<title>Monitoring system for assessment of prestressed railway bridges in the new Lehrter Bahnhof in Berlin</title>

Abstract

A new central railway station - Lehrter Bahnhof- is being built in Berlin. Because of construction activities in immediate vicinity and because of difficult soil conditions, vertical displacements will be expected. In order to avoid damage to the bridges and to a widely spanned glass roof which will be supported by two concrete bridges these two bridges have to be monitored right from the beginning of construction until commissioning as well as later on for several years. For this purpose, a long-term monitoring concept has been developed. Sensors with excellent long-term stability have been chosen to carry out the concept. This paper describes the measuring concept as well as components of the system. Especially techniques to monitor settlements and heaves (by means of laser-based optics and hydrostatic leveling components) and to measure strain and inclination of the prestressed concrete bridges (by embedded long-gage length fiber-optic strain sensors, resistive strain gages, and inclinometers) are described. All measures are redundantly monitored. Measurements on-site are referenced by measurements on two large-scale beam models well-defined loaded under laboratory and field conditions.