Improving Robustness and Resilience of Bridges : A brief summary of current practices for design, monitoring, and maintenance
Iannacone, Leandro LU
; Björnsson, Ivar
LU
; Thöns, Sebastian
LU
and Honfi, Daniel
(2026)
In TVBK
- Abstract
- Bridges are critical assets within transportation networks, and their failure, whether due to accidental actions, extreme environmental events, or localized damage, can lead to consequences that extend far beyond the structure itself. In addition to direct safety implications, bridge failures often result in prolonged traffic disruption, economic losses, and reduced network resilience. As traffic demands increase and extreme events become more frequent, the need for explicitly addressing structural robustness in bridge engineering practice has become increasingly pressing.
Robustness is generally understood as the ability of a bridge to sustain local damage or abnormal loading without disproportionate structural or system-level... (More) - Bridges are critical assets within transportation networks, and their failure, whether due to accidental actions, extreme environmental events, or localized damage, can lead to consequences that extend far beyond the structure itself. In addition to direct safety implications, bridge failures often result in prolonged traffic disruption, economic losses, and reduced network resilience. As traffic demands increase and extreme events become more frequent, the need for explicitly addressing structural robustness in bridge engineering practice has become increasingly pressing.
Robustness is generally understood as the ability of a bridge to sustain local damage or abnormal loading without disproportionate structural or system-level consequences. While most design codes acknowledge robustness through qualitative requirements and prescriptive detailing rules, quantitative approaches suitable for routine engineering practice remain limited. This report aims to bridge that gap by consolidating current knowledge on robustness and translating it into concepts that are meaningful and applicable for bridge designers, assessors, and infrastructure owners.
The report examines the current state-of-the-art concerning structural robustness and contextualizes it to the case of bridges. It describes the most common failure progression mechanisms such as zipper-type, domino-type, instability-driven, and mixed collapse scenarios. Understanding these mechanisms allows practitioners to identify critical elements, assess disproportionate collapse risk, and select appropriate mitigation strategies.
Robustness-enhancing strategies with direct practical relevance are presented, separating between preventive, vulnerability-reduction, and damage-containment strategies. Preventive measures aim to reduce the likelihood of initiating events, particularly vehicle and vessel collisions, through the use of signage, clearance portals, hanging chimes, overhead impact bars, dolphins, and artificial islands. Vulnerability-reduction strategies focus on reducing structural sensitivity to damage through detailing, ductility, protection of critical components, and conservative treatment of brittle failure modes. Damage-containment strategies, including alternative load paths and capacity design principles, are discussed as means to limit failure propagation following local damage. Importantly, the report emphasizes that these strategies should be selected and combined based on bridge type, exposure, and consequences, rather than applied uniformly.
A dedicated section of this report is devoted to the quantitative assessment of robustness, addressing the growing need for metrics that allow engineers and decision-makers to move beyond purely qualitative judgments. The section reviews and discusses available robustness indicators, highlighting their underlying assumptions, practical interpretation, and limitations when applied to bridge structures. Emphasis is placed on metrics that can support comparison between design alternatives, identification of critical elements, and prioritization of retrofit or protection measures. Rather than promoting a single universal index, the report underscores the importance of using quantitative robustness measures alongside reliability assessments and consequence evaluations, ensuring that numerical indicators remain meaningful and actionable within engineering practice.
Overall, this report provides practitioners with a coherent framework for understanding, assessing, and enhancing the robustness of bridges. Rather than proposing a single metric or prescriptive solution, it supports informed decision-making by linking structural behaviour, failure mechanisms, and consequences, thereby enabling more transparent and defensible robustness considerations in both new design and assessment of existing bridges.
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Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/70f5965f-83b7-4fd1-abb9-19873384e4ba
- author
- Iannacone, Leandro
LU
; Björnsson, Ivar
LU
; Thöns, Sebastian
LU
and Honfi, Daniel
- organization
- publishing date
- 2026
- type
- Book/Report
- publication status
- published
- subject
- in
- TVBK
- issue
- 3081
- edition
- 3081
- pages
- 65 pages
- publisher
- Div. of Structural Engineering, Lund University
- ISBN
- 978-91-87993-31-2
- 978-91-87993-30-5
- project
- Improving robustness and resilience of bridges as integral links in the transport network
- language
- English
- LU publication?
- yes
- id
- 70f5965f-83b7-4fd1-abb9-19873384e4ba
- date added to LUP
- 2026-06-01 08:48:39
- date last changed
- 2026-06-04 03:28:30
@techreport{70f5965f-83b7-4fd1-abb9-19873384e4ba,
abstract = {{Bridges are critical assets within transportation networks, and their failure, whether due to accidental actions, extreme environmental events, or localized damage, can lead to consequences that extend far beyond the structure itself. In addition to direct safety implications, bridge failures often result in prolonged traffic disruption, economic losses, and reduced network resilience. As traffic demands increase and extreme events become more frequent, the need for explicitly addressing structural robustness in bridge engineering practice has become increasingly pressing.<br/>Robustness is generally understood as the ability of a bridge to sustain local damage or abnormal loading without disproportionate structural or system-level consequences. While most design codes acknowledge robustness through qualitative requirements and prescriptive detailing rules, quantitative approaches suitable for routine engineering practice remain limited. This report aims to bridge that gap by consolidating current knowledge on robustness and translating it into concepts that are meaningful and applicable for bridge designers, assessors, and infrastructure owners.<br/>The report examines the current state-of-the-art concerning structural robustness and contextualizes it to the case of bridges. It describes the most common failure progression mechanisms such as zipper-type, domino-type, instability-driven, and mixed collapse scenarios. Understanding these mechanisms allows practitioners to identify critical elements, assess disproportionate collapse risk, and select appropriate mitigation strategies.<br/>Robustness-enhancing strategies with direct practical relevance are presented, separating between preventive, vulnerability-reduction, and damage-containment strategies. Preventive measures aim to reduce the likelihood of initiating events, particularly vehicle and vessel collisions, through the use of signage, clearance portals, hanging chimes, overhead impact bars, dolphins, and artificial islands. Vulnerability-reduction strategies focus on reducing structural sensitivity to damage through detailing, ductility, protection of critical components, and conservative treatment of brittle failure modes. Damage-containment strategies, including alternative load paths and capacity design principles, are discussed as means to limit failure propagation following local damage. Importantly, the report emphasizes that these strategies should be selected and combined based on bridge type, exposure, and consequences, rather than applied uniformly.<br/>A dedicated section of this report is devoted to the quantitative assessment of robustness, addressing the growing need for metrics that allow engineers and decision-makers to move beyond purely qualitative judgments. The section reviews and discusses available robustness indicators, highlighting their underlying assumptions, practical interpretation, and limitations when applied to bridge structures. Emphasis is placed on metrics that can support comparison between design alternatives, identification of critical elements, and prioritization of retrofit or protection measures. Rather than promoting a single universal index, the report underscores the importance of using quantitative robustness measures alongside reliability assessments and consequence evaluations, ensuring that numerical indicators remain meaningful and actionable within engineering practice.<br/>Overall, this report provides practitioners with a coherent framework for understanding, assessing, and enhancing the robustness of bridges. Rather than proposing a single metric or prescriptive solution, it supports informed decision-making by linking structural behaviour, failure mechanisms, and consequences, thereby enabling more transparent and defensible robustness considerations in both new design and assessment of existing bridges.<br/>}},
author = {{Iannacone, Leandro and Björnsson, Ivar and Thöns, Sebastian and Honfi, Daniel}},
institution = {{Div. of Structural Engineering, Lund University}},
isbn = {{978-91-87993-31-2}},
language = {{eng}},
number = {{3081}},
series = {{TVBK}},
title = {{Improving Robustness and Resilience of Bridges : A brief summary of current practices for design, monitoring, and maintenance}},
url = {{https://lup.lub.lu.se/search/files/251636580/Report_-_Improving_Robustness_and_Resilience_of_Bridges_-_FINAL.pdf}},
year = {{2026}},
}