Research & Development
By current standards, façades are defined as “non-structural” elements. Previously, the calculation of required anchors only assumed static loads such as dead loads, wind, and constraining forces. In countries with seismic risk, the façade’s seismic load can be replaced, using a static equivalent load acting in a horizontal, unfavorable direction. This design practice, common in Europe, can be shown through examples.
For high-rise buildings, these equivalent loads are large. It is more precise to consider the floor response spectra to calculate the transmissible loads for anchor design.
Current design practices assume façades are masses fixed to a building with zero stiffness. Seismic design, however, should not only focus on the load-bearing structure: there is, in fact, significant interaction between main structures and façades, seriously influencing the bearing behavior of the whole structure. In general, new methods for modeling the seismic behavior of heavy façades need to be developed. On the one hand, the loads are supposed to be larger; on the other hand, local damage at the load introduction point may occur. Besides the sufficient resistance, the anchors must have adequate ductility in order to introduce the additional loads into the brittle stone material safely, without local damage. Recommendations for calculating and testing such connections were illustrated in the presentation. Shake-table tests were provided to compare rigid and ductile behavior of fixings. The proposed calculations were explained and the experimental results were illustrated.