Papers by Keyword: Steel Bridge

Abstract: Nonlinear time history analyses of SDOF bridge columns with elasto-plastic flexural behaviour which are subject to eccentric gravity loading are conducted to quantify the effect of ratchetting. Peak and residual displacements were used as indicators of the degree of ratchetting. The effects of member axial loads and design force reduction factors were also investigated. It was shown that displacement demands increased with increasing eccentric moment. For eccentric moment of 30% of the yield moment, the average maximum and residual displacements increase by 4.2 and 3.8 times the maximum displacement, respectively, which the engineers calculate using static methods without considering ratchetting effect. Design curves for estimating the displacement demands for different eccentric moments are also developed. The current NZ1170.5 (2016) provisions were found to be inadequate in estimating the maximum displacement for steel structures, and hence, new provisions for steel structures should be presented.

Abstract: The bridge in Poggio Renatico crossing the Reno river on the railway line between Bologna and Ferrara, consists of steel decks supported by masonry abutments and piers, while foundations and pier caps are made of reinforced concrete. After the 2012 Emilia Earthquake and accounting for the fluvial erosion below the piers foundations, a structural assessment of the bridge was carried out in accordance with to the current Italian rules. Although a sufficient structure capacity against the actual transit loads resulted, the bridge showed some inadequacies with respect to the load models provided by both the national standard for constructions and the guidelines of the Italian railway network company. The retrofitting project consists of an improvement of the structural capacity of all the elements: girders, piers and abutments. An innovative retrofitting solution provides for the strengthening of the existing decks through a suspension system of cables anchored to steel towers standing on both abutments and piers and creating a kind of suspended bridge. The retrofitting is compatible with the normal scheduled interruptions of the rail traffic thereby reducing the maintenance costs of the railway system. The structural solution represents a model easily replicable to solve analogous situations along the railway network.

Abstract: This study presents finite element analyses for a special steel bridge under the action an actual seismic wave. The maximum stress and the maximum deflection of the bridge are calculated based on the dynamic analyses. It is found that the bracing system and the beams between the two columns at the end of the bracing system are the critical members in the steel bridge under seismic action. The maximum displacement of the steel bridge is located at the overhang beams at the bridge end. However, the dynamic response is different when the seismic wave is input in different directions. Based on the numerical results, it is found that the special steel bridge is safe under the seismic action.

Abstract: A failure of eyes bar or pin leads to the collapse of the whole structure. For this reason, inspection and maintenance are important, but also very difficult. In addition there is also the problem of corrosion. Generation of small cracks shows that during the remaining life for bar eyes is quite low, indicating in terms of the rules that the item has high possibility of failure, and a failure of this element may lead to a collapse of the structure.

Abstract: Non-destructive evaluation (NDE) methods are widely accepted for quality control of welding in steel bridges. Recent development of advanced ultrasonic testing technologies enriched the categories of NDE methods used for steel bridges and more importantly these enhanced techniques provided more effective flaw detection and characterization. No guidelines, however, is available in existing bridge welding code for their more widespread applications to bridges. In this study, we overview the state-of-the-art advanced ultrasonic testing technologies in welding inspection. Benefits of the enhanced ultrasonic testing technologies are summarized, aiming to pave the way for deciding methods need for various steel bridge welding inspections.

Abstract: As its good mechanical properties, steel bridge has been widely used in modern highway, railway and urban bridge construction, but its corrosion protection is also a major issue. This paper studies the types of corrosion, the methods of anti-corrosion and focuses on coating protection--the most promising anti-corrosion method currently. It proposes some improvement measures for the corrosion protection, and has a certain reference value for the design and construction of such bridges.

Abstract: Recent studies have proved that there is no fatigue limit for metallic materials; the stress life curve continuously drops even after 10⁷ cycles. However, existing design codes assume that there is a fatigue limit. Therefore, it is important to use appropriate safety factors if existing codes are used for life evaluations. This paper first describes a method to extend high cycle fatigue stress life curves which are developed using tests on small scale specimens, to the gigacycle regime. Then the difference between the stress life curves of small scale specimens and full scale tests related to steel bridges are explained. Finally, the paper presents a case study on a fatigue critical element of a steel railway bridge to show the significance of the gigacycle regime for fatigue life evaluation.

Abstract: A simplified seismic evaluation method for steel members with thin-walled stiffened box sections is developed. First, a finite element model based on the shell element was carried out and its effectiveness was validated by comparison with the experiment. Twelve numerical cases were then simulated by the shell model and the fiber model, respectively, and their accuracies were discussed. Numerical results showed that the proposed method using the fiber model, employing the bilinear kinematic hardening relation, is of good accuracy. If the maximum strength is taken as the ultimate point, the bilinear stress-strain relation, replacing the yield point by the buckling stress, was recommended. If a point corresponding to 95% of the maximum strength after the peak is regarded as the ultimate point, the elastic-perfectly plastic stress-strain relation was suggested.

Abstract: Fire accidents are dangerous and uncertain. The steel bridges are particularly serious fire threat due to the steel own shortcomings. Steel bridges in the planning, design and operation need a complete set of fire relief measures. For steel bridges, the paper presents fire safety, fire loss distribution function and fire safety design. For a steel bridge, the paper presents specific fire safety measures and rescue processes.

Abstract: Taking Beijiang Bridge as an example, using 3D finite element method, influence of side stringer to deck deformation of four-lines high-speed railway cable-stayed bridge with double cable planes is studied. The results show that the stiffness of the side stringer hardly influence the long wave of bridge deformation and the ratio of deflection to span, but significantly affects the short wave and transversal wave of the bridge deformation. The location of the side stringer influences the long wave slightly, but influences the short wave and transversal wave significantly. If the distance between the side stringer and the center of the main trusses changed, the long wave changes slightly, while the maximum short wave and transversal wave change a lot. The larger the distance, the less the transversal span of the deck and panel beams are, and the less the short wave and transversal wave are. The influence of the axial stiffness of horizontal K-shaped brace to the bridge deformation is small.