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.
Field monitoring study of an integral abutment bridge supported by prestressed precast concrete piles on soft soils
Abstract Integral abutment bridges (IABs) have been constructed during the past several decades around the world. The purpose was to eliminate expansion joints and minimize joints induced problems. Even though IABs have been widely accepted due to the satisfying performances, yet they have not been largely applied in practice. Some of the reasons may be attributed to the uncertainties of these bridges under different loading conditions, especially the daily and yearly varying temperature effects. In this paper, the behavior of the first IAB constructed on the soft soil condition in Louisiana is discussed. A field monitoring program is introduced and the measured results from 08/11/2011 to 03/15/2014 are presented. The field monitoring program leads to the following observations, (1) significant seasonal and daily temperature variations are observed on the bridge slabs but within the AASHTO temperature design specification; (2) the displacements and rotations of bridge components are well correlated with the temperature variations; (3) the thermal stresses generated in the slabs may exceed the allowable material cracking capacity; (4) the soil behavior behind the abutments is complicated and long term monitoring program is needed; (5) the integral abutment primarily behaves in translation rather than rotation; and (6) the pile inflection (zero bending) point is observed and the strong and weak axels bending are all important due to the bridge skewness.
DAILY AIR TEMPERATURE AND PRESSURE SERIES FOR STOCKHOLM (1756-1998)
Daily meteorological observations have been made at the old astronomical observatory in Stockholm since 1754. Complete daily mean series of air temperature and sea level pressure are reconstructed from the observational data for 1756-1998. The temperature and pressure series are reconstructed and homogenized with the aid of metadata, statistical tests and comparisons with data from other stations. Comparisons with independently reconstructed daily series for nearby Uppsala (1722-1998) show that the quality of the daily Stockholm data is good, although the reliability is lower before the mid-19th century. The daily temperature data show that the colder winter mean temperatures of the late 18th to early 19th centuries were connected with a particularly high fre- quency of very cold winter days. The warmer summers of the same period are more connected with a general shift of the temperature distribution towards higher temperatures than in the late 20th century.