Determination of the optimum parameters of triple friction pendulum isolators through economic design approach

In this thesis study, an algorithm has been developed to obtain optimum parameter values for the production of three curved friction pendulum isolation units, which are suitable for superstructure characteristics and provide the targeted structural performance at the lowest cost. With this algorithm, different isolators with variable geometric and friction properties have been derived using values of the friction coefficient, curvature radius, and displacement capacity that change within certain ranges. Among the derived isolators, the most rigid one was selected as a reference, and the parameters of the isolator were analyzed in an equivalent earthquake load and time-domain analysis of a four-story reinforced concrete structure. The earthquake records used for the time-domain analysis were selected from sets consisting of eleven earthquakes created with one hundred different records. The most suitable set of earthquake records was formed by scaling the records whose acceleration spectra were the most compatible with the target spectrum. The analysis results were examined, and the types of isolators that satisfied the required base displacement demands for both analysis methods were determined and ranked according to cost increase. The cost ranking was made by calculating the total volumes of the inner and outer concave plate of the derived isolators. The minimum plate thickness calculation was made in accordance with the TS EN 1337-2 specification. Relative story displacement, story acceleration, base displacement, and other structural responses were analyzed continuingly with the parameter values of the isolators listed, until a type meeting the requirements in ASCE 7-22 was found. Additionally, parametric relationships affecting the cost of isolators were examined using the obtained data, and value ranges were proposed for some parameters. It was observed that very close values for critical design targets, such as the displacement capacity of the isolation system, period, and shear forces transmitted from the isolation interface to the superstructure, can be achieved at significantly different costs. These cost discrepancies can reach levels of around 35%. Calculations and analyses were performed using integrated operations of MATLAB and ETABS programs. With this developed algorithm, the most economical isolator parameter values that provide the expected structural performance can be obtained in a very short time, allowing for final design.