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
由薄壁钢桁架和轻骨料混凝土构成的新型组合楼板,具有轻质、高强和施工便捷等优点,可广泛用于住宅钢结构楼盖及各种施工平台等。对承载条件下的5块简支组合楼板试件开展了烃类火灾作用下的试验研究,得到了它们的火灾热响应及位移响应。...由薄壁钢桁架和轻骨料混凝土构成的新型组合楼板,具有轻质、高强和施工便捷等优点,可广泛用于住宅钢结构楼盖及各种施工平台等。对承载条件下的5块简支组合楼板试件开展了烃类火灾作用下的试验研究,得到了它们的火灾热响应及位移响应。试验结果表明,承载2 k N/m2的组合楼板试件,在最高炉温为650℃的烃类火灾作用下,当响应位移达到L/26、且试件已出现多处裂缝时,组合楼板试件仍保持良好的整体性。对试验结果的分析表明,对于所采用的新型抗剪键,I型预制板及抗剪键分布的抗火性能明显优于II型预制板及其相应的抗剪键分布。钢桁架梁斜腹杆的壁厚对于组合楼板的火灾后残余位移有明显影响(当腹杆壁厚增加60%时,残余位移降低56%)。因此从减小组合楼板火灾后残余变形的角度出发,宜适当加大钢桁架腹杆壁厚。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.
文摘由薄壁钢桁架和轻骨料混凝土构成的新型组合楼板,具有轻质、高强和施工便捷等优点,可广泛用于住宅钢结构楼盖及各种施工平台等。对承载条件下的5块简支组合楼板试件开展了烃类火灾作用下的试验研究,得到了它们的火灾热响应及位移响应。试验结果表明,承载2 k N/m2的组合楼板试件,在最高炉温为650℃的烃类火灾作用下,当响应位移达到L/26、且试件已出现多处裂缝时,组合楼板试件仍保持良好的整体性。对试验结果的分析表明,对于所采用的新型抗剪键,I型预制板及抗剪键分布的抗火性能明显优于II型预制板及其相应的抗剪键分布。钢桁架梁斜腹杆的壁厚对于组合楼板的火灾后残余位移有明显影响(当腹杆壁厚增加60%时,残余位移降低56%)。因此从减小组合楼板火灾后残余变形的角度出发,宜适当加大钢桁架腹杆壁厚。
