Snow Load Research Articles

Collapse Behavior of Pipe-Framed Greenhouses with and without Reinforcement under Snow Loading: A 3-D Finite Element Analysis

Collapse Behavior of Pipe-Framed Greenhouses with and without Reinforcement under Snow Loading: A 3-D Finite Element Analysis

Eurocode-compliant system-level reliability analyses of trussed portal frames under climatic loads

Eurocode 3 provides Geometrically and Materially Nonlinear Analysis with Imperfections-method (GMNIA) in which the entire structure can be designed in system-level. In GMNIA, reliability of structural system is verified by using a system safety factor which is obtained in Eurocode 3 based on numerical or experimental capacity test results. Unfortunately, such test results are scarcely published in the literature thus complicating the determination of the factor for a design engineer. In the so-called Direct Design Method, however, system safety factors are provided in advance for the design engineer by system-level reliability studies. This study determines the Eurocode-compliant GMNIA system safety factor for Warren truss portal frames by using the approach of the Direct Design Method. Advanced numerical models are utilized to perform Monte Carlo-simulations for entire structural systems. These simulations provide statistical distributions of system resistances which are employed in the First-Order Reliability Method to derive the system safety factors. Studied structures are made of S700 cold-formed hollow sections. Various system geometries, system configurations and load combinations consisting of snow and wind loads are investigated and a suitable system safety factor is proposed for the ultimate limit state design of Warren truss portal frames. The proposed system safety factor is applied in a practical comparison in which Warren system is designed both by the conventional Eurocode 3 method and GMNIA. This comparison reveals that GMNIA has a remarkable potential to offer reduced material consumption in design compared to the conventional method.

Methodology for selecting the method of mirror antenna protection in SHF-EHF bands from meteorological precipitations

Exhaustion of SHF band capabilities in the organization of space communication channels necessitated the transition to the lower part of the EHF band (up to 95 GHz). At the transition stage space channel antennas function in the dual frequency range. This leads to the fact that the methods of protection of ground sector mirror antennas from the impact of meteorological factors should take into account the peculiarities of propagation of millimeter-wave radio waves in the layer of precipitation that can occur in the antenna reflector. For a scientifically justified choice of the method of protection there should be a methodology that allows taking into account both electrodynamic peculiarities of propagation of radio waves of SHF and EHF ranges, and meteorological peculiarities of the antenna location. The latter determines the relevance of the proposed research topic. The objective of the article is ensuring minimum power losses and fulfillment of the rain unavailability index of the mirror antenna of the SHF-EHF wavelength bands of space communication channels by means of a reasonable choice of the method of protection against the impact of meteorological precipitation characteristic of the antenna location. It has been shown that the functioning of mirror antennas of satellite ground stations in the dual frequency range of SHF-EHF makes it obligatory to take into account the peculiarities of propagation of millimeter-wave range waves in water formations when choosing methods of protection from the effects of meteorological precipitation. The most important of these features is the increase in energy losses of millimeter-wave radio waves in the layer of water formations, the thickness of which becomes comparable to the wavelength. In addition, the methods of antenna protection should also take into account the peculiarities of digital communication lines, in particular, the fulfillment of an additional requirement (rain readiness index), assuming the restoration of the operating state of the reflector within a time of up to 10 s. The above features allowed us to formulate a criterion for a scientifically justified choice of the method of protection of the antenna of dual frequency range. The developed methodology for selecting the method of protection of the mirror antenna of the dual wavelength range is based on the theory of meteorological electromagnetism. This allows not only modeling the radio wave energy losses in the layer of precipitation taking into account strict electrodynamic models, but also assigning the parameters of the layer of water formations (thickness, type of precipitation) taking into account the climatic features of the location of the mirror antenna. Thus, the developed method provides the following algorithm for selecting the method of protection. By geographic coordinates the climatic region of antenna location is determined. For abnormal climatic regions (temperature from ‑60° to +50°, wind force up to 70 m/s, snow load up to 250 kg/m3) the application of radio transparent shelter (radome) is an alternative protection method. For other climatic regions the choice of the method of protection of the mirror antenna implies three steps: 1) estimation of energy losses in the precipitation layer on the antenna reflector at refusal of protection methods (maximum possible losses); 2) calculation of the complex criterion; 3) selection from the proposed table of the method that most fully satisfies the criterion and is the most effective for the climatic region of antenna placement. The proposed methodology allows on a scientific basis to choose the method of protection of mirror antennas of the dual frequency SHF-EHF range taking into account the meteorological features of the climatic region of its location.

Analiza wpływu obciążeń falowych na instalacje morskie

Given that the loads affecting offshore installations exhibit a broad range of variability in both temporal and spatial parameters, these loads are among the least studied components in the consideration of offshore installations as integrated systems. The existing calculation models and approaches used in design are rather conditional. When determining loads affecting offshore installations, the most common error is the description of loads in terms of time parameters, which lead to a distortion of the dynamic behavior of offshore installations. This is primarily because dynamic effects on the structure clearly demonstrate feedback between the influence of loads and the system itself. These loads can be classified as external and internal. Internal loads include loads from installation and construction processes, as well as loads from auxiliary and technological equipment, and external loads include ice, seismic, snow and wind loads. There are several approaches to solving problems related to the impact of wind waves on offshore installations. For this reason, an analysis and comparison of these methods were conducted to improve modeling process of offshore installations. Taking into account the impact of wave loads is a critical aspect of in developing the calculation model for the operational assessment of the residual resource of offshore installations.

Snow loads on multi‐span roofs

AbstractSnow loads have an important influence, particularly on the design of lightweight steel structures. For multi‐span roofs, local drift surcharges and global drift losses play a central role. During the review of the snow load distribution for multi‐span roof according to prEN 1991‐1‐3:2023, 7.5.4, attention was only given to minor changes of the shape coefficients. The inconsistency of shape coefficients and more importantly their limitations, trends and the resulting snow loads seem to have been neglected. Partly, problems have been inherited from the regulation in the first generation of the Eurocode EN 1991‐1‐3:2010, 5.3.4. The currently reviewed draft prEN 1991‐1‐3:2023 is insufficiently revised. In this paper, the background for the snow load distribution on multi‐span roofs is given, the impact and consequences of the regulation are shown and possible improvements proposed.

Concept and Life Cycle Assessment of a Tiny House Made from Root Section Structures of a Decommissioned Large-Scale Wind Turbine Blade as a Repurposed Application

With the green energy transition, the wind industry has grown rapidly in recent decades. Wind turbine blades (WTBs) are primarily manufactured from glass fibers and thermoset matrix composites. Considering their lifetime from 20 to 25 years, significant amounts of wind turbine components will eventually enter the global waste stream. Currently, recycling is not sufficiently optimized and commercially available. Other strategies, such as repurpose, are becoming relevant to divert components from waste streams. This research explores a pathway to sustainable repurposing of decommissioned WTBs. The concept of a tiny house constructed from the root section of a 5 MW/61.5 m WTB is presented (“5 MW house”). The deformations and stresses of the repurposed composite structures were investigated using a finite element analysis based on the three load cases, defined by (1) a combination of snow load and payload, (2) a combination of wind load and payload, and (3) a thermal stress analysis of a critical temperature distribution of the 5 MW house. Furthermore, a life cycle assessment (LCA) was conducted to evaluate the environmental impacts of the proposed concept. The numerical analysis results showed that the 5 MW house can withstand the applied loads, and that the deformations are within acceptable limits. A reduction of up to 97% in environmental impacts for most impact categories was calculated, compared to a wooden tiny house, whereas climate change, ozone depletion, and eutrophication potential were up to 3.7 times higher, mainly due to the weight and composition of the 5 MW house. The authors believe that the proposed concept may be a high-volume repurposed solution for large-scale WTB root sections.

Wood- and Cable-Based Variable Tilt Stilt-Mounted Solar Photovoltaic Racking System

The prohibitive costs of small-scale solar photovoltaic (PV) racks decrease PV adoption velocity. To overcome these costs challenges, an open hardware design method is used to develop two novel variable tilt racking designs. These are the first stilt-mounted racking designs that allow for the manual change of the tilt angle from zero to 90 degrees by varying the length of cables. The racks are designed using the calculated dead, wind, and snow loads for Canada as a conservative design for most of the rest of the world. Structural capacities of the wooden members are then ascertained and the resisting bending moment, shear force, tensile force, and compressive force is calculated for them. A structural and truss analysis is performed to ensure that the racking design withstands the applicable forces. Moreover, the implications of changing the tilt angle on the wooden members/cables used to build the system are also determined. The systems offer significant economic savings ranging from one third to two thirds of the capital expenses of the commercially available alternatives. In addition, the racking designs are easy-to-build and require minimal manufacturing operations, which increases their accessibility. The stilt-mounted designs can be employed for agrivoltaic settings while allowing farm workers shaded, ergonomic access to perform planting, weeding, and harvesting.

Adapting to climate change: snow load assessment of snow galleries on the Iron Ore Line in Northern Sweden

The snow galleries along the Iron Ore railway line in northern Sweden have faced problems in recent years due to increasingly large snow loads, and several galleries have been damaged. These incidents motivated an evaluation of the maximum load supported by the galleries before collapse, which is presented in this study. In 2021, a monitoring system was installed in one of the main frames of two snow galleries built in the 1950s to follow up with temperature and displacements, including a trigger that sends out a warning message when a critical load is reached. A literature review on snow loads was performed, followed by calculations on snow distribution on the galleries based on the Eurocodes and National Swedish Standards. Finite element 2D and 3D models were created using AxisVM to accurately assess the efforts in the structural elements. Analysis and discussion are complemented by observations from site visits. It was concluded that the critical loads supported by the galleries are lower than the requirements of today’s standards, but since secondary construction elements were damaged before the main frames reached their full capacity, no major collapse has yet taken place. The cobweb effect (load re-distribution between the neighboring elements in a 3D structure) influenced the behavior of the galleries in the 3D analysis and the capacity of the main frames proved to be significantly increased compared to the 2D assessment.

Аналіз тенденцій довготривалих змін кліматичних навантажень

The purpose of the work is to identify changes in the characteristic values of loads from snow and wind over the past decades, as well as to justify the need to take these changes into account when developing load standards for buildings and structures. Characteristic values of wind pressure are determined by the probabilistic model of a random process. The necessary parameters of the Weibull distribution for 13 weather stations of Ukraine are determined by the histograms of the distribution of the results of wind speed measurements obtained in three different periods of meteorological observations during the years 1961...2020. The characteristic values of the snow load are determined by the probabilistic model of the sequence of annual maxima with the Gumbel distribution. For this purpose, the average values and standards of the annual maximum snow cover weight at 54 weather stations, obtained from the results of snow measurement surveys in three different observation periods during 1950...2020, were used. According to the data of each weather station, the rates of characteristic values of loads change over time are determined. Characteristic values of wind pressure at 11 weather stations out of 13 that were considered decrease by an average of 4.5 Pa/year. For two weather stations, the intensity of the decrease is much greater and equals to 13.4 Pa/year and 25.6 Pa/year. At 41 weather stations out of 54 studied, a decrease in the characteristic values of snow cover weight is observed, and at 13 weather stations, the snow load increases over time. Annual increases in the characteristic values of the weight of the snow cover vary within the range of -22...+25 Pa/year with an average decrease of 4.5 Pa/year. As a result of the study, it was found that the significant spread of the rates of change of the characteristic values of loads over time at different weather stations does not allow to generalize this indicator on the territory of Ukraine. In the presence of several groups of data, it is recommended to determine the characteristic values of wind and snow load through the statistical characteristics of wind speed and weight of snow cover, averaged over the data of all available periods of meteorological observations, without taking into account the detected changes in time.

Glass-basalt-plastic materials for construction in temperate and Arctic climatic regions

This article reviews the increasing attention towards glass-basalt-plastic materials in engineering projects within Arctic and temperate climates. Comprising glass-reinforced plastic and basalt fibers, these materials offer strength, lightness, and corrosion resistance, addressing challenges posed by extreme temperatures and harsh weather conditions. Glass-basalt-plastic constructions demonstrate high resistance to low temperatures, making them effective in enduring extreme cold while maintaining structural integrity. Additionally, their high mechanical strength renders them ideal for buildings in windy and heavily loaded areas, crucial in regions with high wind speeds and snow loads. The materials' corrosion resistance further allows usage in marine environments and severe weather conditions. Despite their proven reliability and effectiveness, there is insufficient research on the strength and durability of glass-basalt-plastic materials under various operational conditions. This study aims to provide a comprehensive overview and analysis of the current challenges associated with the use of these materials in construction within temperate and Arctic climatic regions. By exploring potential advantages, applications, and existing research, this article aims to offer engineers and designers insights for informed decision-making. Simultaneously, it may serve as a foundation for further technical advancements and the development of new manufacturing methods, enhancing the efficacy and expanding the application scope of glass-basalt-plastic materials.

Adaptive Mapping of Design Ground Snow Loads in the Conterminous United States

Adaptive Mapping of Design Ground Snow Loads in the Conterminous United States

Structural and Load Analysis of the Belgian Atomic Tower

In order to study the service life of the building and its variable factors, the material composition of the building is analyzed with the example of the Atomic Tower in Belgium. At the same time, in order to study the variable load factors on the building more carefully, the transfer of load on the atomic tower is first analyzed, and then the analysis of wind load, snow load, geometry and dead weight on the Atomic Tower in Belgium is analyzed. In addition, in order to ensure the accuracy of the experiment, the phenomenon that the experiment may fail is analyzed. lognormal distribution is used to show the experimental process. Finally, it is concluded that snow load and wind load are the main variables affecting the stability of the Atomic Tower in Belgium. Moreover, the influence of materials may reduce the limit that the building can withstand due to oxidative corrosion, leading to instability.

Accidents With Oil Spills Triggered by Natural Hazards

In addition to direct social and economic damage, natural hazards also have a devastating impact on technological facilities, which may trigger accidents at these infrastructures. Especially dangerous consequences for the population and the environment are caused by such natural hazard triggered technological accidents (Natechs), which may result in the release of various hazardous chemical substances including mineral oil. This paper analyzes Natech accidents involving spills of oil and oil products. The materials of the author’s database of technological and natural hazard triggered technological accidents occurred in Russia since 1991 are used as initial information for the analyses. The types of natural hazards and adverse natural phenomena that caused accidents with oil spills on the territory of Russia in 1991-2021 are identified. Natechs make up about 6% of all accidents with oil spills. The main triggers of these accidents are hydrological and meteorological hazards such as strong winds, storms, floods, melt waters, rainfalls, lightning, snow loads, and heat wave, as well as landslides and other ground movements. Earthquakes caused the largest damage, but they are less frequent events in Russia. More often, mineral oil leaks occur as a result of ship accidentsor the destruction of oil storage facilities and pipelines. The regions of the greatest risk of accident occurrences with oil spills in Russia are identified.

Finite element analysis of a light-frame wood panelized gable roof

This paper presents a three-dimensional (3D) finite-element analysis of a light-frame wood panelized gable roof. The study developed equivalent macro elements representing the major roof components, such as the roof panel and support wall, in the finite-element model (FEM) by utilizing analytical models of the diaphragm and shear wall of CSA 086–19. The most critical load response of the panelized roof structure was obtained by considering the governing load cases, including the partial load case for snow load. The load path analysis revealed that the panelized roof had a two-way load distribution due to the deep beam action of the support wall. The gable ends of the roof carry approximately one-third of the load. In the gravity load case, the in-plane shear governed the connection design at the eave and support wall lines. Self-tapping screws were very effective in resisting wind uplift forces due to their high withdrawal capacity. Furthermore, the deflection pattern of the ceiling joist revealed the effect of panelized construction on the load path.

Influence of the size of the upper ring on the stressed state of the ribbed-ring metal dome

Studies of several metal ribbed-ring large-span domes on computer models have been carried out. All elements of the dome frames are made of steel I-beams. The dome frames have the same number of ribs and rings, but they have different size of the upper ring. The frame elements cross-sections are oriented normally to the dome surfaces, with the exception of the upper ring. The joints of the frame elements with each other are assumed to be rigid in the normal direction and hinged in the tangential direction. The frames are mounted on support nodes at the level of the lower ring pivotally. All the domes are subjected to the same nodal loads from the weight of the enclosing structures and the weight of snow. The snow load is assumed to be asymmetrical, located only on one side of the dome. Under the combined action of these loads, the dimensions of the upper ring of the domes influence the stress-strain state of their frames. As a result of the research, graphs have been generated representing the stress level in the meridional ribs and in the upper rings of the domes. The conclusion has been made that the stress state of metal dome frames depends on the size of the upper ring. The necessity of increasing the cross-section of the upper ring with an increase in its size has been noted.

Modified FAE method based on CFD simulation for predicting snowdrift on gable roofs

In cold and snowy regions, roof slopes can affect the snow distribution on the gable roof. The finite area element (FAE) method is modified by considering the effect of the snow transport rate, the developmental law of snow transport and the saturated transport distance on the calculation of drifting snow load in this paper. Saltation and suspension of snow transport are also considered respectively in the process of modification. Then, based on the modified FAE method and computational fluid dynamics (CFD), the influence of roof slopes (10°, 20°, 30° and 40°) on the gable roof snow distribution is studied. Meanwhile, for compare the simulation results of the modified FAE method with different combinations of the snow transport rate, the developmental law of snow transport and the saturated transport distance, the test of wind-blown snow redistribution is completed in the wind tunnel using the substitute particles (silica sand) on the scaled gable roofs. The results show that when the saturated transport distance of snow is 210 m, the modified FAE method can reproduce the snowdrift phenomenon on the gable roof more reasonably if adopting the snow transport rate proposed by Owen (1964) and the developmental law of snow transport suggested by O’Rourke et al. (2005) at the same time. Through CFD simulation, it's discovered that the distribution of flow field around the gable roof and friction velocity on snow surface change noticeably with roof slopes, resulting in the increase of the upwind erosion flux and the leeward deposition flux with the incoming wind speed and the roof slope. In addition, when the incoming wind speed remains unchanged, simulation results using the modified FAE method show that the larger slope of the gable roof, the more likely it is to cause the uneven distribution of snow load on the windward and leeward roofs. Moreover, fresh snow is more likely to cause the uneven distribution of snow load on gable roofs than aged snow through analysis sensitivity of the threshold friction velocity.

Probabilistic modeling of 10-min mean wind speed and its application in analytical simulation of snowdrift on building roofs

The typical resolution for long-term wind speed records that are publicly available in China is daily, this is too coarse for a sound analytical simulation of snowdrift on building roofs. Take Harbin, China as an example, an algorithm was proposed in this study to address this issue, where the commonly-used 2-parameter Weibull distribution was applied to fit the distribution of 10-min mean wind speed. A parameter estimation method, which combines the method of moment and cumulative probability, was proposed to estimate the parameters of Weibull distribution using very limited information on wind speed. The fitted probability model was validated using high-resolution wind speed data by comparing the snowdrift estimated by the modeled wind speed and that estimated by the actual wind speed. Finally, an analytical simulation of snowdrift on a flat roof was carried out to illustrate the application of the proposed model, and the probabilistic characteristic of the derived ground-to-roof conversion factors for snow loads were analyzed. It is indicated that the proposed model is easy to implement and provides a good estimation of the snowdrift on building roofs, and the derived conversion factors could be satisfactorily modeled using a Generalized Extreme Value (GEV) distribution or a normal distribution.

Predicting snow damage in conifer forests using a mechanistic snow damage model and high-resolution snow accumulation data

ABSTRACT Forest damage caused by heavy wet snow accumulation in the canopy is the second most important abiotic forest disturbance agent in Nordic conifer stands after wind. The extent and frequency of snow damage in the future climate in the Nordic region is a major uncertainty. Few mechanistic models of snow damage risk to trees exist that could support forest management scenario analysis and decision making. We propose a snow damage risk model consisting of a numerical weather prediction-based snow accumulation model for forest canopies and a mechanistic critical snow load model. Snow damage probability predictions were validated on snow breakage data from the winters of 2016 and 2018 covering 3.5 million individual trees in south-eastern Norway derived from pre- and post-damage aerial laser scanning campaigns. The proposed model demonstrated satisfactory damage and no-damage class separation with an AUC of 0.72 and 0.77 in Norway spruce and Scots pine, respectively, and an F1 score of 0.7 in conifers taller than 10 m that suffered moderate stem breakage. The model achieved a classification accuracy that is comparable to that of statistical models but is simpler and requires fewer inputs.

Wind loads on structural members of rack-supported warehouses

Rack-supported warehouses (RSWs) represent a modern typology of storage racks. In this system, cladding panel weight and corresponding applied loads, such as wind or snow load, are supported by storage racks, in addition to pallet load and seismic action. While this structural system allows for reducing the amount of structural steel, the uprights and beams, composing each rack, are directly exposed to the wind during the earliest erection phases. This load condition may govern the design of the uprights or that of temporary bracings. Wind load estimation requires the knowledge of the aerodynamic coefficients of each structural member section, for any angles of wind incidence. Unlike any common structural steelwork section, no data are available in the literature for RSW member sections. The current work represents a first step to cover this lack in the literature by reporting the results of an extensive wind tunnel campaign carried out on several portions of uprights and beams commonly designed and produced for RSWs. The results highlight the need for wind tunnel tests on RSW member sections when producers can no longer afford an overestimation of the wind load. In addition, conservative values of the aerodynamic coefficients are provided for preliminary wind load estimations or temporary bracings design. Empirical relationships for the aerodynamic coefficients, changing with equivalent side ratio, are also reported. Finally, design recommendations are provided by highlighting a critical structural configuration during the early erection phases of RSWs that govern the design of the uprights or temporary bracings. A worked example is then developed to clarify the application of the present results in the definition of wind loads.

Justifying calculations of snow load distribution on snow retaining structures in avalanche protection system

Snow load estimation is one of the most important tasks in designing snow-retaining structures for avalanche protection of railways and motorways in mountainous areas. The situation is complicated by the fact that avalanches are subdivided, depending on the consistency of snow, into dry, wet and damp avalanches. This paper analyses the existing foreign and domestic snow load calculation methods, based on which was concluded that there is no dependence of the load value on the physical and mechanical parameters distribution of the snow cover in all the considered methods of calculation. Moreover, none of these methods makes it possible to estimate the snow pressure distribution on a snow-retaining structure by its depth. The article proposes an alternative way of calculating the snow layer pressure using the developed discrete model for calculating the static snow pressure distribution on a barrier by its depth. The discrete model peculiarity is to take into account the change of physical and mechanical characteristics of snow — density, specific adhesion and angle of internal friction, by layers of natural deposit. Discrete model verification was performed by comparing the calculated and experimental data obtained as a result of both natural and laboratory experiments. The experiments were conducted in laboratory conditions on a special model, using a material with stable physical and mechanical characteristics that do not change during the course of the experiment. Also, for verification, the field experiment results on determining the naturally deposited snow pressure on an obstacle, taken from the open press, were used.