Abstract. The effect of moisture concentration and the thermal gradient on the free flexural vibration and buckling of laminated composite plates are investigated. The effect of a centrally located cutout on the global response is also studied. The analysis is carried out within the framework of the extended finite element method. A Heaviside function is used to capture the jump in the displacement and an enriched shear flexible 4-noded quadrilateral element is used for the spatial discretization. The formulation takes into account the transverse shear deformation and accounts for the lamina material properties at elevated moisture concentrations and temperature. The influence of the plate geometry, the geometry of the cutout, the moisture concentration, the thermal gradient and the boundary conditions on the free flexural vibration is numerically studied.

Despite its great potential, the use of high strength concrete (HSC) in bridge columns raises concerns associated with the intrinsic brittleness of the material and the insufficient lateral deformation capacity of the columns under seismic loading. To ensure the ductile response of HSC columns, this paper proposes and studies an innovative hybrid confinement method which provides traditional passive confinement combined with thermally triggered active confinement by using fiber-reinforced polymer (FRP) sheets and shape memory alloy (SMA) spirals together. The compressive behavior of HSC confined with the hybrid (SMA-FRP) jackets are experimentally investigated at the material level, and implemented in seismic analysis of a bridge system with HSC columns within a new simulation framework, named material testing integrated simulation. The hybrid confinement jackets show greater performance in improving the compressive behavior of HSC, compared to conventional FRP jackets. The simulation results indicate that the hybrid jackets can effectively protect the plastic hinge regions of HSC columns, and significantly enhanced the capability of the bridge to accommodate strong ground motions as well as large lateral deformations.

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