ASSESSMENT OF CONNECTIONS IN CROSS-LAMINATED TIMBER BUILDINGS REGARDING STRUCTURAL ROBUSTNESS Johannes A. J. Huber 1 , Mats Ekevad 1 , Sven Berg 1 , Ulf Arne Girhammar 1 ABSTRACT: Cross-laminated timber makes timber buildings with an increasing number of storeys achievable. With more storeys, structural robustness needs more attention to make a building survive unforeseen events (e.g. accidents, terrorism) and save lives. For steel and concrete buildings, design methods for robustness focus on connection details. The assessment of joints in cross-laminated timber buildings regarding robustness is rather limited in the literature. The objective of this paper is to conduct an initial assessment of the connectors after the removal of a wall in a platform cross-laminated timber building. We used the finite element method and the component method for the analysis of a case building. The results indicate that the wall-to-wall and the floor-to-floor connectors may fail at low deflection levels leading to high shear loads in the floor panel above the removed wall, which might induce cracking. The removal analysis was only partially completed, but we identified an indication of the deformation behaviour of the case building. Testing and refined modelling of the connections is needed in the future to verify the results. This study may facilitate future investigations regarding robustness of multi-storey cross-laminated timber buildings. KEYWORDS: Robustness, Connection, Component method, Cross-laminated timber, Finite element method, Disproportionate collapse 1 INTRODUCTION 1 A building needs to protect its occupants under both expected and unexpected scenarios. We can assure this protection during expected scenarios but handling the infinite number of unexpected scenarios (e.g. accidents, terrorism) is more difficult. In a robust building, the protective function remains intact even after unexpected loads have led to a local damage and large deviations from the design state [1]. Eurocode [2] demands that a building resists a collapse disproportionate to the cause. Robustness is an intrinsic structural property which describes the global survival tolerance to local damages, independent of the cause [3]. According to [4], an unforeseen exposure on a building may or may not lead to a damage (cf. vulnerability), which in turn may or may not lead to a disproportionate collapse (cf. robustness), as illustrated in Figure 1. The more storeys there are in a building, the more acute is the matter of robustness. Ever since the partial collapse of Ronan Point after a gas explosion in 1968 1 Johannes A. J. Huber, Luleå University of Technology, Division of Wood Science and Engineering, Forskargatan 1, SE-93187 Skellefteå, Sweden, [email protected] Mats Ekevad, Luleå University of Technology, Division of Wood Science and Engineering, Sweden, [email protected] Sven Berg, Luleå University of Technology, Division of Wood Science and Engineering, Sweden, [email protected] Ulf Arne Girhammar, Luleå University of Technology, Division of Wood Science and Engineering, Sweden, [email protected] [5], research into robustness of multi-storey buildings has become more refined for concrete and steel buildings. Since timber buildings have not reached a comparable number of storeys until recently, the knowledge and guidelines concerning robustness of multi-storey timber buildings is still rather limited [3]. Figure 1: The context of robustness Cross-laminated timber (CLT) is a building material made of solid wood boards, glued together in layers which are oriented perpendicular to each other [6]. CLT panels may support loads in the plane and out of plane in different spanning directions due to its crosswise layup. CLT seems to be well suited for the design of tall, multi- storey timber buildings [7]. To evaluate robustness, usually the effects of a notional removal of a load-bearing element from the structure is analysed [3]. After the removal, alternative load paths may be developed, e.g. catenary action, membrane action or deep beam action, to support the remaining structure. The critical points for alternative load paths
ASSESSMENT OF CONNECTIONS IN CROSS-LAMINATED TIMBER BUILDINGS REGARDING STRUCTURAL ROBUSTNESS
Jun 30, 2023
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