Luís F. Ramos

Tube-jack Testing for Irregular Masonry Walls: First Studies

One of the most well-known non-destructive methods for inspection and diagnosis in historical masonry walls is the flat-jack testing. Although it gives qualitative and valuable results about the local stress level and the deformability of the masonry material, when testing on irregular masonry walls, or walls with larger stone units, experimental and practical problems might occur, leading to inaccurate or useless results. In addition, the testing apparatus is labor, with difficulties in sawing task. Another limitation is the difficulty to test multi-leaves walls. To overturn these problems and to achieve more reliable information, an enhanced type of jacks is proposed in the paper. The new testing system consists of tube-jacks instead of the usual flat-jacks. As part of the preliminary research, analyses with FE models to simulate the differences between the conventional and the enhanced method are presented in the paper. The advantages and disadvantages of both methods are discussed and further research steps are presented.

Operational Modal Monitoring of Ancient Structures using Wireless Technology

Operational Modal Analysis is currently applied in structural dynamic monitoring studies using conventional wired based sensors and data acquisition platforms. This approach, however, becomes inadequate in cases where the tests are performed in ancient structures with esthetic concerns or in others, where the use of wires greatly impacts the monitoring system cost and creates difficulties in the maintenance and deployment of data acquisition platforms. In these cases, the use of sensor platforms based on wireless and MEMS would clearly benefit these applications. This work presents a first attempt to apply this wireless technology to the structural monitoring of historical masonry constructions in the context of operational modal analysis. Commercial WSN platforms were used to study one laboratory specimen and one of the structural elements of a XV century building in Portugal. Results showed that in comparison to the conventional wired sensors, wireless platforms have poor performance in respect to the acceleration time series recorded and the detection of modal shapes. However, for frequency detection issues, reliable results were obtained, especially when random excitation was used as noise source.

Seismic Safety Analysis of the Old Portuguese Cathedral in Safi, Morocco

This article presents the main results of the safety analysis of the Safi Cathedral. First a general description of the cathedral and the restoration project are given. To assess the safety of the main arch of this cathedral after the restoration, a seismic line of thrust analysis was used. The results of this uncommon analysis for structures that face seismic hazard were then compared to the results obtained from a phased pushover analysis. The results of the seismic line of thrust analysis turned out more conservative than those of the finite element analysis, although in both cases the results depend on the modeling hypothesis.

Dynamic identification and monitoring of St. Torcato Church

The paper is related to the San Torcato Church, in Guimarães, Portugal. At the moment, the church has significant structural problems due to soil settlements. Cracks can be observed on the main and the lateral façades, the bell-towers are leaning, and the arches in the nave exhibit a failure mechanism with cracks and vertical deformations. Non-stabilized phenomena are present in the structure. To stabilize the damage, a structural intervention is planned to occur soon and the church is already monitored to follow the intervention. The paper clearly presents the problem with emphasis to the dynamic analysis carried out before the structural strengthening, namely: the experimental tests with output-only techniques for frequencies, damping and mode shapes estimation, FE model updating analysis and dynamic monitoring