Abstract

Fiber-reinforced polymer pedestrian bridges are becoming a competitive alternative to conventional concrete or steel pedestrian bridges in the span range from 5 to 30 m. In order to consider it as a viable alternative, it is necessary, among other things, to be price competitive in the total cost of the bridge, including construction and full-life maintenance. One of the ways of making the cost competitive is to normalize a few cross-sections and create a catalog of standard cross-sections and shapes depending on the load conditions and ranges of spans. The objective of this work has been to create this catalog, taking into account the following items: A detailed economic analysis of the impact of every sub cost in the total construction and maintenance cost. A detailed structural analysis and optimization, by using MEF, of different cross-section and laminate solutions has been carried out, both under static and dynamic loads, in order to achieve the best possible design. The preparation of a specialized FEM analysis software that already includes in its database the chosen laminates as well as automatized geometrical construction and standarised load cases definition. With all these tools, it is possible to make highly reusable molds for the laminates and it is possible to make the final cost of the FRP pedestrian bridge more competitive.

Abstract

Fiber reinforced plastics are the current protagonist in the automotive industry, their mechanical properties and their lightweight make them unique in reducing the impact of the weight on fuel consumption. The curing of thermosetting resins as the polymer matrix for an FRP is one of the main issues facing this sector.

Through applications examples, it is demonstrated how the behavior of curing of thermosetting resins can be studied by the techniques of dielectric analysis (DEA) and differential scanning calorimetry (DSC). In-situ cure monitoring is possible by DEA.

Abstract

Corrosion of the steel bars is the first cause of degradation of the reinforced concrete structures. This is the reason why in recent years non-corrosive materials are using to increase the useful life of these structures. Glass fiber reinforced polymer (GFRP) bars are an alternative to traditional steel bars. These bars are manufactured from continuous glass fiber embedded in a polymeric resin by the pultrusión process. Due to the great variability in the mechanical properties provided by manufacturers, it may be useful to define a test procedure to characterize the material in a simple manner. This work shows a procedure to determine the compression, tensile and flexural moduli of a GFRP bar by means of bending tests.

Abstract

High speed crafts made of glass fibre reinforced polymers (GFRP) suffer in-service structural damage due to the slamming impacts, when the bottom surface impacts against the water. It is important to quantify the extend of the damage and progression during the service life of the ship. In this work, it is presented a methodology using non-destructive evaluation for the assessment of the level of damage in the laminated panels. It is also investigated the effect of the introduction of a viscoelastic layer, composed of two polymeric material with different stiffnesses, designed specifically to dissipate the impact energy. The combination of these polymers with different deformation response under compression, and due to the confinement of the elastomer in small cell surrounded by the rigid polymer, constitutes an effective mechanism of energy dissipation due to impacts, protecting the plies beneath the viscoelastic layer and minimizing the damaged generated in the laminates due to slamming. Test specimens have been prepared using GFRP prepregs cured Out-of-Autoclave (OoA) and impacted using a specifically designed device that apply pressure peaks in the laminates that resemble very closely those that appears in the hull due to slamming loads, and compared with and without viscoelastic layer in the laminate. Changes in panel compliance are used for monitoring the evolution of damage in the material, as a function of the number of repeated impacts imposed on the panel for every load condition. Drop weight tests have been also used to understand the percentage of the income energy that is generating damage in the material, and to establish threshold levels for damage initiation both for unprotected panels and those with viscoelastic shielding layer.