Alessandra Dal Cin

SHM of Historic Damaged Churches

The paper shows the results of monitoring activities to check the structural response and the level of damage of two historic monument of LAquila: San Pietro di Coppito and Santa Maria Paganica, that were damaged by the main earthquake of April 2009. The diagnostics operation was planned and carried out in situ and in laboratory to verify the integrity of the residual stiffness of the structures and to define the mechanical parameters of the material. The mechanical characterization of materials was carried out through destructive tests on samples, taken directly on site, and micro-destructive tests through single and double flat jacks. To give a first qualitative assessment of overall was used sonic test (non-destructive test) on the main macro-structure. The global structural health monitoring (SHM) was carried out through ambient vibrations to define the real dynamic behavior in serviceability state and to calculate - via a modal identification of output-only systems-the dynamic parameters (mode of vibration, frequencies, displacements and damping ratios). The aim of this research is to prove the reliability of different diagnostic methodologies, the real extent of global and local damage and the extent of the residual stiffness of the macro elements of the structures (façade, tower, walls of nave, transept) that are subjected to different mechanism of failure.

Knowledge of the Construction Technique of the Multiple Leaf Masonry Façades of Palazzo Ducale in Venice with ND and MD Tests

This paper presents a first program of non-destructive tests carried out on two medieval façades and inside the main rooms of Palazzo Ducale in Venice, i.e. the room of Maggior Consiglio and the room of Scrutinio. A probably multiple leaf load-bearing brick masonry and an external cladding of polychrome stones compose these façades under investigation. The aim of the tests concern the improvement of knowledge about the construction technique and the mechanical features of these important historical facades. The program was set up after a preliminary historic investigation. Non-destructive and minor-destructive investigations (i.e. pattern surveys, endoscopic tests and georadar test) on the inner sides of the two walls of the area under examination were carried out for the analytical determination of the construction technique and structural characteristics, not clearly inferable from the literature.Due to the complexity of the structure and the transformations undergone in seven hundred years of life, and to the very limited investigable areas of the internal surface, the results of investigations cannot be extended to the entire structure. Nevertheless, these tests provide valuable clues to give a correct interpretation of the construction technique and to contribute to identify the possible mechanical properties, which provide knowledge about the health state of the building.

Collapse Mechanisms due to Earthquake in the Structural Typologies of Historic Constructions: The Case of Mirandola

During the seismic event of May 2012 in the Emilia-Romagna Region (Italy), several cultural heritage structures collapsed or were severely damaged. This paper gives a description of the damage/collapse mechanisms observed on some of these buildings. The Church of Gesù, the City Hall and the tower of the Cathedral in Mirandola (MO) were analyzed. In particular, this article focuses on the behavior analysis of a church, a palace and a bell-tower, mainly masonry construction, that are the most widespread types of protected monuments proposed in the Italian code as simplified models for the verifications on the entire cultural heritage of a prior assessment of the seismic risk. The survey permitted to detect the most significant damage, mainly related to the cracks of the masonry and to understand the different collapse mechanisms.

On Expected Performance of a Frame-Structure Made by All GFRP Pultruded Profiles

The research showed focus on the performance comparison between two equivalent frame structure. i.e. the first one made by steel and the second one by all frp (fibre reinforced polymer ) pultruded material. The structure adopted for the analysis is a traditional two floors frame made by connections between columns and beams. The connection has been assumed rigid to simplify the comparison, already very hard and to point out on the overall structural answer of the two different cases. The reason why of the investigation is related to teh need to deep detail the eventually structural benefits in presence of FRP material. However the success is related to a very reduced weight of FRP material (with weight equal to 1600-1800 kg/m3) linked to a not negligible performance in term of strength and durability, even if also the easy employment play a very important rule. The two storeys frame were subjected to static and dynamic actions to analyse also in comparison the response

Design of an Innovative Large FRP Pultruded Structure

The paper shows the approach toward the construction of a very large Pultruded Fibre Reinforced Polymer (PFRP) temporary structure realized to accommodate future restoration work and to cover a historic church stroked and partially collapsed by 2009 LAquila earthquake. The aim regards the analysis and evaluation of seismic performance of that structure made by very light and elastic-brittle material, as FRP material, in a moment in which there is a loss of technical recommendation for specific calculation in seismic field, indeed actually some deepening already present in literature allows only static field. The covering structure is an all FRP spatial-reticular with elements made by pultrusion process, connection plates by bag molding process and steel bolts. The PFRP structure covers more than 1050 meters squares surface with 32 meters height and only 100 kN weight. Detail performance of first part of PFRP structure through mode vibrations and involved percentage mass deduced by numerical approach with discussion of employments perspectives of PFRP material in seismic zones than traditional material are showed.

Model's Calibration for Masonry Reinforced with FRP Mesh-Bars

The paper presents some considerations on the reliability of the available formulas to determine the shear strength of masonry reinforced with FRP (fibre reinforced polymer) material. In detail the outcomes of a model related to the Eurocode 6 is prepared in presence of not usual shear reinforcement as FRP mesh bars jointed to ten surface masonry through steel joints. The model considers the basic contribution due to the masonry material and then add the contribution related to the presence of a material as carbon bars that is characterized by higher behaviour in term of stiffness.

Structural Diagnosis of a Historic Tower Hit by Earthquake

The paper presents a critical analysis of the structural response and the level of damage of a historic tower of Santo Stefano of Sessanio that was hit by the main L Aquila earthquake of April 2009. A FE model was constructed to simulate the structural behaviour during the seismic event. The presence of a reinforced concrete slab in the upper part of the tower probably cause a different dynamic behavior compared with the lower masonry circular walls. Have also been investigated boundary conditions at the base, the different mechanical property of masonry and the contribution of the stiffness of the wooden floors.

Performance of Different Connections for a SFGP-RC Prototype Panel

The aim of this research regards the evaluation of mechanical performance of a prototype panel made by steel fiber reinforced concrete, SFRC, on the top, and fiber reinforced pultruded sandwich panel, GFRP, on the bottom, subjected to combined moment-shear actions through four-bending test. Two different mechanical solutions were used for the connection of the panels. A first steel connection previously designed and a second one with resin applied uniformly on the surface of GFRP panel. The SFRC-G panel involves the analysis of the weakness of GFRP material due to its very low deformability, the risk of the local instability and the elastic brittle behaviour till the collapse, while steel is obviously characterized by elastic-plastic curve. However in the test proposed the ultimate limit state (SLU) involves first of all the loss of bond strength between materials. The panels length/thickness ratio has been previously designed to give prominence to flexural-shear combined actions and in verifying the connections capacity.

Static Monitoring and Non-Destructive Test of a Historic Damaged Palace

The City Hall of Mirandola was stricken and damaged by Emilia-Romagna earthquake sequence of May 2012. This paper presents the procedure for the structural monitoring control of a masonry historic building that presents a serious damage pattern. Structural monitoring was carried out with transducers installed to control the serious cracks that regards the main volumes of the building. The global structural health monitoring was useful to define the actual condition of the dynamic behavior of the damaged construction that are subjected to different mechanism. Ground penetrating radar allows to detect the depth of the cracks and the condition of the masonry. These researches are useful also for the structural future rehabilitation and to define the possible changes in the structural behavior.

Damage Assessment of Historic Buildings Hit by Earthquake

The Church of Gesù and the tower of the Cathedral were stricken and damaged by Emilia-Romagna earthquake sequence of May 2012. This paper presents the procedure for the structural identification of the most widespread types of religious monuments. The dynamic behavior was analyzed using the ambient vibrations test to measure the dynamical properties (mode of vibration, frequencies, displacements and damping ratios) of the constructions using a modal identification of output-only systems. The operational modal analysis OMA has been carried out to identify the modal characteristics through poly-reference Least Square Complex Frequency-domain (pLSFC) estimator. The global structural health monitoring was carried out to define the real dynamic behavior of the damaged constructions that are subjected to different mechanism. These researches are useful for the structural rehabilitation and to define the possible changes in the structural behavior.