Alessio Pipinato

Fatigue tests on riveted steel elements taken from a railway bridge

Assessment of structural integrity and remaining life are essential tools for the management of ageing infrastructures, especially bridges. Compared to bolted or welded structures, little attention has been devoted to the fatigue assessment of riveted details. To fill this gap, extensive experiments are conducted on a short-span two-lane riveted steel-girder railway bridge near Sacile, Italy. In service since 1918, it was dismantled in 2006 and moved to a structural laboratory. Within a fatigue assessment framework, first physical and physical–chemical tests were performed, characterising the material properties; then, static, cyclic and fatigue full-scale tests were carried out. The experimental investigation allowed to test in particular the safe condition of the short riveted diaphragm connections of the bridge, and to compare the current fatigue design curves with experimental results. Moreover, the current practice to equate the fatigue behaviour of rivets to that of non-preloaded bolts proved to be a safe comparison.

A Simplified Management Procedure for Bridge Network Maintenance

Structural problems due to corrosion, ageing, durability, aggressive environments, materials defects, lack of ductility and unforeseen behaviour under seismic loads may significantly compromise the resistance and safety of bridges. Scheduled maintenance of bridges becomes important to ensure complete serviceability of the road network. Among existing bridge management systems (BMSs), this work is a contribution to the evaluation criteria of bridge condition by means of visual inspection, prediction of future structural condition and planning of maintenance intervention. After a brief review of some existing BMSs, a simple new procedure for evaluation of bridge condition by means of visual inspection, aimed at general planning of maintenance in a BMS framework, is presented in this paper. This procedure is applied to stock, including about 200 bridges and viaducts, of the Veneto region road network in the north-eastern part of Italy, and is then discussed.

Assessment procedure and rehabilitation criteria for the riveted railway Adige Bridge

Traffic patterns increasing and the degradation of existing railway steel bridges has lead to the need of an assessment of their remaining fatigue life, and deciding whether to retrofit or supply structure replacement. This paper deals with the structural assessment of an actual case study, the Adige Bridge, which connects the Rovigo and Padua provinces in northern Italy. The bridge has been in service since 1886 and the overall length is about 161m through three spans. As a reference the innovative procedures to estimate the remaining fatigue life of bridges outlined in the JRC-ECCS document Assessment of Existing Steel Structures: Recommendations for Estimation of Remaining Fatigue Life, has been applied for the case study, together with other codes and technical instructions. Stress data, obtained by a 3D finite element model, were used to estimate the remaining fatigue life. Assessment results, obtained by considering different traffic estimations, point out that most of the identified critical details have an infinite remaining safe life, but at the same time some members appear critical. Appropriate retrofitting criteria are proposed to support the designer in common damage situations.

Structural Analysis and Fatigue Reliability Assessment of the Paderno Bridge

The Paderno Bridge along the Adda river in the northern part of Italy is a relevant arch-bridge connecting Milan and Bergamo province in the northern part of Italy: the bridge is part of the Monza-Bergamo line and is in service from 1889. A stepwise and practical approach for evaluating the structural integrity of historical and deteriorated steel bridges, incorporating analytical, mechanical, and structural characterizations, is presented. Critical regions of hot spot members were identified using structural finite-element analysis, and fatigue reliability assessment analysis has been performed along with traffic estimation, taking into account various scenarios of traffic increase, in order to assess the possible remaining fatigue life. This analysis has evidenced that the structure might be kept in service at least for other 10 years. Appropriate retrofitting interventions are also indicated.

Structural Analysis of Historical Metal Bridges in Italy

In this paper different studies on the structural analysis, the fatigue assessment and the damage evaluation of metal bridges are reported. These work examples are related to a widespread amount of works conducted since the first of 2000 in the research area of bridge design and assessment. The most part of these researches are related to railway bridges and historical metal bridges, because of their particular vulnerability to damage decay during their life. The main research topics are presented and discussed.

Fatigue Damage Estimation in Existing Railway Steel Bridges by Detailed Loading History Analysis

Fatigue life estimation of metal historical bridges is a key issue for managing cost-effective decisions regarding rehabilitation or replacement of existing infrastructure. Because of increasing service loads and speeds, this type of assessment method is becoming relevant. Hence there is a need to estimate how long these structures could remain in service. In this paper a method to estimate fatigue damage in existing steel railway bridges by detailed loading history analysis is presented. The procedure is based on the assumption that failure probability is a function of the number of predicted future trains and the probability of failure is related to the probability of reaching the critical crack length.

Moving Loads Bridge Response: Structural Analysis and Eurocode Provisions

Moving loads analysis in bridges are currently undertaken as a result of code provisions. However, this relevant part of the structural analysis in bridges, could be implemented with a wide variety of instruments and analysis. This paper deals with the response of bridges to moving loads: in the first part, in order to take advantage of the high amount of works performed in the past, a review of the principle method for the dynamic response of bridges to moving loads are outlined; in the second part code provisions of Eurocode are presented. Current short and medium span bridge types are analyzed, including long span bridges, as cable-stayed and suspension bridges, having gained much popularity in recent decades for their aesthetic appearance, efficient utilization of structural materials and other notable advantages. A wide amount of references from the analyzed literature are included.

Moving Load and Fatigue Analysis of a Long Span High Speed Railway Bridge

Long span bridges, as cable-stayed and suspension bridges, have gained much popularity in recent decades for their structural shape, efficient use of materials and other optimal solution. A new phase is starting with main span lengths going over thousands of meter. As a matter of fact, small size substructures are required, the development of efficient construction techniques are growing on and faster progress in the FEM and design are evident. Ever since the dramatic collapse of the first examples of such long span structures, as the Tacoma Narrows Bridge in 1940, much attention has been given to the dynamic behavior of these structures. In this paper a moving load analysis performed on a cable stayed high speed railway bridge is presented together with a fatigue analysis of the cable stays, discussed according to the Italian code verification procedure.

Extending the lifetime of steel truss bridges by cost-efficient strengthening interventions

Abstract The large number of existing bridges and viaducts all around the country has become a major problem for bridge owners. In the specific case of steel truss bridges, a reasonable method to extend the lifetime of existing structures is represented by the introduction of new deck systems combined with diffused strengthening interventions. In this study, a stepwise approach considering different loading conditions is presented (historical and Eurocode loads). The structural analysis has been performed on a case study bridge with a finite element model (FEM) calibrated on load tests. It was found that the predicted deformation agreed reasonably with the experimental results. Different strengthening alternatives were analysed and discussed: the introduction of orthotropic deck; the construction of composite deck with differentiating thickness and ordinary concrete strength; the construction of composite deck with differentiating thickness and high concrete strength; in some cases, also steel-to-steel interventions on the bridge are provided. It has been found that the best structural strengthening alternative lies in the construction of a composite concrete or of an ultra high-performance concrete (UHPC) or an ultra high-performance fibre-reinforced concrete (UHPFRC) deck with a reduced thickness (compared with traditional interventions) resting on the existing steel structure combined with steel-to-steel interventions.

Structural Optimization of Network Arch Bridges with Hollow Tubular Arches and Chords

In the framework of bridge engineering, cable structure represent a key argument. The development of innovative bridge solutions are needed in order to keep time and costs at a reasonable level, maintaining at the same time an high level of structural safety and functionality. The network arch bridge solution completely respond to these requirements, and in addition could be designed as a very pleasant and formally elegant structure, because of its slenderness and lightness. In this paper, an introduction on the network arch solution is presented, together with structural analysis and data of relevant structures realized. Furthermore, an optimization of specific types of road and railway bridges is presented in the particular case of hollow sections, considering three alternative of cable disposition.