# APPLICATION OF FINITE ELEMENT ANALYSIS AT INSPECTION TRANSPORT WORKS (ON THE EXAMPLE OF THE RAILWAY BRIDGE)

Sauts Arthur Valerievich1, Savin Sergey Nikolaevich1
1Saint-Petersburg State University of Architecture and Civil engineering

Abstract
The article deals with the application of the finite element analysis with the technical inspection of the railway bridge over the river «Bolshaya Izhora». With the help of a computer program «Scad Office», a mathematical model of the bridge, calculate its deformation, which correspond to the experimental values. A general picture of the movements of the bridge under the influence of its own gravity, and the load of the train.

Category: 05.00.00 Technical sciences

Article reference:
Application of finite element analysis at inspection transport works (on the example of the railway bridge) // Modern scientific researches and innovations. 2013. № 4 [Electronic journal]. URL: https://web.snauka.ru/en/issues/2013/04/23441

The finite element method has gained wide popularity in by 1963 and is now widely used to solve various problems of structural mechanics. Examples of the use of finite element analysis in the examination of the railway bridge over the river Bolshaya Izhora, located some22 km(PC-3) of theSt. Petersburg- Oktyabrskaya railway Volkhovstroy with application «Scad Office». Surveyed the bridge was built in the mid XX century. Spans are farm of cast iron, material supports are rubble masonry, concrete, reinforced concrete. Foundation soil  is sand and sandy loam (Figure 1).

Figure 1 – The scheme of the bridge [1]

Technical inspection of bridge was carried out periodically at intervals of 10-15 years. Since 1969, the discovered characteristic defect, which represents a tilted position-roller support parts of the farm on the first (left-Bank) way. The slope of rollers is 11,5º  to the left coast, the offset is55 mm. This also manifested strain cones embankment foundations in the form of breakdown and collapse of the soil in the river bed. Attempts to restrict the movement of the movable end of the span setting plates movable bearings in normal position, installation of metal pinching gave only a temporary effect, and eventually encounter the rollers tilt state (Figure 2).

Figure 2 – Tilt position-roller support parts of the farm

The most likely cause of this defect is loss of stability of the left pillar of the subsidence of the soil under the influence of load and education floating earth.

Perform a numerical simulation of deformation of bridge from own load and away from traffic on him train (Figure 3). Profiles section take from the old assortments of GOST 14-1932 «Corners equal», GOST 15-1932 «the Corners of unequal», GOST 16-1932 «Goods of equal». The value of load on the composition, conical mounds take from the SN 200-62* «Specifications for design of railway, road and city bridges and pipes», SN 35.13330.2011 «Bridges and pipes». Because of the shrinkage of the pillars in the soil is inelastic character, in the estimated model, we consider them as a relation of the form «the Deformable bottom».

Figure 3 – The deflection of the bridge under the action of a load

Graphical results of a numerical experiment here in Fig. 4, where there is also a shift of skating rinks farm in the direction of the left Bank, and it is56,902 mm, that practically coincides with the experimental data.

Figure 4 – Scheme of strain-bridge, obtained in the «Scad Office»

According to the results of modal analysis in «Scad Office» Lanczos method on an interval of 6.1-8.3 Hz identified the movement of elements of the bridge, as shown in Figure 5.

Figure 5 – Patterns of movement of the bridge structures under dynamic loading at a frequency of 7.9 Hz

A similar pattern was observed in experimental studies [4], in which the same pattern is observed at a frequency of 8.3 Hz, the results of numerical and field experiment are approximately equal. The deviation of the calculated value from the pilot due to the structural heterogeneity of time-children of the bridge, add new parts (triggers stairs, railings, etc.).

Thus, thanks to the «Scad Office» determined that the cause of the offset rollers fermions we cause uneven subsidence pillars (mostly left) under high loads. Further investigation of the model will help in the development of measures for elimination of the defect.

References
1. Книга Большого и Среднего моста. Форма ПУ-12.  СССР-МПС Октябрьская железная дорога, Мгинская дистанция пути. Декабрь1953 г.
2. СН 200-62*: условия проектирования железнодорожных, автодорожных и городских мостов и труб. Утв. Госстроем СССР 30.12.61. – 145 с.
3. СП 35.13330.2011 Мосты и трубы: актуализированная редакция СНиП II-23-81*; утв. приказом Минрегиона РФ от 28.12.10 № 822; и ввод. в действие с 20.05.11– Изд. офиц. – М.: Минрегион России, 2011. – 341 с.
4. Отчёт по результатам инструментального обследования и динамических испытаний железнодорожного моста через реку Б. Ижора, расположенного на22 км(ПК-3) участка Санкт-Петербург – Волховстрой Октябрьской железной дороги. Утв. С.А. Евтюков, рук. работ Савин С.Н., отв. Исп. Георгиади В.В. – СПб.: СПБГАСУ, 2011. – 44 с.: ил.

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