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This paper provides a discussion and thoughtful application on a large sample of the procedures for the classification of existing bridges recently adopted in Italy and defined within the Italian Guidelines for the classification, risk management, safety evaluation and monitoring of existing bridges and the early published Operating Instructions. Focusing on the classification at the territorial level, first the logic flows to the classification on the base of the structural risk are shown, resulting in the definition of the “structural warning class”, providing the motivations that support the criteria for the definition of such procedures. Then, a statistical analysis of the results obtained from the classification of 661 existing Italian bridges is performed, focusing on the vulnerability classification and on the influence of each parameter on its evaluation.

This work aims to explore the potential of the Applied Element Method (AEM) for structural analysis application in the framework of bridge monitoring, focusing in particular on the aspects of model calibration and simulation of the collapse behaviour. An AEM model of a curved roadway bridge undergoing slow landslide-induced movements was built and calibrated by using the results of ambient vibration testing and modal identification. A simulation under increasing displacements caused by the landslide was carried out, predicting the deformation evolution of the bridge and comparing it with the current state of damage observed on site.

This paper presents a mechanical model developed for the simulation of the monotonic behaviour of Steel frames with Reinforced Concrete infill Walls (SRCW). In particular, it deals with a specific typology of SRCW, obtained from the classical one through the interposition of dissipative elements in the columns and by stiffening and shaping the steel frame’s corners in a way to prevent the brittle failure of the concrete in compression. This system has demonstrated in past researches to be able to overcome the typical problems of SRCWs and to assure, through a capacity design approach, a global ductile behavior. The selection of the main components to be included in the model is carried out on the base of the analysis of the available experimental tests and of the results of accurate 3D Finite Element model analyses. The behaviour of each component is represented though consolidated models present in the current state-of-the-art and, where necessary, calibrated using the results of the experimental and numerical analyses. The capacity of the proposed mechanical model in representing the global behaviour of the SRCWs is finally demonstrated comparing the results in terms of force–displacement curves with the ones obtained through the refined 3D Finite Element models.

The results of an experimental test campaign including micro and macro investigations on welded joints typically used in Composite Truss Steel-Concrete beams are presented. The research was carried out with the aim of assessing the relevance of welding effects on the mechanical performance of different typologies of steel grades that can be used to realize the internal truss steel system, connected to the bottom steel plate used with the double structural and formwork function. Two different steel typologies were adopted for the steel truss: the “traditional” structural micro-alloyed steel, normally used for composite steel-concrete elements, and the typical reinforcing steel with TempCore® structure, achieved through the application of two-phase thermomechanical treatment of quenching and tempering. The interest in the possibility of adopting reinforcing steel for the internal truss arises from its potential economic benefit, finding its justification in the intermediate condition in which this structural typology lies, between composite steel-concrete and ordinary reinforced concrete buildings. Welding has a strong impact on such reinforcing steel material, resulting in relevant drops of ductility and brittle failure usually taking place in correspondence of the heat-affected zone. So, it is advisable to refrain from using such steel grade, especially in constructions in seismic-prone areas, where ductility is a major influencing and design factor.

This paper studies the influence of the shear studs distribution, in terms of local and global effects, on the behavior of dissipative hybrid Steel frames with Reinforced Concrete infill Walls (SRCWs). Dissipative SRCWs have been recently proposed as seismic resistant systems, capable of coupling the high stiffness of reinforced concrete walls with the advantages of dissipative systems, in which the energy dissipation takes place in localized and replaceable elements. However, experimental tests showed that the global behavior and the failure mechanism of such systems are strongly influenced by the shear studs distribution along the steel frame—reinforce concrete wall interface. In this paper, this issue is studied through suitable numerical models, calibrated on the base of the available experimental results. Several modeling options and strategies are considered and their influence on the final results has been assessed. The resulting numerical model is used to analyze the mechanical behavior of such system and to perform parametric analyses varying the shear studs distribution. The results obtained help the understanding of the mechanical behavior and of the resisting mechanisms activated on the studied system, supplying relevant information for the development of more accurate design rules.

The tests described in this paper were aimed at evaluating the tensile capacity of the anchorages connecting an automated pallet warehouse with an existing RC foundation. The warehouse is a new steel structure erected in the place of a previous warehouse collapsed due to the Emilia earthquake, but whose foundation remained undamaged. The investigated fastening consists of 10 post-installed, bonded threaded rods with diameter (d) and embedment depth (hef) of 20 and 500 mm, respectively. Neither anchor arrangement nor embedment depth (hef > 20d) was covered by current standards for fastening design. To reproduce the in-situ actual conditions of the fastening, an unconfined test configuration was used. The maximum loads achieved were more than 3 times greater than the seismic demand for the fastening. The tests highlighted the crucial role played by the reinforcing steel which was present in the foundation. Concrete-related failure mechanisms, such as the combined pullout and concrete cone failure mechanism typical of bonded anchors, were not activated. The observed crack patterns rather suggest the onset of a flexural failure mechanism of the concrete slab. This feature is confirmed by analytical calculations showing that, at the maximum loads achieved in the tests, the top reinforcement was likely to be yielded. In six preliminary unconfined tension tests on single anchors, steel rod failure was achieved, associated with limited cracking of the concrete surface in proximity of the anchor.

This paper presents a performance-based earthquake assessment of an industrial structure, aiming at identifying suitable techniques to select and scale natural ground motions for 3D analysis and improve the structural response prediction of complex structures. To this end, an industrial structure characterized by the presence of large masses placed at a significant height and of different horizontal resisting systems, such as moment resisting frames, inverted V bracings and diagonal bracings, is investigated. The structural response is computed via both nonlinear static and dynamic analyses. Two sets of natural ground motions, one coherent with the Uniform Hazard Spectrum and one with the Conditional Mean Spectrum, are selected and scaled with different criteria. The efficiency and sufficiency of each selected ground motion set and scaling criteria is assessed through a probabilistic treatment of the key engineering demand parameters. Results indicate that for the structure analyzed, characterized by different behavior in the two orthogonal directions, the use of more complex ground motions selection and scaling techniques does not improve necessarily the reliability of results or allow the use of a lower number of ground motion recordings.

The present paper shows the results of an experimental test campaign on RC base column joints realized using three different typologies of steel reinforcing bars. Traditional TempCore®B450C rebars were adopted in comparison with enhanced ones with Dual-Phase microstructure. The interest in the use of such kind of reinforcing grade comes from its improved performance in terms of durability in presence of aggressive environmental conditions, being able to provide a lower decrease of the deformation capacity, with residual values higher respect to minimum imposed by current standards. Being characterized by the typical undefined yielding stress–strain behaviour, Dual-Phase steel reinforcing bars need an accurate characterization to be used. In the present work experimental tests on RC-DP sub-structures were performed to assess their structural performance in presence of cyclic/seismic loading conditions, comparing results with traditional RC-TempCore® structures’ behaviour.

The experimental results of a testing campaign including tensile and low-cycle fatigue tests on different reinforcing steel bar types in the as-delivered and corroded condition are presented. Experimental data were statistically analyzed adopting ANOVA technique; Performance Indicators (PIs), describing the mechanical performance characteristics of reinforcements, and Corrosion Damage Indicators (CDIs), describing the detrimental effects of corrosion phenomena, were determined and correlated in order to evaluate the influence of corrosion on the behaviour of reinforcing steels, providing useful information for designers in addition to what is presented in current standards.

This paper reports a statistical analysis of a database archiving information on the strengths of the materials in existing Italian bridges having pre- and post-tensioned concrete beams. Data were collected in anonymous form by analyzing a stock of about 170 bridges built between 1960 and 2000 and located in several Italian regions. To date, the database refers to steel reinforcing bars, concrete, and prestressing steel, whose strengths were gathered from design nominal values, acceptance certificates, and in situ test results, all derived by consulting the available documents for each examined bridge. At first, this paper describes how the available data were collected. Then, the results of a statistical analysis are presented and commented on. Moreover, goodness-of-fit tests are carried out to verify the assumption validity of a normal distribution for steel reinforcing bars and prestressing steel, and a log-normal distribution for concrete. The database represents a valuable resource for researchers and practitioners for the assessment of existing bridges. It may be applied for the use of prior knowledge within a framework where Bayesian methods are included for reducing uncertainties. The database provides essential information on the strengths of the materials to be used for a simulated design and/or for verification in the case of limited knowledge. Goodness-of-fit tests make the collected information very useful, even if probabilistic methods are applied.