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In recent years, an increase to design slender and aesthetically-pleasing structures have resulted in some structures having a low natural frequency. This is because the design calculation did not meet the requirement of serviceability performance. Structures can experience excessive vibrations when they are subjected to different types of dynamic loading. A device can be installed to prevent these vibrations.In this thesis, we study the response of buildings and lateral vibrations of footbridges equipped with Tuned Liquid Damper. The aim is to mitigate the first mode of vibration. Tuned Liquid Damper consists of a container in rectangular, cylindrical or arbitrary shape partially filled with shallow liquid, most often water is used as a regulating device system. The design properties of Tuned Liquid Damper is introduced and it is based on the analogyof the most popular damper, Tuned Mass Damper.An experimental study of a building frame model with four floors is conducted to validate the numerical results obtained from the simulation of the model in ANSYS. The linear and non-linear analysis are performed through a system coupling between Ansys mechanical and Fluent solver. The simulation results obtained are in good agreement with the experimental results.A parametric study is conducted with a simply supported steel footbridge. It is a 45 m long span with 3 m width and the flexural rigidity is modified to get the lateral vibration mode. The first lateral natural frequency obtained is 0.713 Hz. The load case for the study considered is according to Sétra guide. The variable parameters studied is the Tuned Liquid Damper water mass ratios: 0.7%, 1.0%, 2.0%, 3.0% and 4.0%. The results show a satisfactory performance of the footbridge model equipped with Tuned Liquid Damper. The accelerations are below 0.1 m/s2 which satisfied the requirement of 0.15 m/s2.

In recent years the design of pedestrian bridges has become more slender. As a result the bridges has lower natural frequencies and are more prone to excessive vibrations when subjected to dynamic loads induced by pedestrians. Akademiska Hus are building such a bridge at Nya Karolinska Solna where the bridge will span over Solnavägenconnecting the hospital building, U2, and the research facility BioMedicum. Due to practical reasons, it is not possible to connect one of the bridge ends mechanicallyto the building which increases the risk for lateral modes in the sensitivefrequency range of 0-2.5 Hz. The increased risk of lateral modes of vibrations within the sensitive frequency range as well uncertainties when determining the dynamic response led to this thesis. This thesis covers a frequency analysis of the previously mention bridge and an evaluation of the dynamic response under pedestrian loading by implementation of several design guidelines. A literature review was conducted with the aim of giving a deeper knowledge of human induced vibrations and the relevant guidelines for modelling of pedestrian loading. Furthermore, a parametric study was conducted for parameters which might be prone to uncertainties in data. The investigated parameters were the Young’s modulus for concrete and the surrounding fill materialas well as the stiffness of the connection to BioMedicum. The parametric study yielded a frequency range of 2.20-2.93 Hz for the first lateral mode and 5.96-6.67 Hz for the first vertical mode of vibration. By including nonstructural mass the lower limit for the frequencies were lowered to 2.05 and 5.59 Hzin the first lateral and vertical mode respectively. The parametric study also showed that the largest impact on the natural frequencies were obtained by manipulating the parameters for the supports, both for BioMedicum and the substructure. The implementation of the guidelines resulted in a lateral acceleration between 0.05 and0.599 m/s2. No evaluation was conducted for the dynamic response in the vertical direction due to a natural frequency of 5.59 Hz, which is higher than the evaluation criteria stated in Eurocode 0. The results showed that the design of the Skyway bridge is dynamically sound with regard to pedestrian loading and no remedial actions are necessary.