The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolyme...The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolymer composite(EGC)is a promising material featured by eco-friendly,fast-setting and strain-hardening characteristics for emergent strengthening and construction.However,the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain.In this study,laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability,dry shrinkage,and mechanical properties in compression,tension and flexure.The experimental results showed that EGC containing PE fiber exhibited suitable workability,acceptable dry shrinkage and superior mechanical properties compared with other types of fibers.After that,a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements.The tests include autoclaved aerated concrete(AAC)masonry walls subjected to vented gas explosion,reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion.It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios.For AAC masonry walls and panels,with the existence of EGC,the integrity of specimens could be maintained,and their deflections and damage were significantly reduced.For plain concrete slabs,the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.展开更多
Mechanical behavior of concrete slab of large-span through tied-arch composite bridge was investigated by finite element analysis (FEA). Improved methods to decrease concrete stresses were discussed based on compariso...Mechanical behavior of concrete slab of large-span through tied-arch composite bridge was investigated by finite element analysis (FEA). Improved methods to decrease concrete stresses were discussed based on comparisons of different deck schemes, construction sequences and measures, and ratios of reinforcement. The results show that the mechanical behavior of concrete slab gets worse with the increase of composite regions between steel beams and concrete slab. The deck scheme with the minimum composite region is recommended on condition that both strength and stiffness of the bridge meet design demands under service loads. Adopting in-situ-place construction method, concrete is suggested to be cast after removing the full-supported frameworks under the bridge. Thus, the axial tensile force of concrete slab caused by the first stage dead load is eliminated. Preloading the bridge before concrete casting and removing the load after the concrete reaching its design strength, the stresses of concrete slab caused by the second stage dead load and live load are further reduced or even eliminated. At last, with a high ratio of reinforcement more than 3%, the concrete stresses decrease obviously.展开更多
提出一种新型预应力钢筋混凝土叠合剪力墙,通过在预制板内布置水平预应力钢筋,降低板厚,方便运输和吊装。对剪跨比为1.5的现浇剪力墙和预应力叠合剪力墙进行了低周往复加载试验,对比分析了其破坏模式、承载力、延性和耗能能力,结果表明...提出一种新型预应力钢筋混凝土叠合剪力墙,通过在预制板内布置水平预应力钢筋,降低板厚,方便运输和吊装。对剪跨比为1.5的现浇剪力墙和预应力叠合剪力墙进行了低周往复加载试验,对比分析了其破坏模式、承载力、延性和耗能能力,结果表明叠合剪力墙与现浇剪力墙的抗震性能一致。采用有限元分析软件ABAQUS建立了剪力墙的非线性数值分析模型,基于试验结果验证了模型的正确性,并进行了轴压比、剪跨比、初始预应力等参数分析。结果表明,高轴压比及小剪跨比下叠合剪力墙的承载力及延性优于现浇剪力墙。随着初始预应力的增大,承载力提高,试件由剪切破坏转换为弯曲破坏。水平预应力筋延缓了叠合剪力墙斜向裂缝的发展,提高了抗剪承载力,改变了剪力墙的破坏模式,建议张拉控制应力取值为0.50 f ptk。展开更多
为解决反复开挖道路铺设多种管线造成交通拥堵且耗费大量建设成本的难题,提出侧壁出筋叠合板式拼装综合管廊,该管廊具有吊装方便、现场支模少、节点连接可靠、整体性和防水性好等优点。基于ABAQUS大型商用软件,建立水平荷载作用下侧壁...为解决反复开挖道路铺设多种管线造成交通拥堵且耗费大量建设成本的难题,提出侧壁出筋叠合板式拼装综合管廊,该管廊具有吊装方便、现场支模少、节点连接可靠、整体性和防水性好等优点。基于ABAQUS大型商用软件,建立水平荷载作用下侧壁出筋叠合板式拼装综合管廊有限元分析模型。为验证该模型的合理性,开展侧壁出筋叠合板式拼装综合管廊中节点试验,试验结果与有限元分析结果吻合良好。在此基础上,进一步开展叠合板式拼装综合管廊双舱整体结构足尺模型的有限元参数分析,分析参数包括腋角高度和轴压比。分析结果表明:1)双舱整体结构的破坏形态均为弯曲破坏。2)所有试件的峰值承载力在200.5~298.6 k N,层间位移角在1/43~1/27。3)相比于无腋角试件,当腋角高度分别为150 mm和250 mm时,有腋试件的峰值承载力分别提高24.4%和39.7%,峰值侧移分别增加49.3%和60.1%;当轴压比从0增加到0.05、0.10时,有腋试件的峰值承载力分别提升10.3%、19.7%,但峰值侧移分别降低5.2%、18.6%。总体上,侧壁出筋叠合板式拼装综合管廊双舱整体结构具有较大的承载力和较好的变形能力。展开更多
基金National Natural Science Foundation of China(Grant Nos.51908188 and 51938011).
文摘The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolymer composite(EGC)is a promising material featured by eco-friendly,fast-setting and strain-hardening characteristics for emergent strengthening and construction.However,the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain.In this study,laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability,dry shrinkage,and mechanical properties in compression,tension and flexure.The experimental results showed that EGC containing PE fiber exhibited suitable workability,acceptable dry shrinkage and superior mechanical properties compared with other types of fibers.After that,a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements.The tests include autoclaved aerated concrete(AAC)masonry walls subjected to vented gas explosion,reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion.It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios.For AAC masonry walls and panels,with the existence of EGC,the integrity of specimens could be maintained,and their deflections and damage were significantly reduced.For plain concrete slabs,the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.
基金Project(2005k002-c-2) supported by the Science and Technology Development Program of Railways Department, China
文摘Mechanical behavior of concrete slab of large-span through tied-arch composite bridge was investigated by finite element analysis (FEA). Improved methods to decrease concrete stresses were discussed based on comparisons of different deck schemes, construction sequences and measures, and ratios of reinforcement. The results show that the mechanical behavior of concrete slab gets worse with the increase of composite regions between steel beams and concrete slab. The deck scheme with the minimum composite region is recommended on condition that both strength and stiffness of the bridge meet design demands under service loads. Adopting in-situ-place construction method, concrete is suggested to be cast after removing the full-supported frameworks under the bridge. Thus, the axial tensile force of concrete slab caused by the first stage dead load is eliminated. Preloading the bridge before concrete casting and removing the load after the concrete reaching its design strength, the stresses of concrete slab caused by the second stage dead load and live load are further reduced or even eliminated. At last, with a high ratio of reinforcement more than 3%, the concrete stresses decrease obviously.
文摘提出一种新型预应力钢筋混凝土叠合剪力墙,通过在预制板内布置水平预应力钢筋,降低板厚,方便运输和吊装。对剪跨比为1.5的现浇剪力墙和预应力叠合剪力墙进行了低周往复加载试验,对比分析了其破坏模式、承载力、延性和耗能能力,结果表明叠合剪力墙与现浇剪力墙的抗震性能一致。采用有限元分析软件ABAQUS建立了剪力墙的非线性数值分析模型,基于试验结果验证了模型的正确性,并进行了轴压比、剪跨比、初始预应力等参数分析。结果表明,高轴压比及小剪跨比下叠合剪力墙的承载力及延性优于现浇剪力墙。随着初始预应力的增大,承载力提高,试件由剪切破坏转换为弯曲破坏。水平预应力筋延缓了叠合剪力墙斜向裂缝的发展,提高了抗剪承载力,改变了剪力墙的破坏模式,建议张拉控制应力取值为0.50 f ptk。
文摘为解决反复开挖道路铺设多种管线造成交通拥堵且耗费大量建设成本的难题,提出侧壁出筋叠合板式拼装综合管廊,该管廊具有吊装方便、现场支模少、节点连接可靠、整体性和防水性好等优点。基于ABAQUS大型商用软件,建立水平荷载作用下侧壁出筋叠合板式拼装综合管廊有限元分析模型。为验证该模型的合理性,开展侧壁出筋叠合板式拼装综合管廊中节点试验,试验结果与有限元分析结果吻合良好。在此基础上,进一步开展叠合板式拼装综合管廊双舱整体结构足尺模型的有限元参数分析,分析参数包括腋角高度和轴压比。分析结果表明:1)双舱整体结构的破坏形态均为弯曲破坏。2)所有试件的峰值承载力在200.5~298.6 k N,层间位移角在1/43~1/27。3)相比于无腋角试件,当腋角高度分别为150 mm和250 mm时,有腋试件的峰值承载力分别提高24.4%和39.7%,峰值侧移分别增加49.3%和60.1%;当轴压比从0增加到0.05、0.10时,有腋试件的峰值承载力分别提升10.3%、19.7%,但峰值侧移分别降低5.2%、18.6%。总体上,侧壁出筋叠合板式拼装综合管廊双舱整体结构具有较大的承载力和较好的变形能力。
