Дослідження температурного поля та напруженого стану прогонової будови сталезалізобетонного моста

Abstract

Наведено результати експериментальних вимірювань температури сталезалізобетонної балки прогонової будови моста. Запропоновано математичні моделі теплопровідності та напружено-деформованого стану фрагмента балки, лицеві поверхні якого вільні від навантажень і нагріті до різних температур, а бокові поверхні жорстко закріплені. Для дослідження напружено-деформованого стану фрагмента використовуються рівняння термопружності. Припускається, що температура залежить лише від координати, напрямленої вздовж осі аплікат. Приймається, що на межі між різнорідними складовими фрагмента балки виконуються умови ідеального теплового та механічного контакту.

Railway and road bridges are the significant part of the national achievement, one of the most important components of Ukraine’s infrastructure. At the same time their maintenance becomes worse results in the traffic black out because of the poor technical condition or accidents of the bridge, and it causes significant social and economic losses. Neither society, nor the authorities of Ukraine treat this situation as the social and economic risk to the country. However, the problems of the area are urgent. The technical condition of railway and road bridges in Ukraine is as follows: 10% of railway bridges and 54% of bridges in public roads use do not meet the requirements of DBN V.2.3. 14:2006 “Bridges and pipes. The design rules”, 11% of bridges on public roads require immediate overhaul or reconstruction. Adoption of the science-based decisions concerning the need for renewal of one or another bridge element is possible on the basis of the objective estimation of its technical condition and residual resource. One of the most effective ways to evaluate the technical condition of structures and buildings, operating with external force loads and variable seasonal and diurnal temperatures are monitoring of their stress-strain state, which makes it possible to obtain objective information on the history of the load element design for its life cycle, development of its damages and to identify its serviceability term. The results of this monitoring will make possible to detect abrupt and gradual reduction of carrying capacity of individual structural elements;to calculate using appropriate mathematical models residual resource of the individual structural elements and structures in general. A complex design or construction monitoring, consisting of various structural elements, can be realized by the continuous measurement of the local deformations of the most critical elements with the subsequent calculation of the stress-strain state of the whole structure using appropriate mathematical models. Thus, for the monitoring system of such structures it is necessary to develop the methods of determining the stress-strain state individual structural elements composite beams spans bridge structures in particular, which are under the influence of climatic variable temperatures. These studies along with the studying of the effects of constant and variable loads, are the basis for estimation of the strength and reliability of the spans bridge structures. The results of experimental measurements of composite beam bridge spans temperature are presented in the paper. The mathematical models of the heat conductivity and the stress-strain state of the fragment beams, the facial surfaces of which are free from stress and heated to different temperatures, and the lateral surfaces are rigidly fixed, are proposed. To study the stress-strain state of the fragments the equations of thermo-elasticity are used. The temperature is expected to depend only on the coordinate directed along the applicate axis. At the border between heterogeneous components inside the beam the ideal thermal and mechanical contact conditions are assumed to be provided.