Road guardrails of various types (made of reinforced concrete, cable and metal) are installed on the shoulders and traffic lanes of urban and suburban roads. Metal guardrails, consisting of Σ-shape and double T-shape metal posts and a protective W-shape horizontal beam, are the most popular. The deformation processes of the Σ-shape and double T-shape metal posts of the above-mentioned guardrails are examined. A mathematical model of Σ-shape (or double T-shape) metal post is developed. A metal post of Σ-shape (or double T-shape) is modeled, using one-dimensional firstorder finite elements, and taking into account elastic deformations, as well as the effect of soil on the buried post section of the guardrail. The deflections of Σ-shape and double T-shape metal posts caused by the impact of a motor vehicle moving at varying speed are determined.
Abstract. Statistical data on traffi c accidents in 2008 inLithuania is presented. Referring to statistical data, 'grounding on an obstacle' makes one-tenth of all registered traffi c accidents -9.4% (an obstacle may be a road guardrail, a lamp post, a tree, a bar, a gate, etc.). Road guardrails of various types are installed on the shoulders and dividing strips of urban and suburban roads. Th ey are as follows: reinforced concrete guardrails, cable guardrails and metal guardrails. Metal guardrails, consisting of Σ-shape metal posts and a protective W-shape horizontal beam, are most popular. Th e authors of the present paper examine the deformation processes of the elements of the above mentioned guardrail. A mathematical model of metal road guardrail was developed. Metal road guardrail was modelled using onedimensional fi rst-order fi nite elements, taking into account only elastic deformations, as well as the eff ect of soil on the buried post section of the guardrail. Based on the developed mathematical model of metal road guardrail, the defl ections of its elements caused by the impact of a vehicle moving at varying speed were determined. Th e obtained values of defl ections of guardrail elements (a protective W-shape horizontal beam and a Σ-shape post) presented in paper do not exceed the admissible values (of beam defl ections).
Abstract. General data on the network of Ukrainian highways are presented. Th e analysis of design methods of highway reconstruction based on the theory of traffi c fl ows and economic calculations of its repay time is made. Th e relationship between traffi c intensity and speed is shown by considering the theory of traffi c fl ows. Th e methods, taking into account the principle of eff ectiveness of highway reconstruction based on its repay time, are discussed.
Abstract. Hydroplaning or aquaplaning is associated with the complete loss of the grip of a tyre because of the presence of a water film between the tyres of a moving vehicle (an automobile, an airplane, etc.) and the road surface. In this case, a vehicle becomes uncontrollable. Hydroplaning (aquaplaning) occurs when the speed of a vehicle reaches the critical value, when the wheel does not have time enough for water compulsion, which leads to the formation of a permanent water film between it and the road surface. The higher the depth of the water on the road surface under the tyre, the higher the risk of hydroplaning (aquaplaning). In other words, hydroplaning (aquaplaning) is the floating of the wheel on the water wedge. In physical terms, it is the loss of the ability of a tyre of the effective water compulsion from the contact area with the road. As a result, a water film of several millimeters is formed under the wheel, and a vehicle actually floats up. The article presents the results obtained in the experimental study of the flows of liquid, whose depth is comparable with that of depressions and cambers of rough roadway pavement. It is stated that the relationships used for calculating surface flows should be corrected for shallow flows, taking into account the actual roughness of road covering. Shallow flows are mostly laminar. The transition Reynolds numbers are about 3000. The relationships used for calculating shallow flows may be determined more accurately by test pouring of water on the surface of roadway pavement, with further generalization of the data. The experimental research performed is closely related to the study of the problems of aquaplaning and traffic safety of various means of transport.Keywords: traffic safety, road-holding capacity of a tyre, hydroplaning, aquaplaning, shallow liquid flow, depth of a water film, mode of flow, slope, surface roughness.
The recent problem of estimating the residual life of metal structures for handling equipment is actual, since more than 90% exhausted its regulatory resources. The current paper proposes an approach to solve this problem by using the coercive force. It is shown that in order to determinate damage of dangerous element of crane it is needed to know not only a coercive force but also a stress. Mathematical model is proposed to determine the damage of metal ware.
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