This paper firstly proposed high performance composite columns for cold-region infrastructures using ultra-high performance concrete (UHPC) and ultra-high strength steel (UHSS) Q960E. Then, 24 square UHPC-filled UHSS tubes (UHSTCs) at low temperatures of -80, -60, -30, and 30°C were performed under axial loads. The key influencing parameters on axial compression performance of UHSS were studied, i.e., temperature level and UHSS-tube wall thickness (t). In addition, mechanical properties of Q960E at low temperatures were also studied. Test results revealed low temperatures improved the yield/ultimate strength of Q960E. Axial compression tests on UHSTCs revealed that the dropping environmental temperature increased the compression strength and stiffness, but compromised the ductility of UHSTCs; increasing t significantly increased the strength, stiffness, and ductility of UHSTCs. This study developed numerical and theoretical models to reproduce axial compression performances of UHSTCs at low temperatures. Validations against 24 tests proved that both two methods provided reasonable simulations on axial compression performance of UHSTCs. Finally, simplified theoretical models (STMs) and modified prediction equations in AISC 360, ACI 318, and Eurocode 4 were developed to estimate the axial load capacity of UHSTCs at low temperatures.
Jia-Bao Yan — 1)Key Laboratory of Coast Civil Structure Safety of Ministry of Education, Tianjin University, Tianjin 300350, China 2)School of Civil Engineering, Tianjin University, Tianjin 300350, China
Shunnian Hu — School of Civil Engineering, Tianjin University, Tianjin 300350, China
Yan-Li Luo — Architectural Engineering Institute IV, Automotive Engineering Corporation, Tianjin 300113, China
Xuchuan Lin — Architectural Engineering Institute IV, Automotive Engineering Corporation, Tianjin 300113, China
Yun-Biao Luo — 1)Key Laboratory of Coast Civil Structure Safety of Ministry of Education, Tianjin University, Tianjin 300350, China 2)School of Civil Engineering, Tianjin University, Tianjin 300350, China
Lingxin Zhang — Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics, CEA, Harbin 150080, China
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