During an earthquake, the greatest risk for human beings is the collapse of the building or of parts of it, such as walls, windows, glazing or portions of the façade. It is fundamental to assess the behaviour of a building not only as a whole but also as regards each of its elements, so as to be able to ensure adequate safety.
On 24 May, the Eku 50 Glass curtain wall system was subjected to seismic testing with the new equipment provided by the Building Components and Systems Lab of the Institute for Construction Technologies of the Italian National Research Council (ITC-CNR) at San Giuliano Milanese. This is extremely innovative equipment, the first of its kind in Europe, capable of both statically and dynamically stressing full scale portions of the glass façade, assessing their resistance to external atmospheric agents, before and after seismic simulation.
The façade mock-up, of real one floor size, was created using the standard accessories and components of the system. As explained by Mr. Antonio Bonati, an ITC-CNR research engineer, the curtain wall was subjected to a test “in compliance with the American standard AAMA 501.6-01 “Recommended dynamic test method for determining the seismic drift causing glass fallout from a wall system”. This test allows to determine the inter-storey drift (the relative horizontal displacement of two adjacent floors of a building, to which the façade is joined) that causes the fall of fragments of the façade. To obtain this critical drift, a stepped ‘crescendo test’ was performed on a portion of façade using a seismic test rig”.
“The crescendo test consists of a stepped series of sinusoidal cycles of gradually increasing amplitude up to 150mm and with racking frequency varying from 0.8 Hz (for racking amplitudes up to 75 mm) to 0.4 Hz (for racking amplitudes > 75 mm). It is performed uninterruptedly until one of the critical conditions indicated in the AAMA standard occurs, the most severe being glass fallout”.
During the crescendo test on Eku 50 Glass, the first glass fallout occurred at an amplitude of 120 mm. Although it was impossible to refer to a value of magnitude on the Richter scale, the displacements obtained in the test “are so high that most of the buildings would be already severely damaged in terms of structure, making the further improvement of façade performance pointless”.
This means that the Eku 50 Glass system not only simplifies to the utmost the creation of various types of façade, but also provides very high flexibility, adapting to the settlement movement of a building during earthquakes, and is in compliance with the provisions of the Italian Technical Building Construction Regulations (as per Ministerial Decree dated 14 January 2008), that require that non-structural building elements maintain their self-supporting capability vis-à-vis vertical loads even in highly deformed conditions.