Development of Advancded Grid Stiffened (AGS) Fiber Reinforced Polymer (FRP) Tube-Encased Concrete Columns.

摘要

In this project, a new type of confining device, a latticework of interlacing fiber reinforced polymer (FRP) ribs that are jacketed by a FRP skin, is proposed, manufactured, tested, and modeled to encase concrete cylinders. This systematic study includes a thorough literature survey and the state-of-the-art knowledge in this research area was obtained. In the proof-of-concept study, advanced grid stiffened (AGS) tubes were fabricated by the hand lay-up technology per a pin-guided mandrel system. Both circular and square AGS tubes were manufactured and encased concrete cylinders and beams were tested using uniaxial compression and transverse bending. In the automatic manufacturing and parametric study, a pin-guided system assisted by a collapsible mandrel was developed to filament wind the AGS tubes automatically. A building-block test was conducted to reveal the step-by-step development of the composite action. After that, the effect of the rib thickness, skin thickness, and bay area on the structural behavior was evaluated experimentally. Also, the effect of rib thickness on the interfacial bonding strength was investigated using a push-out test. In the fire tolerance test, researchers investigated the enhancement of fire tolerance of AGS tube encased concrete cylinders as a result of incorporating organically modified montmorillonite (MMT) and a traditional fire retardant additive (TSWB) into a vinyl ester (VE) matrix. Two series of specimens were prepared, fire-tested, and compression-tested to determine their residual load carrying capacity. A non-linear finite element analysis considering the nonlinear behavior of concrete, assisted by a non-associative Drucker-Prager plasticity criterion, was implemented to validate the experimental results and conduct the parametric study. In the engineering economic analysis, the life-cycle cost of new cylinders was compared to conventional steel reinforced concrete cylinders, both quantitatively and qualitatively. The results from this project showed that this type of novel cylinders outperforms the regular FRP tube encased concrete cylinders and has great potential to be used as columns in rebuilding or new construction of bridges or other infrastructure.