Title: Hysteretic behaviour of metal connectors for hybrid (high- and low-grade mixed species) cross laminated timber,
Abstract: Cross-laminated timber (CLT) is a prefabricated solid engineered wood product
made of at least three orthogonally bonded layers of solid-sawn lumber that are
laminated by gluing longitudinal and transverse layers with structural
adhesives to form a solid panel. Previous studies have shown that the CLT
buildings can perform well in seismic loading and are recognized as the
essential role of connector performance in structural design, modelling, and
analysis of CLT buildings. When CLT is composed of high-grade/high-density
layers for the outer lamellas and low-grade/low-density for the core of the
panels, the CLT panels are herein designated as hybrid CLT panels as opposed to
conventional CLT panels that are built using one lumber type for both outer and
core lamellas. This paper presents results of a testing program developed to
estimate the cyclic performance of CLT connectors applied on hybrid CLT layups.
Two connectors are selected, which can be used in wall-to-floor connections.
These are readily available in the North American market. Characterization of
the performance of connectors is done in two perpendicular directions under a
modified CUREE cyclic loading protocol. Depending on the mode of failure, in
some cases, testing results indicate that when the nails or screws penetrate
the low-grade/low-density core lumber, a statistically significant difference
is obtained between hybrid and conventional layups. However, in other cases,
due to damage in the face layer or in the connection, force-displacement
results for conventional and hybrid CLT layups were not statistically
significant.