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The safety of existing bridges represents a serious problem in Italy since these structures are fundamental for the national transportation system and, at the same time, can be subject to significant deterioration phenomena linked to the fact that the construction period typically dates back to the 1960s. This study involves the seismic analysis of five case study bridges belonging to the Italian Road Network. Using nonlinear time–history analysis with sets of code-spectrum compatible ground motions, analytical fragility curves have been constructed for each of the five bridges. The results obtained interpreting the analytical fragility curves agree with the fact that the seismic behavior of existing bridges can be problematic and that higher seismicity can be associated with more detrimental behavior. In particular, the results reveal that in regions with higher seismicity, the main problems in bridges are related to bearings and connecting elements located in the piers. Five case studies have also been analyzed to determine the Structural and Foundational Class of Attention and Seismic Class of Attention, following the approach proposed by the 2020 Italian Guidelines. In this way, it is possible to compare two different assessment approaches with different safety levels. The results obtained with the two approaches are in good agreement considering bridges in high seismicity regions, while the procedure of the Guidelines could lead to not reflecting the seismic behavior of bridges when the seismicity of the area is lower. [ABSTRACT FROM AUTHOR]

The Italian road network comprises many bridges that were constructed around the middle of last century and are now close to, or have exceeded, their intended design lives. The advanced state of degradation of many of the bridges has been a contributing factor in a number of collapses in recent years, with the problem being particularly prevalent in prestressed concrete construction. In response to the need for improvements in the reliability of existing Italian bridges, the Ministry of Transport and Infrastructure published in 2020 a new set of guidelines for assessment and monitoring. This article undertakes a critical review of the guidelines, which are currently in a trial phase, through the multilevel assessment of a case‐study prestressed concrete road bridge. Four key areas for potential improvement in future revisions are identified: refinement of the level 3 preliminary assessment approach, greater emphasis on assessment rather than design thinking, objective Knowledge Levels, and treatment of elements with unknown levels of degradation. [ABSTRACT FROM AUTHOR]

Sliding bearings have been extensively used to implement base isolation design in civil engineering works. Testing of isolators is conducted for characterizing the design properties to be used in structural analysis, as well as for verifying the performance of the devices before their application. The quantification of the effects of scaling specimens and testing on the observed coefficient of friction is an issue, due to the nonlinear dependence of friction on several factors like load, velocity and temperature. An effort to quantify such effects is pursued in the study. The coefficient of friction is parameterized as a function of few dimensionless quantities related to heating of the sliding surfaces, and similarity conditions are assessed under which the influence of scaling is below normal production variability. [ABSTRACT FROM AUTHOR]

This paper reports on a series of shaking table tests on a full‐scale flat‐bottom steel silo filled with soft wheat, characterized by aspect ratio of around 0.9. The specimen was a 3.64‐m diameter and 5.50‐m high corrugated‐wall cylindrical silo. Multiple sensors were used to monitor the static and dynamic response of the filled silo system, including accelerometers and pressure cells. Numerous unidirectional dynamic tests were performed consisting of random signals, sinusoidal inputs, and both artificial and real earthquake records. The objectives of this paper are (i) to provide a general overview of the whole experimental campaign and (ii) to present selected results obtained for the fixed‐base configuration. The measured data were processed to assess the static pressures, the dynamic overpressures (related to the effective mass) and the accelerations of monitored points on the silo wall, and to identify the basic dynamic properties (fundamental frequency of vibration, damping ratio, dynamic amplification factors) of the filled silo. The main findings are discussed and compared with the predictions given by available theoretical models and code provisions. It is found that the fundamental frequency slightly decreases with increasing acceleration, while it slightly increases with increasing compaction of the granular material. For close‐to‐resonance input, the dynamic amplification (in terms of peak values of accelerations) increases along the height of the silo wall up to values of around 1.4 at the top surface of the solid content. The dynamic overpressures appear to increase with depth (differently from the EN1998‐4 expectations), and to be proportional to the acceleration. [ABSTRACT FROM AUTHOR]