MSc. Graduation Project:
Timber top-ups on Reinforced Concrete structures to increase dwellings area
Mentors:
Dr. Stijn Brancart
Dr. Olga Ioannou
Dr. Olga Ioannou
MSc Architecture, Urbanism and Building Sciences - Master Track Building technology
Link:
https://repository.tudelft.nl/islandora/object/uuid:5304411b-5fe3-4db3-a509-10da66b86677
https://repository.tudelft.nl/islandora/object/uuid:5304411b-5fe3-4db3-a509-10da66b86677
In response to the growing housing shortage in the Netherlands, the government has initiated a plan to increase new housing construction until 2050. At the same time, environmental commitments necessitate that new and existing housing adhere to current energy performance standards and circular goals by the same target year. In light of these requirements, exploring alternative methods for expanding housing capacity is vital to meet the growing demand while aligning with environmental objectives.
To address this challenge, this research examines timber top-up’s structural feasibility and circular potential to expand existing dwellings’ area as an alternative to a common practice: deconstruct followed by building new. Furthermore, provide an approach to the circular principle of Reuse to transition existing Reinforce Concrete (RC)structure in dwellings from a linear to a circular economy.
For this study, was selected a relevant RC structure typology in the city of Delft as a case study. The objective was to propose a conceptual modular structural design for a Timber Top-up system.
Two specific products were produced by the project: First, an approach for a framework in the decision-making process to evaluate Timber Top-ups feasibility. And second, the conceptual modular design of a Top-up timber system for existing RC structures based on the proposed design framework.
Furthermore, to analyze to what extent it is possible to Top-up with timber, three scenarios with different area capacities are proposed :
Scenario 1 (5RC+1T): Constructing one top-up layer in the existing structure.
Scenario 2 (4RC+3T): By deconstructing one layer of concrete and adding three timber
Scenario 3 (4RC+4T): Deconstructing one layer of concrete and adding three timber.
These scenarios were tested to analyze the structural feasibility of the system based on five structurally predefined criteria:
Reaction to the foundations of the existing Building
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Utilization of the main RC structural components.
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Utilization of the main RC structural components.
Displacements of the main RC structural components.
Utilization of timber components.
Deflection limit of the timber top-up structure.
Followed by analyzing the Upfront carbon of the Timber structure and RC structure for the three top-up scenarios.
The structural assessment tests are performed with the parametric structural analysis software Rhino 3d + Grasshopper, in addition to the use of the Karamaba 3d plugin, followed by the estimation of the CO2 footprint of the scenarios using the software Granta Edupack with its feature Ecoaduti tool.
In the three scenarios, an opportunity is indicated by the results, presented by the excess capacity in the existing RC walls. This capacity allows the current structure to withstand and transfer forces in all three load case scenarios until the utilization limits are reached.
Regarding the reactions in the foundation system, it can be concluded that a similar increase in the reactions in the foundations is achieved by removing one layer of RC components and replacing them with three layers of timber compared to not deconstructing and adding one layer. This means that more area capacity is enabled by removing part of the existing components with a similar increase in load at the base of the building.
From an environmental impact perspective, the addition of mass to increase capacity significantly reduces the upfront energy required for the building in all scenarios, owing to timber’s capacity to sequester carbon. However, the upfront carbon emissions produced during the construction of the original RC structure might not be sufficiently offset by adding a small volume of timber in the top-up. Thus, to maximize the offset of CO2 emissions from the existing structure, it is more favorable to construct top-ups with a high volume of timber.
