Publicação
Load transfer models in joint lines of punched metal plate fasteners
| Resumo: | Timber joints are a key part of timber structures, and their performance is a major requisite to successful timber constructions. Among all the connection types, punched metal plate fasteners are the most economical and e cient, reasons why this connection dominates the prefabricated truss industry. However, the structural load bearing capacity of these timber connections is mechanically complex and di cult to analyse. Besides, the current standards oversimplify many current joint con gurations and don’t provide a guideline to predict the stress distribution within the plate. Most research to date has focused on modelling and testing punched metal plate fasteners from a FEM 3-D perspective, accounting for all its parts (timber, plate, teeth and toothwood interface) whilst knowledge on the 2-D stress distribution within the plate is limited. The complete joint modeling with a 3-D model based on FEM gives precise results on the mechanical behavior of those plates, but requires more time to model and more computational processing. In a truss design point of view, where many connections need to be verify, a 2-D static model is usually the annalist’s choice, and despite the large industrial application of metal plates, the internal force ow still lacks research. The research reported in this thesis describes four methods to account for the stress distribution in punched metal plate fasteners. Each model is based on a particular plate behavior and aims to identify the critic rupture lines to successfully attend the ultimate limit state criteria. A heel joint was taken as starting point to study the stress distribution in the rupture lines, and a computational tool (NPCalc) was developed based on the current standards to verify the main connection aspects. The connection was modeled by the four methods and the results were analysed and compared, seeking to identify how the stress ows within the plate once the loads are applied. Two manual and two numerical methods were presented. The results showed a considerable variability with the model’s choice, and the numerical models pointed to be more conservative. However, the simple regions (delimited by only one rupture line) presented equal results regardless the chosen model. Finally, the conclusions of the elaborated research are presented, discussing the extension of its results and the suggestions for future development, in order to complement the analysis and modeling of wooden trusses with punched metal plate fasteners. |
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| Autores principais: | Paiva, Lucas |
| Assunto: | Timber connections Nail plate trusses Punched metal plate fasteners Stress distribution |
| Ano: | 2020 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Instituto Politécnico de Bragança |
| Idioma: | inglês |
| Origem: | Biblioteca Digital do IPB |
| Resumo: | Timber joints are a key part of timber structures, and their performance is a major requisite to successful timber constructions. Among all the connection types, punched metal plate fasteners are the most economical and e cient, reasons why this connection dominates the prefabricated truss industry. However, the structural load bearing capacity of these timber connections is mechanically complex and di cult to analyse. Besides, the current standards oversimplify many current joint con gurations and don’t provide a guideline to predict the stress distribution within the plate. Most research to date has focused on modelling and testing punched metal plate fasteners from a FEM 3-D perspective, accounting for all its parts (timber, plate, teeth and toothwood interface) whilst knowledge on the 2-D stress distribution within the plate is limited. The complete joint modeling with a 3-D model based on FEM gives precise results on the mechanical behavior of those plates, but requires more time to model and more computational processing. In a truss design point of view, where many connections need to be verify, a 2-D static model is usually the annalist’s choice, and despite the large industrial application of metal plates, the internal force ow still lacks research. The research reported in this thesis describes four methods to account for the stress distribution in punched metal plate fasteners. Each model is based on a particular plate behavior and aims to identify the critic rupture lines to successfully attend the ultimate limit state criteria. A heel joint was taken as starting point to study the stress distribution in the rupture lines, and a computational tool (NPCalc) was developed based on the current standards to verify the main connection aspects. The connection was modeled by the four methods and the results were analysed and compared, seeking to identify how the stress ows within the plate once the loads are applied. Two manual and two numerical methods were presented. The results showed a considerable variability with the model’s choice, and the numerical models pointed to be more conservative. However, the simple regions (delimited by only one rupture line) presented equal results regardless the chosen model. Finally, the conclusions of the elaborated research are presented, discussing the extension of its results and the suggestions for future development, in order to complement the analysis and modeling of wooden trusses with punched metal plate fasteners. |
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