Design Of Instrumentation And Vibration TestingPrograms Of Structures Through AnalyticalInvestigations

Abstract

For the estimation of the dynamic properties of structures, forced vibration tests are often used. Various methodologies for the predetermination of the force level and the position of the shaker have been developed. In the present work the methodologies of field-testing and analytical evaluations of the structural response are defined through an interactive procedure. During field-testing, a group of parameters may vary, such as the position and the direction of the excitation force, and the amount, eccentricity and frequency of the rotating mass. These parameters should be defined and estimated before the actual testing, in order to perform an effective test plan. For this purpose, the structure under investigation is analytically modeled and its dynamic properties (mode shapes and frequencies) are estimated. Parametric analyses follow, by considering a vibrating mass on the analytical model for the simulation of the vibrator action. These analyses are performed for various positions of the vibrator on the analytical model and for various excitation levels and frequencies of vibration in order to evaluate the activated, in each case, dynamic properties of the structure and hence to better design the testing vibration program. The suggested methodology is applied for a specific bridge on Egnatia Highway, which crosses Northern Greece in an E – W direction. Also, a methodology for the installation of the vibrator on an actual structure is proposed, aiming towards the optimum transfer of forces from the vibrator to the structure.