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After 20 years since the publication of the Eurocodes, in 2012, the European Commission gave mandate to the European Committee for Standardization (CEN) to develop a second generation of Eurocodes. Among the different parts of Eurocodes, a substantial revision process has been undertaken for the seismic design rules of timber buildings included in Eurocode 8 (EC8). In particular, a major effort has been made to implement the design rules for Cross‐Laminated Timber (CLT) buildings and to define the behaviour factors q for such structural type. The choice of the behaviour factor q for CLT buildings in the new “timber” chapter of EC8 has been made by examining several proposals available in literature. Most of these studies were not referred to any specific design provision and certainly could not have followed the design rules drafted in the second generation of Eurocodes. This paper presents a study aimed to verify whether the proposed values of the behaviour factors q are consistent with the attained seismic performances of CLT buildings designed in accordance with the new “timber chapter” of EC8. Parametric non‐linear static (pushover) analyses and a risk‐consistent approach, based on the use of Incremental Dynamic Analyses (IDA) and fragility curves were conducted to evaluate the performance of a few selected archetypes. The results obtained from the analyses and the risk‐consistent approach showed that the proposed values of q‐factor for CLT buildings in second generation of Eurocode, namely 2.30 and 3.20 for a ductility class 2 (DC2) and 3 (DC3) respectively, can be reasonably accepted.

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The solution of timber-to-concrete composite (TCC) floors represents a well-established construction technique, which is consistently used for both the retrofitting of existing timber floors and the realization of new diaphragms. The success of TCC floors relies on the intrinsic effectiveness in increasing both the in-plane (for lateral loads) and the out-of-plane (for gravity loads) performance of existing timber floors. As a widespread retrofit intervention, it is common to use existing floorboards as a permanent formwork for the concrete pouring. Rather few research studies of literature, in this regard, highlighted an overall reduction of load capacity and slip modulus due to the presence of such an interposed interlayer. In this regard, the present paper focuses on the use of screws as efficient mechanical connectors and analyses different configurations and inclination angles for their arrangement. This main goal is achieved by performing parametric Finite Element (FE) numerical analyses, validated on previous experimental tests, in order to specifically investigate the influence of the in-between interlayer, as well as the role of friction phenomena and the influence of the test setup and experimental protocol to achieve the basic mechanical performance indicators.

Structures under seismic excitation undergo different inter-story drift levels that can be associated to damage of both structural and non-structural elements, and thus to the expected losses. The Modal-Displacement Based Design (DBD) procedure, in this regard, has been developed to fix major issues of Force Based Design (FBD) approaches, thus to design multi-story buildings in which the inter-story drift can allow one to control damage mechanisms. In this paper, the conventional Modal-DBD methodology is applied to multi-story timber buildings constructed using the Blockhaus technology. Given their intrinsic geometrical and mechanical features (i.e., stacking of logs, door/window openings, gaps and friction mechanisms, etc.), dedicated methods of analysis are required for them, compared to other wooden structures. A three-story case-study Blockhaus system of technical interest is thus presented for the assessment of Modal-DBD calculation steps. As shown, special care must be spent for the selection of convenient inter-story drift limits that in general should reflect the characteristics of the examined structural typology. The backbone parameters are thus collected for each shear-wall composing the 3D Blockhaus building, based on refined Finite Element (FE) analyses of separate log-walls. The overall results of the Modal-DBD process are thus finally assessed by means of a Push-Over (PO) analysis, carried out on a simplified 3D FE model of the examined multi-story structure. The comparison of FE predictions, as shown, demonstrates that reliable estimates can be obtained when the Modal-DBD procedure is applied to timber Blockhaus systems. In particular, base shear loads can be estimated with good accuracy, while the corresponding top displacements are slightly overestimated (with up to +10%–14% the expected values, for the collapse prevention performance level).