A Structural Concept for Free-Form Timber Structures

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Abstract

Timber construction has a promising future in the face of global sustainable development challenges. Using timber as the main structural material, the carbon footprint of a building is strongly reduced since the carbon will be stored for as long as the building stands or the timber is used.

An integrated structural concept was developed for free-form timber structures, which is light and yet strong while trying to keep difficult node connections to a minimum. The structural concept consists of ribbed elements that are covered with plates on the top and the bottom. The ribbed elements are cut from laminated veneer lumber to allow a smooth transition in depth according to the structural demands. The ease of fabrication is achieved by designing simple connections such as an incision in the ribbed elements and the plates are connected by screws. The maximum length subject to fabrication and transportation constraints has been considered. This has been achieved by determining the efficient height and the allowable stresses have been reduced.

For structural design, an automated procedure was developed to yield a smooth height variation of the roof structure and place the material where structurally required and thus achieving a significant weight reduction. Deep sections are used where bending govern the design and shallow section where shell action is dominant. Furthermore, the smooth height variation meets the desired shape from architectural design's point-of-view.

In general, it can be concluded that the developed structural concept is suitable for the design of a free-form timber structure that exhibits both bending and shell behaviour. In order to achieve an integrated structural concept, the inhomogeneous material properties of timber were incorporated in the structural concept. Precaution has been taken in the computational modelling by also taking into account the different directions for the anisotropic material properties.