Abstract:Die Überwachung (Monitoring) von Bauwerken kann einen Betrag dazu leisten, Schäden rechtzeitig zu erkennen und mehr Sicherheit für die Nutzer von Infrastrukturbauwerken zu schaffen [1–3]. Dabei ist es sinnvoll, ausgewählte neuralgische Punkte des Tragwerks zu überwachen, um die Datenmenge nicht zu groß werden zu lassen und die Übersichtlichkeit zu erhalten. Sensoren können zusätzliche Informationen über Zustand, Einwirkungen oder Umwelteinflüsse (z. B. Temperaturverformungen) eines Bauwerks zur Verfügung stell… Show more
“…The system will be used as extensively as possible to measure long- and short-term effects. The warning system is already installed and can be read about in [ 7 ].…”
Section: Discussionmentioning
confidence: 99%
“…The load introduction from a passing truck into the prestressed steel rods is complicated and almost impossible to recalculate. A simple approach with a truss model was tried in [ 7 ]. In order to obtain a correlation between passing truckloads and the measured strains, reference measurements were conducted.…”
Section: Reference Measurements With Defined Loaded Trucksmentioning
confidence: 99%
“…During the insertion of the rods into the borehole, extreme caution was necessary to avoid damaging the sensors. The protection measures for the sensors and the prestressing of the rods are described in [ 7 ].…”
More than 40 years ago, the expansion joints on the Basel border bridge were constructed using corbels and dapped ends. The consoles had to be reinforced as part of the renovation measures due to damage caused by chloride entry and due to the increased loads. Diagonal rods, which were prestressed, were used. Fiber-optic sensors were additionally installed to these highly stressed rods in order to measure the strains and temperatures. This now makes it possible to measure the actual strains in the strengthening of the corbel, estimate fatigue loads, and set up a warning system in case of overstressing. This article presents the design of the measurement system and the analysis of the data. Furthermore, the reference measurements that can establish the relationship between the measured strains and the loads passed over are presented.
“…The system will be used as extensively as possible to measure long- and short-term effects. The warning system is already installed and can be read about in [ 7 ].…”
Section: Discussionmentioning
confidence: 99%
“…The load introduction from a passing truck into the prestressed steel rods is complicated and almost impossible to recalculate. A simple approach with a truss model was tried in [ 7 ]. In order to obtain a correlation between passing truckloads and the measured strains, reference measurements were conducted.…”
Section: Reference Measurements With Defined Loaded Trucksmentioning
confidence: 99%
“…During the insertion of the rods into the borehole, extreme caution was necessary to avoid damaging the sensors. The protection measures for the sensors and the prestressing of the rods are described in [ 7 ].…”
More than 40 years ago, the expansion joints on the Basel border bridge were constructed using corbels and dapped ends. The consoles had to be reinforced as part of the renovation measures due to damage caused by chloride entry and due to the increased loads. Diagonal rods, which were prestressed, were used. Fiber-optic sensors were additionally installed to these highly stressed rods in order to measure the strains and temperatures. This now makes it possible to measure the actual strains in the strengthening of the corbel, estimate fatigue loads, and set up a warning system in case of overstressing. This article presents the design of the measurement system and the analysis of the data. Furthermore, the reference measurements that can establish the relationship between the measured strains and the loads passed over are presented.
“…In order to be able to precisely record the amplitudes of the loads, they must be separated from the long-term influences. A sampling rate of a few tenths of a second is required for precise measurement, which can lead to large amounts of data being stored [7]. This publication describes the problem and an approach to solving it.…”
Knowing the actual fatigue effects helps to assess the structural safety of bridges more accurately. Especially when the actions change or increase, it is important to be able to determine this. This paper deals with the measurement and recording of actual fatigue loads at a critical point of an existing bridge. It shows how long-term effects can be separated from short-term effects and how amplitudes from passing trucks can be counted. The paper also highlights the challenges that arise when measuring actual fatigue loads.
“…Die Erhaltungsmaßnahmen werden durch das Ingenieurbüro Schmidt + Partner Bauingenieure Basel) projektiert (vgl. auch [2]). Bauherr ist das schweizerische Bundesamt für Strassen (ASTRA).…”
Zahlreiche Brücken aus den 1970er und 1980er Jahren sind heute deutlich höheren Verkehrslasten ausgesetzt als damals bei der ursprünglichen Bemessung. Unterdessen wurden die normativen Regelungen eher verschärft oder verfeinert, sodass diese Bauwerke den heute geltenden Regeln oft nicht standhalten können. Mit der Einführung der sogenannten Erhaltungsnorm SIA 269 ff. wurde versucht, dieser Tatsache entgegenzuwirken, insbesondere, indem günstige Einflüsse wie Materialnacherhärtung oder Reduktion der Restnutzugsdauer Eingang fanden. Im Falle der Grenzbrücke Basel hätte ein üblicher Querkraftnachweis zu einer aufwendigen Querkraftverstärkung in großen Bereichen der Brücke geführt. Unter Ansatz der Querbiegebewehrung für die Querkrafttragfähigkeit konnte jedoch auf die ursprünglich geplante Verstärkungsmaßnahme verzichtet werden. Die Wirkung der Querbiegebewehrung auf den Querkraftwiderstand wurde anhand eines zusätzlichen zweiten Fachwerkmodells erfasst. Die notwendige Erhöhung des Biegewiderstands ergab sich durch einen Spannungszuwachs im Spannglied bei der Findung des horizontalen Kräftegleichgewichts. Mit einer nichtlinearen Finite‐Elemente‐Berechnung konnten die Ergebnisse überprüft und die Verträglichkeit der beiden Fachwerkmodelle aufgezeigt werden.
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