Name: Monir AhmadEnglish 259Fall II 2018Technical WritingTTH 1-4:25PMProfessor LindaA comparative study of semi- active control strategiesfor base isolated buildings   Earthquake ResistanceEarthquake is a violent and sudden shock of the earth, whichis often caused by two layers of the ground slipping from one another.Earthquakes are measured in accordance with their magnitudes. The earthquakeswith higher magnitudes have higher destruction levels.

Scientists believe thatearthquakes can occur anywhere, anytime, and are unpredictable. The engineeringsociety believes there are no systems that can reduce the magnitude of theearthquakes but they have several techniques that would protect the safety ofbuildings in earthquakes.There are several methods used in the control of semi-activecontrol which includes;(i)                ”Maximum energy dissipation algorithm andmodulated homogeneous friction algorithm”The behavior of devices that are semi-active is mostlynonlinear, and as such, one of the major challenges during application of thistechnology is the appropriate development of control algorithm. A number ofalgorithms are tested for use with the MR (Magneto rheological Damper), asemi-active control device that’s been innovated and is quite promising to thecivil engineering applications. Discussion of each control system takes placeafter simulation, with results indicating that the control systems’ performanceis dependent on the employed algorithm (Dyke and Spencer Jr., 1997).(i)                ”Sliding mode control”SMC is a nonlinear control methodwhich forces a system slide over a cross-section of the systems’ normalbehavior through alteration of the nonlinear systems’ dynamics.

The method canswitch from one continuous structure to another making the method a variablestructure method (Komatsu et al., 2007). (ii)              ”Backstopping control technique andquantitative feedback theory”Suspension systems are crucialeven in vehicles. The suspension systems are designed to ensure the comfort ofthe passengers, protect the chassis, and load. Suspensions have been designedto mitigate uncomfortable and harmful vibrations through the use of dampers.

Incases where the suspension systems are used in semi-active controls, twocontrol methodologies are used in making use of magneto rheological dampers.For the appropriate performance of these dampers, their nonlinear dynamicsrequires the use of control methodologies that are nonlinear. The firstmethodology involves the use of the backstopping technique. The other methodologyis the QFT (Quantitative Feedback Theory). Despite the fact that QFT isdesigned for linear systems, it could also be used for nonlinear systems.

Achievement of this can only be possible in the event nonlinear dynamics arerepresented as linear systems, with representations of uncertainties that areapproximately true with the behavior of the plant to be controlled (Zapateiroet al., 2010). (iii)            ”Force tracking”Force tracking is a method used intesting structures and facilities and is widely applied in seismic and civilengineering. For there to be efficient suppression of the surplus force thatresults from acceleration motion during the force control process, an FVFC(Force and Voltage Feed forward Controller) and FIDOB (Feed forward Inversewith Disturbance Observer) is presented. As an inner loop feed forwardcontroller, it constitutes the real-time control voltage signal and thegenerated force feedback signal of the actuators’ acceleration as compensationfor the specimens’ acceleration motion for better disturbance rejection model.The FVFC requires little information of the parameters or dynamic structure ofthe system. FIDOB is then combined with FVFC to deal with remainingdisturbances as an outer-loop for the controlled testing of the electro-hydraulichybrid system.

Therefore, there is an integration of the proposed controlleradvantages of FVFC controller and FIDOB in terms of high tracking performanceand easy implementation. The uniaxial electro-hydraulic hybrid test rig is usedto carry out comparative experiments, with the effectiveness of the proposedcontrol strategy being seen from the results from the xPC rapid prototypingtechnology and experiments (Dyke and Spencer Jr., 1997). 

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