Intended Ignorance: The Collapse of the I-35 W Mississippi River Bridge on 1 August 2007

At 6:05 PM on 1 August 2007, the I-35 W Highway Bridge crossing the Mississippi River in Minneapolis, Minnesota, collapsed due to the failure of crucial parts of the bridge’s steel truss structure. Thirteen people died in the disaster, 145 were injured. A report of United States National Transportation Safety Board (NTSB) revealed that the Minnesota Department of Transport, over a long period of time, had ignored available information about the structurally deficient status of the bridge in anticipation of ‘budget busting’ repair costs. Which resulted in a preference for less expensive patch-up measures to improve the drivability of the bridge rather than a retrofit of the fracture-critical components of the steel truss whose failure triggered the disaster of 1 August 2007.

Evaluation of Crossability between Nicotiana benthamiana and Nicotiana excelsior

Wild tobacco species in the Nicotiana section Suaveolentes are promising genetic resources to introduce their disease resistance to cultivated tobacco, Nicotiana tabacum. However, hybrid lethality is observed in hybrid seedlings from crosses between most Suaveolentes species and N. tabacum. In particular, N. benthamiana belonging to the section Suaveolentes produces only viable hybrids after crossing with N. tabacum. In the present study, crossability between N. benthamiana and N. excelsior (section Suaveolentes) was investigated to test the possible usefulness of N. benthamiana as the bridge parent to transfer desirable genes of N. excelsior to N. tabacum via bridge crossing. After reciprocal crosses using three accessions of N. benthamiana and N. excelsior each, several crossing barriers such as cross-incompatibility, seed abortion, and male and female hybrid sterility were observed. Although reciprocal hybrids between N. benthamiana and N. excelsior showed a high degree of chromosome pairing in meiosis, univalents and multivalents, as well as chromosome bridges and lagging chromosomes, were observed. These meiotic abnormalities were thought to cause hybrid sterility. The possible usefulness of reciprocal hybrids between N. benthamiana and N. excelsior is discussed.

BRIDGE as a Linguistic and Cultural Symbol

The paper deals with a linguistic and cultural conceptualization of reality. A symbolic dimension of a concept is analyzed on the basis of its notional, perceptive and axiological features. The concept BRIDGE has been described in its verbal representation in the Russian and English linguistic cultures. The material of the study includes definitions from dictionaries and encyclopedias, textual samples from the Russian and English national corpuses, proverbs and aphorisms and poetic texts. Metaphorically, a bridge is understood as an opportunity to move on along the road via some natural obstacles, usually rivers. Symbolically, the following ideas come to the fore when applied to the concept BRIDGE: crossing an obstacle, raising up, possibility or impossibility of coming back, safety or insecurity. The novelty of the research consists in the description of these vectors of conceptualization of a BRIDGE as a cluster of the symbolic meanings of building or destroying a bridge and going up or falling down from it.

STUDY ON THE ASSESSMENT OF IMPACT FORCE BETWEEN SHIP AND BRIDGE PIER

The bridge crossing water way is in the risk of impact by vessel, and thus it is very important to estimate the collision force for the safety of bridge. The impact force between bridge pier and vessel is investigated by numerical simulation and various empirical formulae. The collision response between a 5000t DWT bulk carrier with bulb bow and rigid bridge pier is simulated in the explicit finite element code of ANSYS LS-DYNA. The difference of the impact force between the empirical formulae and FE analysis are discussed. Based on the comparison of the results, the coefficient in the formulae is suggested for obtaining more accurate assessment of impact force.

Experimental studies of the kinematics flow and bottom’s reformations in the area of bridge pier during the construction of the bridge crossing

The results of laboratory modeling of bottom reformations in the area of bridge pier crossing over water barriers are presented. The basics of hydraulic modeling are described taking into account the similarity criteria. The flow around a rectangular box (tongued-and-grooved protection of a constructed pier) is experimentally studied, the pattern of erosion if an ice-cutter device is installed in front of the box in the form of a triangle directed at an acute angle towards the flow is considered. The structure of the bottom relief in the vicinity of the tongued-and-grooved box is experimentally studied under the conditions of the bottom erosion. Two cycles of experiments were performed for different values of the flow depth and specific discharge of water. Localization and quantitative characteristics of washouts and alleviation of sandy soil in the vicinity of the streamlined design are established. It is noted that the main mechanism for the formation of the bottom relief is a horseshoe vortex at the base of the pier. A stagnation zone is formed inside the horseshoe. In the absence of an ice cutter, the main zones of soil erosion occur in the corners of the frontal bezel of the box, alluvium forms in the rear unit of the design. By installing an ice-cutter device in front of the box, the erosion zones move to the vicinity of the corners lying at the base of the triangular ice-cutter facing the box. The alluvium remains in the wake of the box. At the same time, the absolute values of the erosion depth and the height of the alluvium under installing the ice-cutter close to the box are reduced. The data of velocity measurements on the free surface and in the flow thickness are also given.

Innovative Monitoring Techniques for Wadi Flash Flood by Using Image-Based Analysis

Flash floods in wadi systems are a very important environmental issue, and their monitoring is necessary for many applications, including water resource management, irrigation and flood control. However, monitoring networks are very rare and lack spatial distribution features. In this study, image-based techniques were used to quantify and monitor flash floods in wadi channels by using two different methods. In the first section, we employed photogrammetry processing technique to quantify post-peak flood discharges by using a drone survey to build a digital elevation model (DEM) with a high resolution and calibrated and validated the model with a field survey (levelling measurements). This technique used drone-collected images to construct a DEM for extracting a cross-sectional profile and elevation points to calculate the peak discharge using the slope-area method with the Manning equation. In the second section, we combined the previous technique with the large-scale particle image velocimetry (LSPIV) technique to measure flash flood discharge by installing a fixed camera on a road bridge crossing a wadi channel and using a digitally extracted cross section from the DEM in the analysis. The results of those techniques show a high efficiency that is equivalent to that of conventional methods.

The principles of compiling and the content of the Geocryological Map in the area of the bridge crossing over the Lena River

For the safe construction and operation of a bridge it is necessary to have a clear understanding of the landscape, geocryological and hydrogeological features of the territory. In this regard, a review of the geocryological study of the permafrost zone of the bridge crossing area has been prepared; the analysis of the published and archive literature on the geological structure and hydrogeological conditions of the area under study was carried out; field and fund data and data of engineering and geological surveys were studied and analyzed; control and linking field routes and geothermal measurements in wells were carried out. The results obtained in the course of this work served as the basis for the compilation of a permafrost landscape map and then a geocryological map of the bridge over the Lena river in the area of Yakutsk on a scale of 1 : 5 000. The geocryological map shows the spatial heterogeneity of the permafrost-landscape conditions of the territory under consideration due to zonal (altitudinal-belt), regional and local factors. The information base of geocryological characteristics was the data of engineering and geological surveys.

CONVOLUTIONAL NEURAL NETWORKS FOR DETECTING BRIDGE CROSSING EVENTS WITH GROUND-BASED INTERFEROMETRIC RADAR DATA

This study focuses on detecting vehicle crossings (events) with ground-based interferometric radar (GBR) time series data recorded at bridges in the course of critical infrastructure monitoring. To address the challenging event detection and time series classification task, we rely on a deep learning (DL) architecture. The GBR-displacement data originates from real-world measurements at two German bridges under normal traffic conditions. As preprocessing, we only apply a low-pass filter. We develop and evaluate a one-dimensional convolutional neural network (CNN) to achieve a solely data-driven event detection. As a baseline machine learning approach, we use a Random Forest (RF) with a selected feature-based input. Both models’ performance is evaluated on two datasets by focusing on identifying events and pure bridge oscillations. Generally, the event classification results are promising, and the CNN outperforms the RF with an overall accuracy of 94.7% on the test subset. By relying on an entirely unknown second dataset, we focus on the models’ performances regarding the distinction between events and decays. On this dataset, the CNN meets this challenge successfully, while the feature-based RF classifies the majority of non-event decays as events. To sum up, the presented results reveal the potential of a data-driven DL approach concerning the detection of bridge crossing events in GBR-based displacement time series data. Based on such an event detection, a prospective assessment of bridge conditions seems feasible as an extension to previous structural health monitoring approaches.