Search for: All records

Sheet piles are interlocked segments used for temporary or permanent soil and water retaining structures such as below-grade parking structures and sea walls. Although steel is commonly used due to its strength and ease of manufacturing, it rusts in saltwater. Fiber reinforced polymer (FRP) composite sheet piles are resistant to chlorides and have higher corrosion resistance, but their mechanical properties vary in length and width. Stress risers at corrugation corners make soil-structure interaction a challenging design issue. This research aims to develop a standardized test procedure to determine the resisting moment capacity of FRP composite sheet piles. Cantilevered FRP sheet piles fixed with a sand-concrete mixture of ~70 psi (0.48 MPa) compressive strength were tested under static loads. Strain gages and LVDTs were used to collect data on deformation response up to and beyond peak induced stress. Results suggest that the refined test procedure can assist engineers in designing efficient sheet pile structures and become a basis to develop ASTM standard.

 

Abstract A novel method is developed for reusing the waste glass fiber-reinforced polymer (GFRP) powder as a precursor in geopolymer production. Several activation parameters that affect the workability and strength gain of GFRP powder-based geopolymers are investigated. The results of an experimental study reveal that the early strength of GFRP powder-based geopolymer pastes develops slowly at ambient temperature. The highest compressive strength of GFRP powder-based geopolymer pastes is 7.13 MPa at an age of 28 days. The ratio of compressive strength to flexural strength of GFRP powder-based-geopolymers is lower than that of fly ash and ground granulated blast furnace slag (GGBS)-based geopolymers, indicating that the incorporation of GFRP powder can improve the geopolymer brittleness. GGBS is incorporated into geopolymer blends to accelerate the early activity of GFRP powder. The binary geopolymer pastes exhibit shorter setting times and higher mechanical strength values than those of single GFRP powder geopolymer pastes. The GGBS geopolymer concrete mixture with 30 wt% GFRP powder displayed the highest compressive strength and flexural strength values and was less brittle. The developed binary GFRP powder/GGBS-based geopolymers reduce the disadvantages of single GFRP powder or GGBS geopolymers, and thus, offer high potential as a building construction material. 

This paper focuses on recent advances made in design, development, manufacturing, evaluation and modeling of load bearing fiber reinforced polymer (FRP) composite sandwich panel systems including tongue and groove joints. Several processes have been researched in collaboration with industry partners for production of composite panels, including: 1) pultrusion, 2) high temperature resin spread and infusion, 3) vacuum assisted resin transfer molding (VARTM), and 4) compression molding. The advantages and disadvantages of each process are discussed with emphasis on the high temperature resin infusion process. Composite laminates are characterized in terms of strength and stiffness under tension, bending, and shear in relation to longitudinal and transverse fiber orientations. Thermo-mechanical property variations of the FRP composite sandwich panels including joint responses are presented in terms of: 1) production processes, 2) carbon versus E-glass fiber, 3) vinyl ester versus epoxy, and 4) panel and joint design and efficiency including classical lamination theory. The sandwich panels are evaluated at component and full scales under static four point bending loads and further analyzed using classical finite element models for their mechanical responses. 

Abstract The composite sandwich structures with foam core and fiber-reinforced polymer skin are prone to damage under local impact. The mechanical behavior of sandwich panels (glass fiber-reinforced polymer [GFRP] skin reinforced with lattice webs and syntactic foams core) is studied under crushing load. The crushing behavior, failure modes, and energy absorption are correlated with the number of GFRP layers in facesheets and webs, fiber volume fractions of facesheets in both longitudinal and transverse directions, and density and thickness of syntactic foam. The test results revealed that increasing the number of FRP layers of lattice webs was an effective way to enhance the energy absorption of sandwich panels without remarkable increase in the peak load. Moreover, a three-dimensional finite-element (FE) model was developed to simulate the mechanical behavior of the syntactic foam sandwich panels, and the numerical results were compared with the experimental results. Then, the verified FE model was applied to conduct extensive parametric studies. Finally, based on experimental and numerical results, the optimal design of syntactic foam sandwich structures as energy absorption members was obtained. This study provides theoretical basis and design reference of a novel syntactic foam sandwich structure for applications in bridge decks, ship decks, carriages, airframes, wall panels, anticollision guard rails and bumpers, and railway sleepers.