When the earth shakes... the house stands strong

"Being able to carry out a test not just with a wall, but with an entire house, is something special," reports Dr. Lorenzo Miccoli, project manager at Xella Technologie- und Forschungsgesellschaft mbH at the Department of Applied Research / Building Physics. Together with Markus Hesse, head of international product management at Xella, he was in France at the CEA Paris-Saclay Center to supervise the tests.

The Ytong house stands strong

"We are very satisfied with the result: our Ytong house has exceeded expectations: it showed a high performance when subjected to strong intensity seismic actions," says Dr. Miccoli. The reason for this is that the house was built using a confined masonry system with Ytong autoclaved aerated concrete and Ytong thin-bed mortar, which was developed for the German market but can and should also be used internationally.

The house was built over a period of about two months this summer, then the test could finally be carried out at the end of October. The so-called shaking table, i.e., the plate on which the finished house is placed, simulated ground motions at increasing levels of intensity. The maximum level achieved was comparable to an earthquake of magnitude 7 - a high intensity seismic event. However, this high intensity is not expected in the case of an earthquake in Germany. "Nevertheless, it was important for us to test the building in extreme conditions if we ever had the opportunity," Dr. Miccoli continues. And the last few years have shown that earthquakes are increasing in number and intensity in countries such as Italy and Turkey, making earthquake safety one of the biggest challenges for modern building materials.

During the tests, the Tamaris shaking table at CEA Paris-Saclay simulates an earthquake ground motion of a certain magnitude shaking the building for about 30 seconds. The fact that the house built of aerated concrete remains steadfast buys valuable time to allow the building to be evacuated in an emergency.

Focus on earthquake resistance

Since its founding in 2004, the Xella T&F has placed a strong emphasis on the topic of earthquake resistance, with the first studies by Ytong and Hebel in this area dating back to the late 1980s.

Xella T&F has a large network in the field. The project ERIES-ECORE (Earthquake-Resilient, Innovative, Efficient Structures), which ran from February 2023 until the end of the tests, focuses on the experimental investigation of the seismic behavior of lightweight reinforced concrete structures. These methods use slabs and beams made of lightweight concrete with pumice aggregate, with external and internal walls made of autoclaved aerated concrete blocks integrated into the reinforced concrete frame using special connections. This work is part of the larger project ERIES: Engineering Research Infrastructures for European Synergies (https://eries.eu/) which made the very expensive tests possible in the first place.

Independently of this, Xella T&F has been working on the earthquake resistance of autoclaved aerated concrete for a long time and regularly tests the products for their durability against dynamic actions. Normally, a wall-size building element can be placed on the testing rig, but in this case, for the first time, a full-scale building was tested.

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