A multiaction hybrid damper (MHD) is designed to have independent hysteretic characteristics under small and large loading conditions, and its control performance for building structures excited by wind or earthquake load is verified. The MHD is composed of steel elements, two friction pads, and two lead rubber bearings (LRBs). Because the friction pads and the LRBs are in series connection, only the LRBs deform before the friction pad slippage occurs. After the friction slippage, the damper deformation concentrates on the friction pads. The initial stiffness and hysteresis are dependent on the properties of the LRB, and the maximum force is determined by the friction pad. Accordingly, the load-deformation behaviors before/after the friction slippage can be independently designed to show optimal performance for a building structure subject to wind and earthquake loads. The cyclic loading tests of a full scale MHD were conducted to evaluate the multiaction behaviors and energy dissipation capacity of the MHD. The control performance of the MHD damper is analytically investigated by using a 20-story steel structure subject to wind loads and a 15-story RC structure excited by earthquake loads. The MHD damper showed good performance for reducing both the linear wind-induced and nonlinear earthquake-induced responses.

Aging and structural deterioration under severe environments are major causes of damage in reinforced concrete (RC) structures, such as buildings and bridges. Degradations such as concrete cracks, corrosion of steel, and deformation of structural members can significantly degrade the structural performance and safety. Therefore, effective and easy-to-use methods are desired for repairing and strengthening such concrete structures. Various methods for the strengthening and rehabilitation of RC structures have been developed over the past several decades. Recently, FRP composite materials have emerged as a cost-effective alternative to conventional materials for repairing, strengthening, and retrofitting deteriorating/deficient concrete structures, by externally bonding FRP laminates to concrete structural members. The main purpose of this study is to investigate the effectiveness of the FRP retrofit for circular type concrete columns under the framework of the adaptive neuro-fuzzy inference system (ANFIS). Retrofit ratio, strength of existing concrete, thickness, number of layer, stiffness, ultimate strength of fiber, and size of specimens are used as input parameters to predict strength, strain, and stiffness of the post-yielding modulus. These proposed ANFIS models show reliable increased accuracy in predicting the constitutive properties of concrete retrofitted by FRP, compared to the constitutive models suggested by other researchers. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

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The purpose of this study is to evaluate the applicability of seismic isolation devices for marine accidents under seismic loads. The lighthouse structure is a very important facility when the ship approaches the port. However, it is necessary to reinforce the structure to protect it from earthquake. This study presents isolation technology as a method to enhance the seismic performance of lighthouse structures built before seismic design criteria were established. This paper analyzed improvement of seismic performance in three cases of seismic isolation by applying the proposed method of isolation technology. In Case 1, the entire lighthouse structure is isolated, and in Case 2, only the lighthouse lens, the most important component of the lighthouse structure, has been isolated to assure constructability and economy. In Case 3, isolation effect was analyzed by comparing Case 1 and Case 2 with lighthouse structures.

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