Redchenko V. Development of methods of dynamic tests of bridges and algorithms of the spectral analysis for processing their outcomes

Subject of inquiry is processes of the forced and free oscillations of bridges constructions. Thesis objective is development of new methods of dynamic tests and improvement of algorithms of spectral analysis for determination of dynamic parameters and estimation of the technical state of road-transport bridges constructions. Research methods: methods of mathematical design and theory of vibrations at research of vibrations of construction; methods of structural mechanics and dynamics of buildings at establishment of dependentness of modal parameters of construction from the nature of defect; analytical and statistical methods of analysis of spectral estimations of free vibrations of the linear systems at the improvement of algorithms of spectral analysis; methods of experimental research of mathematical and original models for verification of analytical conclusions. Theoretical and practical results: the methods of determination of dynamic parameters of road-transport bridges constructions are developed, which make possible to get more exact, as compared to the known methods, results, that enables, except for the solving of traditional tasks of dynamic tests, to use them for monitoring of the technical state of building and clarification of it’s calculation model; created hardware/software complex, which admits to determine actual dynamic parameters of bridge spans from the results of dynamic tests to form it’s model and to calculate reaction on an various load. Novelty of the research: improved mathematical model of the linear dynamic system as a result of it’s creation based on synthesis of modal transfer functions; the method of vibrodiagnostics of bridges constructions is improved, which is based on the analysis of influence functions of damage on the sizes of relative changes of natural frequencies of construction; a method of determining of damage influence functions by dynamic tests with the use of additional mass is first developed; the methods of determination of modal parameters of bridge constructions got step forward as a result of development new and improvements of existent algorithms of spectral analysis, which provide an increased resolution ratio in the conditions of concentration of natural frequencies; the method of determination of natural frequencies forms of the frame constructions with the use of additional mass is first developed; new information is got, which sets dependence between the modal parameters of original constructions and their technical state. Implementation extent: working results are used at the development of normative documents; at the field dynamic tests for determination of the technical state for 45 bridges; at the projects of restoration for 17 bridges. Range of application: at the research of load carrying structures of bridges; at the report generation of bridge restoration; at the teaching situations.