Abstract. The performance of multiple tuned mass dampers (MTMD) installed at the top floor of the wind excited benchmark building under across wind loads is investigated. The performance of MTMD is compared with that of single tuned mass damper (TMD) having same total mass. The governing equations of motion of the building with MTMD/ TMD are solved by employing state space formulation. Initially, the TMD is installed at the top floor of the benchmark building and the optimum parameters of the damper for the minimization of various performance criteria of the building are obtained for different mass ratios. Later on, the MTMD is installed at the top floor of the building and the optimum parameters are obtained for the minimization of various performance criteria of the building for different mass ratios and number of dampers. As it is easier to maintain the same stiffness of dampers, the stiffness of each damper in MTMD is maintained as constant. From the study, it is found that the MTMDs are quite effective and robust in the vibration control of the benchmark building.
The response of the benchmark building is investigated under across-wind loads. The governing equations of motion are solved by employing state space theory. Generally, the dampers are connected to successive fl oors of a building (Type-I arrangement). As the relative velocity and inter-storey drift between the alternate fl oors would be larger, the performance of dampers is studied by connecting them to alternate stories with two innovative (Type-II and Type-III) arrangements, and the comparison of response is made with that of the conventional (Type-I) arrangement. Optimization of location and number of dampers is also carried out with the help of a controllability index, which is obtained with the help of root-mean-square value of the inter-storey drift. Further, a parametric study of semi-active variable friction dampers and linear viscous dampers by varying gain multiplier and damping ratio, respectively, is carried out. From the numerical study, it is observed that Type-II and Type-III arrangements are found to be quite effective in reducing the response quantities. It is also found that a considerable amount of economy is achieved by optimization of location of dampers. performance criteria of the building with LVDs and SAVFDs with the proposed arrangements with those of the conventional arrangement, in order to measure the effectiveness of the alternate arrangement; (c) to optimize the location of the LVDs to achieve the performance criteria comparable to those obtained with sample controller; and (d) to optimize the location of the SAVFDs to achieve the performance criteria comparable to those obtained with Type-III arrangement. BENCHMARK BUILDINGThe wind-excited benchmark building is a 76-storey, 306-m offi ce tower proposed for the city of Melbourne, Australia. The plan and elevation are shown in Figure 2. The building is an reinforced cement concrete building consisting of a concrete core and concrete frame. The mass density of the building is 300 kg per cubic metre. The building is slender with a height-to-width ratio of 306.1/42 = 7.288; therefore, it is wind sensitive. The outer dimension for the central reinforced concrete core is 21 × 21 m. The 24 columns on the periphery of the building are distributed equally on each of the four sides of the building. These columns are connected to a 900-mm-deep and 400-mm-wide beam on each fl oor. The lightweight fl oor construction is made up of steel beams with a metal deck and a 120-mm slab. The compressive strength of concrete is 60 MPa and the modulus of elasticity is 40 GPa. Column sizes, core wall thickness and fl oor mass are varying along the height. The building has six plant rooms. The building is modelled as a vertical cantilever beam (Bernoulli-Euler beam). The portion of the building between adjacent fl oors is considered as a classical beam, and the fi nite element model (FEM) model is constructed. The 76 rotational degrees of freedom have been removed by the static condensation. This results in 76 degrees of freedom representing the displacemen...
Fluid power is one of the courses required for most engineering technology programs and thus enrolls more than 200 students annually. Studies show that fluid power modules related to hydraulic and pneumatic systems result in a relatively high W/D/F rate (Withdrawals, D and F grades), where many students struggle to connect the theory with practice. From a pedagogical perspective, this rate is due to the traditional laboratory syllabus that is insufficient to address the complexity of hydraulic and pneumatic systems. This work aims to enhance fluid power education by conducting a research study for testing and examining the efficacy of integrating state-of-the-art simulation courseware into the laboratory work of fluid power courses. For conducting the study, interfaceable Computational Fluid Dynamics (CFD) modules of a hydraulic Gerotor pump are developed and incorporated into the laboratory syllabus of the MET:23000 Fluid Power course at Purdue University. The CFD simulation modules were designed and implemented in the labs in collaboration with Simerics. A survey was designed and conducted with 93 students to measure their perceived learning of fluid power concepts and examine their attitudes toward the CFD simulation used for instruction. The survey outcomes revealed that the executed CFD simulation assisted the students in understanding the overall operation of the Gerotor pump. The results show that the simulation courseware supported students in acquiring the fundamentals of fluid power, which could assist them in conducting future engineering decisions. Besides the conceptual understanding, students were engaged in the lab modules. They enjoyed visualizing the variation in pressure contours, velocity vectors, and cavitation bubbles.
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