Damage Identification in Warren Truss Bridges by Two Different Time–Frequency Algorithms

Recently, a number of authors have been focusing on drive-by monitoring methods, exploiting sensors mounted on the vehicle rather than on the bridge to be monitored, with clear advantages in terms of cost and flexibility. This work aims at further exploring the feasibility and effectiveness of novel tools for indirect health monitoring of railway structures, by introducing a higher level of accuracy in damage modelling, achieve more close-to-reality results. A numerical study is carried out by means of a FE 3D model of a short span Warren truss bridge, simulating the dynamic interaction of the bridge/track/train structure. Two kinds of defects are simulated, the first one affecting the connection between the lower chord and the side diagonal member, the second one involving the joint between the cross-girder and the lower chord. Accelerations gathered from the train bogie in different working conditions and for different intensities of the damage level are analyzed through two time-frequency algorithms, namely Continuous Wavelet and Huang-Hilbert transforms, to evaluate their robustness to disturbing factors. Compared to previous studies, a complete 3D model of the rail vehicle, together with a 3D structural scheme of the bridge in place of the 2D equivalent scheme widely adopted in the literature, allow a more detailed and realistic representation of the effects of the bridge damage on the vehicle dynamics. Good numerical results are obtained from both the two algorithms in the case of the time-invariant track profile, whereas the Continuous Wavelet Transform is found to be more robust when a deterioration of track irregularity is simulated.

Continuous Arch Bridges Over Lake Tisza, Hungary

<p>The design and construction process of the unique cycling bridges at Lake Tisza are presented in this article. The 4 new bridges are parts of the closing segment of the cycle route around the artificial reservoir, which is a popular tourist destination in Hungary, and part of the UNESCO World Heritage. The proximity of the natural environment motivated the use of organic, flowing shapes.</p><p>The unique Eger- and Szomorka bridges are independent continuous half-through arch bridges, 8 spans with a total length of 308.46m, and 3 spans with a total length of 86.30 m, respectively. The bridge over River Tisza is a 5 span bridge with a total length of 279.47 m, which is placed on the extended piers of the existing roadway bridge. It consists of 2 deck truss bridges on the side-spans and 3 network arch bridges in the mid- spans. A 5.70 m span bascule bridge over one of the draining canals of the lake was also accomplished as part of the project.</p><p>The Eger and Szomorka bridges are internationally unique due to the fact that the Designers have dreamed a continuous sinusoid wave on the supports; which, by twirling under and above the deck, results in a continuous structure. The successful construction of the Tisza River Bridge also required some special and unprecedented construction methods.</p>

Assessment of Provisions for Load Rating Gusset Plates in Steel Truss Bridges

Many states have load rated their truss bridge gusset plates following the guidelines published in 2009 by the Federal Highway Administration in response to the catastrophic failure of the I-35W Bridge. As the Manual of Bridge Evaluation released new load rating provisions after 2014, the urgency in adopting and applying these mandated provisions became a pending burden for state agencies requiring extensive work to update the ratings of gusset plates. Moreover, this paper argues that the current states’ load rating practices do not involve the rating for the welded gusset plate owing to the lack of established provisions. In addition, the gusset plate with no plans also poses particular challenges for the state agencies. To provide state agencies with better insights on the load rating approach of gusset plates, this paper presents a study that carefully reviewed the states’ current practices and load rating provisions. The results of the study indicate the necessity of adopting the new provisions, as the former load rating methodology exhibited inaccurate results in some cases. Additionally, this paper reviews extensive work done for welded connections and proposes a load rating guidance for welded gusset plates. To deliver better interpretations, a case study is provided for the welded gusset plates. This paper also reviews the evaluation method for deteriorations and staggered bolt patterns with relevant case studies. Lastly, the paper provides guidance on estimating the unknown bolt strength as well as weld metal strength for the gusset plate.