Low-Damage Envelope Design Made of Unitised Panels with Innovative Corners for Multi-Storey Timber Buildings in Seismic Prone Regions

Abstract

In response to climate change, there is an urgent need to improve sustainability in society, particularly through our approach to architecture. As increasing populations concentrate in urban areas, multi-storey buildings mitigate the pressure on land. For these applications, timber is still a relatively under-used material with renewability and lower embodied energy that could replace concrete and steel. Innovative construction technologies have driven increasing attention to mass timber buildings in the market. Earthquakes are a critical factor that influences the durability of buildings, possibly triggering demolition and replacement at a city-wide scale. Low-damage design for seismic control has become preferable to prevent elements from breaking, or to provide repairability. Extensive damage to non-structural envelopes has been observed in several major earthquakes. The primary factor causing the damage was identified as inter-storey drifts. In order to reduce the damage, this thesis focused on low-damage design for envelopes composed of non-structural unitised panels, which can accommodate a maximum of 2.5% inter-storey drift without breaking. This thesis introduces a strategy to modify only the corner parts of existing seismic curtain wall systems, which can allow panels to slide in a controlled manner without breaking. Through three-dimensional analysis, seismic issues at the corners of slidable rigid panels were identified and visualised. The issue was solved by redesigning the corner mullions and adding corner angles. This strategy is applicable to both small and large rigid unitised panels. It only requires slidable plug-in joints and special corner components to be adopted, thus enabling the design of façades to be flexible. The ability to accommodate drifts brings environmental benefits and reduces costs through reducing the size of the primary structural elements required in the building, and avoiding new carbon emissions created by replacement after earthquakes.