A shaking table testing of a 16.6 t five storey steel frame structure with and tuned mass damper (TMD) named as Tuned Mass Control System (TMCS) installed at the top has been carried out in the Dynamic Testing Laboratory at the Institute of Earthquake Engineering and Engineering Seismology (IZIIS) in Skopje, Republic of Macedonia. For estimation of the effectiveness of Tuned Mass Control System (TMCS) large number of shaking table experiments have been performed. Simulating different earthquake time histories on the model structure with and without TMCS it has been demonstrated that this system is capable to reduce the responses in order from 10% to more than 50% depending on the frequency content of the seismic input and the corresponding sensitivity of the structure. Given a high quality analytical model of a structure and a dynamic absorber, a series of variant analyses have been performed within the study to investigate the effect of the individual parameters and evaluate the efficiency of the dynamic absorber. The analyses have been performed to define the effect of the location of the absorber, also, upon the dynamic behaviour of the structure in the case the absorber is installed at the different level (storey) of the structure. Comparative analysis of the structure with TMCS having optimally tuned its mechanical properties versus structure that has TMCS having the same mechanical properties as tested specimen showed that the TMCS additionally improves the structural behaviour, depending on frequency content of earthquake excitation.

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A vibration test of the Mavrovo dam in West Macedonia was carried out in order to find out the dynamic properties of the dam. Mavrovo dam is an earthfill dam with a central clay core 56·0 m high, 215 m long at the crest and 286 m thick at the base; average slopes are 1:2·50 and 1:2·86 for downstream and upstream slopes respectively. The dam was excited to steady-state vibrations in the frequency range 2·5–7·40 Hz by two synchronized rotating eccentric mass vibration exciters (GSV-100) operating onfhe crest in the upstreamdownstream direction. During the vibration tests accelerations were measured Jon the crest, on three downstream berms 8·0, 16·0 and 24·0 m below the crest and on the first upstream berm. By the dynamic tests the first, third and fifth (symmetric) and the second (asymmetric) horizontal vibration mode of the crest of the dam and the first two downstream berms were recorded as were the first three vertical modes of vibration at the highest cross section of the dam. Equivalent viscous damping coefficients were obtained from frequency response curves for corresponding modes of vibration. A mathematical model was formulated using experimentally obtained characteristics. Two theoretical solutions were used showing significant correlation with the experimental results. This investigation shows that, by formulation of the mathematical model from the results obtained from full-scale forced vibration studies, dynamic response for earthfill dams for small amplitudes of vibrations can be predicted. On a effectué des essais de vibration au barrage de Mavrovo en Macédoine Occidentale, dans le but de mettre en évidence les propriétés dynamiques du barrage. Le barrage de Mavrovo est un barrage en terre, à noyau central en argile, de 56 m de hauteur, 215 m de longeur de créte et de 286 m d'epaisseur à la base; les pentes moyennes sont respectivement de 1:2·5 et 1:2·86 pour les pentes aval et amont. Le barrage a été mis en vibration dans le domaine de fréquence 2·5–7·40 Hz. au moven de deux mécanismes d'excitation synchronisés à masse excentrée en rotation (GSV-100) installés sur la créte dans la direction amont-aval. Au tours des essais de vibration, on a mesuré les accélérations sur la créte, sur trois bermes d'aval à 8, 16, et 24 m audessous de la créte, et sur la premiére berme d'amont. On a pu mesurer au tours de ces essais dynamiques, les premier, troiséme et cinquiéme (symériques) et le second (asymétrique) modes de vibration horizontale de la créte du barrage et des deux premiérres bermes d'aval, ainsi que les trois premiers modes de vibration verticale de la section type (la plus haute). On a obtenu les coéfficients d'amortissement visqueux à partir des courbes de réponse de fréquence correspondant à ces modes de vibration. On a établi un modéle mathématique en se servant des Caractéristiques obtenues au tours des expériences. On s'est servi de deux solutions théoriques qui donnent une corrélation étroite avec les résultats expérimentaux. Cette étude montre que, gràce au modéle mathématique à partir des résultats obtenus lors d'essais de vibration forée à grande échelle, on peut prédire la réponse dynamique de barrages en terre pour les vibrations de faible amplitude.

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