Experimental Study on Creep of Concrete Filled Steel Tube Under Eccentric Compression

Abstract

Several concrete-filled steel tube (CFT) arch bridges have been built over the past few years around the world. Current design codes do not address the design of CFT arch bridges, particularly with consideration of concrete creep effects, which can be very important. This paper presents experimental results from tests conducted on 7 specimens to evaluate the creep behavior of CFT eccentric compression members. The results from experiment indicate that the creep development of CFT eccentric compression members is the same to axial load member, which is increasing faster in the early 60 days and then slower after that. Creep strain is smaller with the higher of strength grade of concrete. The earlier the loading age of concrete, the larger the creep strain. The difference is that when the eccentric creep is stable, the deformation is earlier than the axial compression creep. An experimental database is compiled using results from this paper and 16 additional tests from the literature. The comprehensive database is used to evaluate six commonly used creep models for predicting short-term (up to 250 days) creep strains of the concrete infill in CFT eccentric compression members. The selected models are the CEB-FIP MC78 model, CEB-FIP MC90 model, fib MC2010 model, ACI 209R-92 model, GL2000 model and the B3 model. Analytical results indicate that fib MC2010 model, CEB-FIP MC90 model and ACI 209R-92 model have a most prediction accuracy for the creep strain of CFT eccentric compression members.