Chiara Bedon
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14 records found
1
Purpose: Glass material is largely used for load-bearing components in buildings. For this reason, standardized calculation methods can be used in support of safe structural design in common loading and boundary conditions. Differing from earlier literature efforts, the present study elaborates on the load-bearing capacity, failure time and fire endurance of ordinary glass elements under fire exposure and sustained mechanical loads, with evidence of major trends in terms of loading condition and cross-sectional layout. Traditional verification approaches for glass in cold conditions (i.e. stress peak check) and fire endurance of load-bearing members (i.e. deflection and deflection rate limits) are assessed based on parametric numerical simulations. Design/methodology/approach: The mechanical performance of structural glass elements in fire still represents an open challenge for design and vulnerability assessment. Often, special fire-resisting glass solutions are used for limited practical applications only, and ordinary soda-lime silica glass prevails in design applications for load-bearing members. Moreover, conventional recommendations and testing protocols in use for load-bearing members composed of traditional constructional materials are not already addressed for glass members. This paper elaborates on the fire endurance and failure detection methods for structural glass beams that are subjected to standard ISO time–temperature for fire exposure and in-plane bending mechanical loads. Fire endurance assessment methods are discussed with the support of Finite Element (FE) numerical analyses. Findings: Based on extended parametric FE analyses, multiple loading, geometrical and thermo-mechanical configurations are taken into account for the analysis of simple glass elements under in-plane bending setup and fire exposure. The comparative results show that – in most of cases – thermal effects due to fire exposure have major effects on the actual load-bearing capacity of these members. Moreover, the conventional stress peak verification approach needs specific elaborations, compared to traditional calculations carried out in cold conditions. Originality/value: The presented numerical results confirm that the fire endurance analysis of ordinary structural glass elements is a rather complex issue, due to combination of multiple aspects and influencing parameters. Besides, FE simulations can provide useful support for a local and global analysis of major degradation and damage phenomena, and thus support the definition of simple and realistic verification procedures for fire exposed glass members.
Structural glass beams with embedded GFRP, CFRP or steel reinforcement rods
Comparative experimental, analytical and numerical investigations
Laminated glass components are usually realized by bonding glass plates using interlayer polymers that develop adhesion forces during lamination. Recently, these adhesion forces have been used also to realize special adhesive connections for structural glass components and assemblies. The typical example of such a joining technique is conventionally known as “embedded laminated connection” where a metal insert is encapsulated in multi-ply laminated glass components. In this study, careful consideration is paid for the investigation of the mechanical behaviour of embedded laminated connections with thick metal insert. To this aim, small-scale laboratory tests, Finite Element (FE) numerical models and analytical considerations are presented. Firstly, the results of experimental investigations at different temperatures are discussed, giving evidence of the geometrical and mechanical parameter effects on the so observed performances. It is observed, in particular, that the temperature affects not only the maximum load carrying capacity but also the failure mode of the studied connection typology. Non-linear numerical simulations are then developed in ABAQUS on FE models, able to account for the geometrical and mechanical properties of the reference connection specimens. Further analytical considerations are also presented, in support of the observed experimental findings. It is shown, in particular, that as far as high temperatures are not attained, the mechanical performance and failure mode of the examined connections is strictly related to glass breakage. In addition, it is also observed that at high temperature, failure mode (i.e. bubble formation) and failure location are in line with the expectations. Rather close correlation can be also found for the same embedded connections between test results, FE numerical simulations and analytical assumptions.
Compared to existing literature efforts related to reinforced glass beams – typically including external steel or FRP tendons and/or reinforcement sections adhesively bonded to glass edges in tension – careful consideration is given to the still rather innovative concept of traditional LG beams that contain pultruded GFRP rods embedded within the interlayer foils. Taking advantage of past experimental results and preliminary Finite Element (FE) outcomes for hybrid glass beams, the quasi-static bending performance at room temperature of several geometrical configurations of LG beams with GFRP-embedded rods is compared. These geometrical configurations include variations in number, size and position of rods. The effects and possible benefits due to initial pre-stressing forces for the GFRP rods are also investigated. As shown for some selected configurations only, GFRP-embedded rods can provide active contribution to traditional LG beams, both in terms of post-cracked resistance and ductility. At the same time, given a reference geometry, a certain level of initial pre-stress can further exploit the potential of the same GFRP rods, acting as pre-tensioned tendons thereby enhancing the initial fracture strength. Several aspects should be properly taken into account to assess and optimize the overall performance of these systems, however, since both their elastic and post-cracked performance are highly sensitive to various mechanical and geometrical input parameters. ...
Compared to existing literature efforts related to reinforced glass beams – typically including external steel or FRP tendons and/or reinforcement sections adhesively bonded to glass edges in tension – careful consideration is given to the still rather innovative concept of traditional LG beams that contain pultruded GFRP rods embedded within the interlayer foils. Taking advantage of past experimental results and preliminary Finite Element (FE) outcomes for hybrid glass beams, the quasi-static bending performance at room temperature of several geometrical configurations of LG beams with GFRP-embedded rods is compared. These geometrical configurations include variations in number, size and position of rods. The effects and possible benefits due to initial pre-stressing forces for the GFRP rods are also investigated. As shown for some selected configurations only, GFRP-embedded rods can provide active contribution to traditional LG beams, both in terms of post-cracked resistance and ductility. At the same time, given a reference geometry, a certain level of initial pre-stress can further exploit the potential of the same GFRP rods, acting as pre-tensioned tendons thereby enhancing the initial fracture strength. Several aspects should be properly taken into account to assess and optimize the overall performance of these systems, however, since both their elastic and post-cracked performance are highly sensitive to various mechanical and geometrical input parameters.
Numerical analysis of glass-FRP post-tensioned beams
Review and assessment
In this paper, the structural bending performance of post-tensioned, glass-FRP hybrid beams is evaluated by means of advanced Finite-Element (FE) numerical analyses. To this aim, a concise recapitulation of existing research on several typologies of glass-FRP hybrid beams is first provided. Based on earlier experimental and preliminary FE research outcomes, further detailed discussion is then proposed for the specific concept of glass-FRP post-tensioned glass beams. FE parametric simulations for quasi-static bending loading configuration and room temperature are compared for such systems, typically including a laminated glass (LG) cross-section and an adhesively connected, post-tensioning FRP tendon. As shown, several aspects should be properly taken into account when investigating the overall performance of these systems, as far as both their elastic and post-cracked performance are highly sensitive to various mechanical and geometrical input parameters. A sensitivity FE study is hence presented, aiming to better explore their typical performance. ...
In this paper, the structural bending performance of post-tensioned, glass-FRP hybrid beams is evaluated by means of advanced Finite-Element (FE) numerical analyses. To this aim, a concise recapitulation of existing research on several typologies of glass-FRP hybrid beams is first provided. Based on earlier experimental and preliminary FE research outcomes, further detailed discussion is then proposed for the specific concept of glass-FRP post-tensioned glass beams. FE parametric simulations for quasi-static bending loading configuration and room temperature are compared for such systems, typically including a laminated glass (LG) cross-section and an adhesively connected, post-tensioning FRP tendon. As shown, several aspects should be properly taken into account when investigating the overall performance of these systems, as far as both their elastic and post-cracked performance are highly sensitive to various mechanical and geometrical input parameters. A sensitivity FE study is hence presented, aiming to better explore their typical performance.