Articles > 2026
Karlo Ožić
13 July 2026 > Research article > DOI
Historic masonry buildings in European urban centres, particularly those predating codified seismic requirements, represent a significant portion of the existing building stock and pose considerable challenges in terms of seismic safety assessment and rehabilitation. This study focuses on unreinforced masonry structures with timber floor systems typical of Zagreb, Croatia, a region of moderate to high seismic hazard, as evidenced by the destructive earthquakes of 2020. Such buildings commonly exhibit structural deficiencies including inadequate wall-to-floor connectivity, insufficient stiffening elements, and irregular stiffness distribution, all of which contribute to unfavourable seismic performance. The primary objective of this work is to quantify the influence of two key structural parameters: the percentage of facade wall openings and the type of interstory construction on the global seismic response of historic masonry buildings. These parameters were selected due to their critical role in governing stiffness distribution, mass distribution, and damage mechanisms under seismic excitation. A comparative numerical analysis was conducted across ten representative building configurations, enabling a systematic evaluation of how variations in these parameters affect structural behaviour. This study is intended as a supplement to an existing empirical vulnerability assessment method, addressing identified asymmetries in parameter distributions observed in real building datasets. By combining analytical modelling with insights drawn from empirical observations, the approach aims to reduce uncertainties inherent in the assessment of heterogeneous historic structures. The results contribute to a more refined understanding of seismic vulnerability in traditional masonry construction and support the development of more reliable loss models.
Dean Čizmar
11 July 2026 > Research article > DOI
Numerical models of timber trusses used in engineering practice and structural condition assessment typically assume pin-jointed web-to-chord connections. This article demonstrates that such models systematically underestimate measured vertical displacements — by 3 to 44% at the first load point (U₁) and 48 to 70% at midspan (U₂) — which is unsafe from a serviceability assessment perspective. An alternative spring model is proposed in which longitudinal and rotational slip moduli of the connections are incorporated explicitly. Results are presented for six full-scale timber trusses with two fastener types (Wolf 15N punched metal plate fasteners, PMPF, and M10 bolts) and two timber grades (C24 solid timber and GL24h glulam). The spring model reduces the U₁ error to within ±15% for five of six configurations and achieves 3–6% accuracy for midspan displacement U₂ in bolt-fastened trusses. One exception is identified: for the N-web truss with Wolf 15N plates (R1), the spring model overestimates U₁ by 26.5%, attributed to overrepresentation of the rotational spring contribution for that geometry. Experimentally determined longitudinal slip moduli agree well with normative values. Rotational stiffness of Wolf 15N plates is reported experimentally for the first time. Implications for robustness assessment of existing timber roof structures are discussed.
Javier Ortega, Savvas Saloustros, Mislav Stepinac, Pablo Sanz-Honrado, Fernando Ramonet, Mati Ullah Shah, Katrin Beyer, Sofia Aparicio
22 May 2026 > Research article > DOI
The paper reflects on the role that robotics, automation and digital technologies can assume in the context of evaluating the physical condition and structural integrity of masonry heritage structures. The main research motivation is that all these processes, from structural surveying and inspection to computational modelling and structural assessment, can be improved with these disciplines that have gained great importance in recent years. Recent research shows that progress in mechatronic systems and digital technologies can help in reducing the time cost, at the operational and data processing level, enhancing the practicability and applicability of inspection systems, as well as in reducing uncertainties at the level of interpretation, processing and analysis of data. The main objective of the paper is to identify: (1) recent solutions that built on these disciplines for solving surveying inspection challenges of cultural heritage structures; (2) strategies on the use of digital technologies to develop advanced computational models for structural analysis that consider the detailed structural information collected during inspection, e.g., geometry and masonry microstructure, material properties and damage. The focus is placed on works showing advances that can improve our ability to perform structural diagnosis and analysis of masonry heritage structures, particularly through the onsite characterisation of the masonry inner morphology and the integration of this information into numerical models.
Arnas Majumder, Monica Valdes, Mariangela Albano, Patrizia Serra, Filippo Schintu, Flavio Stochino
29 April 2026 > Research article > DOI
This study investigates the physical, mechanical, and thermal properties of cement-stabilised unfired earth bricks. Cement-stabilised earth bricks were fabricated using soil from Sidi Amor, Tunisia, and 3% cement by dry weight with respect to the soil dry mass. The bricks exhibited apparent dry densities ranging from 1687 to 1853 kg/m³. Whereas moderate capillary water absorption coefficients were found between 9.4 and 23.9 g/m²·s, these results confirm that these bricks exhibit the typical characteristics of lightly stabilised earthen materials. Ultrasonic pulse velocity values (ranging from 1175 to 1670 m/s) indicate satisfactory material continuity. While moderate surface hardness has been confirmed through rebound hammer tests. Flexural strengths of 0.66 to 0.98 MPa and compressive strengths between 1.7 and 8.6 MPa have been obtained through mechanical tests. These brick samples have shown good insulation properties; the thermal conductivity values increase with increasing sample temperature, measuring 0.435, 0.446, and 0.462 W/m·K at 10 °C, 20 °C, and 30 °C, respectively. Overall, the results confirm that cement-stabilised unfired earth brick is a promising candidate as a sustainable masonry in low-rise and non-load-bearing construction.
Berk Karakus, Andrea Lisjak, Omid Mahabadi, Christian Viau, Bora Pulatsu
27 April 2026 > Research article > DOI
Unreinforced dry-joint stone masonry walls (DJ-SMWs) are the load-bearing elements in historic structures and buildings that are well known for their seismic vulnerabilities. In this study, the Finite-Discrete Element Method (FDEM) is used to computationally investigate the in-plane lateral behaviour of DJ-SMWs under varying pre-compression loads. The adopted modelling strategy enables the simulation of cracking within stone units and captures the frictional mechanism along the contact planes between adjacent blocks. Once the proposed framework is validated, it is demonstrated that increasing vertical load enhances the lateral load-carrying capacity while reducing ultimate displacement, accompanied by excessive damage in masonry units. The failure mechanisms, which transition from rocking failure under low axial compression to mixed-mode diagonal cracking at higher axial loads, are effectively captured using FDEM for the analyzed DJ-SMW aspect ratio. The proposed framework also provides detailed fracture response of DJ-SMWs, offering better predictive capability compared to conventional modelling approaches. Finally, Equivalent Energy Elastic-Plastic bilinear curves and ductility index analyses are used to quantify the deformation and failure mechanisms. The results contribute to a deeper understanding of DJ-SMW behaviour, facilitating the development of conservation and strengthening strategies for heritage masonry structures.
Marjo Hysenlliu, Altin Bidaj, Huseyin Bilgin
21 April 2026 > Research article > DOI
Albania and the broader region possess a considerable inventory of low- and mid-rise unreinforced masonry buildings dating from the post-World War II era till 1990s. Many structures of this type have shown vulnerability in recent seismic events in the region and succumbed to destruction during the catastrophic 2019 Albania earthquake sequences, resulting in loss of life, injuries, and property damage. The structures in question typically range from three to five stories in height and feature clay brick masonry walls, along with rigid floor slabs. This study outlines a case study focusing on a URM school building that sustained damage during the 2019 Albania earthquake. Geotechnical investigations were carried out to characterize the soil conditions at the sites of the school foundations. Nonlinear static analyses were conducted to evaluate the seismic capacity, determine the performance point, and define damage states, based on a performance-based assessment methodology. The analysis of capacity curves and performance metrics revealed significant structural deficiencies in the school buildings. Findings indicate that buildings constructed before the adoption of modern seismic codes do not meet current performance criteria, underscoring the need for immediate strengthening measures and risk mitigation strategies.