Effect of creep on the strength of high strength concrete-filled steel tubes

Abstract

High strength concrete filled steel tubes (HSCFSTs) are being increasingly used as columns in tall buildings, bridges, and other critical infrastructure and complex structural systems. Very little research has been done to study the performance of these columns under long-term sustained loads where creep effects take place, and no study exists on the long-term performance of these columns under eccentric sustained loads at the large scale. Six large scale (2700 mm height) HSCFSTs were tested in this paper under sustained eccentric compression for a period of five months. After that, the columns were tested to failure and their performance was compared to another six companion HSCFSTs that were kept unloaded for the same time period. A decrease of about 13% in the load carrying capacity was observed after creep. It was also observed that creep significantly changed the force distribution between steel and concrete. A study of the force redistribution showed that the force carried by the steel increased by >50% of its initial value.