NLFEA of Sulfate-Damaged Circular CFT Steel Columns Confined with CFRP Composites and Subjected to Axial and Cyclic Lateral Loads

Abstract

It is rather costly and difficult to experimentally evaluate the performance of concrete-filled tubular (CFT) circular steel columns exposed to combined axial and cyclic lateral loads. This research paper uses the nonlinear finite element (NLFEA) technique to assess the influence of using carbon-fiber-reinforced polymer (CFRP) laminates on the structural response and failure mode of damaged-by-sulfate CFT circular steel columns. At the beginning, twenty-one CFT circular steel column models were devised and checked for soundness using the findings of previously conducted research. Next, the models were broadened to investigate how the models’ behavior was influenced by the CFRP number of layers and the level of sulfate damage. For experimental purposes, the numbers of CFRP layers were set to be zero, five, six, seven, eight, nine, and ten, while there were three levels of sulfate damage, namely: level 0 (undamaged), level 1 (73 days), and level 2 (123 days). Some of the models were left unconfined with CFRP wraps for comparison. The CFRP confinement was at the end of the models due to its importance regarding the models’ capacity of lateral load. The columns’ ends were confined to prevent the models from outward local buckling, which led to higher strength, bigger net drift, and enhanced energy dissipation. The NLFEA models were then appropriately modified and adjusted in accordance with credible previously conducted experimental research; after which, a parametric study was performed to investigate how the models’ behavior was affected by the number of CFRP layers and the level of axial load. The study found that the CFT circular steel column models’ performance significantly enhanced when the models were wrapped with five to ten CFRP layers. It must be mentioned, though, that using eight, nine, and ten CFRP layers gave almost similar results. In addition, the NLFEA results revealed that when the damaged-by-sulfate models were repaired externally with CFRP wraps, there was an improvement in the models’ cyclic behavior, as they showed a raise in the load capacity, an enhancement in the horizontal displacement, a greater displacement ductility, better energy dissipation, and little deterioration in secant stiffness. The study found that using wraps of CFRP proved a great efficiency with the change in the sulfate damage level.

Experimental study of reinforced concrete piles wrapped with fibre reinforced polymer under vertical load

“…However, corrosion in hostile environments can be a problem for these materials, which is why FRP piles have become increasingly popular in geotechnical engineering in recent years [12][13][14]. Studies on FRP piles have been conducted, with topics including the piles' structural behavior, the features of different FRP kinds, and the piles' corrosion resistance [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. The soil condition is an essential component that must be addressed for FRP piles because piles are used to support massive constructions, yet most of the works discussed over FRP piles and do not include soil effects.…”

Axial compression performance of square concrete filled double skin SHS steel tubular columns confined by CFRP

“…Prabhu et al 17 and Sundarraja et al 18 investigated the applicability of CFRP sheet for enhancing CFST columns under compression by considering the effects of number of layers, width and spacing. Al-Rousan et al 19 and Li et al 20 used FRP to enhance the corrosion and sulfate resistance of CFST. Liang et al 21 investigated the effect of different CFRP reinforcement schemes on the mechanical properties of recycled aggregate concrete filled steel tube (RACFT) columns.…”

Preliminary Study on the Behaviour of Fibre-Reinforced Polymer Piles in Sandy Soils

“…Thus, the use of FRP piles for geotechnical engineering has recently become more popular because of its advantages of being easy to maintain, having a long durability, and being environmentally friendly [11][12][13]. Investigations of FRP piles have been undertaken, including the structural behaviour of FRP piles, the characteristics of FRP types, and the resistance against corrosion [14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”