RELIABILITY ANALYSIS AND DISPROPORTIONATE COLLAPSE FOR MULTI-STOREY CROSS-LAMINATED TIMBER BUILDING

This paper focuses on developing finite element models and subsequent sensitivity and reliability analyses to evaluate the probability of disproportionate collapse of a twelve-storey case study Cross-Laminated Timber (CLT) building, following extreme loading events such as earthquakes. As an initial damage, the methodology mimics event - independent scenarios that include a sudden removal of a vertical loadbearing element. This investigation emphasises on the rotational stiffness (k) of the joints by considering nonlinear dynamic analyses of the structure at global, component and connection levels. The rotational stiffness demand required to prevent disproportionate collapse is checked against the supply at all levels of structural idealisation. A sensitivity analysis at the sub - frame level shows that an improved structural detailing, to carry tie forces between structural members, as well as adequate thickness of structural elements, are important to prevent disproportionate collapse. The reliability analysis of the optimised structural model proves that the required k value, to develop resistance mechanisms, is too large to be practically achieved by means of common CLT joint detailing, which is provided by angle brackets and screws. As a result, connection detailing and size of members of the case study building need to be re-evaluated in order to avoid disproportionate collapse in the twelve-storey CLT building.