Significant advances have been made in the past decade in the field of high performance and lightweight concrete with novel products being developed by combining structural steel with these concrete to develop next generation of composite structures that exhibit exceptional mechanical properties making themwell suited for high-rise and offshore construction. This paper presents the recent experimental investigation at the National University of Singapore (NUS) on ultra-high strength concrete (UHSC) filled single- and double-tube columns. The test results are compared with Eurocode 4 predictions. It is found that Eurocode 4 approach can conservatively predict the ultimate resistance of UHSC filled composite columns, but the confinement effect should be ignored. In addition, this paper reports the design and experimental studies of steel-concrete-steel sandwich system in which ultra-lightweight structural concrete with density less than 1400 kg/m3 was used to produce ultra-lightweight composite panels.Novel J-hooked shear connectors are employed to enhance composite action between concrete and steel. Experimental results on flexural and punching resistance of sandwich panels are presented to illustrate the feasible use of lightweight in-filled material and effectiveness of the shear connectors to resist the applied loads.