Markus Gabler

Bridges with Glass Fibre-Reinforced Polymer Decks: The Road Bridge in Friedberg, Germany

In July 2008, the first road bridge in Germany using glass fibre-reinforced polymers (GFRP) was completed in Friedberg/Hessen. The structure has a span of 27 m and acts as a flyover across the federal road B3. The high durability of the new construction material and the fast assembly of the bridge were decisive factors in favour of GFRP. During the preceding years, several lightweight bridges using FRP had been constructed in the USA, Japan and also in Europe. Through these projects, valuable experience was gathered regarding construction, and the use and performance of composites could be demonstrated. The bridge in Friedberg extended this experience by taking into account the composite action between the FRP deck and the steel girders. It also followed, consequently, the approach of durable bridge construction by omitting any bearings or expansion joints and making the innovative material visible to passers-by.

From Nature to Fabrication: Biomimetic Design Principles for the Production of Complex Spatial Structures

In the current paper the authors present a biomimetic design methodology based on the analysis of the Echinoids (sea urchin and sand dollar) and the transfer of its structural morphology into a built full-scale prototype. In the first part, an efficient wood jointing technique for planar sheets of wood through novel robotically fabricated finger-joints is introduced together with an investigation of the biological principles of plate structures and their mechanical features. Subsequently, the identified structural principles are translated and verified with the aid of a Finite Element Model, as well as a generative design system incorporating the rules and constraints of fabrication. The paper concludes with the presentation of a full-scale biomimetic prototype which integrates these morphological and mechanical principles to achieve an efficient and high-performing lightweight structure.

New Design Concepts for Advanced Composite Bridges – The Friedberg Bridge in Germany

Rapidly increasing maintenance costs of reinforced or concrete bridges have led to an enhanced interest of public authorities in alternative technologies for bridge design. Bridge deck systems made out of fibre reinforced polymers (FRP) offer new options. Maintenance costs and assembly time can be reduced significantly. Especially hybrid structures are competitive, i.e. steel girders combined with a pultruded FRP bridge deck. Based on this technology the design of a highway flyover in the state of Hessen was developed. The exploitation of composite action in it introduces an innovative element in FRP bridge design. The bridge, to be constructed during 2006-07, will be the first major FRP road bridge in Germany. The innovative technology, its economical aspects and the design of the bridge are highlighted in this paper.

Integration Methods of Sensors in FRP Components

Structural health monitoring is an important research topic in the field of fiber reinforced plastics (FRP). An effective way to detect defects or overloads in these FRP has still not been found. One way to monitor the actual state of FRP components is via integrated sensors. Integrating current standard sensors negatively affects the flux of force. Therefore investigations about integration methods of sensors in FRP components have been made. The integration of an optical fiber sensor into FRP profiles via a pultrusion process was investigated. It could be shown that the pultrusion process is suitable method for the integration of fiber optic sensors for strain measurements. Another investigated sensor principle was the integration of piezoelectric polyvinylidene fluoride (PVDF) fibers via a vacuum assisted process. The PVDF fibers were integrated into 3-point bending specimen and the piezoelectric effect was tested with and without polarization. The investigation showed that it is possible to measure the piezoelectric effect of PVDF fibers integrated into a 3-point bending test specimen. It could also be shown that carbon fibers can be used as textile electrodes for the measurement of the generated charge on the PVDF surface.

Automatically produced FRP beams with embedded FOS in complex geometry: process, material compatibility, micromechanical analysis, and performance tests

The main goal of the presented work was to evolve a multifunctional beam composed out of fiber reinforced plastics (FRP) and an embedded optical fiber with various fiber Bragg grating sensors (FBG). These beams are developed for the use as structural member for bridges or industrial applications. It is now possible to realize large scale cross sections, the embedding is part of a fully automated process and jumpers can be omitted in order to not negatively influence the laminate. The development includes the smart placement and layout of the optical fibers in the cross section, reliable strain transfer, and finally the coupling of the embedded fibers after production. Micromechanical tests and analysis were carried out to evaluate the performance of the sensor. The work was funded by the German ministry of economics and technology (funding scheme ZIM). Next to the authors of this contribution, Melanie Book with Röchling Engineering Plastics KG (Haren/Germany) and Katharina Frey with SAERTEX GmbH & Co. KG (Saerbeck/Germany) were part of the research group.

The FRP Bridge in Friedberg Germany: Design, Analysis and Material Tests

Public authorities look for innovative bridge systems that allow for minimum traffic interference both during their assembly as well as maintenance. In this light, bridge deck systems made out of fibre reinforced polymers (FRP) offer promising options, mainly high strength combined with low weight, rapid installation by high degree of prefabrication and resistance against corrosion. On behalf of the Hessian Road an Traffic Authority a design for a bridge was developed, which combines longitudinal steel girders with an adhesively bonded FRP bridge deck. In contrast to other FRP bridges in the US or UK, the composite action is considered. The absence of general accepted structural analysis methods, design codes and building regulations for fibre reinforced polymers necessitates extensive testing programmes. The conceptual design of the bridge, the material specific way of analysis as well as the results of the extensive material tests are highlighted in this paper. By the time of writing this paper, the bridge was in tendering phase.