| dc.description.abstract | The constant increase in height of buildings, especially in countries with high seismic activity, suggests that some characteristics that comprise the overall performance of the structure should be revised. During the design process, the reduction of elastic forces in elements (displacement response) is of critical importance. Since accelerations are closely related to human perception, it is strongly recommended to control them as well. As the main form to achieve these objectives is by increasing the dissipating forces, supplemental damping is commonly provided as one of the cost-efficient solutions.
In the present research, a type of velocity-dependent dampers, known as Fluid Viscous Damper (FVD), is employed in parallel with a spring, both provided in the interface of floor and core of the upper storeys of an illustrative 250-metre building. Based on the differential movement of both parts (floor and core), the system consists of mobilising the own mass of each floor to provide damping to the structure.
Four stiffness arrangements for the last ten storeys of the building are proposed and investigated in terms of inter-storey drifts, absolute accelerations, and displacements at the top of the structure. All the analyses are carried out under earthquake and wind loading. For that purpose, seven earthquake records are considered, as well as two wind profiles generated by using a first-order Markov chain.
Overall, the best performance is achieved by a linear ascending distribution, which consists of an arrangement of stiffnesses in which the spring at every storey has a higher stiffness than the previous (lower) one, following a linear relationship. This distribution provides 6.6% equivalent damping in the first mode, which means 4.5% additional damping.
Moreover, when analysing the performance in terms of inter-storey drifts reduction of this distribution, a reduction in the range of 55% to nearly 100% for earthquake loading, and 70% to 95% under wind loading, is achieved. This results in accomplishment of code limits after applying supplemental damping under the considered configuration. Furthermore, the reductions of maximum absolute accelerations in the storeys are up to 60% under earthquake loading, and in the interval of 35% to 65% for wind loading. Lastly, although there is no agreement in top displacement limits, this distribution appears not to accomplish the thresholds imposed by common practice.
Under these considerations, a new arrangement is suggested, based on the linear ascending distribution, and aiming for a chosen objective of top displacement, which leads to more flexible links in each storey. | |
