The analysis of technical condition of tower steel frames according to their dynamic characteristics

Abstract

EN: In Ukraine there are a lot of structures in operation which werecalculated according obsolete standards. The periods of their service life exceed the periods oftheir design working life. The structures are damaged and the current loads exceed those thatwere designed. Moreover, their replacement is not planned. The assessment methods of technical condition of load-bearing tower steel frames based onthe comparative analysis of dynamic characteristics are developed . The methods of structuraldynamics analysis can be successfully applied to solve risk problems and durability problemstaking into account the service life of a structure.Purpose of the study. Steel space frames, such as water-cooling tower (27 m tall, with9.5 m between the bands in the lower section and 6.8 m – in the upper section);technologicalstructure with dynamic test facility of zero-gravity (18m × 18m, 40 m high); three-edged latticetower of ventilation duct with cross diagonal web (113.5 m high, with 5.5 m outer diameter ofgas exhaust duct inside the tower) were taken as survey items.Methods of research – examination of technical condition of building structures according to [5]; measurements of structure vibrations with the use of Vibran devices of Interpribor company and seismic sensors; modeling and calculations by means of SCAD Office 21.1 software package.The techniques to analyze dynamic characteristics of structures in order to evaluate fasttechnical condition of load-bearing structures is developed. The methods of practical evaluationof technical condition [5], methods of dynamic models, methods of dynamic calculations andtests, as well as forecasting methods of dynamic response of structure [1; 3; 4] were summarized to be the basis of this approach.The comparative analysis in order to identify frequency and forms of vibrations before andafter damage is performed. Processing of vibration records of free decreasing vibrations allowsfor the analysis of friction changes in construction (additional parameter for comparison).Computer models are specified according to the field measurements results of dynamiccharacteristics.