<p>Many developed countries have a national road network including a significant number of bridges in need of renovation or replacement in the coming years. The reason for this is their technical and functional capacity becoming insufficient due to aging and changes in societal demands. Therefore, these bridges need to be adjusted or replaced. National authorities in The Netherlands currently require a design life of 100 years for new bridges, however nowadays it seems reasonable to have a certain flexibility for this parameter. Since the selected design life has its implications on structural solutions and choice of materials, the identification of the optimal design life for bridges seems necessary. This paper gives a summary on the issue regarding the optimum design life of bridges and it highlights the framework of the upcoming research activities.</p>

As many bridges are reaching the end of their service life, researchers are searching for new solutions to extend the lifespan of those bridges. Fibre reinforce polymers (FRP) could be possible a solution for bridges with deck problems. Lightweight FRP decks can be installed quickly via bolted connectors on steel substructure. In general, shear force in the connector is not taken into account during the design of FRP decks because slip behaviour and interaction with steel substructure is unknown. This research connects to research at TU Delft on non-slip shear connectors for FRP decks. Aim of this paper is to quantify shear forces in bolted connectors due to traffic and temperature loads. The direction of webs, fibres in panel facings and the expansion coefficient of resin has been investigated to determine the influence of the FRP deck on the shear force in the connectors. To investigate the results of traffic loading and temperature loading on real bridges, a database of bridges in the Netherlands has been used. Results from the analyses offer an indication of the influence of the laminates on the shear force in the connectors and show shear force ranges that can occur in existing bridges.

<p>The Dutch Directorate-General for Public Works and Water Management (Rijkswaterstaat) is assessing its bridges as a part of the major renovation and replacement task of bridge-structures in the Netherlands. For assessments it appears that calculations show that an increasing number of existing bridges no longer comply with current assessment standards or are becoming restricted in their functionality. Complete renovation is costly, results in disruption of traffic, and is not sustainable. The Eurocode permits to demonstrate sufficient safety using a nonlinear finite element analysis (NLFEA). NLFEA offers a possibility to demonstrate additional structural safety of the existing bridge-structures.</p><p>The challenge is to gain confidence that the approach gives reliable results for the structural safety of the considered bridge. Moreover, experience learns that NLFEA demands many choices to be made by Rijkswaterstaat as a client and will not always lead to unambiguous results. These choices concern modelling aspects, applied safety format, load positions, and the required sensitivity analyses. Another question is what conclusions, based on the obtained results of this analysis, can be drawn for similar structures.</p><p>This paper shows how Rijkswaterstaat has dealt with these challenges with case 'Peddemors' and what lessons are learned, all from the viewpoint of a client.</p>