News

DURABRIDGE research team member Mladen Srbić presented the paper Seismic Assessment of the Existing Arched Bridge by Application of the Pushover Method at the 15th Central European Congress on Concrete Engineering (CCC2026), held in Vodice, Croatia, from 5 to 7 October 2026. The paper presents the seismic assessment of an existing reinforced concrete arch bridge using linear response spectrum analysis and nonlinear static pushover analysis. The paper was prepared within the framework of the DURABRIDGE project and published in Engineering Proceedings (MDPI).

Participation in the conference also provided DURABRIDGE research team members Jelena Bleiziffer, Marija Kušter Marić, Anđelko Vlašić, and Mladen Srbić with an opportunity to follow other topics relevant to the project, particularly those addressing the impact of climate change on the service life of concrete bridges, the application of dynamic measurements in structural condition assessment, bridge sustainability, and uncertainties in nonlinear analysis of reinforced concrete structures.

DURABRIDGE Project Leader, Prof. Ana Mandić Ivanković, participated in the IABSE Annual Meetings, held on 14–15 September 2026, including meetings of the Executive, Technical and Permanent Committees. The Technical Committee discussed the activities of IABSE Commissions and Task Groups, with particular relevance to DURABRIDGE from Commission C1 “Performance and Requirements”, chaired by Prof. Mandić Ivanković, as well as C5 “Existing Structures” and C6 “Sustainability”.

The Annual Meetings were followed by a three-day IABSE conference, where Prof. Mandić Ivanković together with prof. Yaojun Ge from Tongji University co-chaired the Keynote Lecture “Norwegian Experiences in Floating Bridge Technology” by Dr. Ketil Aas-Jakobsen. Further on, within the session “Fragility and Resilience Estimation of Infrastructure Subject to Natural Disasters”, she presented the DURABRIDGE paper “Determination of Parameters for Dynamic Bridge Analysis: Specifics of Croatian Bridges and Condition-Based Adjustments”.

Other topics particularly relevant to DURABRIDGE included calibration of partial safety factors for existing bridge assessment, structural damage and deterioration assessment, condition assessment and rehabilitation, and non-destructive testing (NDT). Participation in the conference provided valuable opportunities for knowledge exchange and insight into current international approaches to the assessment and management of existing bridges.

The project leader, Prof. Ana Mandić Ivanković, participated as a member of the PhD defence committee of Luis Francisco Rincon Prada on 1 September 2026. The PhD thesis, entitled Condition assessment of concrete coastal infrastructure considering the combined effect of chloride ingress, carbonation and climate change. Although the PhD research is not part of the DURABRIDGE project, the topics of concrete infrastructure degradation, condition assessment, and environmental and climate effects are closely related to the project's research areas. One of the PhD supervisors, Prof. Emilio Bastidas-Arteaga from La Rochelle University, France, an expert in stochastic modelling, degradation of marine infrastructure, and climate change effects, has provided support to the project and its research team in achieving the project objectives. Participation in the PhD defence further contributes to knowledge exchange and strengthens international collaboration in research areas relevant to the DURABRIDGE project.

During August and September, the inspection report for the Slunjčica Bridge was finalized. The results of the visual inspection and non-destructive testing were analysed, and characteristic damage and indicators of the structural condition were identified. Based on these analyses, recommendations were prepared for the development of a global structural model accounting for the condition of the structure. In parallel, a baseline numerical model of the Slunjčica Bridge was developed based on the design documentation and other available bridge documentation, while analyses of characteristic loads are currently underway.

The field investigation of the Posedarje Bridge was carried out on 7 July 2026. In addition to a detailed visual inspection of the entire bridge, non-destructive testing was conducted on selected structural elements: the piers, the abutment cap beams with spill-through embankments, and the bridge deck slab. A Profometer was used to determine the location, spacing and diameter of the reinforcement, as well as the concrete cover thickness. The modulus of elasticity was estimated using the ultrasonic pulse velocity method, while the compressive strength of the concrete was estimated using a Schmidt hammer. The electrical resistivity of the concrete was measured using a Resipod, and the half-cell potential of the reinforcement was measured using a Profometer to assess the probability of reinforcement corrosion. Some photographs from the field investigation are presented below.

Team gathering in front of the bridge

Detection of the location, spacing and diameter of the reinforcement, and determination of the concrete cover thickness on the bridge pier using a Profometer

Application of the ultrasonic pulse velocity method to estimate the modulus of elasticity of the pier concrete

Estimation of the compressive strength of the pier concrete based on surface hardness using a Schmidt hammer

Measurement of the electrical resistivity of the pier concrete using a Resipod

Detection of the location, spacing and diameter of the reinforcement, and determination of the concrete cover thickness of the abutment cap beam with a spill-through embankment

Preparing for measurement of the half-cell potential on the abutment cap beam

During June, we are preparing the inspection report for the Slunjčica Bridge, which will present the results of the visual inspection and non-destructive testing, together with recommendations for updating the bridge model to better reflect its actual condition.

In parallel, we have selected a representative continuous slab bridge with piers monolithically connected to the superstructure as the next case study in our research. Located in the coastal area of Posedarje, the bridge is exposed to wind and a marine environment, making it an ideal case for investigating potential deterioration caused by corrosion. We are currently analysing the bridge and preparing the visual inspection and non-destructive testing programme. The same equipment used for the Slunjčica Bridge inspection will be employed, including a Profometer, ultrasonic pulse velocity tester, Schmidt hammer, and Resipod.

Members of the DURABRIDGE team actively participated in the 9th International Conference on Road and Rail Infrastructure (CETRA 2026), held from 27 to 30 May 2026 in Bol on the island of Brač, Croatia. The conference brought together researchers and professionals from around the world to exchange the latest knowledge and developments in the field of transport infrastructure.

Through his role in chairing the Special Session: Advanced Assessment and Monitoring of Bridges, dedicated to advanced methods for bridge condition assessment and monitoring, Anđelko Vlašić contributed to discussions on modern approaches to bridge assessment, monitoring, and safety enhancement. The session was co-chaired with Aleš Žnidarič, one of Europe’s leading experts in bridge monitoring and condition assessment.

Within the same session, Marija Kušter Marić presented the paper Impact of Flooding on Bridge Condition: Insights from Two Case Studies, co-authored by Tomislav Rinkovec, Petar Uremović, and Mladen Srbić. The paper examines the impact of flooding events on bridge condition through two case studies and contributes to the objectives of the DURABRIDGE project, aimed at improving the understanding of degradation processes, assessing the condition of existing bridges, and developing more reliable approaches to infrastructure management throughout their service life.

The field investigation of the bridge over the Slunjčica River in Slunj (Rastoke) was carried out on April 28, 2026. In addition to a visual inspection, non-destructive testing was performed at several accessible locations on the bridge: on the arch, on the piers, and on the underside of the deck structure. A cover meter (profometer) was used to determine the location, spacing, and diameter of reinforcement, as well as the concrete cover thickness. Ultrasonic testing was applied to assess the homogeneity of the concrete and to estimate its modulus of elasticity. A rebound hammer (Schmidt hammer) was used to estimate the compressive strength of the concrete. Electrical resistivity of the concrete was measured using a resistivity meter, while half-cell potential measurements were conducted using the profometer to assess the probability of reinforcement corrosion. Below are some images from the field investigation:

Team gathering in front of the bridge

Detection of reinforcement layout, spacing, diameter, and concrete cover on a bridge pier using a profometer

Detection of reinforcement location, spacing, and diameter, as well as determination of concrete cover on the underside of the deck structure using a profometer

Ultrasonic testing for determining the modulus of elasticity of the pier concrete

Estimation of compressive strength of the arch concrete using a rebound hammer

Measurement of the pier concrete electrical resistivity using a resistivity meter

Half-cell potential measurement at the interface between the pier and the arch using a profometer

Half-cell potential measurement on the underside of the deck slab using a profometer

During the first few months of the project, we reviewed the archives of the Chair of Bridges and identified the Slunjčica Bridge as a representative arch bridge (WP1) that will be the focus of our further research. Based on our previous studies, arch bridges are of particular interest regarding their seismic behaviour. Furthermore, the bridge location and the use of de-icing salts during winter months require investigation of potential bridge degradation due to corrosion.

Currently, we are collecting all available documentation on the bridge from the archives and preparing for the inspection of the Slunjčica Bridge to determine the structural condition and collect data relevant for engineering load analysis (WP2), bridge degradation assessment (WP3), and numerical modelling and simulations (WP4). We are analysing the bridge documentation and preparing the sequence and the scope of the visual inspection and non-destructive testing of the arch, piers, and the underside of the superstructure.

For non-destructive testing, we will use the following existing equipment:

• Ultrasonic pulse velocity testing device V-Meter Mark IV
  https://www.croris.hr/oprema/oprema/5427
• Profometer 630 AI – device for reinforcement detection, determination of concrete cover, reinforcement diameter, and half-cell potential measurements
  https://www.croris.hr/oprema/oprema/5428
• Schmidt rebound hammer (sclerometer)
  https://www.croris.hr/oprema/oprema/5430
• Resipod – device for measuring the electrical resistivity of concrete
  https://www.croris.hr/oprema/oprema/5429
• Crack width microscope
  https://www.croris.hr/oprema/oprema/5431

We have received permission from the road authority Hrvatske ceste d.o.o., responsible for the management, construction, and maintenance of state roads, to carry out the bridge inspection for research purposes. We would like to express our gratitude for their support and cooperation.