Advanced Structures & Composites Center

Published: 2004

Publication Name: Journal of Composites for Construction

Publication URL: https://pilemedic.com/wp-content/uploads/2023/02/FRP-Composite-Wood-Pile-Interface-Characterization-by-Push-Out-Tests.pdf

Abstract:

Structural restoration of spliced or damaged wood piles with fiber reinforced polymer FRP composite shells requires that
shear forces be transferred between the wood core and the encasing composite shells. When a repaired wood pile is loaded, shear stresses
develop between the wood pile and the FRP composite shell through the grouting material. Alternatively, shear force transfer can be
developed through mechanical connectors. The objective of this study was to characterize the interfaces in wood piles repaired with FRP
composite shells and grout materials. Two interfaces were studied: wood pile/grout material and a grout material/innermost FRP composite shell. A set of design parameters that control the response of both interfaces was identified: 1 extent of reduction of cross section
of wood pile due to deterioration necking; 2 type of grout material cement-based or polyurethane; 3 use of mechanical connectors;
and 4 addition of frictional coating on the innermost shell. Push-out tests by compression loading were performed to characterize the
interfaces and discriminate the effect of the design parameters. The outcome of the push-out tests was evaluation of the shear stress and
force versus slip response and characterization of the failure mechanism. A set of repair systems that represent different combinations of
the design parameters was fabricated and the interfaces evaluated. It was found that the combination of cement-based grout and polymer
concrete overlay on the innermost shell provided the most efficient shear force-slip response. A simplified piecewise linear model of shear
stress versus slip at the wood/grout and grout/FRP composite interfaces with and without mechanical connectors is proposed to synthesize
the experimental response.