Steering of continuity stresses in beam structures by temperature induction

Löschmann, Jens; Stolzuoli, Niccolò; Ahrens, Alexander; Mark, Peter

doi:10.1016/j.engstruct.2020.111621

Cited by 8 publications

(14 citation statements)

References 26 publications

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“…Considering all four ranges, a piece-wise defined function of the average steel strain is available that covers all phenomenological aspects introduced above. Elsewhere, it has already been applied to compute realistic deformations of a wide variety of RC structures [52][53][54]. For this purpose, the average steel strain must first be converted into an average curvature and then (numerically) integrated.…”

Section: Computational Approachmentioning

confidence: 99%

Correlation of Load-Bearing Behavior of Reinforced Concrete Members and Velocity Changes of Coda Waves

et al. 2022

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The integral collection of information such as strains, cracks, or temperatures by ultrasound offers the best prerequisites to monitor structures during their lifetime. In this paper, a novel approach is proposed which uses the collected information in the coda of ultrasonic signals to infer the condition of a structure. This approach is derived from component tests on a reinforced concrete beam subjected to four-point bending in the lab at Ruhr University Bochum. In addition to ultrasonic measurements, strain of the reinforcement is measured with fiber optic sensors. Approached by the methods of moment-curvature relations, the steel strains serve as a reference for velocity changes of the coda waves. In particular, a correlation between the relative velocity change and the average steel strain in the reinforcement is derived that covers 90% of the total bearing capacity. The purely empirical model yields a linear function with a high level of accuracy (R2 = 0.99, RMSE≈90μstrain).

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Section: Computational Approachmentioning

confidence: 99%

Correlation of Load-Bearing Behavior of Reinforced Concrete Members and Velocity Changes of Coda Waves

et al. 2022

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“…It depends on L i and its location defined by the distance a between induction and the support (Equation ). The maximum of M i is obtained when ΔT i is acting over two thirds of L 32

M_{i} ((), x) goodbreak= \frac{α_{T} ∆ T_{z}}{h} ∙ \frac{L_{normali}}{L^{3}} ∙ ((), 6 x ((), 2 a goodbreak+ L_{i} goodbreak- L) goodbreak+ L ((), goodbreak- 6 a goodbreak- 3 L_{i} goodbreak+ 4 L)) EI .

In multispan beams, M i ( x ) continues with decreasing amplitudes in the following spans and approaches zero at the last support.…”

Section: Steering Of Moments By Temperature Inductionmentioning

confidence: 99%

“…Temperature differences ΔT y over the width are usually small enough to be neglected. ΔT m (Equation ) and ΔT z (Equation ) can be determined by removing the nonlinear portion ΔT e from the entire field ΔT ( z ) 32

Δ T_{m} goodbreak= \frac{1}{A} \int T ((), y, z) italicdA,

Δ T_{z} goodbreak= \frac{h}{I_{normaly}} \int T ((), y, z) ∙ z italicdA .

Since plane cross sections tend to remain plane according to Bernoulli's hypothesis, deformations from the nonlinear temperature portion are directly restrained by adjacent cross section fibers.…”

Section: Steering Of Moments By Temperature Inductionmentioning

confidence: 99%

Strengthening of beams or slabs using temperature induction

Löschmann

Mark

2021

Structural Concrete

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Several aged reinforced concrete (RC) structures need to be strengthened. A typical method is to subsequently add rebar into slots filled with bonding mortar. However, this kind of strengthening only acts for live loads, not for dead loads, if no prestressing or prior lifting is applied. To overcome this deficiency, a novel method is presented. It activates the postinstalled reinforcement for all types of loading by temporarily inducing temperature from the outside. Doing so, statically indeterminate structures are locally relieved from stresses by constraint moments from systematically induced vertical temperature gradients during strengthening. To set the size of the gradients, the nonlinear material behavior, especially the significant reductions in constraint forces due to softening, is taken into account. If tempering is stopped after strengthening, stresses from dead loads redistribute over the newly formed total cross section. The method is theoretically derived, discussed, and verified in the lab on a two‐span RC girder. It turns out appropriate to enhance the bending resistance of beams or slabs.

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“…Das Potential der Temperaturregelung für das Bauwesen ist groß. Erste Ansätze liegen in der Erwärmung von Brückenfahrbahnplatten zur Enteisung [4, 5], der Konditionierung von Beton während der Erhärtung [6–8] oder seit Kurzem auch in der gezielten Einbringung von günstigen Zwangskräften [9, 10]. Bei Verstärkungen von Bestandsbauwerken [11–13], wie etwa ermüdungsgefährdeten Brücken [14] oder Deckenplatten, erhöht eine Temperaturinduktion erheblich die Effizienz [9].…”

Section: Introductionunclassified

“…Dabei werden die Zwangskräfte geregelt und Schnittgrößen gezielt voreingestellt. Solch eine Voreinstellung ist auch im Brückenbau hilfreich, wo Zwang aus Bauzuständen reduziert oder gänzlich eliminiert werden kann [10]. Darüber hinaus ist der Einfluss von Temperaturänderungen [15] auf beispielsweise Ultraschallwellen [16] und damit auch die experimentelle Induktion in Stahlbetontragwerke Gegenstand aktueller Forschung.…”

Section: Introductionunclassified

Temperaturinduktion in Betontragwerke

Clauß

Löschmann

Ahrens

et al. 2021

Beton und Stahlbetonbau

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Das Enteisen von Brückenfahrbahnen, die gesteuerte Erhärtung von Beton oder die Tragwerksverstärkung bei Temperierung sind Anwendungen für eine gezielte Temperaturinduktion in Betontragwerke. Der Beitrag behandelt dazu grundlegende Methoden. Dies sind das Erwärmen mit Infrarotstrahlern, Wärmematten oder erhitztem Wasser und das Kühlen mit Peltier‐Elementen, Kühlflüssigkeiten oder Trockeneis. Diskutiert werden die nominellen elektrischen Leistungen, die Fixierung am Bauteil, Interaktionen zwischen Temperierung und Bauteil, die Temperaturregelung und mögliche Verluste. Die Verfahren werden mit ihren Eigenschaften vorgestellt und bewertet. Als Basis dient eine Versuchsserie an Balken mit Einhausung durch Wärmedämmung. Die einzelnen Temperierverfahren werden separat untersucht und zur Erzeugung eines Temperaturgradienten kombiniert. Es zeigt sich, dass besonders Wärmematten oder Infrarotstrahler für das Heizen und die Peltier‐Kühlungen bzw. Kühlwasser für das Kühlen geeignet sind. Für die praktische Anwendung werden Empfehlungen abgeleitet.

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Steering of continuity stresses in beam structures by temperature induction

Cited by 8 publications

References 26 publications

Correlation of Load-Bearing Behavior of Reinforced Concrete Members and Velocity Changes of Coda Waves

Correlation of Load-Bearing Behavior of Reinforced Concrete Members and Velocity Changes of Coda Waves

Strengthening of beams or slabs using temperature induction

Temperaturinduktion in Betontragwerke

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