Workshops: Is Earthquake Resistance a Privilege of Lightweight Façades?

Matthias Roik
Research & Development
HALFEN, Cologne

Even though façades are defined as non-structural elements, they must be designed to withstand earthquakes, to prevent personal injury during an earthquake and to ensure free escape routes afterwards. As façades are fastened to a building, they become part of the whole structural system, so, during the design process, seismic forces have to be respected to provide sufficient resistance of the fasteners. The loads to be absorbed result from the accelerations acting on the structure. Together with the mass of the components, they form the forces to be transmitted between the façade and the structure. In order to keep these forces low, façades with low mass (e.g., glass and steel) are usually preferred. However, these "light" facades have disadvantages, especially from the point of view of building physics. So-called "heavy" façade systems do not have these disadvantages, due to their mass. Due to their thermal storage capacity, they reduce temperature peaks, and thus have a positive effect on the room climate. Furthermore, the mass might improve the dynamic behavior of the building.

Nevertheless, “heavy” façades are rarely used for higher buildings, since the anchor systems must have a higher load-bearing capacity and have to be designed accordingly. The load-bearing capacity of the anchors is usually confirmed mainly by tests or calculation, if possible. Here, three test methods are presented, differentiated by the size of the test specimen, at the micro, meso and macro scale. Examples are given for each construction method of "heavy" façades, i.e., for masonry, natural stone and concrete. The examples were chosen to show that architecturally demanding façades can also be sufficiently safe against earthquake loads.