Le développement de la construction bois, en particulier de moyenne et grande hauteur, est un enjeu clef de la transition environnementale du domaine de la construction. Il doit se faire de façon la plus qualitative possible. Des opérations de construction bois de moyenne et grande hauteur sont déjà menées par des acteurs précurseurs et doivent être envisagées comme des piliers pour préfigurer les développements à venir.
Le Rapport REX sur les constructions bois de plus de 8 m de hauteur permet de capitaliser et de valoriser leurs retours d’expériences afin de sensibiliser et de guider l’ensemble des acteurs de la filière aux enjeux de la construction bois. Cette montée en compétences par le partage des points de vigilance et des bonnes pratiques est le gage d’un développement à la hauteur des objectifs de qualité, de performance et de confort visés.
As part of its research work on wood buildings, FPInnovations has recently launched a Design Guide for Timber-Concrete Composite Floors in Canada. This technique, far from being new, could prove to be a cost-competitive solution for floors with longer-span since the mechanical properties of the two materials act in complementarity. Timber-concrete systems consist of two distinct layers, a timber layer and a concrete layer (on top), joined together by shear connectors. The properties of both materials are then better exploited since tension forces from bending are mainly resisted by the timber, while compression forces from bending are resisted by the concrete. This guide, which contains numerous illustrations and formulas to help users better plan their projects, addresses many aspects of the design of timber-concrete composite floors, for example shear connection systems, ultimate limit state design, vibration and fire resistance of floors, and much more.
This project studied the feasibility and performance of a mass timber wall system based on
Nail Laminated Timber (NLT) for floor/wall applications, in order to quantify the effects
of various design parameters. Thirteen 2.4 m × 2.4 m shear walls were manufactured and
tested in this phase. Together with another five specimens tested before, a total eighteen
shear wall specimens and ten configurations were investigated. The design variables
included fastener type, sheathing thickness, number of sheathings, sheathing material,
nailing pattern, wall opening, and lumber orientation. The NLT walls were made of SprucePine-Fir (SPF) No. 2 2×4 (38 mm × 89 mm) lumber and Oriented Strand Lumber (OSB)
or plywood sheathing. They were tested under monotonic and reverse-cyclic loading
protocols, in accordance with ASTM E564-06 (2018) and ASTM E2126-19, respectively.
Compared to traditional wood stud walls, the best performing NLT based shear wall had
2.5 times the peak load and 2 times the stiffness at 0.5-1.5% drift, while retaining high
ductility. The advantage of these NLT-based wall was even greater under reverse-cyclic
loading due to the internal energy dissipation of NLT.
The wall with ring nails had higher stiffness than the one with smooth nails. But the
performance of ring nails deteriorated drastically under reverse-cyclic loading, leading to
a considerably lower capacity. Changing the sheathing thickness from 11 mm to 15 mm
improved the strength by 6% while having the same initial stiffness. Adding one more face
of sheathing increased the peak load and stiffness by at least 50%. The wall was also very
ductile as the load dropped less than 10% when the lateral displacement exceeded 150 mm.
The difference created by sheathing material was not significant if they were of the same
thickness. Reducing the nailing spacing by half led to a 40% increasing in the peak load
and stiffness. Having an opening of 25% of the area at the center, the lateral capacity and
stiffness reached 75% or more of the full wall.
A simplified method to estimate the lateral resistance of this mass timber wall system was
proposed. The estimate was close to the tested capacity and was on the conservative side.
Recommendations for design and manufacturing the system were also presented.
Advanced sustainable lateral load resisting systems that combine ductile and recyclable materials offer a viable solution to resist seismic load effects in environmentally responsible ways. This paper presents the seismic response of a post-tensioned timber-steel hybrid braced frame. This hybrid system combines glulam frame with steel braces to improve lateral stiffness while providing self-centreing capability under seismic loads. The proposed system is first presented. A detailed numerical model of the proposed system is then developed with emphasis on the connections and inelastic response of bracing members. Various types of braced frames including diagonal, cross and chevron configurations are numerically examined to assess the viability of the proposed concept and to confirm the efficiency of the system. A summary of initial findings is presented to demonstrate usefulness of the hybrid system. The results demonstrate that the proposed system increases overall lateral stiffness and ductility while still being able to achieve self-centring. Some additional information on connection details are provided for implementation in practical structures. The braced-frame solution is expected to widen options for lateral load resisting systems for mid-to-high-rise buildings.