Post-peak Behaviour of Composite Column Using a Ductile Lightweight Aggregate Concrete

Oil palm shell (OPS) concrete filled steel tube (CFT) columns are acknowledged to be a new type of sustainable composite column. In this type of column, the conventional coarse aggregate was partially replaced with OPS lightweight aggregate to provide a green composite column. This type of CFT column showed higher energy absorption and flexibility compared to CFT columns with normal weight concrete. This research studied the effect of the strength of OPS concrete on the axial compressive behaviour of CFT columns for two grades of OPS concretes. The behaviour was comparable to that of CFT columns with two grades of normal concrete. The results showed that the CFT columns with OPS concrete achieved a new post-peak behaviour. The experimental results of the axial compressive load were compared with the estimation of two international standards. EC4-1994 and ACI318-14 showed a reliable and conservative estimation of the axial load capacity of CFT columns, respectively.

Automated summary

Oil palm shell concrete filled steel tube columns, which partially replaced conventional coarse aggregate with lightweight aggregate, demonstrated higher energy absorption and flexibility compared to normal weight concrete filled steel tube columns. The axial compressive behavior of OPS concrete filled CFT columns was studied for two grades of OPS concretes, showing comparable performance with normal concrete filled CFT columns but exhibiting a new post-peak behavior. The experimental results were compared with international standards EC4-1994 and ACI318-14, which provided reliable and conservative estimations of the axial load capacity of CFT columns.