## 5 Conclusions  
The metaheuristic algorithm called harmony search is successfully modified to optimize the physical parameters of a mass damper and the controller gains of PID controller, which generates a control signal to produce an active control force. Based on the results, it is clearly seen that ATMD is both effective in the reduction of displacements under critical excitation and the other excitations considered in the optimization process. In the structure case tested for the method, it is possible to reduce maximum top story displacement by 39.78% for the most limited case of the stroke of ATMD, while TMD is effective by 31.22%. By the increase in the stroke capacity, TMD is not effective to show a better reduction performance, but ATMD can reduce displacements up to 53.71%. The reduction percentages are plotted for TMD and ATMD for different st_max values in Figure 7.  
Figure 6: Maximum top story displacement plot for FEMA P-695 far-field ground motions. Figure 7: The reduction percentages for TMD and ATMD for st_max cases. In order to provide the optimum control, the amount of the need maximum control force is 16.23%, 38.32% and 41.12% of the total weight of the structure for st_max = 2, st_max = 3 and st_max = 4 cases, respectively. By the increase of the stroke limitation, the extreme increase of the control forces may also increase the cost of application due to the required actuator. Another disadvantage of the usage of high stroke capacity for ATMD is the increase of the maximum accelerations. For the critical excitation, it is possible to reduce the maximum acceleration by 23% for the stroke capacity limited by 2, while ATMD with higher strokes increase it by 23% and 29%. In these cases, and if non-constructive components such as machine, equipment, shelfs, statues etc. need to be protected, additional use of base isolators is recommended. Passive TMD has an advantage on accelerations with 32% compared to uncontrolled structure. As the final remark related to the final technical issue about structural control, the decision to use TMD and ATMD can be made by trying the structural case, since both systems have advantages and disadvantages. For high stroke capacity limitations, optimum ATMD is very effective in the reduction in structural displacements, but these cases may have a high cost for the constructor or designer of ATMD system. The optimum TMD cases have less reduction capacity than ATMD for structural displacements, while the constraint about stroke limitation cannot gain bigger values than 2.0755 for the cases with maximum 3 and 4 permitted. This situation proves that usage of TMD may be a feasible way in cost, but ATMD can reduce the displacements if the demanded stroke can be physically provided by considering the rapid increase in the cost of the system. For different runs of the optimization methodology, it is possible to find different optimum design variables. This situation is generally seen for PID controller gain. The different sets of PID controller parameters can be effective in generating similar control forces. Hence, the objective function value of all optimum sets is be equal to each other. Modifying the HS algorithm with the use of the current best solution with a possibility called BSCR helps solve the complex vibration problem including the random vibration behavior of seismic excitations. The trapping to a local optimum solution was prevented by using a 30% possibility of using the best current solution. The PID-controlled ATMD, which is optimized according to time-domain analysis with the employment of the modified HS, is an effective and feasible approach for ATMD controlled seismic structures. In the future studies, different objectives and various design constraints can be also considered in the optimization methodology of tuning of ATMD. Parametric structural cases and multiple cases of structures also need to be conducted for global conclusions about optimum design. [PERSON] was in the control of all sessions, since the study is a part of her PhD thesis.