In-plane behaviors of FRP confined concrete-filled steel tubular arches under mid-span concentrated loads

In order to address corrosion issues in concrete-filled steel tubular (CFST) arches, the fiber reinforced polymer (FRP) confined concrete-filled steel tubular (CCFST) arch, consisting of an FRP-steel composite tube and a core concrete, are proposed in this paper. To investigate the in-plane behaviors of CCFST parabolic arches, one bare CFST arch and five CCFST arches with a span of 6 m were tested and analyzed under the mid-span concentrated load. The main parameters considered in the test included various FRP wrapping methods (spiral winding, longitudinal and spiral winding, and braided shell) and different rise-to-span ratios (1/8, 1/6 and 1/4). The failure patterns and mechanisms were studied, and the confining effect of FRP-steel composite tube to the concrete at failure was investigated. The test results showed that the CCFST arch with spiral winding exhibited symmetric instability failure, akin to CFST arches; whereas CCFST arches with longitudinal winding failed due to the sudden rupture of longitudinally wrapped FRP strips. In addition, the finite element model of CCFST arches was established with solid element and verified based on test results. The parametric analysis indicated that the in-plane bearing capacity of CCFST arches under mid-span concentrated loads increased with the increase of the FRP layers, the rise-to-span ratio and the steel ratio, but decreases with the increase of the slenderness ratio.