Determining Regularities in the Distribution of Noise Load From Motorways and Road Bridges Depending on the Distance to A Residential Area

This paper reports the improved model for estimating transport noise from highways at a roadside lane under the influence of noise load from traffic flow moving on an open section of the highway and over a bridge. It has been established that with an increase in the distance from the sound source to the coordinates of the noise load measurement, the noise decreases, both in the presence of a noise-protective screen and in the case of an open section of the highway. At 100 m from the sound source, the noise load level decreases by 13.4 % in the case of the car moving over a bridge, and by 13.3 % when driving a car along an open section of the road. It has been found that the noise level on bridges exceeds the level of noise pollution from the road to 10 dB, which is explained by the propagation of different frequencies of noise load from the bridge. It has been determined that due to the special nature of sound waves, diffraction through noise screens does not change all frequencies evenly. High frequencies diffract to a smaller degree while lower frequencies diffract deeper into the "shadow" zone behind the screen. Therefore, the screen is more effective at reducing sound waves with a high frequency compared to sound waves with lower frequencies. Experimental studies into the effectiveness of noise-protective screens made of metal perforated structures on sections of public roads were carried out, taking into consideration distances from noise sources to noise load measurement sites. It is established that noise-proof screens made of steel (perforated) sheet reduce the level of noise load from vehicles to the environment by up to 14 %. It was found that when driving cars on the road, the equivalent sound level at a distance of 1 m in front of the noise protection screen is 88.6 dBA while the maximum sound level at a distance of 1 m in front of the noise protection screen is 103.9 dBA. It has been established that in the presence of a drain hole in the noise protection screen, its acoustic efficiency is reduced to 3 dBA

Procedure for Determining the Thermoelastic State of A Reinforced Concrete Bridge Beam Strengthened with Methyl Methacrylate

This paper reports the analysis of methods for determining temperature stresses and deformations in bridge structures under the influence of climatic temperature changes in the environment. A one-dimensional model has been applied to determine the temperature field and thermoelastic state in order to practically estimate the temperature fields and stresses of strengthened beams taking into consideration temperature changes in the environment. The temperature field distribution has been determined in the vertical direction of a reinforced concrete beam depending on the thickness of the structural reinforcement with methyl methacrylate. It was established that there is a change in the temperature gradient in a contact between the reinforced concrete beam and reinforcement. The distribution of temperature stresses in the vertical direction of a strengthened reinforced concrete beam has been defined, taking into consideration the thickness of the reinforcement with methyl methacrylate and the value of its elasticity module. It was established that the thickness of the reinforcement does not have a significant impact on increasing stresses while increasing the elasticity module of the structural reinforcement leads to an increase in temperature stresses. The difference in the derived stress values for a beam with methyl methacrylate reinforcement with a thickness of 10 mm and 20 mm, at elasticity module E=15,000 MPa, is up to 3 % at positive and negative temperatures. It has been found that there is a change in the nature of the distribution of temperature stresses across the height of the beam at the contact surface of the reinforced concrete beam and methyl methacrylate reinforcement. The value of temperature stresses in the beam with methyl methacrylate reinforcement and exposed to the positive and negative ambient temperatures increases by three times. It was established that the value of temperature stresses is affected by a difference in the temperature of the reinforced concrete beam and reinforcement, as well as the physical and mechanical parameters of the investigated structural materials of the beam and the structural reinforcement with methyl methacrylat

Devising A Procedure to Calculate and Analyze Parameters for Passing the Flood and Breakthrough Wave Taking Into Consideration the Topographical and Hydraulic Riverbed Irregularities

It has been established that the most likely period of breakthrough wave occurrence is the time of spring flooding or heavy rain when water-head facilities are subjected to significant loads that lead to the collapse of their individual elements or the entire structure. In addition, the possibility of man-made accidents that can occur at any time cannot be ruled out. It has been proven that breakthrough wave formation depends on the nature of the destruction or the overflow through a water-head facility. For the study reported in this paper, a model of the kinematics of riverbed and breakthrough flows was used, which is based on the equations of flow, washout, and transport of sediments that are averaged for the depths of the stream. The differential equations describing the nonstationary flow averaged for depth are solved using the numerical grid system FST2DH (2D Depth-averaged Flow and Sediment Transport Model), which implements a finite-element method on the plan of a riverbed's topographic region. These tools are publicly available, which allows their wide application to specific loads and boundary conditions of mathematical models. The construction of an estimation grid involving the setting of boundary conditions and the use of geoinformation system tools makes it possible to simulate the destruction of a culvert of the pressure circuit and obtain results for a specific case of an actual riverbed and a water-head facility. It has been established that there is a decrease in the speed of wave propagation along the profile, from 3 m/s to 1 m/s. The impact of bottom irregularities, the effect of floodplains, and the variety of bottom roughness have also been assessed, compared to the results of their calculation based on one-dimensional models given in the regulatory documents. Hydraulic calculations were carried out taking into consideration the related properties of the main layer of the floodplain, which consists of peat accumulations, and the heterogeneity of the depths and roughness of floodplain surfaces of soils. It has been established that there is almost no erosion of supports in the floodplain zone in this case. It was found that as the distance between the flow and breakthrough intersection increases, there is a decrease in the height of the head from 2.1 m to 1.25 m