Optimization of Synergetic Seismic and Energy Retrofitting Based on Timber Beams and Bio-Based Infill Panels: Application to an Existing Masonry Building in Switzerland

This paper presents an optimization process for the design of a novel synergetic seismic and energy retrofitting strategy that combines the favorable mechanical properties of timber and the attractive thermal insulation properties of bio-based materials. The novel method, defined as Strong Thermal and Seismic Backs (STSB), comprises the attachment of timber frames and bio-based thermal insulation panels on the vertical envelope and the facade walls of existing masonry buildings, thus improving both the seismic behavior and the energy performance of these buildings. This strategy is integrated and visualized in a novel synergetic framework for the holistic evaluation of the seismic behavior, the energy performance and the carbon footprint of existing buildings, defined as the Seismic and Energy Retrofitting Scoreboard (SERS). The benefit of the novel retrofitting strategy is quantified based on the numerical simulation of the seismic behavior of an unreinforced masonry building located in Switzerland, an assessment of the energy performance of the building and an evaluation of the carbon footprint of the proposed retrofit solution. Three retrofitting alternatives are investigated for the synergetic seismic and energy retrofitting of the building, comprising timber beams and two different bio-based materials for the thermal insulation of the vertical envelope of the building: cork and recycled natural grass. The optimal seismic and energy retrofitting strategy for the building among the alternatives assessed in this study is chosen based on a Multi-Criteria Decision Making (MCDM) procedure.ISSN:2075-530

Dataset from the dynamic shake-table test of a full-scale unreinforced clay-masonry building with flexible timber diaphragms

This paper provides information related to the sensor measurements obtained from an unreinforced masonry building subjected to incremental dynamic shake-table tests at the EUCENTRE facilities in Pavia, Italy. These tests provide a unique data set that captures at full scale the in-plane and out-of-plane behavior of unreinforced masonry walls, and the influence of flexible diaphragms on the dynamic global response of a complete building. The authors made this information available to assist in the development of analytical and numerical models, necessary to estimate the dynamic response and the engineering parameters for the performance-based seismic assessment of unreinforced masonry buildings. All recorded data (acceleration and displacement time histories) and the videos of the tests can be requested online on the EUCENTRE repository at the URL www.eucentre.it/nam-project referring to EUC-BUILD-2. For further interpretation of the sensor recordings, and for a detailed discussion on the seismic performance of the building specimen, the reader is referred to the article entitled “Experimental seismic performance of a full-scale unreinforced clay-masonry building with flexible timber diaphragms” (Kallioras et al., 2018) [1]

Shaking table test on a full scale URM cavity wall building

A shaking table test on a two-storey full scale unreinforced masonry (URM) building was performed at the EUCENTRE laboratory within a comprehensive research programme on the seismic vulnerability of the existing Dutch URM structures. The building specimen was meant to represent the end-unit of a terraced house, built with cavity walls and without any particular seismic design or detailing. Cavity walls are usually composed of an inner loadbearing leaf and an outer leaf having aesthetic and weather-protection functions. In the tested specimen, the loadbearing masonry was composed of calcium silicate bricks, sustaining two reinforced concrete floors. A pitched timber roof was supported by two gable walls. The veneer was made of clay bricks connected to the inner masonry by means of metallic ties, as seen in common construction practice. An incremental dynamic test was carried out up to the near-collapse limit state of the specimen. The input motions were selected to be consistent with the characteristics of induced seismicity ground motions. The article describes the characteristics of the building and presents the results obtained during the material characterization and the shaking table tests, illustrating the response of the structure, the damage mechanism and its evolution during the experimental phases. All the processed data are freely available upon request (see http://www.eucentre.it/nam-project)

Dataset from the dynamic shake-table experiments on a full-scale unreinforced clay-brick masonry building with chimneys

This data paper outlines detailed information on the acquisition and use of sensor measurements from shake-table experiments on a full-scale unreinforced masonry building. The tests were carried out at the shake-table facilities of the National Laboratory for Civil Engineering in Lisbon, Portugal. The building specimen, replicating a typical Dutch single-storey detached house, was made of solid clay bricks and featured a gambrel roof and two chimneys. It was densely instrumented with accelerometers, potentiometers, and LVDTs, recording the response of various structural and non-structural elements. A series of unidirectional dynamic tests of increasing shaking intensity was performed, providing a unique dataset that captures at full scale the in-plane and out-of-plane behaviour of walls and the influence of flexible timber diaphragms on the dynamic global response of an entire building. The dataset is instrumental in improving the accuracy and reliability of simulations focused on the dynamic response, progressive damage, and collapse of unreinforced masonry buildings under seismic actions. The authors made this data available to support the development of analytical and numerical models, advancing research in earthquake engineering and performance-based seismic assessment of unreinforced brick-masonry buildings. The comprehensive dataset, including acceleration and displacement time series, is hosted on the Built Environment Test Data platform and is freely accessible without any restrictions through https://www.betestdata.eu/, assisting researchers and engineers in effectively utilising the data for further studies

Experimental seismic performance of a full-scale unreinforced clay-masonry building with flexible timber diaphragms

This paper presents the results of a unidirectional shake-table test performed on a full-scale, single-storey unreinforced masonry building. The specimen represented a typical detached house of the Groningen region of the Netherlands, consisting of double-wythe clay-brick unreinforced masonry walls, without any specific seismic detailing. The building prototype included large openings and a reentrant corner, causing a discontinuity in one of the perimeter walls. The floor was made of timber beams and planks, resulting in a flexible diaphragm. The roof, characterized by a very steep pitch, consisted of a series of timber trusses connected by wood purlins and boards. The two façades perpendicular to the shaking direction were designed to represent two typical gable geometries. An incremental dynamic test was conducted up to the near-collapse state of the specimen, using input ground motions compatible with induced-seismicity scenarios for the examined region. This paper summarizes the main characteristics of the specimen and the shake-table experimental results, illustrating the dynamic response of the structure, the evolution of the damage mechanisms, and the attainment of significant limit states

Experimental and Numerical Assessment of the Seismic Performance of a Half-Scale Stone Masonry Building Aggregate

The region of Basel is considered one of the most seismically vulnerable in Switzerland: in 1356, a very damaging earthquake hit the city, which nowadays is characterized by a significant concentration of population and economic activities. Hence, the Canton of Basel and the Swiss Federal Office for the Environment have promoted a comprehensive experimental and numerical research program, spanning from the evaluation of the seismic vulnerability of Basel's heritage building stock to the identification of appropriate retrofit strategies. In particular, the experimental program aims at characterizing the mechanical properties of natural stone masonry and investigating the seismic performance of building aggregates typical of the historical city center. To this end, a unidirectional shake-table test was performed on the half-scale model of a natural stone masonry building aggregate, incorporating the main architectural and structural features of existing buildings in Basel's historical center. The aggregate consisted of two three-story units. Double-leaf rubble stone masonry walls, with undressed blocks and river pebbles, constituted the vertical structural elements, while timber floors, simply supported by the transverse walls, provided flexible horizontal diaphragms. The two units were covered by roofs with different truss configurations, pitches, and side-gable wall heights. An incremental, unidirectional dynamic shake-table test was performed up to near-collapse conditions of the specimen, using input ground motions representative of realistic seismic scenarios (natural and induced) for the examined region. The selected records were scaled at different amplitudes, reaching spectral accelerations close to twice those associated with a 475-years return period for the region. The experimental response of the prototype building was also simulated via nonlinear static analysis. The structure was modeled using an equivalent-frame approach with nonlinear macroelements, as implemented in the TREMURI software. The numerical results were compared with the experimental response in terms of pushover and backbone curves and lateral displacement envelopes. The consistency between numerical simulations and experimental results was also verified in terms of damage pattern and activation of damage mechanisms