Speakers

Fazlur R. Khan Plenary Lecturer

Structural engineering innovations with FRP composites: my journey over the past three decades

Jin-Guang Teng

President and Chair Professor
Structural Engineering
The Hong Kong Polytechnic University

Over the past three decades, fibre-reinforced polymer (FRP) composites have emerged as a promising alternative to steel and concrete for both strengthening existing structures and constructing new ones, due mainly to their excellent corrosion resistance in marine and other aggressive environments. Around the world, FRP is now widely used as a mainstream material in the strengthening of structures to extend their service life. For new construction, the development and application of various FRP products have been explored, including FRP rebars, FRP filament-wound tubes and FRP cables, to replace their steel counterparts for enhanced durability and a longer service life. The extension of service life of structures through the use of FRP offers an effective means for substantial reductions in carbon emissions per service year, thereby contributing to a more sustainable future of infrastructure development.

In this presentation, I will first provide a review of the development of the FRP strengthening technology, covering both research and practical applications, to demonstrate that this is now a mainstream strengthening technology. I will then provide a critical overview of the structural use of FRP in new construction, with an emphasis on several promising FRP products that have the potential to replace their steel counterparts to enhance the durability of structures. An examination of the obstacles to the wider/faster adoption of FRP in new construction will next be offered, together with strategies for overcoming these obstacles. Finally, I will use FRP-concrete-steel double-skin tubular members, a new class of FRP-enabled hybrid structural members invented by the speaker, as an example to demonstrate their great potential and to illustrate the long journey from conception to practical implementation of new-material structures.

Plenary Keynote Speakers

Life-Cycle Engineering – Influence on Structures at All Scales

Mark Sarkisian

Partner
Skidmore, Owings & Merrill LLP
USA

Life-Cycle Civil Engineering has become an essential framework for the design of structures at all scales. Considering a structures entire life of service has led to key considerations for life safety, performance, maintenance, resilience, cost, and impacts on the environment. For several years considerations for bridge structures have been obvious because of direct exposure to the elements, but less so for building structures. Recent efforts centered around defining an expected life of occupied structures especially in areas of high seismicity has led to important approaches to Life-Cycle Engineering. Through specific examples, the presentation and paper will explore life-cycle engineering for structures at all scales from small scale residential structures to high-rise commercial buildings. The emission of carbon dioxide is a key consideration for structures engineered life-cycle design. There are three primary components that contribute to the carbon emitted and the time of construction (embodied) and potentially through operation. The components are material, the construction process, and probabilistic damage. Material types and quantities used typically have the greatest impact on embodied carbon, but construction time and processes are significant contributors. Probabilistic damage considerations are the final significant contributor to emissions. Buildings typically design for life-safety per current standard building codes allow for significant damage to structures during an earthquake. This damage causes significant impacts on the environment since repairs require material and construction time. If the building is significantly damaged and deemed to be unoccupiable, then the carbon associated with demolition and reconstruction must be considered. There are significant initiatives to create structural systems and components that are resilient and limit damage in major seismic events so that structures do not require repair or replacement after a major seismic event.

Challenges and Opportunities in Life-Cycle Bridge Engineering

Fabio Biondini

Professor
Politecnico di Milano

Asset management of bridges and infrastructure systems is a high priority for public authorities and managing bodies due to the detrimental impact of aging and deterioration processes and exposure to multiple hazards in a changing climate. Multi-disciplinary risk-based life-cycle-oriented criteria, methodologies, and tools are necessary to inform the decision-making process for rational allocation of limited resources and efficient prioritization of bridge maintenance and repair interventions at infrastructure scale under uncertainty. In fact, in most developed countries, huge stocks of bridges and infrastructure facilities built over the last half century and more are rapidly approaching the end of the service life. The scale of repair or replacement needs is remarkably large and represents a key obstacle to sustainable development of countries. This situation is exacerbated by the effects of climate change, which can alter the exposure to environmental hazards and increase the rate of structural deterioration and infrastructure aging. To face these challenges, bridge engineering is undergoing a profound change towards a life-cycle approach and embracing a systemic vision at infrastructure scale. This paradigm shift is of key importance to consolidate and enhance criteria, methods and procedures to protect, maintain and improve safety, reliability, redundancy, robustness, functionality, disaster resilience, and sustainability of critical infrastructure systems. However, although risk-based life-cycle assessment methods are well established, their robust validation and accurate calibration are difficult tasks because of the limited availability of information about long-term performance of in-service structures. Collecting data from inspection of existing structures and experimental testing is therefore essential for a successful implementation of life-cycle methods in practice. Dealing with these challenges might also unlock multiple opportunities to foster and advance bridge engineering, including the extensive use and innovation of structural health monitoring systems, the exploitation of digital inventories to manage structural data about bridges and viaducts in real time, and the development of smart infrastructure through the implementation of emerging technologies such as Artificial Intelligence, Internet of Things, and Digital Twins, among others. This lecture presents a review of research advances and accomplishments, including results of recent research projects and case studies, to address challenges, opportunities, and future prospects in life-cycle bridge engineering.

The pursuit of multi-hazard life-cycle resilience in an era of smart and objective modeling

Jamie Padgett

Professor
Rice University

Reliable, effective functioning of structures and infrastructure systems during and following hazard events, like earthquakes, hurricanes, and floods, is essential to public safety, economic vitality and quality of life. Risk-informed decisions that promote infrastructure resilience (or its ability to withstand, adapt and recover) require confident predictions of system performance when exposed to such stressors throughout its lifetime. However, this future brings uncertainties regarding dynamic, evolving conditions; challenges with respect to a legacy of disparate impacts of natural hazards and infrastructure (under)investment; and opportunities related to smart systems and emerging data and algorithms. This lecture discusses a paradigm shift toward smart and equitable life-cycle resilience modeling of infrastructure exposed to multiple hazards. We discuss the characteristics and dimensions of such a modeling framework intended to infuse intelligence and promote equity considerations in both algorithms and outcomes of infrastructure resilience pursuits. Case studies across hazards, systems and scales are leveraged to highlight recent advances in risk and resilience modeling from the structure to infrastructure to community scale.

Concrete carbonation, steel reinforcement corrosion and Green House Gas implications.

Robert E. Melchers

Professor
The University of Newcastle
Australia

Reinforcement corrosion for inland reinforced concrete structures often is attributed to ‘carbonation’. This is based on the claim that the entry of atmospheric carbon dioxide lowers the pH of the concrete sufficiently for corrosion of steel to initiate in the presence of moisture. Mostly only the depth of permeation of carbon dioxide is considered, usually in laboratory observations often in solutions rather than in actual concretes. Direct evidence of significant reinforcement corrosion is seldom reported. Herein detailed observations are reported for carbonation depths, concrete pH and reinforcement corrosion for several reinforced concrete columns taken from different elevations and locations after 60 years continuous atmospheric exposure in a temperate climatic zone. Despite being boldly exposed, without protection of any kind, none showed evidence of reinforcement corrosion. All showed carbonation only some 10-15 mm into the concrete matrix and reduction of concrete pH progressively from the interior to the outer surfaces. These observations are interpreted using modern corrosion science. In summary, reinforcement corrosion initiation and progression can occur only with the gradual, long-term, loss by leaching of concrete alkalis and thus loss of concrete pH. In contrast, carbonates as formed by carbon dioxide are actually protective through blocking concrete pores and thereby slowing the rate of alkali leaching. A simple model for predicting the onset of reinforcement corrosion is proposed. The present observations indicate that provided the concrete matrix is of high quality, carbonation can act as a sink for atmospheric carbon dioxide without serious risk of reinforcement corrosion. Such absorption of atmospheric carbon dioxide is beneficial for reducing green house gas in the atmosphere. It is concluded that the often-quoted fear of reinforcement corrosion through 'carbonation' is based on poor experimental representations of actual concretes and their interpretation and is mis-placed.

Multi physics field and multi-scale predictive theory for durability and resilience of concrete structures

Airong Chen

Professor
Tongji University
China

The durability and resilience of concrete bridges are significantly affected by degradation processes such as carbonation, chloride ingress, elevated temperatures, rebar corrosion, and concrete cracking, all of which compromise structural integrity. To address these challenges, current research has shifted towards multi-physics, multi-scale prediction theory that investigates the coupled effects of environmental, material, and mechanical factors, including temperature, humidity, chemical reactions, and mechanical stress. Key scientific challenges include understanding crack initiation and propagation, accurately modeling the coupling of multi-field processes, and linking mesoscale mechanisms to the behavior of large-scale structures. This presentation introduces a multi-physics field coupling theory at the mesoscale to address degradation mechanisms such as carbonation, chloride penetration, rebar corrosion, cracking, and fire-induced damage. The model integrates chemical, electrochemical, thermal, and mechanical processes, providing in-depth insights into the interactions between these factors and laying a foundation for informed bridge maintenance strategies.

Streaming-Based Mechanical Digital Twin for Lifecycle Health Monitoring and Maintenance of Cable-Stayed Bridges

Hong Hao

ARC Laureate Fellow
John Curtin Distinguished Professor
Curtin University

Traditional IoT-based health monitoring systems for cable-stayed bridges facilitate the transmission and integration of sensor data, but they often lack direct interaction with finite element (FE) mechanical models. Typically, sensor data is indirectly used for modal updating or manually inputted to adjust FE models, limiting the efficiency of real-time structural assessments. In this study, we propose an innovative framework that uses streaming computation to directly integrate real-time sensor data with FE models, enabling continuous, automated updates of the mechanical model. This reduces manual intervention and allows near real-time reflection of structural condition changes in the digital twin. Although minor latency arises from data transmission and FE model updating, the system remains effective for lifecycle health monitoring. Using Unity 3D, we visualize the mechanical model in real-time, creating a unified platform for sensor data, FE analysis and model updating, and digital twin visualization. This approach enhances the precision and responsiveness of bridge monitoring by connecting the sensor data and physical model of the bridge in the digital twin system. It sets a new standard for lifecycle management in civil engineering.

Multi-objective Optimum Life-Cycle Management and Decision-Making for Deteriorating Structures

Sunyong Kim

Professor
Wonkwang University
Republic of Korea

Deteriorating structures and infrastructure are continuously subjected to external loads, mechanical stressors, environmental conditions, and extreme events throughout their service life. These factors, highly uncertain in nature, complicate accurate assessment and prediction of structural performance and remaining service life. To address these challenges, timely inspection and monitoring are essential. However, inspection and monitoring alone cannot extend service life or improve performance. Thus, integrating inspection, monitoring, and maintenance management is crucial for the effective life-cycle management of deteriorating structures. This paper focuses on optimizing life-cycle inspection, monitoring, and maintenance planning, based on multiple objectives. These objectives include: (a) performance-based, (b) cost-based, (c) damage detection-based, (d) service life-based, and (e) risk-based objectives. In this paper, the formulations of these objectives and approaches for both single- and multi-objective optimization of inspection, monitoring, and maintenance management are presented. The decision-making process to select the best management strategy is provided. Furthermore, the updating process, leveraging information from inspection and monitoring, is addressed to enhance the accuracy of life-cycle inspection, monitoring, and maintenance planning.