Chiara Bedon*, Riccardo Del Bello, Nicola Cella, Luca Cozzarini, Marco Fasan (2026)
Ensuring appropriate levels of post-fracture security and structural safety for laminated glass (LG) elements in constructions are a primary need. Besides, these features are rather challenging to assess, due to a multitude of influencing parameters and uncertainties. As such, roughly simplified strategies are taken into account in the design of LG, to ensure suitable residual stiffness and resistance in case of possible partial damage. For safety purposes, any mechanical contribution from a cracked glass layer is fully disregarded in the analysis of the residual LG section. In this study, small-scale 2-ply LG specimens (50 mm wide × 100 mm in length) composed of annealed (AN) glass and bonded by EVA or SG interlayers are investigated. The specimens (60 in total) are subjected to randomly imposed partial fracture for one of the constituent glass layers, and tested in a three-point-bending setup in the so-called STAGE 2 (57 tests). A cyclic quasi-static protocol is imposed to the specimens, to quantify their mechanical response and partially fractured bending stiffness. The experimental results are also exploited to derive the equivalent modulus of elasticity for the cracked glass layer. In general, the experimental analysis shows a relatively stable performance of mechanical features for the given number of cycles, which suggests the availability of a minimum post-fracture capacity. However, the effect of some important influencing parameters is also highlighted.
Nicola Cella, Chiara Bedon* (2025)
Insulated glass units (IGUs) represent composite systems that are extensively utilised in buildings, due to their superior thermal and acoustic potentials. From a structural standpoint, an IGU exhibits higher performances in comparison to a single monolithic or laminated glass pane, thanks to the collaboration of its components. Besides, the mechanical analysis of IGUs is rather challenging due to the influence of multiple parameters, including basic geometrical features (i.e., thickness and size of the constituent glass panes), as well as properties of edge connections and mechanical boundary conditions. Additionally, fluid-structure interaction phenomena due to the presence of the gas-filled cavity and its features (i.e., thickness and type of infill) should be properly considered. These influencing parameters could be even more critical for in-service IGUs, where long-term phenomena or unfavourable operational conditions could lead to possible loss of functionality. For maintenance optimization, it is thus important to find key performance indicators that could be used for structural assessment and monitoring purposes. This paper thoroughly investigates the vibration response of selected IGUs by means of more than 100 modal analyses carried out in ABAQUS, pointing out the effect of such a multitude of factors on the vibration frequencies and shapes. The vibration frequencies implicitly reflect a possible change in terms of mechanical performance of the IGU and can consequently represent a preliminary but meaningful diagnostic parameter. The parametric analysis highlights some important quantitative and qualitative variations in terms of key vibration parameters and can thus suggest the elaboration of an efficient monitoring strategy for in-service IGUs.
Chiara Bedon *, Marcin Kozlowski, Nicola Cella (2025)
“Gaps in the post-breakage out-of-plane bending stiffness assessment of 2-ply partially damaged laminated glass elements under short-term quasi-static loads”
Engineering Structures, 327: 119617, https://doi.org/10.1016/j.engstruct.2025.119617
The mechanical response of partially fractured laminated glass elements is rather challenging to assess and quantify. In this paper, the attention is focused on the contribution that fractured glass can offer to the out-of-plane bending stiffness of a partially broken 2-ply laminated glass element. Literature and technical standard assumptions are briefly recalled and discussed, pointing out the effect of cracked glass removal in structural calculations. Original experimental tests in beam-like setup are then introduced, for a total of 60 deflection measurements, to focus on the out-of-plane bending response of 2-ply laminated glass samples bonded by EVA films, and composed of annealed (AN), heat-strengthened (TVG) or fully tempered (ESG) glass panes, respectively. With the support of numerical modelling, the quasi-static response of the tested specimen is verified and used as a reference for the calibration of an equivalent cracked modulus for fractured glass only, which is able to account for the type of glass, size and type of fragments and loading setup. Literature bending test results for 2-ply laminated glass elements are also used in support of the parametric analysis. Comparative analyses are presented based on other simplified strategies of literature, with a critical discussion of possible effects and limits.
Chiara Bedon * (2024)
“Frequency-Based Early Crack Detection and Damage Severity Measure in Structural Glass Members: Application to Beams in Bending”
Journal of Architectural Engineering, 30(4): https://doi.org/10.1061/JAEIED.AEENG-167
As is known, the propagation of cracks in a structural member is associated with local modifications of rigidity and thus possible major effects that can strongly affect its load-bearing capacity and dynamic parameters. As such, among others, the natural frequency control represents a consolidated and efficient approach for damage detection, damage severity assessment, and in situ monitoring for several structural typologies. In this paper, attention is given to typically brittle-in-tension structural glass members and to the analysis of first-crack initiation in terms of natural frequency decrease. The goal is to assess the potential and feasibility of a standardized approach for in situ structural health monitoring (SHM) assessment. To this aim, the investigation takes advantage of a literature analytical model for frequency assessment (i.e., as a function of crack position and depth), and of finite-element (FE) numerical simulations carried out to predict the cracked vibration frequency of various configurations of technical interest. As a first step of this possible methodology assessment, glass beams under an in-plane bending setup are considered, given that they are largely used as stiffeners or fins. It is shown that while glass material is typically brittle in tension and cracks can originate from edges due to several reasons, traditional frequency-based monitoring tools can be efficiently adapted for early detection and to quantify damage in existing glass structures. For the examined configurations, it is shown that frequency reductions up to ≈−20% can be expected due to first-crack initiation. Most importantly, the FE numerical analyses show that crack shape/geometry can further emphasize the expected frequency decrease, and thus additionally enforce the need of specific protocols/performance indicators for SHM purposes in existing structures, as well as for the optimal design of new systems.
Silvana Mattei, Luca Cozzarini, Chiara Bedon * (2025)
“Numerical simulation of anti-shatter films (ASF) for mechanical post-breakage analysis of retrofitted glass”
Advances in Structural Engineering, 28(4), 627-641, https://doi.org/10.1177/1369433224129125
Post-breakage strength and residual mechanical capacity improvements are important tasks for load-bearing structural components in general, and even more for glass elements, in order to protect people from injury in case of breakage. For this reason, among others, the design of glass components and structures is based on key concepts that are generally summarized in structural safety, robustness and redundancy. With regard to the last fundamental requirement, nowadays the use of laminated glass (LG) sections is spread for many applications and new projects, such as automotive or aircraft windshields, but especially curtain walls and many other load-bearing applications in buildings. This strategy derives from the intrinsic safety and security levels of LG sections after possible glass breakage. When LGs are not available (i.e., existing components), anti-shatter safety films (ASF) for the retrofit of monolithic glass elements are expected to provide very similar post-breakage structural performances against bending and impact actions, by reducing the possible spread of glass shards. Besides, the residual load-bearing capacity of glass components retrofitted by ASF is still challenging to quantify. In this paper, the Cohesive Zone Model (CZM) theory is considered to investigate, with the support of experiments and Finite Element (FE) numerical models, the performance of small-scale monolithic glass specimens retrofitted by ASF under bending loads. Different ageing procedures and imposed displacement-rates are considered to evaluate the influence of basic operational parameters, such as temperature and humidity, on the mechanical efficiency of common ASF layers. In doing so, the sensitivity of fundamental input parameters (i.e., maximum tensile strength of glass and fracture energy of the ASF adhesive) on the mechanical performance at pre- and post-breakage stages of retrofitted monolithic glass elements is explored.