Search

This study investigated the structural response characteristics of a novel single-point mooring gravity-type deep-water (SPM-GDW) net cage under irregular waves and currents. A hydrodynamic numerical model of the cage was created and validated through model experiments. Based on the validated cage model, the structural response characteristics such as cage motion response, mooring line forces, and floating collar stress were studied, considering the actual operating conditions in the target sea area. The response time history curves, wave height time history, and spectral density statistics were studied and compared. The results showed that the heave motion of the cage was consistent with wave elevation in the vertical direction and mainly influenced by wave conditions. The surge motion of the cage was closely related to the current, with a significant lag effect compared to wave elevation motion. Low-frequency loads under the combined action of waves and currents had a significant impact on the surge motion of the cage. In addition, the mooring line tension and pontoon stress were closely related to the wave elevation, with peak values of tension and stress occurring almost simultaneously with the peak wave elevation. However, the pontoon stress exhibited high-frequency response characteristics while satisfying the wave frequency response trend. It was found that the flow velocity had a significant impact on the spectral density of mooring line tension and pontoon stress in the low-frequency range, with an increase in spectral density values as the flow velocity increased. The structural response characteristics identified in this study provide a computational basis for the optimized design and analysis of single-point mooring gravity-type deep-water cages. [ABSTRACT FROM AUTHOR]

Copyright of AIN Journal is the property of Arab Institute of Navigation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Floating bridges face potential hazards due to ship collisions throughout their operational lifetime. In a situation where a pontoon is significantly damaged from an accident, a floating drydock may be used to compensate for the lost buoyancy and provide a dry atmosphere for operations. As the repair might take months, a primary concern is whether the repair can be in-site conducted without shutting down the road traffic. This study aims to investigate the feasibility of using a drydock for the repair. The numerical model of the in-operation damaged bridge is established for a comparative dynamic analysis with the intact end-anchored bridge. Eigenvalue analysis is conducted, and pendulum modes of oscillation are found with an eigen-period of around 15 s. The dynamic responses are analyzed through a series of fully coupled time-domain simulations under various environmental conditions. The results indicate that the standard deviation of the moment about the girder weak axis increases significantly at the damaged pontoon axis due to the excitation of low-frequency resonant response. Swell wave loads might induce dynamic amplification to the damaged bridge, even with a relatively small wave height. In addition, the internal stress of the bridge girder is investigated and found to be larger, especially, at the lower locations of the cross section. It is suggested that the responses can be managed by limiting the excitation of pendulum modes or providing special damping devices in practical engineering. [ABSTRACT FROM AUTHOR]

As a passive fishing gear, pocongan becomes a shelter for lobster fry. The material used to make pocongan is a 1 inch nylon mono-filament mesh size with a net height of 1.5-2 m. Pocongan is operated at night by floating bagan (pontoon) or boats and uses white LED lights, both surface and underwater. The aim of this research is to determine the composition of lobster fry catches as the main catch and other juveniles as by-catch and to determine the effect of using yellow and white LED lights on the operation of pocongan fishing gear. Experimental fishing activities were carried out for 10 trips with 2 treatments (yellow and white LED lights) and 3 pocongan units for each treatment. The results of the research showed that the use of yellow lights resulted in a greater number of lobster fry catches compared to white lights and had a significantly different effect. The use of yellow lights produces fewer by-catch catches compared to white lights. [ABSTRACT FROM AUTHOR]

Copyright of Materiały Budowlane is the property of Wydawnictwo SIGMA-NOT and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As a potential fire scenario for bridge structures, the safety impact of an FRP anti-collision floating pontoon fire on bridge structures cannot be ignored. Taking the FRP anti-collision floating pontoon fire that occurred in a continuous rigid-frame bridge as the engineering background, the damage condition of the actual bridge fire scene was first investigated. In addition, FDS 5.3 software was used to simulate the FRP anti-collision floating pontoon fire scenario. Furthermore, the thermal–structural coupling method was used to investigate the thermodynamic response of double-armed thin-walled piers under fire. The results show that the FRP anti-collision floating pontoon fire causes localized concrete carbonization and spalling on the surface of the P2 pier, and the FRP anti-collision floating pontoons are largely destroyed. The fire has the greatest impact on the P2-1 pier, with the highest temperature of 667 °C on the windward side and the highest temperature of 326 °C on the leeward side. The temperature impact range is 6 m above the bearing platform, and the maximum damage depth of pier body concrete is 84.58 mm. The deformation and stress of the P2 pier under fire do not show significant changes and do not exceed the allowable limits for structural deformation and material stress. Therefore, the impact of this fire accident on the structural safety of the continuous rigid-frame bridge is minor. This study's results provide reliable guidance for the fire safety assessment and post-fire structural repair of the continuous rigid-frame bridge. [ABSTRACT FROM AUTHOR]

This paper presents a case study on the use of 3D concrete printing (3DCP) to qualify rocky pontoons with spaces for recreational use—namely sitting areas, circulation trails and fishing spots—and biodiversity protection—providing habitat and refuge for native marine species—with a focus on the challenges and opportunities associated with 3DCP prefabrication for such a complex topographical context. We first discuss the benefits and disadvantages of 3DCP over traditional methods for retrofitting strategies with the support of state-of-the-art literature review. We then present a methodology and an experimental case study, organized in three stages: (1) a photogrammetric survey and digital reconstruction of the site´s rocky landscape, (2) the creation of a tool to generate and optimize custom-fit slabs based on their location on site, intended use and role in the protection of the natural ecosystem, and (3) the robotic fabrication of these slabs through 3DCP. Finally, we present our key findings, revealing that 3DCP offers a viable and more efficient alternative for appropriating and revitalizing sites with a disorderly and highly complex topography. [ABSTRACT FROM AUTHOR]

Whole Genome Duplications (WGDs) are events that double the content and structure of a genome. In some organisms, multiple WGD events have been observed while loss of genetic material is a typical occurrence following a WGD event. The requirement of classic rearrangement models that every genetic marker has to occur exactly two times in a given problem instance, therefore, poses a serious restriction in this context. The Double-Cut and Join (DCJ) model is a simple and powerful model for the analysis of large structural rearrangements. After being extended to the DCJ-Indel model, capable of handling gains and losses of genetic material, research has shifted in recent years toward enabling it to handle natural genomes, for which no assumption about the distribution of markers has to be made. The traditional theoretical framework for studying WGD events is the Genome Halving Problem (GHP). While the GHP is solved for the DCJ model for genomes without losses, there are currently no exact algorithms utilizing the DCJ-Indel model that are able to handle natural genomes. In this work, we present a general view on the DCJ-Indel model that we apply to derive an exact polynomial time and space solution for the GHP on genomes with at most two genes per family before generalizing the problem to an integer linear program solution for natural genomes. [ABSTRACT FROM AUTHOR]

Pillar restoration at the Alte Brücke Heidelberg Most people are probably familiar with the Alte Brücke Heidelberg as a photo motif. Built in 1788 as a masonry bridge made of sandstone, it spans the Neckar with seven arches with a view of Heidelberg Castle. However, what happened in the shadow of the bridge in recent years remained undiscovered by most people. During structural inspections in 2008 and 2016, damage was detected and documented on all pillars of the Alte Brücke Heidelberg, both in the water change zone and in the permanently dammed area. These were primarily foot washouts and damage to the natural sandstones. In addition, stone clamps were reworked and impact angles on the pillar tips were replaced and supplemented during these investigations. In order to carry out the necessary renovation work, the pillars had to be drained. Due to the adjacent shipping openings and the resulting tight space conditions, a slim caisson had to be constructed for this purpose, which could be placed exactly on the foundation base of the pillars and did not obstruct the ongoing shipping. The two‐part caisson had a total weight of almost 32 ts and was floated into place around the respective bridge pillars in short shipping blocks during the night using two specially assembled pontoons. The two halves of the caisson were then connected, lowered and anchored to the ground to create a closed, sealed working area around the bridge pillar. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Art History / Sanat Tarihi Dergisi is the property of Ege University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A three-dimensional numerical model was established based on ANSYS-AQWA (R19.0) software for the purpose of analyzing the hydrodynamic characteristics of a floating breakwater. This study examines three distinct floating breakwaters with different cross-sectional designs in order to evaluate their respective wave dissipation capabilities. It is suggested that the horizontal multi-cylinder floating breakwater exhibits a superior ability to dissipate waves when compared to both the single-cylinder and square pontoon configurations and can be deemed the most advantageous shielding strategy for potential engineering applications. Subsequently, this study examines the effects of influential parameters, including a large cylinder diameter, a small cylinder diameter, the angular position of the small cylinder, and the height and period of the incident wave, on the wave transmission coefficient. An empirical formula for the wave transmission coefficient was derived based on the numerical results. Additionally, the effects of influential parameters, including wind speed, current velocity, incident wave height and period, and water depth, on the maximum total mooring force were investigated. Furthermore, an empirical formula for the maximum total mooring force is proposed for practical implementation in engineering. [ABSTRACT FROM AUTHOR]

Launching of the railroad bridge Oder near Küstrin For the construction of self‐anchored arch bridges, pre‐assembly on an easily accessible pre‐assembly area with subsequent launching into the final position has established as an economical and fast assembly variant. Based on the example of the realization of the Oder railroad bridge near Küstrin, the following article describes various concepts for a longitudinal launching over a river with and without the use of pontoons as well as their respective special features. The fluctuation of the water level of the Oder in combination with the required minimum water level at the time of launching with pontoons is a major influencing factor. In addition to the independence from the water level, the special properties of the hanger net also speak in favor of a variant without pontoons, but with an auxiliary support in the river during the construction period: The carbon tension members used with chain link‐like connections can withstand a recurring relief of pretension in the assembly state without damage. This opens up the possibility of an insertion with stationary sliding supports without stiffening the hanger net. Based on this experience, the variant presented here for the assembly of net arch bridges with carbon hangers can be taken into account from the outset in the future. [ABSTRACT FROM AUTHOR]

After drought conditions were experienced across New Zealand in 2019, Watercare determined that the 175 million litres per day (MLD) upgrade to the Waikato River to Redoubt Reservoir (R2R) project should be increased in capacity by including a 50 MLD water treatment plant (WTP) on the Waikato River at a remote location 60 km south of Auckland, New Zealand. Required for urgent drought mitigation, the WTP was designed and commissioned within 12 months, enabling water delivery to Auckland by southern hemisphere Winter 2021. As a conventional pump station could not have been constructed at this remote site within the timeframe, a floating pump station was developed utilising modular Linkflote pontoons to support the equipment, gangways for services and access and tubular piles for restraint. With principal issues of constructability and short programme, the superstructure design incorporated a steel spreader frame to distribute relatively high, concentrated loads over the Linkflote pontoon system. [ABSTRACT FROM AUTHOR]

Aporocotylid blood flukes Cardicola forsteri and C. orientalis are an ongoing health concern for the Southern Bluefin Tuna (Thunnus maccoyii, SBT) industry, where infections can lead to morbidity and mortality in ranched SBT populations. This study compared blood fluke infection in SBT from two companies during the 2021 ranching season. Both companies administered the same dosage of praziquantel approximately 5 weeks after transfer, feeding with frozen baitfish daily; the only difference in the company's practices was that the pontoons were located 2.5 km apart. Infection severity was measured as prevalence and intensity by quantifying adult C. forsteri in SBT heart and copy numbers of C. forsteri and C. orientalis ITS-2 DNA in SBT heart and gills. Data from the 2018 and 2019 harvests of SBT were used to make comparisons with 2021 harvest data. Cardicola orientalis was detected at transfer and no longer detected after treatment with praziquantel. Cardicola spp. were present in 83% of sampled SBT in 2021. Both companies demonstrated similar patterns of infection, and Company A had higher prevalence and intensity of Cardicola spp. infection. Based on C. forsteri ITS-2 DNA, infection intensity at harvest was significantly greater for both companies in 2021 when compared to 2018 and 2019. Continued monitoring of Cardicola spp. in SBT and improvements in diagnostics contribute to our understanding of Cardicola spp. epizootiology and the detection of changes in treatment efficacy. [ABSTRACT FROM AUTHOR]

The pendulum-tuned mass damper (PTMD) is a widely used vibration-damping device capable of transferring and dissipating structural vibration energy, resulting in reduced structural amplitude, and offering both structural and performance advantages. Given the susceptibility of the submerged expendable conductivity, temperature, and depth profiler (SSXCTD) buoyancy platform to flow-induced vibrations during the upwelling process, the PTMD effectively suppresses the main structure's amplitude under flow field effects. To this end, we investigated the application and design of the PTMD in the SSXCTD buoyancy platform and analyzed its vibration reduction performance. Moreover, we conducted finite volume simulations of the structure using ANSYS FLUENT fluid simulation software, providing insights into its motion under flow field effects and validating the PTMD's effectiveness in mitigating the buoyancy platform's flow-induced vibrations. Our research results demonstrate that the PTMD effectively alleviates the impact of seawater flow on the buoyancy platform, leading to a significant improvement in its operational stability. The proposed research methodology and findings serve as valuable references for the design and optimization of other expendable marine detection equipment. [ABSTRACT FROM AUTHOR]

Wind, wave, displacement, and acceleration data have been collected in a measurement campaign on Norway's Bergsøysund Bridge, an end-supported pontoon bridge, between the years 2014 and 2018. The data set is now available in an open-access research entry for free access and download. The data are collected in two hierarchical data format (h5) files, with sampling rates of 2 and 10 Hz, downsampled from the raw sampling rate of 200 Hz. The data have undergone some minimal signal processing and adjustment. Some examples of how to import and browse through the data using an openly available Python package are also given. [ABSTRACT FROM AUTHOR]

The popularity of modern water bikes increases due to the relatively high speed developed with the use of a human muscle power only. For example, the maximum speed of prototypes reaches the value 3 m/s. Similar vehicles can be used not only for recreation and fitness, but also for transportation. To increase their speed and tonnage, we recommend improving the pontoon shape and using electrical power. The underwater part of the pontoon shape was recommended to be similar to the body shape of the fastest fish in order to decrease the wave resistance and total drag. The optimal depth of the movement of corresponding shapes was calculated. The total drag and maximum speeds of the vehicles with the human muscle and electrical power are estimated. Expected success in improving the pontoon shape opens wide prospects for the use of these special-shaped hulls in shipbuilding. [ABSTRACT FROM AUTHOR]

A high-speed catamaran with a suspension system and flexible pontoons to reduce motion is proposed, and the vertical motion characteristics of the vessel are investigated. The results demonstrate that altering the stiffness of the flexible pontoon can significantly alter the motion characteristics of a high-speed vessel when subjected to wave excitation. The maximum relative error between the theoretical and experimental values of the vertical dynamic characteristics of the flexible pontoon, considered as a gas spring, is 10.5%. The vertical force exerted by the pontoon exhibits nonlinear behavior in response to compression, yet displays approximately linear behavior within its primary operational range. The design of the Linear Quadratic Regulator controller, utilizing genetic algorithm optimization, avoids the issue of subjectively setting weight coefficients typically found in traditional control systems. This approach achieves the objective of determining the optimal feedback matrix within specified constraints. Simulation results illustrate that the LQR controller developed using genetic algorithm significantly enhance the semi-active suspension performance compared to the passive suspension system. The Root Mean Square value of the main cabin acceleration is reduced by 85.82%, simultaneously reducing the RMS value of the suspension dynamic travel by 85.03% and the RMS value of the pontoon dynamic displacement by 24.42%. These outcomes thoroughly substantiate the effective reduction in vertical motion, effectively attenuating the motion of high-speed vessels under wave excitation. [ABSTRACT FROM AUTHOR]

Floating offshore wind turbine (FOWT) is an innovative technology with little industry guidance for its hull design. Various FOWT floaters with different hull shapes claim to support the same turbines. Structural integrity and material expense analyses of different pontoon shapes were conducted, and it was found that some configurations, such as those with every two columns connected by both pontoon and bracing, have advantages over others. However, it is important to note that the choice of pontoon shape should be based on the wave loading conditions the floater will be exposed to. While a T-shaped pontoon provides a cost-effective solution under certain wave loading scenarios, it may not be the best option for all conditions. Specifically, ring pontoon designs with full bracing were found to be necessary for withstanding certain wave loads. Therefore, it is important to consider different Dominant Load Parameters (DLP) and ensure that a FOWT floater can withstand all applicable DLPs. An uneven hexahedral column shape, which combines the best attributes of square and round shapes, is proposed as a better alternative to cylindrical columns. It offers ease of manufacture and reasonably low drag. Bracing is found to be necessary for withstanding the wind turbine's incurred moment and forces. The conclusion is that platform design should prioritize manufacturing costs and strength over maximizing hydrodynamic performance. [ABSTRACT FROM AUTHOR]

The accuracy of estimated sea conditions, specifically wave height and peak/average wave periods, affects the estimation of electrical energy production from wave energy converters. This study investigates the uncertainty in wave energy harvesting estimated by the SWAN wave model and determines possible improvements by adjusting the model's tunable parameters. Three different wave energy converters (OEBuoy, WaveBob, and Pontoon) and ten different locations along the Atlantic coast of the Iberian Peninsula are used in the study. The SWAN model is calibrated using the ST6 term package based on both wave height and peak period wave parameters. Different wave hindcast data produced by different model settings are used to estimate the wave energy produced by the wave energy converters at ten buoy locations and compared to wave energy produced estimated based on wave observations. The study finds that the physical settings of the SWAN model have a considerable influence on the uncertainty in the estimation of the power output produced by the device. The best-fitting calibrated model improved the mean energy output value of all locations compared to the SWAN default settings. The study concludes that adjusting the SWAN model parameters can improve the accuracy of the estimation of the energy output. • SWAN model calibration significantly improves wave resource accuracy. • ST6 physical source terms of the SWAN model were adjusted for the Atlantic coast of the Iberian Peninsula. • Estimation of wave power harvested can amplify wave resource uncertainties. • OEBuoy, WaveBob, and Pontoon WECs were used as case studies. • Calibration of the SWAN model corrected mean energy output by around 10% for the 3 considered WECs. [ABSTRACT FROM AUTHOR]

This study experimentally investigates a dynamic behavior of an end‐anchored floating bridge under the joint actions of earthquakes and water waves. A truncated model with a geometrical scale of 1:100 was utilized for the hydrodynamic test, and an actuator was used to generate the earthquake input. A series of trials were conducted for the floating bridge model under the combined action of two different sea states and three earthquake inputs with increasing intensity based on the concept of the incremental dynamic analysis method. For comparison, the dynamic responses of the floating bridge model under earthquake action in still water and pure wave action were also conducted. Based on the test data, the dynamic responses, particularly focused on the sway, heave, roll, and pitch motions of the pontoons, of the test model were experimentally analyzed. The experimental results showed that earthquake excitation along the longitudinal axis of the bridge girder would induce noticeable oscillation of the bridge pontoons in still water. The magnitude of the coupled effects of earthquakes and water waves is dependent on the intensity of the earthquake inputs and the sea state. [ABSTRACT FROM AUTHOR]

Floating photovoltaics (FPVs) have been developed rapidly in the past few years and will gradually become the "third pillar" of the photovoltaic industry. To better understand the performance of FPV floaters, this paper provides an in-depth study on the hydrodynamics of a single FPV module and the coupling effects of multiple modules. The results show that a conventional frequency domain approach, which includes both panel and Morison models, may not necessarily provide realistic results. Even after adding an additional damping matrix for the floaters based on empirical values from the oil and gas (O&G) industry, and a free surface damping model between the pontoons, the responses were still not convincing. Therefore, a nonlinear time-domain hydrodynamic solver was introduced. Further studies and comparisons were performed to understand the behavior of the module, and some updated damping coefficients were summarized. Thereafter, a multibody hydrodynamic model was built to check the coupling effects. With the additional damping surface on the gap surface among the modules, some attempts were made to derive reasonable results, when the model test was not available. Preliminary studies of both a scaled-down system (with 9 modules and mooring lines) and a full-scale system (with 90 modules, buoys, and mooring systems) were also investigated, and some initial results were demonstrated. [ABSTRACT FROM AUTHOR]

Marinas are known to act as species reservoirs, facilitating the persistence and spread of non-native species. Monitoring of marinas for non-native species is therefore an essential element of any integrated monitoring programme. Baseline and updated survey data are needed to understand the abundance, distribution and rate of spread of non-native species within marinas over time in order to support management strategies, develop applicable biosecurity measures and inform rapid response plans. Rapid assessment surveys (RAS) were employed to survey floating pontoons, as well as opportunistically survey intertidal structures, for non-native biofouling species in 22 marinas across the Republic of Ireland. A total of 25 nonnative species were recorded: 19 invertebrates and 6 macroalgae, with ascidians being the most represented group. Four non-native species not previously reported in published literature from the Republic of Ireland were recorded: devil's tongue weed, Grateloupia turuturu Yamada, 1941, the compass sea squirt, Asterocarpa humilis (Heller, 1878), the San Diego sea squirt, Botrylloides diegensis Ritter & Forsyth, 1917 and the branching bryozoan, Bugulina simplex (Hincks, 1886). Other species identified as part of this study and previously reported from Ireland were shown to have increased their range. [ABSTRACT FROM AUTHOR]

Research on the layout of large oil terminals under complex conditions in the Three Gorges Reservoir area plays an important role in improving the comprehensive transportation system in the Three Gorges Reservoir area. Based on the analysis of the characteristics of vertical and floating oil terminals, a new type of modular floating wharf is constructed according to the topographic, geological and hydrological conditions in the reservoir area. Through the engineering practice, the layout of a modular floating wharf is compared with that of a conventional floating wharf. The proposed layout of the new modular floating wharf can better adapt to various complex natural conditions such as large water level difference and steep terrain in the reservoir area and can effectively reduce the displacement of pontoons, adapt to various working conditions such as deep water anchoring, and effectively improve the safety of the oil terminal, thus providing reference for the design of large and medium size oil terminals with large water level difference in the reservoir area. [ABSTRACT FROM AUTHOR]

The determination of the long-term extreme distribution for a wave-loaded structure requires computing the second-order statistics of the responses and their time derivatives under various short-term sea states. In a spectral context, these statistics are typically obtained on a modal basis by integrating the power spectral densities of the corresponding responses over frequency. In this paper, a semianalytical approximation is developed for computing these integrals with the aim to reduce the computational cost of each short-term analysis. To do so, a state-space formulation is considered for the equations of motion, and the general framework provided by the multiple timescale spectral analysis is implemented. It hinges on the existence of distinct peaks in the integrands to express the variances and the covariances of the modal state responses as the sum of two components with simple expressions: the resonant and the loading component. New techniques are investigated to formulate them. For the former, the structural kernel is expanded in partial fractions while it is fitted by a monomial of a given degree for the latter. The resulting decomposition is validated on a minimalistic example first and is then verified on a simplified model inspired by the Bergsøysund Bridge, which is an actual floating pontoon bridge located in Norway. [ABSTRACT FROM AUTHOR]

The quagga mussel Dreissena rostriformis bugensis was identified in a horizon scan of species likely to arrive in Ireland. We report on the first records of this dreissenid from two lakes, a reservoir and interconnecting navigable river sections on Ireland's largest river, the Shannon, during July 2021. The abundance in Lough Ree was greater than in the larger downstream lake of Lough Derg. Specimens occurred to depths of 24 m and 32 m in each of these lakes respectively. Highest densities were in the southern region of Lough Ree attached to piles supporting floating pontoons and quay walls. Here D. r. bugensis outnumbered the D. polymorpha present. It was present at lower densities downstream to Lough Derg and the Parteen Reservoir. This species has a wide range of colour morphs from a pale yellow to dark concentric or longitudinal banding. [ABSTRACT FROM AUTHOR]

To study the problem of the dynamic responses of the damaged floating bridge, this paper establishes the numerical model of a nonlinearly connected floating bridge based on the Kane method. The accuracy of the numerical model is verified by comparing the results from relevant literature and the model test conducted. Subsequently, considering the damaged opening at the bottom of the pontoon, the impact of different vehicle speeds, opening sizes, as well as connection gaps between pontoons on the dynamic responses of the damaged floating bridge is studied. Some conclusions are obtained: The flooding brought by the damaged opening causes the rise in vertical displacements of the damaged pontoon and the forces on the connectors. The opening and closing of the longitudinal gaps affect the sinking speed of the damaged pontoon, and the size of the gap influences both the maximum sinking displacement and the vibration period of the floating bridge. The maximum vertical displacements of the damaged pontoon and the flow rate variation at the opening location increase as the opening size expands. Reasonable selection of vehicle speeds and connection gaps between pontoons can prevent excessive dynamic responses of the damaged floating bridge. [ABSTRACT FROM AUTHOR]

This study assessed PBDE congeners in surface water and sediment from the Buffalo River estuary, East London, South Africa. Samples were collected across three seasons in 2020 and analyzed using GC–MS and GC-μECD to respectively identify and quantify analytes. The concentration of ∑ 6 PBDEs in the surface water and sediment ranged from n.d. to 0.947 μg/L and from 1.87 to 2554 ng/g (dw), respectively. We found the relative abundance of the congeners in water and sediment to be in this order: BDE-66 (36 %) > BDE-100 (25 %) > BDE-17 (21 %) > BDE-183 (9 %) > BDE-153 (6 %) > BDE-47 (3 %) and BDE-66 (26 %) > BDE-100 (23 %) > BDE-17 (18 %) > BDE-47 (15 %) > BDE-153 (10 %) > BDE-183 (9 %) respectively. The ecological risk assessment reveals that the risk quotient, RQs, of BDE-100 (85.1), BDE-47 (2.1) and BDE-183 (1.1) for surface water and BDE-47 (229606), BDE-153 (1192) and BDE-100 (141) for surface sediment were all significantly higher than one, indicating high ecological hazards for both water and sediment-dwelling organisms. The point sources of PBDE pollution were the First and the Second Creek, which regularly carry residential and industrial effluents into the estuary. Sediment under the Pontoon Bridge is the most polluted due to non-point sources. Regular dredging of the estuary is highly recommended to reduce the levels of PBDEs in the sediment. [Display omitted] • The surface water and surface sediment from BRE are moderately polluted. • BDE-66 is the dominant congener in both water and sediment. • Both pelagic and benthic organisms are at high ecological risk levels of BDE-47 and BDE100. • The First and Second Creeks as well as the overhead Pontoon bridge are the primary sources of PBDEs pollution. [ABSTRACT FROM AUTHOR]

This article discusses developing a methodology based on visual inspection for quantifying bridge damage (WABIM). The proposed methodology was developed through the application of weighted averages and a case study. Many current visual inspection methodologies, manuals, or guides related to bridges only allow qualitative results to be determined. Consequently, a high degree of inefficiency and inaccuracy was identified in the results from traditional methodologies; since they have a subjective approach, the results merely depend on the observer. Therefore, a methodological proposal was generated that allowed qualitative results to be described quantitatively, increasing the objectivity of the analysis and the accuracy of bridge maintenance plans. Rating ranges are used with weighted averages for each pathology, applied directly to the structural elements of the bridges. The classification guidelines and pathologies of bridge structures are adapted according to the Manual for the Visual Inspection of Bridges and Pontoons of Invías, Colombia. The case study was developed on a bridge in the city of Pereira, Colombia, presenting more significant surface deterioration and equipment deterioration. The WABIM methodology identified that periodic maintenance is required and the intervention's emphasis. [ABSTRACT FROM AUTHOR]

Floating pontoons have played a supreme and indispensable role in crises and disasters for both civil and military purposes. Floating bridges and ferries are exposed to blast loadings in the case of wars or terrorist attacks. The protection effectiveness of sacrificial cladding subjected to a blast was numerically investigated. In this study, a steel ferry has been simulated and exposed to side explosions with different explosive charges at certain stand-off distances, according to military standards from NATO and American standard TM5. In this simulation, nonlinear three-dimensional hydro-code numerical simulation ANSYS autodyn-3d has been used. The results reported that the ferry could withstand a charge of 5 kg TNT at a stand-off distance of 1 m without failure. The main objective of this research is to achieve a design that would increase the capacity against the blast loading with minimal plastic deformation in the absence of any failure in the ferry. Therefore, an innovative mitigation system has been proposed to dissipate the blast energy of the explosion based on the scientific theory of impedance using sacrificial cladding. The new mitigation system used a specific structural system in order to install the existing pontoon structure without any distraction. The response, elastic deformations, plastic deformations and plastic failure of the ferry were illustrated in this paper. Furthermore, the results revealed that the proposed mitigation system could mitigate more than 50% of the blast waves. The new design revealed promising results, which makes it suitable for mitigating blast waves. Finally, the results were provided with a reference for the preliminary design and application of sacrificial cladding for structural protection against blast waves. [ABSTRACT FROM AUTHOR]

Based on the construction of the Heishui River Bridge during the reconstruction of National Highway G353 in Ningnan County, a supporting project of Baihetan Hydropower Station, the paper presents the research on the bridge construction technology to convert land-based construction to over-water construction of piers for the continuous rigid frame bridge located in a mountainous reservoir. After comparison of pontoon bridges with cable cranes and catwalks, the "pontoon bridge" proposal was selected and accepted, with the pontoon bridge made up of fabricated polythelene pontoons together with a floating platform, a transfer construction elevator and tower cranes. The results show that the "pontoon bridge" proposal had advantages in construction under such special working conditions, and may provide reference for similar projects. [ABSTRACT FROM AUTHOR]

Piled floating pontoons are public access structures that provide a link between land and sea. Despite floating pontoons being frequented by the public, there is limited data available to coastal or maritime engineers detailing the dynamic motions (acceleration and rotation) of these structures under wave action and the impact of these motions on public comfort and safety to inform their design. This contribution summarises results from a set of laboratory-scale physical model experiments of two varying beam width piled floating pontoons subjected to boat wake conditions. Observed accelerations and roll angles were dependent on beam-to-wavelength ratio (B/L), with the most adverse motion response observed for B/L ~0.5. Internal mass of the pontoon played a secondary role, with larger mass structures experiencing lower accelerations for similar B/L ratios. Importantly, these new experimental results reveal the complex interaction between the piles and pontoon that result in peak accelerations more than six times the nominated operational safe motion limit of 0.1g. Root mean square (RMS) accelerations were more than three times the nominated comfort limit (0.02g) and angles of rotation more than double what would be perceived as safe (6 degrees) for the boat wake conditions tested. The frequency of acceleration also suggests patrons standing on these platforms are likely to experience discomfort and instability. Laboratory results are compared against a series of field-scale experiments of pontoon motion response and patron feedback. The dynamic motion response of pontoons tested in both field-scale and laboratory experiments compared well. [ABSTRACT FROM AUTHOR]

The focus of this paper is to investigate the damage characteristics and protective structure design of pontoons as an important barrier for the protection of ports. Two types of protective measures of pontoons are investigated: filling tanks with water and installing springs in tanks. In this paper, the damage characteristics of two types of pontoon side structures under the action of near-field explosion loads are simulated by using LS-DYNA explicit dynamic analysis software and the ALE algorithm. According to the numerical experiment results for filling different volumes of water in the side tanks, the volume of water for the minimum deformation of the shell plate is 100%, and for the first longitudinal bulkhead, it is 30-40%. Moreover, by applying weights to their deformations based on the actual explosion-proof performance requirements of the shell plate and the first longitudinal bulkhead, the pontoon side structure with the best explosion-proof performance can be obtained. The plastic deformation of the pontoon structure equipped with different types of springs is an order of magnitude smaller than that of the ordinary structure and of the pontoon structure filled with a water medium in the positive tanks. The explosive shock wave energy absorbed by the pontoon is effectively reduced by the addition of water or springs to the protective tanks. The minimum energy absorbed by the pontoon structure with water added in the protective tanks is 18.31% of the energy absorbed by the ordinary structure, and the corresponding volume ratio of water added in the protective tanks is 100%. The pontoon structure with springs in the side protection tanks absorbs only 7.2% of the energy absorbed by the ordinary structure. Both new side protection structures have demonstrated excellent explosion-proof performance. [ABSTRACT FROM AUTHOR]

Telescopic water intake structures play an important role in a water management system. The article is devoted to the improvement of telescopic water intake structures and the development of a solution for regulating their operation. Different types of water intakes are analyzed, and their shortcomings are identified. The structures of known telescopic water intakes are reviewed, and their operating principles are analyzed. It has been determined that the design of existing telescopic water intake structures lacks a device for stopping the operation of the intake of water. A structural solution for stopping and regulating the operation of a telescopic water intake is proposed. The construction of an additional ballast pontoon to be welded to the first section of the telescopic pipeline is proposed in order to regulate and stop the operation of the water intake. A methodology for calculating and designing an additional ballast pontoon for a telescopic water intake has been developed, and a specific example for its implementation has been provided. Based on the results of the research, the main parameters of the additional ballast pontoon structure have been established, and the methodology for its calculations has been developed. [ABSTRACT FROM AUTHOR]

Simple Summary: Relocation of endangered freshwater cetaceans in natural reserves is an effective conservation strategy to recover their populations. However, due to historical reasons, some natural reserves have facilities that cannot be removed, such as water intake pontoons that are important for residents nearby. These facilities generate underwater noise which may affect cetaceans. To investigate the potential impacts of underwater noise from water intake pontoons on freshwater cetaceans, this study measured such noise within a Yangtze finless porpoise (Neophocaena asiaeorientalis) nature reserve, analyzed its effects on porpoise behavior, vocalization, and hearing, and explored porpoise adaptation to the transient holding pen environment. This study provides a reference for assessing whether human facilities have impacts on freshwater cetaceans. Underwater noise pollution caused by human activities may affect freshwater cetaceans to different degrees. To analyze the impacts of water intake pontoons on Yangtze finless porpoises (Neophocaena asiaeorientalis), this study collected underwater noise data from such a pontoon in a nature reserve, plotted the power spectral density of acoustic signals, and calculated the root mean square sound pressure levels and the magnitude of sound source levels. The 1/3-octave sound pressure level root mean square values at the transient holding pens were <18.0 kHz, 39.5−60.0 kHz, which were slightly higher than the Yangtze finless porpoise hearing threshold curve values and therefore could be perceived. However, the results indicated that the porpoises would not develop a temporary hearing threshold shift. Meanwhile, pontoon noise did not interfere with the porpoises' high-frequency acoustic signal nor did it affect their echolocation; it significantly interfered with their low-frequency acoustic signal, however, and the mother–child communication of the finless porpoises was affected, but this effect was quickly compensated due to the limited space range of the holding pens. Through this study of Yangtze finless porpoises, this paper provides a reference for assessing whether human facilities have impacts on freshwater cetaceans. [ABSTRACT FROM AUTHOR]