Seismic testing of curtain wall system
The Construction Technologies Institute (ITC-CNR) has just carried out a first set of seismic tests using the new testing facility developed and built in the framework of the activities of the Research Unit SG1, coordinated by Mr. Antonio Bonati, in the Building Components and Systems Laboratory in San Giuliano Milanese (Milan). Metalsigma s.r.l. conducted the testing based on an ITC-CNR project with the advice of Prof. Giuseppe Maddaloni from the University of Sannio, associated partner of ITC, who is one of the leading experts in seismic equipment worldwide.
The tragic earthquakes that have recently struck Italy have raised the interest of manufacturers and designers in the assessment of the seismic behavior of facade elements, non-loadbearing elements of buildings that play an extremely important role in the operation and performance of the building (service conditions) and safety of people (damage limit state and ultimate limit state).
The physical and mechanical testing facility of ITC is fit for traditional air permeability, watertightness and resistance to wind load tests aimed at the certification of curtain walls as well as for the evaluation of the seismic behavior of curtain walls under static and dynamic conditions. In fact, the facility is fitted with seismic beams transmitting strains to the curtain wall system both in-plane and out-of-plane.
The company Metra S.p.A. installed a curtain wall with mullions and transoms onto this unique testing facility, which allowed to perform quasi-static and dynamic tests. The static test involved slow displacements so to avoid inducing dynamic effects or cause acceleration. One or two seismic beams were simultaneously subjected to different displacement sequences, reaching the maximum interfloor displacement value of 168 mm, which resulted in no significant damage to the curtain wall system.
The first phase of the dynamic test involved the performance of the “Crescendo Test” as laid down in American standard AAMA 501-6, that is, application of displacements with increasing magnitude and frequency. Dynamic tests were then carried out with variable magnitude and frequency up to frequencies of 20 Hz. The curtain wall was also subjected to the accelerometer of the earthquake of August 2016 in Amatrice and to displacements with variable magnitude and frequency also out-of-plane.
The strong and innovative contribution that this new testing facility can make in the assessment of seismic behavior of elements that form part of the building envelope is emphasized by the excellent results obtained with the tests described above.