Inclined Approach Slab Solution for Jointless Bridges: Performance Assessment of the Soil–Structure Interaction

In recent years, the so called jointless or integral bridge design has seen a significant rise in popularity in Europe. Whereas in the last decades, designers preferred clearly defined statical systems and only adopted jointless design principles for small structures, the new generation of engineers pushes for integral design wherever possible. This development is to some degree motivated by a paradigm shift towards life-cycle cost-orientated design. Integral bridge structures lack joints and bearings, which typically are the least durable elements and thus remove the need for costly inspections and replacements. However, the obvious advantage of reduced direct and indirect maintenance costs entails novel and complex design solutions, especially for the transition area between structure and soil body. Furthermore, their statically indeterminate nature leads to increased importance of the soil–structure interaction. Both aspects are associated with significant uncertainty. This contribution focuses on the probabilistic performance assessment of an inclined approach slab solution for integral bridge structures of up to 150 m of total length. Findings are presented by the example of a recently constructed and ever since monitored 67-m-long prototype structure. Monitoring data recorded by a multisensor monitoring system during the first 30 months after construction serves as inputs for a probabilistic, extreme value-based assessment of critical design assumptions. In particular, (1) the modeling of boundary conditions, (2) the activated degree of earth pressure against the abutment wall, and (3) the strain distribution in the fiber-reinforced soil above the inclined approach slab are investigated.