Publicação
Structural glass flexural strengthening with CFRP composites and Fe-SMA based on passive, active and hybrid techniques
| Resumo: | Contemporary architecture encourages the use of glass in structural applications. Glass industry has developed the thermal toughening to increase its tensile strength and lamination to prevent brittle failure. However, glass can still fail unexpectedly due to the growth of surface flaws. Recent studies have focused on glass composite systems, mainly using steel as reinforcement. Other reinforcement materials (e.g. CFRP and Fe-SMA) and application techniques (e.g. prestressing) need also to be explored, given their promising features to face the growing structural challenges. This thesis aimed at covering two main topics related to structural glass: (i) post-cracking performance and (ii) mechanical post-tensioning. Its main objective was to evaluate the feasibility of using CFRP and Fe-SMA as reinforcement in flexure to obtain ductile failure modes, as well as the application of post-tensioning to reduce the unpredictability of the glass fracture strength. The experimental programs included (i) tensile tests on double-lap joints to assess the bond performance of glass-to- CFRP adhesive connections, (ii) flexural tests on small-scale monolithic glass beams with externally bonded CFRP or Fe-SMA reinforcements, and (iii) flexural tests on large-scale laminated glass beams with hybrid (EBR + NSM) strengthening. It was possible to obtain ductile failure modes when glass was strengthened with CFRP and Fe-SMA. The post-cracking performance was sensitive to the adhesive type, reinforcement material, strengthening system and, in the case of Fe-SMA reinforced glass, the activation temperature. Hybrid strengthening systems prevented premature debonding of the reinforcement and made better use of its tensile capacity. NSM-CFRP composite systems were safely prestressed and FRP peeling-off failure was avoided during load releasing. Considering the importance of design rules for practitioners, numerical modelling was carried out to assess (i) the efficiency of different constitutive models to simulate the non-linear behaviour of glass in tension and (ii) the influence of design parameters on the numerical response of glass composite systems. Further numerical simulations were performed to better understand the structural performance of CFRP reinforced glass elements, including at the level of the glass-to-CFRP adhesive joint. The results obtained were promising, and although additional studies are needed, new perspectives were opened for a future safer and widespread use of glass as a structural material. |
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| Autores principais: | Rocha, Jorge Araújo |
| Assunto: | CFRP Fe-SMA Glass composite systems Flexural response Prestressing Numerical modelling Pré-esforço Reposta à flexão Simulação numérica Sistemas compósitos de vidro Engenharia e Tecnologia::Engenharia Civil |
| Ano: | 2023 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Contemporary architecture encourages the use of glass in structural applications. Glass industry has developed the thermal toughening to increase its tensile strength and lamination to prevent brittle failure. However, glass can still fail unexpectedly due to the growth of surface flaws. Recent studies have focused on glass composite systems, mainly using steel as reinforcement. Other reinforcement materials (e.g. CFRP and Fe-SMA) and application techniques (e.g. prestressing) need also to be explored, given their promising features to face the growing structural challenges. This thesis aimed at covering two main topics related to structural glass: (i) post-cracking performance and (ii) mechanical post-tensioning. Its main objective was to evaluate the feasibility of using CFRP and Fe-SMA as reinforcement in flexure to obtain ductile failure modes, as well as the application of post-tensioning to reduce the unpredictability of the glass fracture strength. The experimental programs included (i) tensile tests on double-lap joints to assess the bond performance of glass-to- CFRP adhesive connections, (ii) flexural tests on small-scale monolithic glass beams with externally bonded CFRP or Fe-SMA reinforcements, and (iii) flexural tests on large-scale laminated glass beams with hybrid (EBR + NSM) strengthening. It was possible to obtain ductile failure modes when glass was strengthened with CFRP and Fe-SMA. The post-cracking performance was sensitive to the adhesive type, reinforcement material, strengthening system and, in the case of Fe-SMA reinforced glass, the activation temperature. Hybrid strengthening systems prevented premature debonding of the reinforcement and made better use of its tensile capacity. NSM-CFRP composite systems were safely prestressed and FRP peeling-off failure was avoided during load releasing. Considering the importance of design rules for practitioners, numerical modelling was carried out to assess (i) the efficiency of different constitutive models to simulate the non-linear behaviour of glass in tension and (ii) the influence of design parameters on the numerical response of glass composite systems. Further numerical simulations were performed to better understand the structural performance of CFRP reinforced glass elements, including at the level of the glass-to-CFRP adhesive joint. The results obtained were promising, and although additional studies are needed, new perspectives were opened for a future safer and widespread use of glass as a structural material. |
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