Summaries

Temel Türker, Research Ass Alemdar Bayraktar, Prof. Civil Engineering Department, Karadeniz Technical University In this study, an assessment was attempted to determine the effect on dynamic behaviour at buildings that have steel bearing systems the employment of cross bracings in consideration of natural frequencies, modal extinction rates and changes on mod forms. For this purpose investigations were carried out on the plane created in lab conditions on a model 3 floored steel structure with two spans on both directions. To determine the effect of cross bracings the dynamic characteristics of the steel building model for braced and nonbraced conditions were determined by operational modal analysis method. Experimental measurements were realized by taking measurements for each floor in 3 phases and using seismic accelerometers, 9 in total. Synthetic tremors created by a plastic headed hammerwere used to vibrate the model and measurements were done fora duration enough to represent the behaviour of the model. Modal parameters obtained for unbraced conditions were taken as basis to show the cross bracing effects. From the study it is observed that the bracing system created on the steel structure model caused increase in two fold at frequencies and furthermore causes a change in the modal behaviour.