Circular Concrete-Filled Tubes for Improved Sustainability and Seismic Resilience
Circular Concrete-Filled Tubes for Improved Sustainability and Seismic Resilience
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DOI：
10.1061/(asce)st.1943-541x.0001103
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发表时间：
2015-03-01
影响因子：
4.1
通讯作者：
Berman, Jeffrey W.
中科院分区：
文献类型：
--
作者：
Lehman, Dawn E.;Kuder, Katherine G.;Berman, Jeffrey W.
混凝土填充管（CFTs）通过使用含有大量辅助胶凝材料（SCMs）的混凝土来替代水泥，为更可持续的结构系统提供了机会。然而，由于固化时间较长，SCM混凝土可能无法承受早期（施工或恒载）荷载，因此需要将应力转移到钢管，可能导致钢管屈曲。此外，这些荷载是永久性的，使用SCM混凝土的CFTs的长期响应也是未知的。本研究评估的反应，CFTs与常规和大体积SCM混凝土立即压缩，持续和极端负载。两个大规模（508毫米直径）钢管混凝土柱与基脚连接标本，一个与高容量的SCM用于取代波特兰水泥，进行了长期压缩和循环荷载下的测试。收缩和蠕变进行了评估的大型CFT和同伴圆柱体。SCM和常规混凝土中的总蠕变应变被发现在未密封的圆柱体中比CFT试样大得多。蠕变系数被认为是相似的密封圆筒和CFT标本。干燥收缩被认为是可以忽略不计的CFTs和SCM混凝土被发现有稍大的收缩比传统的混凝土在密封和未密封的圆筒。CFT试件进行循环横向荷载，以评估其对极端荷载的响应，徐变荷载和SCM混凝土对性能的影响可以忽略不计。
Concrete-filled tubes (CFTs) provide an opportunity for more sustainable structural systems through the use of concretes with high volumes of supplementary cementitious materials (SCMs) to replace cement. However, there is concern that the SCM concrete would not be able to sustain the early (construction or dead) loads due to the longer cure time, necessitating stress transfer to the steel tube, possibly leading to tube buckling. Further, these loads are permanent and the long-term response of CFTs with SCM concretes is also unknown. This research evaluates the response of CFTs with conventional and high-volume SCM concretes to immediate compressive, sustained, and extreme loadings. Two large-scale (508mm diameter) CFT column-to-footing connection specimens, one with a high volume of SCM used to replace portland cement, were tested under long-term compressive and cyclic loadings. Shrinkage and creep were evaluated for both the large-scale CFT and companion cylinders. The total creep strain in the SCM and conventional concretes was found to be much larger in the unsealed cylinders than the CFT specimens. Creep coefficients were found to be similar for the sealed cylinders and the CFT specimens. Drying shrinkage was found to be negligible in the CFTs and the SCM concrete was found to have slightly larger shrinkage than conventional concrete in both sealed and unsealed cylinders. The CFT specimens were subjected to cyclic lateral loading to evaluate their response to extreme loads and the effects of creep loading and the SCM concrete on performance were negligible.