Teachers fr om the Department of Roads, Bridges and Tunnels of the St Petersburg State University of Architecture and Civil Engineering (SPbGASU) presented the results of their research at the congress of the International Association for Bridge and Structural Engineering (IABSE) in India. In their scientific work, they identified opportunities to prevent the destruction of bridges, and also confirmed in practice the effectiveness and cost-effectiveness of terrestrial laser scanning (TLS) technology.

Nikolay Kozak

The more durable the elements, the more reliable the bridge

Senior lecturer at the department Nikolay Kozak spoke about the study that revealed the dependence of the state of the bridge span structure on possible damage and destruction of its elements. The research was carried out by the department's scientific team consisting of PhD of Engineering Sciences Nikolay Kozak and PhD of Engineering Sciences Anton Syrkov, PhD of Engineering Sciences Vladimir Bystrov and senior lecturer Dmitry Yaroshutin.

“This topic develops my dissertation research, in which I examined the issues of accumulation of fatigue damage in the assembly elements and studied their impact on the overall structure: whether the bridge span can collapse if 10, 100 or all elements of the assembly fail over time? During the numerical experiment, I excluded individual groups of assembly elements from the work, and then calculated how well the structures can withstand permanent and temporary transport loads. The results of the study showed that at the initial stages, the destruction of the joining elements increases the stress in the main beams by up to 3% and slightly increases the deflections, which, in general, is not critical for most span structures. Uncontrolled progressive development of destruction of assembly elements (including not for reasons of exhaustion of endurance) can increase stress by up to 20%,” explained Nikolay Kozak.

According to the researcher, such an increase in stress in the absence of initial engineering reserves can lead to the destruction of the main load-bearing structures of the span. This confirms the need to regulate the endurance requirements for assembly elements of the steel and reinforced concrete parts of road bridge spans. In the future, the author of the study plans to give a quantitative assessment of the risks of such destruction of span structures and connect the reliability indicators of the elements of the association with the general reliability indicators of the span structure. 

Dmitry Yaroshutin gives a presentation on the use of ЕLS technology

Laser scanning instead of classical approaches

Senior lecturer Dmitry Yaroshutin shared his experience in using terrestrial laser scanning technologies when inspecting artificial structures on highways and planning a transport corridor for carrying excess load in the Arctic zone of Russia. This study was carried out by a research team consisting of senior lecturer Dmitry Yaroshutin, PhD of Engineering Sciences Anton Syrkov and PhD of Engineering Sciences Nikolay Kozak, as well as PhD of Engineering Sciences from St Petersburg State Transport University Dmitry Shestovitsky.

“We have applied the TLS technologies on more than 250 bridge structures and over 80 intersections of the transport corridor with overground networks. Thus, they have proven their effectiveness and cost-effectiveness - advantages over the classical approach, which often requires significant time investment in organizing access using industrial mountaineering methods, scaffolding, and mechanical lifting equipment. The accuracy provided by modern models of laser scanners is sufficient to solve the problems of diagnosing a significant part of bridge structures (small, medium and large bridges), and their compact size and low weight do not require additional costs for transporting equipment,” explained Dmitry Yaroshutin.

He emphasized the need for further development and improvement of the regulatory framework in the field of application of TLS technology for transport structures, as well as the development of new methods for processing terrestrial laser scanning data, which requires the involvement of specialists in the field of artificial intelligence (computer vision algorithms, neural networks, etc.).

Master classes and technical excursions 

Master classes on the calculation of reinforced concrete structures using the TIE-AND-STRUT method (offers solutions in cases wh ere the methods set out in regulatory documents are insufficient), as well as on evidence-based and forensic engineering (analysis of the causes of destruction of bridge structures and their prevention) were productive.

“As part of the technical excursion, we got acquainted with the consequences of the flood in the state of Himachal Pradesh, which last summer almost completely destroyed the access to the city of Manali. On the one hand, the destruction became direct evidence of the climate changes taking place in the world, on the other hand, it confirms the presence of technical prerequisites for destruction. Therefore, bridge builders will have to take this factor into account,” concluded Dmitry Yaroshutin.

Nikolay Kozak appreciated the unusual arrangement for organizing the construction of a bridge across the Yamgua River in Delhi, built in 2018: all its metal structures were manufactured and assembled into large blocks at a factory in China, transported by sea to Mumbai, and then by land transport to Delhi.

The relevance of the topic, “Engineering for Sustainable Development”, confirmed the scale of the congress: it brought together over 400 participants from more than 50 countries, the program included 150 reports on scientific research.

Anton Syrkov takes an active part in the work of the International Association for Bridge and Structural Engineering, being the chairman of the IABSE working group 1.5 “Considering cases of collapses in the design of bridges.”