Strength parameters for fasteners determined in accordance with the methods prescribed for the European CE-marking leads to quite different values for seemingly similar products from different manufactures. The results are hardly repeatable, to some extent due to difficulties in selecting representative on engineered wood products...
The introduction of Cross-laminated Timber (CLT) as an engineered timber product has played a significant role in the considerable progress of timber construction in recent years. Extensive research has been conducted in Europe and more recently in Canada to evaluate the fastening capacity of different types of fasteners in...
Cross-laminated timber (CLT) products are gaining popularity in the North American market and are being used in midrise wood buildings, in particular, in shearwall applications. Shearwalls provide resistance to lateral loads such as wind and earthquake loads, and therefore it is important to gain a better understanding of the behavior of CLT shearwall systems during earthquake events. This paper is focused on the seismic performance of connections between CLT shearwall panels and the foundation. CLT panels are very stiff and energy dissipation is accomplished by the connections. A literature review on previous research work related to damage prediction and assessment for wood frame structures was performed. Furthermore, a test program was conducted to investigate the performance of CLT connections subjected to simulated earthquake loads. Two different brackets in combination with five types of fasteners were tested under monotonic and cyclic loading protocols. In total, 98 connection tests were conducted and the monotonic load-displacement curves and hysteretic loops were obtained. In this paper, an energy-based cumulative damage assessment model was calibrated with the CLT connection test data. Finally, a correlation between the damage index and physical damage is provided.
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.