Comparative life cycle assessment of composite structures incorporating uncertainty and global sensitivity analysis

In recent years, there have been increasing efforts seeking novel material and structural alternatives to alleviate environmental and economic burdens caused by conventional engineering structures. However, research on long-term environmental impact and cost of the design alternatives is limited. This paper presents a comparative life-cycle assessment (LCA) and life-cycle cost analysis (LCCA) of three composite columns over a service life of 100 years. The studied cases are typical composite structural forms consisting of: (1) concrete-filled steel tubular column (CFST); (2) concrete-filled fiber-reinforced polymer (FRP) tubular column (CFFT); and (3) hybrid FRP-concrete-steel double-skin tubular column (DSTC). The CFFT is expected to have extended service life due to corrosion resistance of FRP. The DSTC is designed to reduce concrete consumption by leaving a void at the center of the column. Both deterministic and probabilistic results are discussed in this study. Specifically, Sobol's index is selected to aid the probabilistic LCA and LCCA analyses. The deterministic LCA results indicate that CFFT has the least CO2 emission: 50% less than DSTC and 60% less than CFST. While LCCA results show that for the investigated scenario the DSTC costs the most across the studied service life, about 15% more than CFST and CFFT. The probabilistic results indicate that the production and maintenance stage are two significant influential factors of the LCA and LCCA results. In general, CFFT and DSTC are more economic and environmental-friendly alternatives compared to CFST.