Performance of concrete-filled steel tube truss girders strength by adding reinforcement

Abstract

Abstract Concrete filled steel tube (CFST) truss girder usually consists of CFST chords and hollow braces. The performance of steel tube truss girders filled with self-compacting concrete was investigated in this study. A total of eight CFST truss girders (Warren-vertical truss) specimens were tested. The main parameters were the concrete compressive strength and adding a reinforced bar in the concrete core of the bottom chord. Two of specimens without reinforcement were suggested as reference specimens. This study shows the load-deflection curves at the midspan, overall deflections, ultimate loads, flexural strength and failure modes of the tested specimens. The Proposed design equation found in the literature was used to predict the flexural strength of CFST trusses. The failure mode includes: weld fracture and shredding around joints and local buckling of the diagonal braces. Results show that the increase of concrete compressive strength caused a slight increase of the CFST truss strength by about (2.8%-10.34%), also the results showed that the best addition to the core concrete of the bottom chord was the circular steel tube compared with the addition of the steel bars.