For a secondary mass damper such as tuned liquid damper (TLD) or tuned liquid column damper (TLCD), whose moving mass is liquid, it is impossible to prefabricate the damper in a factory for the identification of dynamic properties. Also, it is not easy to prefabricate a concrete tuned mass damper (TMD), whose moving mass is made of concrete, in a factory. In this article, an identification method for finding dynamic properties of secondary mass dampers based on the fullscale field test is presented. Decoupled equations of motion are derived from a coupled equation of motion of building and damper. The decoupled equations of motion are then used for system identification using the response of the damper as an input and the response of the building as an output. The proposed method is applied to numerical examples and an actual TMD and TLCD installed in buildings.

In this paper we investigate a systematic procedure for determining frequency-dependent weighting functions for an H2 controller in the frequency domain. Based on experimental results from the system identification of a model structure with an active mass driver, we choose frequency-dependent weighting functions, including filters on an earthquake input model, sensor noise, control output, and control force. These are incorporated into the plant to produce an optimal controller. Combining the weighting functions and filters and comparing the trade-off problem between response reduction and control force, an optimal combination of weighting functions and filters is determined. The performance of the designed H2 controller is evaluated by shaking-table tests of a three-story scaled model with an active mass driver.

We conduct wind-tunnel experiments on three different uniform roughness arrays composed of sparsely distributed rectangular cylinders for the estimation of surface parameters. Roughness parameters such as the roughness length z 0 and zero-plane displacement d are extracted using a best-fit approximation of the measured wind velocity. We also perform a large-eddy simulation (LES) to confirm that four sampling points are sufficient to surrogate a space average above the canopy layer of the sparse roughness arrays. We propose a new morphological model from a systematic analysis of experimental data on the arrays. The friction velocity predicted by the proposed model agrees well with the peak value of the measured Reynolds shear stress (− u w ) 0.5 . The proposed model is further validated in an additional wind-tunnel experiment conducted on a scaled configuration of a real urban area exposed to four wind directions. The proposed model is found to perform very well

<p>In general, the stabilizing measures by temporary tied-down cables during typhoon are used to the free cantilever construction for a cable stayed bridge. However, it needs temporary concrete blocks or pile foundations to rest on 30m deep sea in the Busan~Goeje fixed link (BGFL) site. Thus it is a very expensive temporary method and could cause an environmental pollution problem to dredge the ground in the sea. Moreover, it could disturb the route of the ships or induce ship collisions.</p><p>A TMD (Tuned Mass Damper) is proposed to the three-pylon cable stayed bridge during construction to suppress the wind-induced vibrations and ensure the aerodynamic stability. The stabilizing measures by TMD do not need any foundations. Thus it could solve the environmental problem and avoid the risk of the ship collisions induced by the temporary cables. In addition, it is more economical in comparison with the temporary tied-down cables.</p>

<p>Lotte World Tower which is a supper tall building with about 555m height (123 stores) has been under construction in Seoul, Korea. When the Lotte World Tower is constructed, it will become the highest building in East Asia. Generally, supper tall buildings shall be checked for vortex-induced vibration and aeroelastic instability by the appropriate methods such as wind tunnel tests. The wind tunnel tests on the Lotte World Tower were conducted by RWDI. Wind tunnel tests were performed to determine the structural wind loads and building motions by high frequency force balance (HFFB) test, and local wind loads on cladding of the building by pressure measurement test, respectively. To evaluate the habitability of the building, acceleration responses at specific structural levels were compared with present acceleration criteria from International Organization for Standardization</p><p>(ISO 10137: 2007) criteria, Architectural Institute of Japan (AIJ 2004) guidelines, and RWDI’s criteria. Those results for Lotte World Tower were reviewed and discussed in this paper.</p>