Towards slender, innovative concrete structures for replacement of existing viaducts

A majority of the bridges and viaducts in the Netherlands were built in the sixties and seventies of the last century and many of them will need to be replaced in the near future due to technical or functional reasons. This is a replacement issue, faced by many countries worldwide. But what about the concrete structures? Should we replace them with the same structural systems and by using the same conventional concrete as used before? Or do we apply the newly developed concrete types, such as Ultra High Performance Concrete (UHPC) and Strain Hardening Cementitious Composites (SHCC) and install them with structural health monitoring techniques? In the paper the findings of several exploratory studies, performed at Delft University of Technology, are presented. In general, but especially for the replacement of existing structures, there is a tendency for increasing the slenderness of the concrete structures. In tenders it is even seen that contractors can get an increased bonus when building with reduced heights. A driving force is the fact that piers in roads are highly undesirable (freedom in space), while, in order to reduce additional costs, the new bridge should stay aligned with the existing roads. Most of the existing viaducts in the Netherlands are three or four span plate bridges with a total span between 20 and 60 m. Is it feasible to replace these by single span bridges with slenderness as high as 60? In a feasibility study, the possibilities for this are investigated and steps to be made are addressed. The exploratory study focuses on long, slender concrete structures, which can be obtained by applying Advanced Cementitious Materials (ACMs) while furthermore new building methods are explored. In general, the idea is to make steps towards our future SMART bridges for which structural health monitoring, sustainability, no hinder, zeroenergy, no maintenance and aesthetics are keywords.Steel & Composite Structure