Panel Zone Shear Failure in Glue Laminated Wood Beams

摘要

Modern designs of timber structures often incorporate pre-engineered products in an effort to create longer spans and larger openings. In order to attain the published values for these products that correspond to laboratory testing, specific installation requirements must be fulfilled. However, engineers frequently utilize installation methods for these components not directly intended by the manufacturer and not supported by proper testing. The Simpson Strong-Wall is a prefabricated structural element that requires direct anchorage to a concrete foundation. Timber designs with the Strong-Wall and other pre-manufactured shearwalls are being constructed without the intended concrete anchorage. This study investigates the behavior of a timber connection sub-assemblage consisting of a Simpson Strong-Wall anchored to a glue laminated beam rather than directly to concrete. This type of construction is being used to design buildings in the field without proper research to verify its performance under excessive loading conditions. Results of the laboratory experiments show that while allowable strength values published by the manufacturer are conservative when used in this way, the failure was catastrophic for certain specimens. Testing sub-assemblages consisting of the more narrow walls resulted in a local bearing failure while the larger walls triggered a joint shear failure in the glue laminated beam (glulam) panel zone. This phenomenon of joint shear failure is generally overlooked in the practice of timber design. Conclusions made in this paper from test and analytical results provide a methodology for protecting against this non-ductile mode of failure.