Iron-Based shape memory alloy for strengthening of 113-Year bridge

This study focuses on the large-scale application of a Fe-Mn-Si shape memory alloy (Fe-SMA) for strengthening a historic roadway bridge in Petrov nad Desnou (113-years), Czech Republic. To the best of the authors’ knowledge, this is the first application of an iron-based SMA (Fe-SMA) for prestressed strengthening of a bridge. In this study, the shape memory effect (SME) of the Fe-SMA was used for the prestressed strengthening of bridge girders. A mechanical anchorage system was developed to apply multiple Fe-SMA strips to the steel girders of the bridge subjected to daily passengers and heavy trucks. The SME of the Fe-SMA was activated by heating to approximately 260 ◦C using ceramic heating pads. The test results showed that the recovery stress of the Fe-SMA strips resulted in a compressive stress of approximately –33 MPa in the lower flange of the bridge girder. This compressive stress significantly increased the yield and fatigue capacity of the strengthened girder. Before and after the strengthening, the bridge was loaded with a 45-ton crane to assess the efficiency and performance of the system. Laboratory experiments were performed to optimize the mechanical anchors and examine the feasibility of the proposed strengthening method prior to application to the bridge. Finally, long-term monitoring of the prestressed Fe-SMA plates after installation on the bridge was conducted. The results showed that the main loss of the prestressing force caused by relaxation occurred within the first 30 days after activation and was approximately 20% of the original prestress.The authors are grateful to the Ministry of Culture of the Czech Republic for funding the research work within the framework of the Program of Applied Research and Development of the National and Cultural Identity (NAKI-II) project: Methods for achieving sustainability of industrial heritage steel bridges, ID: DG18P02OVV033. The authors also thank the re-fer AG Company for providing materials used for this study

Uncertainties in Characteristic Strengths of Historic Steels Using Non-Destructive Techniques

The use of various non- or minor-destructive tests (NDTs) is often preferred to reduce the cost of structural surveys of historic structures made of cast and wrought irons or old carbon steels. This contribution thus explores the measurement errors associated with common NDT techniques and quantifies uncertainties in characteristic strength estimates based on NDTs only. It appears that a unity mean and coefficient of variation of 12% might be adopted for the measurement uncertainty of the methods under study (Brinell, Leeb, Poldi, Vickers, Rockwell). On average, the true characteristic ultimate strength is by ~15% larger than that based on many NDTs. This represents the expected gain when the characteristic value is estimated from five DTs instead of a large number of NDTs. In practice detailed reliability assessments should always be based on resul

Hierarchical Modelling of Uncertainty in NDT Tests of Historic Steel Bridges

Sustainable development can be supported by extending the service lives of existing road and railway bridges. Preservation and upgrade should be based on improved surveys, monitoring, reliability assessment, and strengthening methods. In the case of metallic materials, hardness methods (NDT) calibrated by a few tensile tests (DT) were shown to be associated with reasonable measurement uncertainty. This contribution discusses the current practice in assessment based on NDT results and introduces the hierarchical modelling of the measurement uncertainty in hardness tests. Preliminary results suggest that the variability of ultimate strength can hardly be estimated on the basis of NDTs only. It seems that the systematic component of measurement uncertainty has a lower coefficient of variation (3%) than the random component (8%); the variability of the latter may thus often exceed the variability of the ultimate strength of a homogeneous material.Ostrav

The residual lifetime of steel bridges under the action of fatigue and corrosion effects

Decades-old steel bridges have to face the unfavourable environment that causes the ageing and deterioration of material properties. Moreover, especially railway bridges, which are famous for permanent resistance to heavy movable load, are exposed to large number of stress ranges that may lead to fatigue damage. Combination of both phenomenon has significant impact on the condition of bridges and their remaining service life. The subject of the proposed paper is observation the response of steel bridge structures containing construction elements weakened by corrosion on cyclic load. For the purpose, the series of laboratory fatigue tests were performed on samples of riveted connections. Specimens with various level of corrosion weakening had been taken from historical railway bridge and were loaded by cycling force in tension subsequently. The laboratory tests were supported by numerical analysis. This paper presents knowledges gained from the study that was focused on how to take into account the combined effect of degradation process and fatigue. The evaluation of the tests indicates that the service life of members may be significantly reduced due to fatigue. The developed relationship between corrosion loss and reduced detail category is statedThe research reported in this paper was supported by the Grant Agency of the Czech Technical University in Prague, grant No. SGS17/126/OHK1/2T/11 "Changes in fatigue behaviour of steel bridge structures weakened by corrosion" and by COST CZ (LD) project of the Ministry of Education, Youth and Sports (No. LD15127).info:eu-repo/semantics/publishedVersio

Methods for Achieving Sustainability of Industrial Heritage Steel Bridges

International audienc

Heritage value assessment method – Application to historic steel bridge in Prague

International audienc

Heritage value assessment method – Application to historic steel bridge in Prague

International audienc

Dealing with defects and strengthening historical steel bridges

Published online: 26 Oct 2022This paper describes traditional strengthening methods and proposes new approaches for strengthening historical steel bridges with the use of modern materials. There is a discussion of known bridge-strengthening methods, and several new ways to strengthen bridges are proposed. The first section presents the history of steel bridges, and discusses structural materials and bridge design. Types of structures and decks used for railway and roadway traffic are mentioned. This section also describes how the materials were joined, and how they were assembled by riveting. The second section lists the flaws and defects that typically occur on historical steel bridges. Each defect is described with respect to its origin, its effect on the structure and possible consequences. This section also introduces the main points that should be investigated when inspecting a steel bridge. The third section discusses ways of strengthening steel bridges. Issues to consider when choosing the most suitable strengthening method are introduced. Traditional methods are presented, followed by modern strengthening methods. The benefits and drawbacks of each method are listed. Finally, new strengthening methods with the use of modern materials such as shape memory alloys, ultra high performance concrete and carbon-fibre-reinforced polymers are proposed.This work was supported by the Ministry of Culture of the Czech Republic within the framework of the Program of Applied Research and Development of National and Cultural Identity (NAKI-II) project: Methods for achieving sustainability of industrial heritage steel bridges [ID DG18P02OVV033]

Methods for Achieving Sustainability of Industrial Heritage Steel Bridges

International audienc