Among a number of technical sessions being held at Glass Performance Days (GPD) in Tampere, Finland, this week, was one today provided by Claire Grenier and Michel Cossavella of Centre Scientifique et Technique du Bâtiment (CSTB) in France titled “Curtainwall under Seismic Solicitations.”
The two aimed to determine the behavior of glass facades under seismic solicitations and “to identify their degradation modes in order to give recommendations on their dimensioning in agreement with the new seismic normative frame based on Eurocodes.”
The researchers tested both curtainwalls and structural glazing kits using “quasi-static cyclic in-plane displacements applied on the top of a vertical 3-meter high test specimen simulating the relative floor displacements and dynamical solicitation of it simulating seismic shaking.”
They found that “specimens deformed elastically under dynamic solicitations but showed metallic frame residual deformations and glass breakage under static deformation.”
“These observations led to recommendations on glass treatment and frame dimensioning depending on building category and geographical situation,” write Grenier and Cossavella in their abstract.
According to their report, the research came about when a new French code related to seismic damage “impose[d] the qualification of non-structural elements.”
“A large experimental campaign has been realized at CSTB to verify the resistance of different types of non-structural elements, such as cladding systems, sandwich panels or curtainwall, under seismic solicitations,” reads the report. “This study describes the experimental method applied on curtainwall. It explains the requirements induced by the regulation, the experimental device simulating seismic effects and results obtained on curtainwall. The analysis of these results led to specific recommendations for curtainwall conception.”
Based on their research, Grenier and Cossavella observed that in a seismic situation, “the metallic frame [of a curtainwall] deforms elastically and glass is not damaged.”
“Critical behavior occurs during static deformation, when glass comes into contact and breakage appears,” they write. “This occurs when glass has moved by translation and rotation to the maximum allowable space.”
They continue, “These observations highlight the predominant role of conception spaces in the curtainwall resistance under seismic action.”
They recommend that “for important buildings, like for example hospitals or fire station, where no glass damage should occur, laminated glass and tempered glass will allow curtainwall set-up.”
In conclusion, they write, “This campaign has been extended to glazing kit façades, which have shown an adequate deformability under static deformation in addition to equivalent behavior under dynamic shaking. The qualification of attached glazing façades is more complex due to multiple anchoring systems and should be conducted for each product.”
Stay tuned to www.usglassmag.com for our final report from the event, which ends tomorrow, on Monday.