PSI - Issue 5

V. Epin et al. / Procedia Structural Integrity 5 (2017) 620–626 R. Tsvetkov / Structural Integrity Procedia 00 (2017) 000 – 000

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6. Conclusion

The analysis of the measured results obtained for the crack width and beam deflections revealed a number of trends in the deformation behavior of the load-bearing elements of the air-bridge. Of most importance are the cyclic changes of vertical displacements, which correlate with seasonal and diurnal ambient air temperature changes. Due to variations in ambient temperature, the length of the metal support columns changes, causing thus the displacement of beam-column junctions, beam deflection and crack growth. Recurring of this process leads to a gradual increase in the damage degree of the structure and crack opening, which is the main cause of the deformation of the load-bearing elements of the air-bridge. The validity of the developed mathematical model was verified using the experimental measurements obtained in this investigation. Based on the monitoring data, the model was updated, which allowed us to evaluate the limiting values of measurements (i.e. the values, at which the critical state of the structure can be achieved). The safe service life of the structure is warranted at the values of measured parameters not exceeding 80% of the limiting values. Acknowledgements This resea rch was performed under the grant of the Russian Science Foundation (grant № 14 -29-00172- П ). Barazzetti, L., Scaioni, M., 2009. Crack measurement: Development, testing and applications of an automatic image-based algorithm. ISPRS journal of photogrammetry and remote sensing 64(3), 285-296. Epin, V.V, Tsvetkov, R.V., Shestakov, A.P., 2016. Application of feature recognition to hydrostatic leveling systems. Measurement Techniques 59, 405-409. Kachanov, L.M., 1971. Foundations of Theory of Plasticity, North-Holland, Amsterdam, pp. 496. Krakhmal'ny, Ɍ.Ⱥ. , Evtushenko, S.I., Krakhmal'naya, M.P., 2016. New System of Monitoring of a Condition of Cracks of Small Reinforced Concrete Bridge Constructions. Procedia Engineering 150, 2369-2374. Maas, H.G., Hampel, U., 2006. Photogrammetric techniques in civil engineering material testing and structure monitoring. Photogrammetric engineering and remote sensing 72(1), 39-45. Stanton, J.F., Eberhard, M.O., Barr, P.J.,2003. A weighted-stretched wire system for monitoring deflections. Engineering Structures 25, 347-357. Staszewski, W.J., Robertson, A.N., 2007. Time – frequency and time – scale analyses for structural health monitoring. Philosophical Transactions of the Royal Society A 365, 449-477. William, K.J., Warnke, E.P., 1974. Constitutive Model for the Triaxial Behavior of Concrete. Proceedings of International Association of Bridge Structural Engineering 19, 1 – 30. References