Semi-active tuned mass damper building systems: Design

Passive and semi-active tuned mass damper (PTMD and SATMD) building systems are proposed to mitigate structural response due to seismic loads. The structure's upper portion self plays a role either as a tuned mass passive damper or a semi-active resetable device is adopted as a control feature for the PTMD, creating a SATMD system. Two-degree-of-freedom analytical studies are employed to design the prototype structural system, specify its element characteristics and effectiveness for seismic responses, including defining the resetable device dynamics. The optimal parameters are derived for the large mass ratio by numerical analysis. For the SATMD building system the stiffness of the resetable device design is combined with rubber bearing stiffness. From parametric studies, effective practical control schemes can be derived for the SATMD system. To verify the principal efficacy of the conceptual system, the controlled system response is compared with the response spectrum of the earthquake suites used. The control ability of the SATMD scheme is compared with that of an uncontrolled (No TMD) and an ideal PTMD building systems for multi-level seismic intensity. Copyright © 2009 John Wiley & Sons, Lt

Semi-active control of mid-story isolation building system

In this paper, a novel Pulsed-Width-Modulated (PWM) half-bridge High Speed Drilling Electrical Discharge Machining (HSDEDM) power supply has been developed. This power supply has excellent features that include minimal component count and inherent protection. This topology has an energy conservation feature and eliminates the output bulk capacitors and current limiting resistances. Energy used in the erosion process will be controlled by the switched Insulated Gate Bipolar Transistors (IGBTs) in the half-bridge network and be transferred to the gap between the tool and work-piece. The relative tool wear and machining speed of our proposed topology have been compared with that of a normal power supply with current limiting resistances

Innovative seismic retrofitting strategy of added stories isolation system

The seismic performance of “added stories isolation” (ASI) systems are investigated for 12-story moment resisting frames. The newly added and isolated upper stories on the top of the existing structure are rolled to act as a large tuned mass damper (TMD) to overcome the limitation of the size of tuned mass, resulting to “12 + 2” and “12 + 4” stories building configurations. The isolation layer, as a core design strategy, is optimally designed based on optimal TMD design principle, entailing the insertion of passive flexible laminated rubber bearings to segregate two or four upper stories from a conventionally constructed lower superstructure system. Statistical performance metrics are presented for 30 earthquake records from the 3 suites of the SAC project. Time history analyses are used to compute various response performances and reduction factors across a wide range of seismic hazard intensities. Results show that ASI systems can effectively manage seismic response for multi-degree-of freedom (MDOF) systems across a broader range of ground motions without requiring burdensome extra mass. Specific results include the identification of differences in the number of added story by which the suggested isolation systems remove energ

Semi-active tuned mass damper building systems: Application

Seismic performance attributes of multi-story passive and semi-active tuned mass damper (PTMD and SATMD) building systems are investigated for 12-story moment resisting frames modeled as ‘10+2’ stories and ‘8+4’ stories. Segmented upper portion of the stories are isolated as a tuned mass, and a passive viscous damper or semi-active resetable device is adopted as energy dissipation strategy. The semi-active approach uses feedback control to alter or manipulate the reaction forces, effectively re-tuning the system depending on the structural response. Optimum TMD control parameters and appropriate matching SATMD configurations are adopted from a companion study on a simplified two-degree-of-freedom (2-DOF) system. Statistical performance metrics are presented for 30 probabilistically scaled earthquake records from the SAC project. Time history analyses are used to compute response reduction factors across a wide range of seismic hazard intensities. Results show that large SATMD systems can effectively manage seismic response for multi-degree-of freedom (MDOF) systems across a broad range of ground motions in comparison to passive solutions. Specific results include the identification of differences in the mechanisms by which SATMD and PTMD systems remove energy, based on the differences in the devices used. Additionally, variability is seen to be tighter for the SATMD systems across the suites of ground motions used, indicating a more robust control system. While the overall efficacy of the concept is shown the major issues, such as isolation layer displacement, are discussed in details not available in simplified spectral analyses, providing further insight into the dynamics of these issues for these systems

Semi-active tuned mass damper building systems: Design

Passive and semi-active tuned mass damper (PTMD and SATMD) building systems are proposed to mitigate structural response due to seismic loads. The structure's upper portion self plays a role either as a tuned mass passive damper or a semi-active resetable device is adopted as a control feature for the PTMD, creating a SATMD system. Two-degree-of-freedom analytical studies are employed to design the prototype structural system, specify its element characteristics and effectiveness for seismic responses, including defining the resetable device dynamics. The optimal parameters are derived for the large mass ratio by numerical analysis. For the SATMD building system the stiffness of the resetable device design is combined with rubber bearing stiffness. From parametric studies, effective practical control schemes can be derived for the SATMD system. To verify the principal efficacy of the conceptual system, the controlled system response is compared with the response spectrum of the earthquake suites used. The control ability of the SATMD scheme is compared with that of an uncontrolled (No TMD) and an ideal PTMD building systems for multi-level seismic intensity. Copyright © 2009 John Wiley & Sons, Lt

Energy-dissipative semi-active tuned mass damper building systems for structural damage reduction”

14-pagesRealistic 12-story energy-dissipative Tuned Mass Damper (TMD) building systems are proposed to mitigate story and structural damage due to seismic loads. The upper two and four stories are isolated and used as the tuned mass, saving excessive non-functional added weight. Further, it is proposed to replace the passive spring damper with semi-active resetable devices, creating more adaptive resetable device based semi-active TMD (SATMD) systems. Semi-actively manipulating the reaction forces effectively retunes the system depending on the structural response, offering a broader more adaptive solution than passive tuning. This proposal thus combines emerging semi-active devices with existing tuned mass damper concepts to create extended seismic response mitigation applications. Inelastic time history analyses are used to demonstrate the efficacy of this concept. Performance is measured in terms of dissipated hysteretic energy and weighted damage values. The SATMD systems outperform passive solutions in most cases, by at least 10%, especially if the passive tuning is not optimal or exact. The impact on the mode shapes and modal contributions is also markedly different for the systems, further illustrating the differences in performance obtained

Design of Semi-Active Tuned Mass Damper Building Systems using Resetable Devices

Passive and Semi-Active Tuned Mass Damper (SATMD) building systems are proposed to mitigate structural response due to seismic loads. A structure’s upper portion itself plays a role as a tuned mass and a viscous damper or a semi-active (SA) resetable device is adopted as a control feature for the Passive TMD (PTMD), creating a SATMD system. Two-degree-of-freedom (2-DOF) analytical studies are employed to design the prototype structural system, specify its element characteristics and determine its effectiveness for seismic response mitigation, including defining the resetable device dynamics. For the PTMD system realistic 15% and much higher optimal TMD damping ratios are compared. For the SATMD system the stiffness of the resetable device design is combined with and without rubber bearing stiffness. From the parametric results, the most effective SATMD system can be derived and then adopted as a practical control scheme. Response spectrum results using suites of earthquake are used to compare the SATMD scheme to an uncontrolled (No TMD) and an ideal passive tuned mass damper (PTMD) building system. The results from this design focused research will be utilised to assess the non-linear seismic response of realistic multi-degree-of-freedom (MDOF) structures

Multi-storey semi-active tuned mass damper building system

To overcome the inability of the Tuned Mass Damper (TMD) system, which has linear properties and limitations on the weight, this paper suggests a multi story Semi-Active Tuned Mass Damper (SATMD) building system using a structure’s upper portion as the tuned mass damper and resettable actuator as a semi-active (SA) control device. For this purpose, it is proposed to segregate the building’s upper story(s) with rubber bearings, and employ SA resettable actuator and viscous damper to the story(s) of upper segment to lower structural elements. The optimal frequency tuning ratio and damping ratio is considered for large mass ratio, for which previously proposed equation was used and the practical optimal stiffness was allocated to the acuator stiffness and rubber bearing stiffness. 2DOF model, including SATMD, is adopted to verify the principal efficacy of the suggested structural control concept and 6 and 12 story moment resisting benchmark frames are investigated to assess the viability and effectiveness of the system that aims at reducing the response of buildings to earthquakes. This research determines the feasibility, design methods and effectiveness of the proposed multi story SATMD building system by numerically analyzing and comparing the response with no control and passive TMD system

Resetable Tuned Mass Damper and Its Application to Isolated Stories Building System

The seismic performances of multi-story passive and semi-active tuned mass damper (TMD) building systems are investigated for 12-story moment resisting frames modeled as ‘10+2’ story and ‘8+4’ story. Segmented upper stories of the structure are isolated as a tuned mass, and a passive viscous damper or semi-active resetable device is adopted for energy dissipation. Optimum TMD control parameters and appropriate matching resetable TMD (RTMD) configurations are adopted from a previous study on a simplified two degree of freedom (2-DOF) system. Log-normal statistical performance results are presented for 30 probabilistically scaled earthquake records. The time history analysis and normalized reduction factor results show the response reductions for all seismic hazards. Thus, large semi-active isolated stories building systems can effectively manage seismic response for multi degree of freedom (MDOF) systems across a broad range of ground motions in comparison to passive solutions. This research demonstrates the validity of the isolated stories building systems using RTMD control strategy for consideration in future design and construction

Analytical modelling and MDOF response considerations for semi-active tuned mass damper building systems subjected to earthquake excitation

plenary keynote paperPassive and Semi-Active Tuned Mass Damper (PTMD and SATMD) building systems can reduce structural response due to earthquake excitation. The structure’s upper portion can be used either as a passive TMD, or as a semi-active resetable device in a SATMD system. The seismic performance of multi-story passive and semi-active tuned mass damper (PTMD and SATMD) building systems are investigated for 12-story moment resisting frames modeled as ‘10+2’ stories and ‘8+4’ stories. Segmented upper stories are isolated to act as the tuned mass. Passive viscous damper or semi-active resetable devices are evaluated using an energy dissipation strategy based on an optimal TMD design stiffness and damping value. The semi-active approach uses feedback control to alter or manipulate the reaction forces, effectively re-tuning the system depending on the structural response. Statistical performance metrics are presented for 30 earthquake records from the 3 suites of the SAC project. Time history analyses are used to compute response reduction factors across a wide range of seismic hazard intensities. Results show that SATMD systems can effectively manage seismic response for multi-degree-of freedom (MDOF) systems across a broader range of ground motions in comparison to passive solutions. Specific results include the identification of differences in the mechanisms by which SATMD and PTMD systems remove energy, based on the differences in the devices used. Less variability is also seen for the SATMD systems, indicating an increased robustness