Stephan Ott

In this study a timber-based integrated solution is presented to solve at once common issues affecting typical reinforced concrete (RC) existing buildings, such as seismic and energy performances, providing an eco-friendly alternative to steel external bracing systems. Cross-laminated timber (CLT) walls are provided perpendicularly to the external façades as strengthening elements while interposed CLT slabs are foreseen at each floor level to host new architectural units together with a new envelope. While the connections to the foundations and to the existing RC frames are provided respectively with steel brackets and axial-connectors distributed along the height of the building, a post-tensioned connection, between CLT panels (PT-CLT connection), is implemented in the system to guarantee resistance to horizontal actions acting parallel to existing façades with consequent structural independence and architectural freedom. On this regards a first look at the findings of an experimental campaign carried on the Technical University of Munich are presented. A numerical model is developed with finite element software characterizing each type of connector for linear and non-linear analyses. Modal analyses with response spectrum are performed to verify structural elements and connectors, while pushover analyses with target displacement checks are performed to assess the obtained seismic improvement. Finally, the preassembled architectural components that allow to renovate the envelope and the provided assembly procedure are revealed.

Eine konsistente Kreislaufführung der zur Verfügung stehenden Ressourcen ist eine der großen Herausforderungen für das Bauen in der Zukunft. Dieser Aufsatz liefert einen Beitrag hinsichtlich der Diskussion und Weiterentwicklung der Recyclingfähigkeit im Bauwesen. Es wird ein Modell vorgestellt, das über die reine Betrachtung von Baustoffen hinausgeht und die Recyclingfähigkeit von bestehenden oder neu zu errichtenden Baukonstruktionen insgesamt beschreibt. Auf diese Weise rücken Aspekte der Fügung und Lösbarkeit der einzelnen Baustoffe sowie Errichtungs‐ und Rückbauprozesse in den Vordergrund. Bei der Entwicklung des Modells wurde darauf geachtet, dass seine Struktur kompatibel ist mit bestehenden Klassifizierungen und Kategorien und an bestehende Rahmenbedingungen und Methoden anknüpft. Das Modell bietet mittelfristig eine Grundlage für eine ganzheitliche Entwicklung und Diskussion der Kreislaufführung im Bauwesen und soll langfristig einen Beitrag zur Entwicklung eines Nachweisverfahrens zur Abbildung einer nachhaltigen Nutzung natürlicher Ressourcen liefern.

The research work presented here belongs to a transnational project which aims at the development of a moisture risk analysis method used for tall timber facades. The major interest covers heat, air and moisture simulation of wind-driven rain-(WDR) exposed multi-story timber-based building envelopes (over their entire cross-section). While available moisture-safety concepts are often rule based with limited performance-oriented parts and are limited to small-scale housing, further exploration involves exposure of tall facades. State-of-the-art research compiles WDR examinations and available field and laboratory data as well as monitoring and simulation results. That is followed by evaluations of simulation methods at a best practice wall cross-section with the aim of examining the sensitivity and uncertainty of different parameters in relation to outdoor climate. This approach is chosen to discern the complex relations between exposure and vulnerability and the number of different facade detailing. The findings hold a categorization model of facade cross-sections that is used for risk analysis to describe moisture impact and reaction of functional layer groups. Furthermore, all WDR models and measured data show a high level of uncertainty and simulation results are strongly dependent on that input. An additional consideration of deficiencies and WDR penetration into the core layer of the facade shows only vague results of moisture accumulation. Under these circumstances failure modes of structural members are hard to determine. Therefore, this research is ongoing with a focus on more suitable exposure parameters and calibration of simulation methods for tall timber facades.