Vibration-based post-Earthquake Rapid Damage Identification in historic masonry towers
ERIES-VERDI
Dataset Description
The ERIES-VERDI project aims to assess the effectiveness and scalability of innovative vibration-based Structural Health Monitoring (SHM) methods for damage localization and quantification in earthquake-excited masonry constructions. The project proposed a dynamic investigation of the behaviour of masonry towers embedded within building aggregate, using shake table testing to validate SHM methods on a stone masonry tower subjected to different seismic inputs.
The dataset contains the results of the experimental campaign carried out at LNEC, in Lisbon. The masonry tower was built with calcareous stone and lime mortar, with boundary conditions reproducing the surrounding aggregates, at a 1:7 scale, featuring a total height of about 6.30 m, a square cross section of 1.0 x 1.0 m2, 0.2 m thick walls and small openings. The material was characterized by vertical compression tests on masonry wallets, three-point bending and compression tests on mortar specimens, and compression tests on stone specimens, all available at the dataset.
The tests on the scaled tower were carried out in two different configurations. In the first configuration, ambient vibration tests (AVT) were performed while it was standing on the floor of the testing hall. In the second configuration, shake table (ST) tests were performed where it underwent dynamic identification through ambient and forced vibration tests, followed by seismic tests with different input motions. The dataset includes recordings from a dense monitoring system collected during all shaking tests, as well as under white- and pink-noise excitations at different damage levels. It also provides detailed information on the damage state at each intensity level, enabling the development and validation of SHM algorithms for earthquake-induced damage.
Specimens
1. Masonry tower
2
In order to study the behaviour of slender masonry towers, a 1:7 scale model representative of this structural typology present in Italy, specifically inspired by the Sciri Tower in Perugia, was built at LNEC.
The geometry of the tower was defined after statistical analysis on historic towers and taking into account scaling laws. The cross section of the tower is square shaped with outer dimensions of 1.00 x 1.00 m2 and 0.20 m thickness, with a total height of 6.30 m. In addition, two side masonry walls were built to represent parts of adjacent buildings, providing boundary conditions similar to those of historic towers within an aggregate, and rising up to a height of 1.80 m.
The specimen walls were made of three leaves of rough shaped stones with average dimensions of 60-70 x 60-70 x 130-140 mm3, mortar joints of about 3-4 mm, and regular horizontal courses. Different layout patterns were combined and alternated throughout the stone layers, making a total of four layouts at the base level where the side walls were present and ten at the tower level, identified as BL# and TL#, respectively. Through stones were only provided at the edge zones or in a single layer each nine courses of stone, namely BL3, BL4, TL7 and TL8. Rectangular openings were distributed across all four façades, aligned at the same elevation on opposite sides and vertically offset between adjacent façades.
A good connection between the concrete slab foundation and the specimen was ensured by using a higher strength mortar in the first three courses. Moreover, interlocking between the side walls and the tower walls was provided through larger stones every two courses and the presence of an FRP grid.
The specimen was built with materials that represent the current conditions of historic masonry towers typical of the architectural heritage present across Europe, especially in the southern countries, namely using natural limestone blocks and a low-strength hydraulic-lime mortar.
1. Ambient vibration tests
Ambient vibration tests were carried out before placing the tower on the shake table to characterise its dynamic behaviour, identifying the first and second modes of the structure, thus, enabling the selection of excitation frequencies for the shake table tests.
Instrumentation
For the ambient vibration tests, only accelerometers were used for the dynamic identification of the tower.
2. Shake-table tests
The shake table tests comprised 97 steps in between seismic tests, dynamic identification tests, ambient vibration tests and other operations performed on the shake table. A set of two ground motion records with increasing intensities was applied to the shake table in both x and y directions.
The ground motions were generated to match a code-compliant design elastic response spectrum (ERS) defined according to the Italian Standard for the seismic hazard at the “Sciri” tower coordinates in Perugia. The target spectrum was calculated for the Damage Limit State, corresponding to a peak ground acceleration (PGA) of 0.094 g (50-year return period), using the Rexel software provided by ReLUIS. The target real scale ERS was interpolated for time history generation with 200 logarithmically spaced frequencies between 0.25Hz and 50Hz. Moreover, because the tested specimen was built at a 1:7 scale, the target ERS was scaled using the Cauchy similitude law, i.e., by dividing the period and multiplying the spectral accelerations by a factor of 7, but keeping the original sampling frequency.
Instrumentation
For the shake table tests, both acceleration and displacement transducers were used.
Project Metadata
Rights
Creative Commons Attribution 4.0 International.
CC BY 4.0
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