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Picture of a white high bridge, taken from below, surrounded by green hills and blue sky

Modeling vibration velocity in longitudinal joints of bridges

The effects of traffic vibrations during concreting work on a newly constructed highway bridge were investigated in the Project MOSIB (2016-2019) as direct contract research for ASFINAG.

The construction works on existing bridges must often be carried out without traffic interruptions. During bridge-widening works or closing of construction joints, the hardening concrete is exposed to traffic-induced vibrations. This can damage the material permanently, depending on the amplitude of vibration velocity.

This study investigated factors that influence amplitude of traffic-induced vibrations of a slab bridge on the A23 motorway in Vienna, which was rebuilt in several construction phases. Transient dynamic simulations were used to analyse the influence of the driving speed, vehicle mass and road evenness. Measured road profile data, which were collected by high-resolution laser scanning of the road surface with the RoadSTAR mobile lab, were used in FEM simulations. Bridge resonance properties were verified by vibration measurements.

While bridge deflections and strains are mainly influenced by vehicle mass, the vibration velocities are primarily determined by the road profile. The predicted vibration velocities were compared to a limit value taken from the literature, the observance of which should not lead to any impairment of the young concrete. The results served as a decision basis for the selection of suitable measures during the critical hardening phase of the concrete in the connection joint (see Ralbovsky et. al. a, b, 2020), so that total building costs could be reduced, and construction time could be saved.

Commissioned by ASFiNAG