Wind resistance of southern carbonate and ordinary сhernozems in agroforest landscapes of the steppe zone of Russia

Relevance. The rate of destruction of chernozems in the steppe zone as a result of deflation is very high. There is a threat of their loss of the humus horizon. To optimize the complex of protective measures, it is necessary to establish the regularities of the formation of wind resistance of these soils.Methods. The seasonal dynamics of the structure of the upper layer (0–5 cm) of chernozems of the steppe zone of the Lower Volga region and the Central Pre-Caucasus in the network of forest belts is studied. The aggregate composition was determined by fractionation of an air dry sample. The wind resistance of the soil was assessed by the total content of particles with a diameter of less than 1 mm.Results. It has been established that the open surface of southern carbonate chernozems is deflationary dangerous at any time of the year. Two spraying peaks were revealed — in early spring and before harvesting grain crops. In the first period, the content of particles with a diameter of less than 1 mm was 33–47%, in the second — 60–61%. Shelter forest belts reduced soil spraying in the zone of effective influence. A change in the internal structure of the deflationally dangerous fraction was detected during the year. The disintegration of large aggregates and an increase in the volume of smaller ones were observed. By the harvesting period, the number of particles with a diameter of 0.5–1.0 mm decreased by 1.7–2.6 times compared to the spring. Number of aggregates with a diameter of 0.1–0.5 mm, most strongly blown by the wind, increased by 1.3–1.8 times. The total dispersion of ordinary chernozem is almost two times lower than that of southern chernozem. However, the amount of particles with a diameter of 0.1–0.5 mm in the deflationary dangerous fraction of southern carbonate chernozem in the spring period is 37%, during the harvesting period — 50–56%. And in ordinary chernozem, already since the spring, there are more than 55% of such particles, in the future their number increases to 60%. As a result, by the harvesting period, the danger of a fraction with a diameter of less than 1 mm becomes the same for both subtypes of chernozems. This requires adjusting the complex of protective measures.

Full-Scale Measurements of Translational and Torsional Dynamics Characteristics of a High-Rise Building during Typhoon Sarika

The field measurement of wind-induced response is of great significance to the wind resistance design of high-rise buildings, in particular torsional responses measured from high-rise buildings under typhoons. The measured high-rise building, with a height of 108 m, has 32 stories and is supported by giant trusses with four massive columns. Acceleration responses along translational and torsional directions were monitored synchronously and continuously during the passage of Typhoon Sarika on 18 October 2016. The wind speed and wind direction at the height of 115 m, the translational accelerations on a total of six floors and the angular accelerations on a total of four floors were recorded. The time and frequency domain characteristics of translational acceleration and torsional angular accelerations were analyzed. The amplitude-dependent translational and torsional modal frequencies of the measured building were identified by NExT-ERA, SSI, and RDT methods. The full-scale study is expected to provide useful information on the wind-resistant design of high-rise buildings in typhoon-prone regions.

Experimental Study of Mitigation of Wind-Induced Vibration in Asymmetric Cable-Stayed Bridge Using Sharp Wind Fairings

This paper investigated the aerodynamic response features of an asymmetric cable-stayed bridge. The wind resistance design parameters for judging the response were first determined, afterwards the bridge dynamic characteristics were analyzed for subsequent aerodynamic analysis. The vortex-induced vibrations (VIV) and flutter response at various wind fairing angles were then examined by using a 1:50 sectional model in the wind tunnel test. Finally, a 1:150 full bridge aeroelastic model was employed to explore the aerodynamic stability and characteristics of the whole asymmetric bridge under different wind attack angles in various flow fields. The results show that the sharp wind fairings could reduce the VIV amplitude of the steel box girder cable-stayed bridge to some extent, and the example bridge has examined to have enough flutter stability through sectional and full bridge aeroelastic model wind tunnel tests. Unlike symmetric bridges, the bridge’s maximum displacement of first torsion mode shape is at the closure rather than the mid-span, which is the essential reason to lead this unique vibration feature. The results from the present study could highlight the important effect of structural asymmetry and fairing shape to the wind-induced bridge vibration and hence may facilitate more appropriate wind design of asymmetric cable-stayed bridges.

Energy Saving Design of Exterior Envelope of Prefabricated Buildings in Alpine Area

In this paper, the exterior envelope of prefabricated buildings in alpine areas is studied. This paper compares the wind resistance of the fabricated structure composed of two different connection modes, connectors with different thickness, lightweight ceramsite concrete peripheral wall panel and wood composite peripheral wall panel. The test results show that the wind resistance of the fabricated structure composed of wood wallboard mainly depends on the thickness of wallboard, connection mode and connector thickness. Whether sand packing is filled or not has no effect on the improvement of wind resistance of this prefabricated enclosure structure. For meeting the wind resistance of the fabricated enclosure used in the support room, it is recommended to use thick wooden wallboard and connect up and down. The wind resistance of the fabricated enclosure composed of wood wallboard mainly depends on the strength of the wood wallboard itself. The use of wood wallboards with higher thickness can improve the wind resistance of this fabricated structure.

The Benefit of Horizontal Photovoltaic Panels in Reducing Wind Loads on a Membrane Roofing System on a Flat Roof

The present paper proposes a measure for improving the wind-resistant performance of photovoltaic systems and mechanically attached single-ply membrane roofing systems installed on flat roofs by combining them together. Mechanically attached single-ply membrane roofing systems are often used in Japan. These roofing systems are often damaged by strong winds, because they are very sensitive to wind action. Recently, photovoltaic (PV) systems placed on flat roofs have become popular. They are also often damaged by strong winds directed onto the underside, which cause large wind forces onto the PV panels. For improving the wind resistance of these systems, we proposed to install PV panels horizontally with gaps between them. Such an installation may decrease the wind forces on the PV panels due to the pressure equalization effect as well as on the waterproofing membrane due to the shielding effect of the PV panels. This paper discusses the validity of such an idea. The pressure on the bottom surface of a PV panel, called the “layer pressure” here, was evaluated by a numerical simulation based on the unsteady Bernoulli equation. In the simulation, the time history of the external pressure coefficients, measured at many points on the roof in a wind tunnel, was employed. It was found that the wind forces, both on the PV panels and on the roofing system, were significantly reduced. The reduction was large near the roof’s corner, where large suction pressures were induced in oblique winds. Thus, the proposed method improved the wind resistance of both systems significantly.

The Analysis of Dry Weather Aerial Photography in Sermo Kulonprogo Reservoir using DJI Spark Drone

Drones are a very important medium in the world of aerial photography to map military operations, agricultural areas, plantations, mining, urban planning, disaster mitigation, and outreach to remote areas and two types have been identified which are the winged and quadcopter. This research was conducted to map the drought-prone areas during the dry season in the Sermo Reservoir area, Kokap, Kulon Progo Regency between 14-15 August 2019. This involved the use of the DJI Spark quadcopter due to its more stability and wind resistance. The process involved connecting the DJI Spark drone remote controller to a smartphone, opening of DJI Go application, DJI Spark drone activation, smartphone installation on the remote controller holder, propeller installation, GPS settings in a locked position, drone flight and position adjustment, and capturing of the images on the smartphone screen. The results showed the water flow of the Sermo Reservoir has decreased by approximately 4 meters due to the dry season. This was evident in the changes from its original position of136.6 meters above sea level to 132.6 meters and this limits the quantity of water available to irrigate rice fields. The reservoir still has the capability to supply 800 liters per second in Pengasih District but the results of the aerial photographs showed the existence of drought and a decrease in the water discharge.