A seismic shake table test of a timber frame building is scheduled to take place next year and will include several different glazing configurations. Dr. Keri Ryan, associate professor of civil engineering at the University of Nevada, Reno and the nonstructural testing lead gave Fenestration & Glazing Industry Alliance (FGIA) members an overview of the test in a webinar titled, “Opportunities for Seismic Shake Table Testing of Fenestration Products.”
The testing team will perform a shake table test of a ten-story mass timber building at the University of California San Diego’s large high-performance outdoor shake table. The table is currently undergoing upgrades which will transform it from a one lateral direction table into a multi-directional table. It’s projected to reopen in March 2021.
The test’s primary objectives are to validate that the performance of the structure meets the design specifications and to quantify the performance of select nonstructural components in the context of functional recovery and resiliency. The ultimate goal is to promote the use of tall timber in commercial construction due its sustainability and ability to support a “healthy forest products industry.”
The building envelope was identified as a priority nonstructural component because of its importance to a building’s safety and function.
“Building envelopes are among the most vulnerable nonstructural component and systems (NCS) because they’re distributed vertically, floor-to-floor, and must accommodate both inter-story drift and accelerations,” said Ryan.
She added that there’s a lack of understanding about seismic performance in regard to the building envelope. According to Ryan, racking tests show that inter-story drifts can be accommodated by glazing systems but in prior earthquakes glass cracking and fallout is a frequent occurrence.
“There’s limited shake table test data compared to other NCS,” she said.
However, after the 2011 earthquake in Christchurch, New Zealand, experts studied 217 building skins and rated them operational, immediate occupancy, life safety or high hazard. Curtainwall, spider glazing and glazing infill had a greater number of high hazard ratings than many other façade types.
Ryan said the benefit of the proposed shake table testing is that it will allow her team to evaluate the complexities of dynamic shaking and how they impact the racking performance of building skins.
“This could bridge the gap between racking test performance and what we’re seeing out in the field,” she added.
The testing team is interested in testing storefront, curtainwall and window wall systems in a variety of configurations, such as heat strengthened, tempered, laminated, insulating glass units, stick built, unitized, mechanically captured and structurally glazed.
Ryan and her team are calling for FGIA members to participate and collaborate in the test. FGIA companies can donate products, provide in-kind and financial backing to support the installation and testing of a variety of skins on the building.
“Collaborators are welcome to be onsite during all testing and fabrication, participate in the inspection and collect their own data,” she explained.
The team is currently expecting to test the structure without building skins first, tentatively in May 2021. Installation of the building skins and instrumentation would follow in June 2021 with shaking of the structure with the building skins taking place in July 2021.