1,720,976 research outputs found
Model's calibration for masonry reinforced with FRP mesh-bars
No full textThe 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
No full textThe 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. © (2014) Trans Tech Publications, Switzerland
On expected performance of a frame-structure made by all GFRP pultruded profiles
No full textThe 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
Damage assessment of historic buildings hit by earthquake
No full textThe 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. © (2014) Trans Tech Publications, Switzerland
Influence of the annex on seismic behavior of historic churches
No full textIn May 2012, two major earthquakes occurred in Emilia Romagna region in Northern Italy, causing widespread damage. The hypocentre of the second one, strokes Mirandola where is located the Gesù Church investigated in this research. The church has a long and important annex to the south built during the same period of the church. This paper addresses how the important annex influenced the seismic response of this historical church and how, more generally, this kind of asymmetric mass can influence the behavior of historic churches. The final considerations are based on the comparison between the structural damage pattern survey and modal and seismic FE analysis. A FE model was constructed considering four different configurations: (i) isolated church, (ii) the church with the presence of the real annex with a perfect connection, (iii) the church with the presence of the same annex but with an interface between the church and the annex and (iv) this last configuration with the stiffness degradation of the interface. Firstly the dynamic modal analysis and subsequently the seismic spectral analysis were performed. The results indicate that the annex's presences play a significant role in the dynamic response of the church and affect the distribution of damages for the whole building. The results of the seismic simulation are in agreement with the observed damage. © 2014 Elsevier Ltd
Static monitoring and non-destructive test of a historic damaged palace
No full textThe 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. © (2014) Trans Tech Publications, Switzerland
Design of an innovative large FRP pultruded structure
No full textThe 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 L'Aquila 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 employment's perspectives of PFRP material in seismic zones than traditional material are showed. © (2014) Trans Tech Publications, Switzerland
Annex and rigid diaphragm effects on the failure analysis and earthquake damages of historic churches
No full textHistorical churches, in the most of cases, are characterised by the presence of annexes and rigid diaphragm that influence their seismic response. Therefore, this research aims to investigate the disadvantages and the benefits which emerge during the horizontal dynamic actions between these structures. This study presents some analyses carried out on the Gesù Church in Mirandola, which was damaged by the 2012 Northern Italy earthquake.The first fundamental steps have been the geometrical, material and in particular the seismic damage survey. An undamaged finite element model of the actual configuration of the Gesù church with a perfectly connected annex was created and was also considered the same model as an isolated structure. Through these FE models preliminary modal dynamic analyses were conducted in the linear elastic field. Subsequently non-linear static analyses were carried out to investigate the ultimate capacity of the building.The churches are characterised by large halls without internal thorn walls, slender walls, pushing elements and lack of intermediate horizontal connection. All these factors lead each macroelement to have an independent dynamics, showing the absence of box-like behaviour. Since the roof trusses are one of the few structural elements that can determine a better global behaviour, it has been decided to perform the same numerical analyses even in the FE models without the roof, then considering the extreme case of a not effective simply supported roof
Evaluation of static and dynamic long-term structural monitoring for monumental masonry structure
No full textThis paper presents the comparative results of the static and dynamic monitoring of damaged masonry macro-elements. The structural health monitoring (SHM) has been carried out over 3 years. The crack opening displacement of the main shear cracks of the overturning mechanisms of the façade, of the bottom walls of transept and the cracks of the arches was monitored using extensometers. Moreover, dynamic sensors for measuring accelerations were used and through the registration of each major seismic vibration event, a modal identification of output-only systems was carried out; the main frequencies were identified. This work highlights the structural damage detection methodology and shows the differences between global and local damage detection techniques. The static monitoring presents the displacement trend of each monitored main crack with its respective temperature–time history. The results of both long-term monitoring systems are compared to develop the reliability and the correlation of the static and dynamic parameters over 3 years. Static and dynamic monitoring are useful to check both the level of damage and the degradation of the cracking survey, to evaluate the interaction with the safety measures, and also to analyze the stability of signals by varying the intrinsic and environmental conditions such as temperature. This research reveals a good reliability between the static and dynamic results, particularly on the detection of the effect of a safety intervention. Moreover, the results highlight the limits and merits of each monitoring system
Performance of different connections for a SFGP-RC prototype panel
No full textThe 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 panel's length/thickness ratio has been previously designed to give prominence to flexural-shear combined actions and in verifying the connection's capacity. © (2014) Trans Tech Publications, Switzerland
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