Numerical Analysis of Axial Compression Behavior of Partially-encased Lightweight Aggregate Concrete Composite Stub Columns

In order to investigate the axial compression behavior of partially-encased lightweight aggregate concrete composite (PELC) stub columns, the finite element analysis model of PELC stub column under axial compression load was established by the software ABAQUS. Through the analysis of typical members, the whole process stress mechanism and failure mode of PELC stub columns under axial compression were revealed. The effects of parameters such as lightweight concrete strength, tie bar spacing, steel ratio and flange width-thickness ratio on the axial compression behavior of PELC stub columns were analyzed. Based on AISC 360 and considering the restraint effect of lightweight aggregate concrete, a calculation method of axial compressive capacity of PELC stub column was proposed. The results show that the main failure modes of PELC stub column under axial compression are lightweight aggregate concrete crushing, H-shaped steel sinusoidal half wave bulging and tie bar yielding. The ultimate bearing capacity of PELC stub columns increase with the rise of the lightweight aggregate concrete strength and steel ratio, and the ductility increase with the improvement of steel ratio, and decrease with the rise of tie bar spacing and lightweight aggregate concrete strength. The research results will provide a theoretical basis for the design and application of lightweight aggregate concrete composite columns in practical engineering.