Finite element modelling of timber infilled steel tubular short columns under axial compression

Timber infilled steel tubular (TIST) columns can be a promising alternative to the concrete infilled steel tubular (CIST) columns, particularly for the lightly loaded prefabricated structures, as timber is lighter and more sustainable material than the conventional concrete. However, limited research studies were dedicated to investigate the structural behaviour of TIST columns. Therefore, in this study an attempt has been made to investigate the parameters that influence the compressive behaviour and to develop appropriate design guidelines through finite element (FE) analyses of TIST columns. A three-dimensional FE modelling technique of TIST has been developed and validated with available experimental results. The developed model considered the steel tube induced confinement on the strength and orthotropic characteristics of timber as well as contact interaction between steel and timber. The validated modelling technique has been extended to parametrically (120 FE models) study the compressive behaviour of TIST columns varying parameters such as strength properties of steel and timber, thicknesses of steel tube, and cross-sectional shapes. The analyses reveal that the TIST columns can be used on par with CIST columns. The calculated strength and ductility indices reveal that the maximum strength and ductility enhancement up to 60% and 65% can be achieved with TIST. Further, the parametric analyses results have been used to verify suitable design formulations for TIST column, subsequently the design formations that are similar to CIST columns can consciously be extended to design the TIST columns.