Compression behavior of CFRP strengthened sawdust-magnesium oxychloride composites columns subjected to eccentric loading

Abstract

Sawdust-magnesium oxychloride cement composites (SMOCC) are new low-carbon and environmentally friendly building material. Previous studies showed that SMOCC columns perform well under compression, but the addition of eccentricity could induce excessive tensile stress, which may cause premature failure to sawdust fibers. Many engineering applications showed that the use of carbon fiber reinforced polymer (CFRP) could effectively improve the mechanical properties of building components. However, the applicability and feasibility of CFRP in SMOCC columns have not been explored. To overcome this research gap, this paper investigates the working mechanism and reinforcement effectiveness of the CFRP strengthened SMOCC columns subjected to eccentric loading. A total of 16 specimens were designed and tested, the investigated parameters include the arrangement modes of CFRP strips and load eccentricity, whose effects on the failure mode, load capacity, ductility and strain behavior are described and discussed. Moreover, the prediction models were proposed to predict the ultimate bearing capacity of the SMOCC columns. The test results indicate that the strengthening technique was effective, particularly as the bearing capacities and ductility of the CFRP strengthened SMOCC columns increased by 39.40 %-104.38 % and 10.60 %-113.51 %, respectively, when compared with those of the un-strengthened SMOCC columns. Moreover, the enhancing effect increased with an increase in the number of the CFRP strips. As the eccentricity was increased from 10 mm to 30 mm, the CFRP strengthened SMOCC column’s bearing capacity and ductility slightly decreased by 19.99 %-21.24 % and 28.63 %-41.46 %, respectively, but the lateral deflection at the mid-height of columns significantly increased by 26.55 %-61.84 %. Strain distributions within the SMOCC column cross section showed linear variation showing compatibility with elastic bending theory. The results predicted using the proposed models showed good agreement with test results, where the errors are within 10 %.