Monitoring of a Swedish Integral Abutment Bridge
Abstract One of the most commonly discussed problems regarding bridges with integral abutments is the influence of longitudinal elongation of the superstructure as a result of seasonal temperature variations. A bridge built with integral abutments is often supported by a row of piles made of steel or concrete. The longitudinal elongation of the superstructure induces a displacement and a rotation at the top of the pile, which in turn may cause strains that exceeds the yield strain. Such seasonal variations may lead to low-cyclic fatigue failure in the pile. Therefore, it is of great interest to investigate the amplitude of these strains, as well as the general behaviour of the bridge. In 2005, the European R&D project, INTAB (RFSR-CT-2005-00041, “Economic and Durable Design of Bridges with Integral Abutments, 2005–2008”) was started. Within the INTAB project a composite bridge was built and monitored in Northern Sweden.
Finite element simulation of pile behaviour under thermo-mechanical loading in integral abutment bridges
To study the behaviour of piles in integral abutment bridges, under seasonal and daily thermal loading, a three-dimensional, nonlinear finite element model was constructed for a bridge. The model was parametrically run for five different bridge lengths that varied from 122 to 549 m. A sinusoidal model was used to represent the daily and seasonal temperature variations. The results showed that maximum lateral displacement of the piles occurs during the winter when the thermal contraction and the dead and live loads on the bridge produce displacements in the same direction. Maximum stress occurred in the pile furthest from the centre of the bridge and was found to be in the flange of the pile immediately below the concrete abutment. Plastic deformation was observed in all of the piles for all bridge lengths. The lateral displacement and maximum plastic deformation in piles increased as the length of the bridge increased. A linear relationship was found between the length of the bridge and the lateral displacements for both seasonal and daily temperature variations.
Neotectonic rotations in the Orava-Nowy Targ Intramontane Basin (Western Carpathians): An integrated palaeomagnetic and fractured clasts study
Abstract The objectives of this contribution are: (1) to promote the application of fractured clasts analysis in conglomerates for regional stress reconstructions and (2) to advance reconstruction of the Western Carpathians structural development. Our results show that the Neogene fill of the Orava-Nowy Targ Intramontane Basin underwent CCW rotation of about 30°. We infer that the rotation terminated after 8 Ma and was related to shift along NW-SE to NNW-SSE trending faults at the NE termination of the sinistral Mur-Žilina Fault Zone. Our results show that, fractured clasts analysis can be good tool for regional tectonic reconstructions. The tool is especially useful when other tectonic tools are scarce or absent. Results of our palaeomagnetic study and fractured clasts analysis verify and supplement each others. In the studied case, palaeomagnetic results allow to distinguish between regional stress field rotation and rotation of the Orava-Nowy Targ Basin Neogene fill, whereas, results of fractured clast analysis help to constrain the age of rotation.