The S4H team designed and installed tilting and settlement tables. Experiments on masonry corners have already been conducted on the tilting table, highlighting the effect of loading orientation on their collapse. The shaking table and the new 6-cameras DIC system have also been successfully installed at UMinho, and an extensive experimental programme involving free- and forced-rocking of free-standing single-blocks has been completed. A large campaign encompassing vertical spanning strip walls on the shaking table was finished on April 2024. A large campaign on U-shaped masonry structures is now being initiated.
The S4H team has investigated the dry-joint interface stiffness and damping parameters of block-based structures. A new experimental procedure based on vibration tests has been proposed to identify such properties. A novel methodology to correlate the numerical viscous damping with the analytical coefficient of restitution for the dynamic analysis of rocking structures based on extensive numerical simulations was developed. It also revealed the conditions under which rocking motion terminates even when the structure is still subjected to ground motion. The team demonstrated the great impact of low dry-joint stiffness on the seismic capacity of masonry structures, underlining that current design recommendations are not appropriate for these structures. An extensive experimental campaign has been carried out to characterise the mechanics of dry-joint interfaces. Based on such outcomes, numerical models were constructed, and interface stiffness and damping were quantified.
In addition to the real catalogue, a homogeneous simulated dataset covering a wide range of earthquake magnitude, distance and soil categories has been developed through the stochastic source-based approach. A novel stochastic site-based simulation methodology has also been proposed to simulate the low-frequency portion of records accurately. Machine-learning-based ground motion models have been developed to be integrated with the site-based approach for the simulation of scenario events in the next stages. The outcomes of these simulations are being used to understand the effect of signal characteristics on the response of masonry and rocking structures. For instance, the team investigated the seismic response of rocking structures through machine-learning algorithms. Additionally, the suitability of simulated datasets has been numerically tested for alternative masonry prototypes in assessing their seismic response in parallel to code-based ground motion selection and scaling. The team is also investigating the optimal intensity measures for probabilistic seismic assessment of masonry buildings considering both in-plane and out-of-plane responses to define suitable rules for selecting and scaling the ground motions.
Various engineering tools have been developed. A comprehensive limit analysis model for the failure of masonry corners has been developed based on the outcomes of tilting tests. A rapid tool for the seismic assessment of masonry structures, capable of combining limit analysis and rocking dynamics, has been proposed. The team has also provided a graphic tool capable of quickly generating masonry structures with various masonry patterns.
Finally, novel time-based vulnerability curves for the out-of-plane seismic safety assessment have been developed, providing the capacity for different out-of-plane geometric indexes and their seismic response for a wide range of seismicity levels in Europe. Additionally, numerical fragility curves have been derived through a probabilistic performance-based seismic framework and supported by stochastic seismic signals to evaluate the expected damage in regions with limited recorded seismic activity.
