Moment-Curvature Analysis of Hybrid Concrete-Filled Fiber Reinforced Polymer Tube Columns

摘要

In recent years, the concrete-filled fiber reinforced polymer (FRP) tube (CFFT) system has been widely studied as a durable and cost-effective alternative design for bridge columns. This system has been formally recognized by AASHTO for application as load-carrying components of bridges. This system eliminates the need for scaffolding, framework, and form removal that leads to cost savings and simplified construction. While a CFFT system with no rebar reinforcement is attractive in its ease of construction, the inadequate energy dissipation capabilities limit its use as structural components in areas subjected to extreme loadings such as earthquakes. Research has shown that a lightly reinforced CFFT system provides the energy dissipation required for resisting extreme events. A novel hybrid concrete-filled FRP tube (HCFFT) column system is proposed to combine the ease of construction of conventional CFFTs with energy dissipation characteristics of lightly reinforced CFFT columns. The HCCFT column system consists of a hybrid metal-nonmetal FRP tube filled with unreinforced concrete. The hybrid FRP shell is manufactured by adding layers of longitudinal steel fibers during the filament winding process. The hybrid FRP combines the energy dissipation capability and ductility of continuous steel fibers with the excellent strength-to-weight ratio and re-centering capabilities of glass fibers. The polymeric resins improves the durability of the columns. The manufacturing process for the hybrid shell is presented. To evaluate the performance of the system, moment curvature analyses were conducted using material properties obtained from experimental tests. The material properties used in the analysis were evaluated on a component level. The material properties were applied to the column model and validated with compression data for a 152.4 mm (6 in) HCFFT. The validated model was then used to conduct moment-curvatures analyses on (16 in) diameter HCFFT columns to characterize the axial load-bending moment relationship. The axial force-bending moment interaction curves are presented for various steel fiber reinforcement ratios. This data is expected to help development of design guides for the HCFFT column system.