17711. |
- Hochreiner, Georg, et al.
(författare)
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Structural behaviour and design of dowel groups : experimental and numerical identification of stress states and failure mechanisms of the surrounding timber matrix
- 2017
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Ingår i: Engineering structures. - : Elsevier. - 0141-0296 .- 1873-7323. ; 131, s. 421-437
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Tidskriftsartikel (refereegranskat)abstract
- Dowel-type fasteners in combination with steel plates are widely used in engineered timber structures. Since dowel groups are designed as semi-rigid connections subjected to an arbitrary set of internal forces, the corresponding structural behaviour of the surrounding timber matrix must be considered in the design process accordingly, including the effect of reinforcements. Corresponding stress states and failure mechanisms in the timber matrix of dowel groups are discussed herein. Surface strain fields from tests of dowel groups under complex loading situations were used to identify the sequence of cracking, as well as to assign the related failure modes. First cracking events were caused by stress peaks at the most loaded dowels and by a combination of shear stresses and stresses perpendicular to the grain, while later crack- ing events were associated with a predominant action of individual stress components. Thus, the non- linear global moment-relative rotation behaviour of dowel groups could be related to failure mechanisms in the surrounding timber matrix. The corresponding strain state was qualitatively as well as quantita- tively reproduced by means of a numerical model, which gave access to stresses in the timber matrix and has potential to be implemented as a sub-model in engineering design software. The numerical model supported the feasibility of a decomposition of the stress state due to the global bending moment into stresses caused by a couple of equal forces parallel and perpendicular to the grain, which could be used in the design process. Based on experimental and numerical findings, essential aspects for a design procedure for the timber matrix in dowel groups loaded by a combination of internal forces are proposed.
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17712. |
- Hochreiner, Georg, et al.
(författare)
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The Historic Roof Structure of the Spanish Riding School in Vienna : Structural Assessment
- 2015
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Ingår i: Proceedings of the International Conference on Structural Health Assessment of Timber Structures, SHATIS15. - : Dolnoslaskie Wydawnictwo Edukacyjne (DWE). - 9788371252563 ; , s. 248-259
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Konferensbidrag (refereegranskat)abstract
- In 2012, the historical roof structure of the Spanish Riding School, built in the years from 1729 to 1735 as part of the ensemble of the Vienna Imperial Palace (called Hofburg), was documented by students and staff of the Vienna University of Technology. The survey was performed deformation- accurate and included both, the main structure and corresponding joints. Consequently, the documentation highlights deviations from the initial perception of the roof structure such as broken joints, inactivity of compressive devices like knee braces or excessive displacements of single structural members. Probably, these damages led to strengthening measures (=additional substructures) that were added in recent times to avoid progressive failure. This documentation formed the basis for the assessment of this historical roof structure from a structural and timber engineering point of view, which will be presented herein. The focus of the structural modelling was placed on the assessment of the two initial structural concepts, namely the main hall with and without the timber dome structure that was added in 1734, by visualisation of the internal forces and displacements. For this purpose, the nonlinear load carrying capacities and failure modes of the carpentry joints were assessed. Subsequently, alternative structural systems could be found by iterative recalculation revealing the capabilities for redundancy of the timber roof structure. Corresponding results were checked again with in-situ observations. Consequently, the findings of this study highlight the benefits of integrating modern structural and timber engineering methods and tools in the context of building history and building survey.
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17713. |
- Hochreiner, Georg, et al.
(författare)
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Timber Matrix Failure Modes in Multi-Dowel Connections
- 2016
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Ingår i: 17th International Conference on Experimental Mechanics, Rhodes, Greece, July 3-7, 2016.
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Konferensbidrag (populärvet., debatt m.m.)abstract
- The engineering design of dowel type steel-to-timber connections is comprehensive and shall also include the surrounding timber matrix, as required by the principles specified in Eurocode 5. As one part of a hierarchically structured research program, the loading and failure modes of multi-dowel connections has been investigated, including both the elastic as well as the cracked domain of the load history. Depending on the presence of local reinforcement, in order to prevent premature brittle failure and to insure local ductile dowel behavior, the global response became more or less ductile. The monitoring of surface deformations of the timber by means of a contact free displacement measurement system (DIC) supported the identification of stepwise changing structural systems. This data constitutes a valuable basement for the completion resp. improvement of the present design procedures with respect to consistency and effectiveness.
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17714. |
- Hoehler, Matthew, et al.
(författare)
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Fire Safety Challenges of Tall Wood Buildings : Large-scale Cross-laminated Timber Compartment Fire Tests
- 2018
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Ingår i: SiF 2018– The 10th International Conference on Structures in FireFireSERT, Ulster University, Belfast, UK, June 6-8, 2018. - : New University of Ulster.
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Konferensbidrag (refereegranskat)abstract
- This study investigates the contribution of cross laminated timber (CLT) building elements to compartment fires. Six compartments (9.1 m long × 4.6 m wide × 2.7 m high) were constructed using 175 mm thick 5‑ply CLT structural panels and fire tested using residential contents and furnishings to provide a fuel load density of 550 MJ/m2. The results show that gypsum board can delay or prevent the involvement of the CLT in the fire, and that the ventilation conditions and exposed surface area of the CLT play a decisive role in the outcome of the test. The results highlight the need to use heat-resistant adhesives in cross laminated timber to minimize delamination.
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17715. |
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17716. |
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17717. |
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17718. |
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17719. |
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17720. |
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