artificial structures
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2022 ◽  
Vol 19 (4) ◽  
pp. 22-33
Author(s):  
N. M. Kvashnin ◽  
I. S. Bondar ◽  
M. Ya. Kvashnin

Reliability of transport artificial structures and transit of trains at sanctioned speed should be provided with the necessary and sufficient load-bearing capacity, strength, rigidity, and stability of engineering structures.The objective of this work was to substantiate the possibility of using well-known methods for controlling the stress-strain state of structures using automated systems of structural health monitoring of bridge spans.It is extremely important regarding operation of transport artificial structures designed according to the standards of the first half of the 20th century.Under these conditions, the experimental determination of the stress-strain state of bearing structures of bridges becomes the most important component of the task of a comprehensive assessment of physical wear and tear as well as of operational reliability of the structures. Monitoring the structural health and technical condition of bridges and planning of timely measures aimed at the repair, strengthening or reconstruction of spans will extend their service life and ensure safety during operation.Maximum permissible deflections of spans under a movable temporary vertical load have been revealed since to ensure smooth movement of vehicles it is necessary to control horizontal longitudinal and transverse displacements of the top of the bridge piers, as well as vertical settlements.The paper suggests methods of interpreting data measured by inclinometers and electric strain gauges, tensiometers to use them in an automated system for monitoring the structural health of railway bridges. The method of strain measurement is described in detail in the proposed options for installing resistance strain gauges on structures to measure tensile-compression stresses and longitudinal forces due to a temporary vertical load.Monitoring the technical condition of bridge structures, using the methods for measuring deflections and deformations proposed by the authors in this article, will make it possible to assess the change in bearing capacity of the structure over the entire period of operation. The study used regulations and experience of the Russian Federation and the Republic of Kazakhstan. 


2022 ◽  
Author(s):  
E. Ortega-Jiménez ◽  
F. Sedano ◽  
F. Espinosa

AbstractMollusc communities are getting endangered in the aftermath of urban sprawl because artificial structures do not surrogate natural substrates. In this study, we compared the diversity, community and trophic arrangements of molluscs among different models of artificial substrate and their adjacent natural rock, to detect relationships between some abiotic variables and the mollusc communities. Complexity, chemical composition and age were tested as potential drivers of the community. Diversity, community and trophic structure differed between natural and artificial substrates. Complexity at the scale of cm was detected as the most important factor driving the community structure. In addition, a chemical composition based on silica and/or scarce calcium carbonates seems to be relevant for molluscs, as well as for the secondary substrate where they inhabit. However, age did not seem to be a driving factor. Among the different artificial structures, macroscale complexity was detected as the main factor diverging a drastically poor community at seawall from other artificial structures. In this context, macro and microscale complexity, chemical composition and mineral type are variables to consider in future designs of artificial substrates.


2021 ◽  
Vol 9 (12) ◽  
pp. 1377
Author(s):  
Yuichi Preslie Kikuzawa ◽  
Chin Soon Lionel Ng ◽  
Shu Qin Sam ◽  
Tai Chong Toh ◽  
Koh Siang Tan ◽  
...  

Accelerated urbanisation has replaced many natural shorelines with coastal defences, resulting in the loss of natural habitats. However, structures such as seawalls can support some biotic assemblages, albeit of lower species richness. Ecological engineering techniques such as coral transplantation can enhance biodiversity on these artificial structures, but its success is circumscribed by high costs. Little is known about the fusion of discrete coral colonies that could potentially improve coral transplantation success on seawalls, particularly for the slow-growing massive species that are generally well-adapted to living on seawalls. Here, we investigated the feasibility and cost-effectiveness of transplanting Platygyra sinensis on seawalls by comparing the survivability and growth of fragments transplanted adjoining with those transplanted further apart. Fragments (approximately 3 cm diameter; n = 24) derived from three individuals were randomly grouped into two treatments, transplanted at 0.5 cm and 5 cm apart. Fragments in the former treatment came into contact with each other after three months. We observed that in all cases, the contact zones were characterised by a border of raised skeletal ridges without tissue necrosis, often termed nonfusion (=histoincompatible fusion). The adjoining transplants showed better survival (75 vs. 43%) and grew at a rate that was significantly higher than fragments transplanted 5 cm apart (3.7 ± 1.6 vs. 0.6 ± 1.1 cm2 month−1). Our projections demonstrated the possibility of reducing transplantation cost (USD cm−2) by 48.3% through nonfusion. These findings present nonfusion as a possible strategy to increase the overall cost-effectiveness of transplanting slow-growing massive species on seawalls.


2021 ◽  
Vol 173 ◽  
pp. 113058
Author(s):  
Adriana Gracia C. ◽  
Jeferson Durán-Fuentes ◽  
Nadiezhda Santodomingo ◽  
Nelson Rangel-Buitrago

2021 ◽  
Author(s):  
Elena Ortega-Jiménez ◽  
Francisco Sedano ◽  
Free Espinosa

Abstract Mollusc communities are getting endangered as a result of urban sprawl because artificial structures do not surrogate natural substrates. In this study, we compared diversity and community and trophic structures of molluscs among different models of artificial substrate and its adjacent natural rock, to detect relationships between some abiotic variables and the molluscs community. Complexity, chemical composition and age were tested as potential drivers of the community. Diversity, community and trophic structure differed between natural and artificial substrates. Complexity at the scale of cm was detected as the most important factor driving community structure. Besides, a chemical composition based on silica and/or scarce calcium carbonates seems to be relevant for molluscs, as well as for the secondary substrate where they inhabit. However, age did not seem to be a driving factor. Among the different artificial structures, macroscale complexity was detected as the main factor diverging a drastically poor community at seawalls from other artificial structures.


2021 ◽  

Ocean sprawl is the proliferation of engineered artificial structures in coastal and offshore marine environments. These include ship hulls; infrastructure associated with land reclamation and urbanization (e.g., seawalls, bridges, floating docks); fisheries (artificial reefs, aquaculture installations); coastal defence structures (e.g., breakwaters, groynes); resource extraction (oil and gas rigs, renewable energy devices); and shipwrecks. Only fixed permanent and semipermanent structures are considered here and ship hulls are not included. Single structures can scale up with dramatic consequences for the local environment. Extreme examples of this include: the “New Great Wall” of China—seawalls enclosing coastal wetlands covering 60 percent of the total length of the Chinese coastline; “The World”, Dubai—an archipelago of over three hundred artificial islands constructed in the shape of a world map; and the “Steel Archipelago,” which describes more than four thousand oil and gas structures in the Gulf of Mexico. The placement of these fixed artificial structures modifies the local physical and chemical environment with cascading impacts on the composition, functioning, and service provision of surrounding species, habitats, and ecosystems. These structures also provide novel habitat which can offer surface for attachment, food, and protection for myriad marine species. They can act as fish aggregating devices, attracting fishing and other human activities. These structures may also have wide-reaching impacts through acting as barriers or conduits to ecological connectivity—the movement of organisms, materials, and energy between habitat units within seascapes. An improved understanding of the biological communities associated with artificial structures, coupled with the global drive for sustainable development, is driving an explosion of research into the design of multifunctional structures with built-in secondary ecological or socioeconomic benefits. Results to date have been promising but greater integration of the fields of ecology, engineering, and social sciences is necessary to better connect theory and practice in this emerging discipline.


2021 ◽  
pp. 24-28
Author(s):  
Т.А. Диканова

Рассматривается проблема приведения в нормативное состояние мостов и путепроводов на автодорогах. Приводятся нарушения, связанные с ненадлежащим содержанием и контролем за содержанием этих объектов, а также анализ нормативных правовых актов и предложения по устранению нарушений. The article deals with the actual problem of bringing bridges and overpasses on highways into a normative state; the violations identified by the regulatory authorities related to the improper maintenance and control over the maintenance of these artificial objects are presented, the analysis of regulatory legal acts regulating this maintenance and control is given, proposals for eliminating violations are given.


2021 ◽  
Vol 8 ◽  
Author(s):  
Grant Hopkins ◽  
Ian Davidson ◽  
Eugene Georgiades ◽  
Oliver Floerl ◽  
Donald Morrisey ◽  
...  

The number, extent, diversity, and global reach of submerged static artificial structures (SSAS) in the marine environment is increasing. These structures are prone to the accumulation of biofouling that can result in unwanted impacts, both immediate and long-term. Therefore, management of biofouling on SSAS has a range of potential benefits that can improve structure functions, cost-efficiency, sustainability, productivity, and biosecurity. This review and synthesis collates the range of methods and tools that exist or are emerging for managing SSAS biofouling for a variety of sectors, highlighting key criteria and knowledge gaps that affect development, and uptake to improve operational and environmental outcomes. The most common methods to manage biofouling on SSAS are mechanical and are applied reactively to manage biofouling assemblages after they have developed to substantial levels. Effective application of reactive methods is logistically challenging, occurs after impacts have accumulated, can pose health and safety risks, and is costly at large scales. Emerging technologies aim to shift this paradigm to a more proactive and preventive management approach, but uncertainty remains regarding their long-term efficacy, feasibility, and environmental effects at operational scales. Key priorities to promote more widespread biofouling management of SSAS include rigorous and transparent independent testing of emerging treatment systems, with more holistic cost-benefit analyses where efficacy is demonstrated.


Oceans ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 634-647
Author(s):  
Kara Noonan ◽  
Thomas Fair ◽  
Kristiaan Matthee ◽  
Kelsey Sox ◽  
Kylie Smith ◽  
...  

Throughout the Caribbean, coral reefs are transitioning from rugose, coral-dominated communities to flat, soft coral-dominated habitats, triggering declines in biodiversity. To help mitigate these losses, artificial structures have been used to re-create substrate complexity and support reef inhabitants. This study used natural and artificial structures to investigate the factors influencing the use of habitat by reef fish. During 2018 and 2019, divers added artificial structures and monitored the fish assemblages associating with both the artificial structures and naturally occurring corals. Overall, there were more fish on natural structures than on artificial structures. While structure shape did not influence fish use, there was a non-significant trend for increased use of larger structures. Fish observations did not differ across a gradient of shallow, complex reefs to deeper, flatter reefs; however, analyses of feeding guilds revealed clearer patterns: herbivores and omnivores were positively associated with low rugosity reefs where macroalgal abundance was higher, whereas invertivores preferred more rugose reefs. These results suggest that as reefs lose structural complexity, fish communities may become dominated by herbivores and omnivores. It also appears that the addition of artificial structures of the type used here may not mitigate the effects of structure loss on reef fish assemblages.


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