VIBRATION CONTROL OF HIGH-RISE BUILDING USING ACTIVE BRACES AND THEIR OPTIMAL PLACEMENT

 These days, there are a lot of high-rise buildings and it is important for these buildings to be reinforced against earthquakes. As a device to reduce the response of the building, active braces are used. In this paper, their optimal placement method to reduce building's response by limited number of them is researched.<br> Firstly, to search optimal placement to set active braces, response comparisons of four setting patterns, which are named Upper, Lower, Middle and Uniform, are carried using sine waves. These sine waves have the same periods with natural periods of the building. It shows that control forces become large at layers which story drifts are large. Thus, the values of the feedback gain matrix on Linear Quadratic Regulator (LQR) method are compared. It appears that the feedback gain matrix has large gains where they are related to displacement. In addition, equation of control force shows each layer's story drift has a great influence on deciding control forces.<br> Secondary, setting methods named MSD and NOD are proposed and their effectiveness is verified. MSD places active braces around the layers which will have large story drift and NOD places them around nodal points. In this paper, two earthquakes which have large power on building's 1st or 2nd natural period are used. It is confirmed that Lower pattern is effective for the 1st mode earthquake, but against the 2nd mode earthquake, Upper pattern is more effective. So these setting patterns can't work effectively for all earthquakes. About MSD and NOD pattern, though their effectiveness aren't the best, but they can reduce responses against several frequencies. This means that they can work more effectively for several types of earthquakes.<br> Thirdly, to research the safer setting method, the robustness is compared when one active brace breaks down at upper, lower or middle layer. In this paper, three setting patterns, MSD, NOD and Uniform, are used to compare. On almost all of the layers, responses of Uniform became larger than MSD and NOD when the break down happened. From the comparison of MSD and NOD, when the break down happened at lower and middle layer, responses of each layer don't show large difference. But the case when the break down happened at upper layer, responses of NOD pattern became larger than that of MSD pattern. It means MSD pattern has more active braces at effective layers than NOD.<br> In this paper, effectiveness comparison on four simple patterns shows that control forces become large at the layers which have large story drift. To research their relationship, the feedback gain matrix is researched. Control forces are decided from the displacements and velocities of each layer and displacements have larger influence. From this relation, two setting patterns, named MSD and NOD, are proposed and comparison of their effectiveness and robustness were carried. Results shows that MSD and NOD can reduce responses on some modes, thus they will work more effectively for many type of earthquakes. In addition, MSD has better effectiveness than NOD when break down happens.<br> In future studies, advanced setting pattern which has some active braces for each selected layer will be researched. In addition, optimal control design which considers many types of earthquakes including imitation wave and time lag between earthquake input and control force are needed to research.