The study presents experimental results of an investigation on a novel shear connection system for hybrid bridge girders composed of laminated composite beams and concrete slabs. The special connector comprised of a steel plate and welded bolts is attached to beam’s top flange by adhesive bonding and with a preset torque of nuts. The study’s purpose is to check ductility, safety, reliability and robustness of the shear connection before its implementation in the first Polish composite bridge. Three static push-out tests and fatigue test were performed to evaluate the shear connection behavior under static and cyclic loading. The load–slip curves, shear capacity, fatigue strength and failure mechanisms of the novel shear connectors are discussed. The high-slip modulus indicates that the connectors can very efficiently promote the composite action. The ultimate resistance and the fatigue strength obtained from the test was about 12% and 66% higher than the characteristic resistance and the fatigue strength of common headed studs, according to Eurocode 4, respectively. An estimated global safety factor of 3.67 showed the high safety, reliability and robustness of the novel connection system. The study discusses the structural performance of the proposed connection system, demonstrating its technical suitability.

This paper presents an experimental material campaign focusing on fiber-reinforced polymers (FRP) to be applied in a novel bridge deck panel. Laminas based on most commonly used fibers, i.e., glass, carbon, basalt and aramid, were prepared and studied in tension, shear and compression. In the subsequent test stages, different fabric reinforcements (uni- and bi-directional fabrics, woven fabrics, CSM layers) were considered for glass laminas only, and finally, a resultant laminate was designed and tested. Such an approach gives a great opportunity to create “tailor-made” laminates, as required in FRP bridge deck panels. Simultaneously with the laboratory tests, analytical calculations were performed using a few micromechanical models that aimed to determine engineering constants and strength parameters. Then, the results obtained from material testing and analytical calculations were compared, and conclusions on the compliance were drawn. Based on this validation, further analytical calculations may replace time-consuming laboratory tests and facilitate FRP deck design.

The paper presents initial results of a new approach to FRP composite bridge construction that is presently being developed and tested in Poland. The concept combines lightweight concrete with FRP composites to create a durable highly optimised structure. The paper describes the bridge system itself and presents the research results on its development. The basic design is presented together with research results on its development: FEM analysis and a range of static test results of full-scale bridge beam experiments. The paper finishes with some test results of a full scale bridge that was constructed near Rzeszow in December 2015.

The paper presents an analysis of the parameters of live load transverse distribution in the span of a road bridge that is made of four box FRP composite girders and a composite deck slab made of lightweight concrete. The parameters were determined experimentally and computationally using the orthotropic plate model included in the Cusens-Pam solution and also the numerical FEM model. The measured values of load transverse distribution factors and influence lines were determined during bridge load testing. A comparison of the measured and calculated load transverse distribution factors is shown on the basis of the analysis of the girders' deflection in their cross-section in the middle of the bridge span. As a result of this comparison, it was proved that the analytical model of the orthotropic plate and also the numerical shell-solid FEM model have a high compliance of load transverse distribution with the distribution obtained from the measurements. In addition, computational analysis and tests showed a sufficient flexural rigidity and high torsional rigidity of the bridge span (the bridge construction belongs to a group of structures with a low overall rigidity of k = 300 kN/mm), confirming that the FRP composite girders that were used for its construction can be an alternative to the concrete and steel girders that are commonly used in the construction of bridges.

FRP composite bridges have been in operation since the mid-1990s, allowing for the evaluation of their long-term behaviour. Many of the early FRP bridges in the USA and Western Europe were equipped with monitoring systems to assess their structural integrity after years of use. In Poland, the first all-FRP composite bridge was also equipped with a modern structural health monitoring (SHM) system based on distributed fibre optic sensing (DFOS) to enable long-term performance monitoring. Over nearly a decade of use, the bridge’s strain, stiffness, and dynamic properties have been evaluated three times through static and dynamic load tests. Research findings indicate that the bridge has maintained satisfactory structural integrity and durability over an eight-year operational period. However, the quality of the adhesive joints between the girders and the deck panels was found to be inadequate, resulting in a slight decrease in the bridge’s performance, specifically in stiffness and dynamic characteristics. Fortunately, these negative changes did not compromise the bridge’s safety or serviceability, as stipulated by the design requirements. An effective repair was completed, restoring the bridge to its full operational efficiency.

In the 1960s, a unique and modern thin-walled steel superstructure was implemented for several road bridges in Poland. However, the structure has several structural and technological weaknesses that, over time, have led to severe structural damage (e.g., weld cracks, local buckling, etc.). The paper focuses on one of these bridges, which has been in service for over fifty years, where observed damages during detailed inspections necessitated a thorough experimental and numerical investigation to assess the structural safety of the superstructure. For this purpose, the new national guidelines for evaluating the safety of existing road bridges were utilised for the first time. The guidelines were based on the new Eurocode prEN 1990-2, which provides the basis for assessing existing structures. To enable reliable and rational maintenance decisions regarding repair or strengthening, a finite element analysis was conducted considering the condition survey, NDT, and material testing. Based on the experimental and numerical results within this new assessment framework, the final decision was made to close the bridge for service and replace the existing steel structure.