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Seismic Design
In recent years, it is thought that resisting the seismic forces only by raising stiffness of the individual structural member when large-scale seismic force acts has the limit. The fact that a lot of structures suffered serious damege by the seismic force outside assumption has proven this in the Hyogoken-nanbu earthquake in January, 1995. Therefore, it is said that it is important to suppress damage to the minimum by taking the member with the energy absorption performance to the structure at the same time as improving the stiffness of the structure, and to prevent the stability of the entire structure being lost. Then, in our laboratory, we try to do dynamic analysis at a large earthquake of bridge structure that is adopted seismic isolation bearing, and cable-stayed bridge which has the horizontal beam where a seismic isolation device was taken at, to consider the difference of the characteristic in presence of a seismic isolation device, and to search for the possibility of new seismic isolation tequnic.
ex.1: Study on the Damper of Steel Tower
Against the huge earthquake movement like Hyogoken-nanbu earthquake, it is so difficult to design all structural members of gate type structure, such as viaduct with steel rigid frame, steel tower of suspension bridge or cable-stayed bridge, within the range of elasticity. Today, it is thought that it is effective to keep safety as a structure system by adopting damper to a certain part. Then, in this research, we aim at the improvement of steel tower's earthquake-proof performance by using damper device.
ex.2: Study on the influence of horizontal beam given to the response
In resent years, earthquake-proof design that keeps health state without damaging all structural members against all assumed seismic forces is so difficult. And, the design to allow damaging partly of the structure within the range where the function as the structure is not ruined, in addition to improving the stiffness of the structure is important. Therefore, the number of cases to adopt seismic design concept in the bridge structures increases to meet these demands. Then, in this research, nonlinear dynamic analysis for steel tower of cable-stayed bridge whose horizontal beam is composed of member that has damping performance is performed to examine the effect.