Experimental Investigation of the Behaviour of Perforated Steel Cold-formed Column Encased in Lightweight Concrete

In recent years, cold-formed steel elements have been used more and more as primary load-bearing structures. The development of cost-effective structures is also a main concern in the field of structural engineering. That led to the combination of several materials to achieve this goal. This paper presents an experimental study conducted on cold-formed steel sections with perforations encased in lightweight concrete to investigate their behaviour during subjection to axial compression load. First, the material properties were determined from the tensile coupon test for steel used in cold-formed sections and standard cube/cylinder tests for lightweight concrete. Then, a total of twelve specimens were examined under the axial compression test, with two different cross-sections and various heights. The study's goals are to find out how lightweight encasement affects the behaviour and failure mode of the cold-formed steel column sections. Lightweight concrete encasement has greatly enhanced ultimate axial compression capacity, with a ratio ranging from 74.5–321.1% and 19.5–154.6% based on unit cost. Also, it enhanced the behaviour of cold-formed steel columns, eliminating distortional buckling failure mode and greatly restraining the lateral displacement of both the web and flanges of the cold-formed section. Furthermore, a comparison was conducted between international codes and test results to assess and estimate the behaviour and ultimate compression capacity of perforated bare steel and encased columns subjected to pure axial compression force.