Parametric study of stress concentration factors in KT connections reinforced with concrete subjected to axial loads

Abstract

This research investigates the effect of stress concentration factors (SCFs) in KT -connections retrofitted with concrete under axial loadings. 972 finite element models of KT -connections with various types of concrete and geometrical parameters have been modeled and analyzed using ANSYS APDL. SOLID 186 was used to mesh all parts of the model and to design the weld profile AWS recommendations were followed. The interaction between concrete and the chord was defined using ANSYS contact capability. Available experimental data was utilized to validate those models. Afterwards, the validated models were used to study the SCFs in different kinds of KTconnections filled with concrete. The results indicate a reduction of the maximum SCFs by around 50%-60% at the saddle points, and 17%-43% at the crown points compared to empty KT -joints. The reduction effect increases significantly when the concrete nominal compressive strength grades from C2, C40, and C50. In addition, in all types of loading conditions at the saddle points, the SCFs values increase. Among the nondimensional parameters, theta significantly affects SCFs crown points at the outer braces and saddle points at the central brace. Despite the clearly identified advantage of using concrete filling to reduce SCFs in the KT -joints, there are no studies or equations on these joints filled with concrete. Therefore, to calculate SCFs in KT -connections filled with concrete, some new formulae are developed and validated against the UK DoE acceptance standard.