كنترل نيمه‌فعال ارتعاش قايم پل‌هاي معلق در برابر زلزله با استفاده از ميراگرهاي مگنتوريولوژيك و منطق فازي

Semi-active Control of Vertical Vibration of Suspension Bridges Subjected to Earthquake Excitations using MR Dampers and Fuzzy Logic

در اين پژوهش، كاهش ارتعاش قايم پل‌هاي معلق با استفاده از ميراگرهاي نيمه فعال مگنتوريولوژيك و منطق فازي مورد مطالعه قرار گرفته است. لذا از يك ميراگر مگنتوريولوژيك بزرگ‌مقياس 2200 كيلونيوتني استفاده و پل معلق وينسنت توماس در آمريكا به‌عنوان مثال عددي انتخاب شده است. يكي از مسايل چالش‌برانگيز در اين پژوهش، نحوه‌ي نصب ميراگرها در درجات آزادي دور از پايه‌هاي پل، جهت افزايش كارآيي ميراگرها بوده است؛ كه براي حل آن، استفاده از خرپاي صلب پيشنهاد شده است. در اين پژوهش، 2 مدل بهينه از نظر تعداد و موقعيت ميراگرها ارايه و براي هر مدل نيز 3 نوع كنترل‌گر فازي پيشنهاد شده و مطالعات نشان داده است كه مدل 2 با 8 ميراگر با استفاده از كنترل‌گر فازي نوع يك، كه يك ورودي دارد، بهترين عملكرد را در كاهش پاسخ‌هاي پل دارد. در ضمن ميراگرهاي نصب‌شده قادر به كاهش پاسخ پل در جهت افقي هم هستند.

In this paper, a semi-active control technique is presented to mitigate the seismic vertical response of suspension bridges using magneto-rheological (MR) dampers and fuzzy logic. Fuzzy logic is a kind of controller that can directly determine the input voltage of an MR damper from the responses of the structure, and MR dampers are semi-active control devices in the structure which MR fluid is used in their structure. MR dampers have received significant attention in recent years because they retain the reliability of passive control systems and the advantage of adjustable parameter characteristics of an active control system, simultaneously. The magneto rheological damper is an attractive candidate in semi-active control of structures because of its advantageous features including: no need for a major energy source and high power capacity, adjustable power, fast response, and safe operation in cases of power failure. To achieve this goal, a large scale MR damper (2200 KN) is used, and the Vincent-Tomas suspension bridge, located in Los Angeles, USA, has been chosen for the numerical example. Installation of the dampers at degrees along the bridge span, far from the towers, should be highlighted as an extremely challenging problem in this study to increase damper efficiency. In order to solve this problem, use of a rigid truss is proposed, and different schemes are also suggested to install MR dampers along the bridge span. The equation of motion of the system, using generalized modal coordinates, is written in the state-space form and the responses of the bridge are calculated under application of 15 major, world-wide earthquake accelerograms. Different inputs and rule bases are proposed for the fuzzy controller in this research. The characteristics of the fuzzy controller, and the number and position of the dampers are optimized by the trial and error method. Finally, three models with optimal position and number of dampers with optimal fuzzy control parameters are proposed. A comparison between the uncontrolled and controlled responses indicates that the proposed semi-active control technique can effectively suppress the vertical responses of the example bridge.