Performance of SRCFST member under long-term loading and preload on steel tube

Abstract

To further improve the structural performance, steel-reinforced concrete-filled steel tubular (SRCFST) column is widely used in different building structures. Due to the fact that during the whole life cycle, the columns may be subjected to preload on the steel tube and long-term load, the mechanical behaviour of SRCFST column becomes more complex under the combined load. Therefore, 12 specimens are prepared and tested to study the compressive behaviour of SRCFST column under the combined load. Through the experiment, the longitudinal strain versus time curves of circular SRCFST members in the creep phase, the failure modes and load-deformation curves in the load-bearing capacity failure phase are obtained. The test results show that considering the combined load has an impact on the mechanical behaviour of the specimen. The testing is followed by the numerical methodologies, a finite element model is established and validated using test results. The influence law of the main factors on the strength index of load-bearing capacity is evaluated. Based on the parameter study, the calculation formula of the ultimate load-bearing capacity for circular SRCFST members under combined preload on steel tube and sustained load is proposed, which provides reference for engineering design or assessment.