试验柱在经历有限的地震作用后进行长期荷载作用下的轴压试验。试验表明,FRP加固柱的徐变变形远小于对比柱的徐变变形;带损伤的加固柱在长期荷载作用下的变形发展受加固柱的损伤程度和持荷大小的控制,并与FRP的弹性模量有关;在试验条件下,带损伤的加固柱长期轴向变形呈稳定态势。采用AEMM和F ind ley模型为基础,考虑损伤程度、密封状态、三向应力状态和应力重分布等因素的影响,建立了损伤加固柱的徐变计算模型,并进行了验证。分析表明,损伤对加固柱的徐变发展和徐变破坏时限有显著影响。展开更多
In this study,the cooling rate was manipulated by quenching with water of different temperatures(30,60 and 100℃).Surface and internal residual stresses in the quenched 6061 aluminum alloy samples were measured using ...In this study,the cooling rate was manipulated by quenching with water of different temperatures(30,60 and 100℃).Surface and internal residual stresses in the quenched 6061 aluminum alloy samples were measured using hole-drilling and crack compliance methods,respectively.Then,the processability of the quenched samples was evaluated at cryogenic temperatures.The mechanical properties of the as-aged samples were assessed,and microstructure evolution was analyzed.The surface residual stresses of samples W30℃,W60℃and W100℃is−178.7,−161.7 and−117.2 MPa,respectively along x-direction,respectively;and−191.2,−172.1 and−126.2 MPa,respectively along y-direction.The sample quenched in boiling water displaying the lowest residual stress(~34%and~60%reduction in the surface and core).The generation and distribution of quenching residual stress could be attributed to the lattice distortion gradient.Desirable plasticity was also exhibited in the samples with relatively low quenching cooling rates at cryogenic temperatures.The strengthes of the as-aged samples are 291.2 to 270.1 MPa as the quenching water temperature increase from 30℃to 100℃.Fine and homogeneous β"phases were observed in the as-aged sample quenched with boiling water due to the clusters and Guinier-Preston zones(GP zones)premature precipitated during quenching process.展开更多
与高性能混凝土类似,含粗骨料超高性能混凝土(Ultra High Performance Concrete with Coarse Aggregate,UHPC-CA)经历高温后残余力学性能会发生变化,甚至出现高温爆裂行为。为了推进UHPC-CA的实际应用进程,结合现有文献分析了含湿量、...与高性能混凝土类似,含粗骨料超高性能混凝土(Ultra High Performance Concrete with Coarse Aggregate,UHPC-CA)经历高温后残余力学性能会发生变化,甚至出现高温爆裂行为。为了推进UHPC-CA的实际应用进程,结合现有文献分析了含湿量、纤维、加热速率、骨料、加载应力和混凝土强度等因素对UHPC-CA高温爆裂的影响;分析了高温后UHPC-CA的残余抗压强度、残余劈拉强度和残余断裂能等残余力学性能的变化;分析了UHPC-CA高温性能的改善措施。结果表明:随着含湿量、加热速率、加载应力和混凝土强度的增加,UHPC-CA的高温爆裂程度均呈现加重趋势,加入粗骨料与纤维后可减轻UHPC-CA的高温爆裂;随目标温度的升高,UHPC-CA的残余抗压强度与残余劈拉强度均呈现先增大后减小的趋势,残余断裂能逐渐下降;热水—干热组合养护可避免UHPC-CA的高温爆裂,显著改善其高温性能。展开更多
文摘本文对8根大比例的FRP加固钢筋混凝土桥柱模型在轴压比为0.2的恒定轴压力下进行拟静力试验,再对其中5根试验柱在经历有限的地震作用后进行长期荷载作用下的轴压试验。试验表明,FRP加固柱的徐变变形远小于对比柱的徐变变形;带损伤的加固柱在长期荷载作用下的变形发展受加固柱的损伤程度和持荷大小的控制,并与FRP的弹性模量有关;在试验条件下,带损伤的加固柱长期轴向变形呈稳定态势。采用AEMM和F ind ley模型为基础,考虑损伤程度、密封状态、三向应力状态和应力重分布等因素的影响,建立了损伤加固柱的徐变计算模型,并进行了验证。分析表明,损伤对加固柱的徐变发展和徐变破坏时限有显著影响。
基金Project(2021GK1040)supported by the Major Projects of Scientific and Technology Innovation of Hunan Province,ChinaProject(52375398)supported by the National Natural Science Foundation of China。
文摘In this study,the cooling rate was manipulated by quenching with water of different temperatures(30,60 and 100℃).Surface and internal residual stresses in the quenched 6061 aluminum alloy samples were measured using hole-drilling and crack compliance methods,respectively.Then,the processability of the quenched samples was evaluated at cryogenic temperatures.The mechanical properties of the as-aged samples were assessed,and microstructure evolution was analyzed.The surface residual stresses of samples W30℃,W60℃and W100℃is−178.7,−161.7 and−117.2 MPa,respectively along x-direction,respectively;and−191.2,−172.1 and−126.2 MPa,respectively along y-direction.The sample quenched in boiling water displaying the lowest residual stress(~34%and~60%reduction in the surface and core).The generation and distribution of quenching residual stress could be attributed to the lattice distortion gradient.Desirable plasticity was also exhibited in the samples with relatively low quenching cooling rates at cryogenic temperatures.The strengthes of the as-aged samples are 291.2 to 270.1 MPa as the quenching water temperature increase from 30℃to 100℃.Fine and homogeneous β"phases were observed in the as-aged sample quenched with boiling water due to the clusters and Guinier-Preston zones(GP zones)premature precipitated during quenching process.
文摘与高性能混凝土类似,含粗骨料超高性能混凝土(Ultra High Performance Concrete with Coarse Aggregate,UHPC-CA)经历高温后残余力学性能会发生变化,甚至出现高温爆裂行为。为了推进UHPC-CA的实际应用进程,结合现有文献分析了含湿量、纤维、加热速率、骨料、加载应力和混凝土强度等因素对UHPC-CA高温爆裂的影响;分析了高温后UHPC-CA的残余抗压强度、残余劈拉强度和残余断裂能等残余力学性能的变化;分析了UHPC-CA高温性能的改善措施。结果表明:随着含湿量、加热速率、加载应力和混凝土强度的增加,UHPC-CA的高温爆裂程度均呈现加重趋势,加入粗骨料与纤维后可减轻UHPC-CA的高温爆裂;随目标温度的升高,UHPC-CA的残余抗压强度与残余劈拉强度均呈现先增大后减小的趋势,残余断裂能逐渐下降;热水—干热组合养护可避免UHPC-CA的高温爆裂,显著改善其高温性能。
