Yazar "Aydin, E." seçeneğine göre listele

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    DETERMINATION OF OPTIMAL ELASTIC SPRINGS FOR CANTILEVER BEAMS SUPPORTED BY ELASTIC FOUNDATION
    (Acad Sci Czech Republic, Inst Theoretical & Applied Mechanics, 2018) Aydin, E.; Ozturk, B.; Dutkiewicz, M.
    In this study, the optimum distribution of the elastic springs in which a built-in cantilever beam is seated, so as to minimize the shear force on the support of the beam, is investigated. The Fourier transform is applied to the vibration equation of the beam written in the time domain and is shown by the structural behaviour transfer function which is made independent from the external influence. For the first and second modes of beam, the optimum locations and amounts of the springs were investigated so that the shear force transfer function amplitude was minimal. Stiffness coefficients of springs are taken as design variables. There are active constraints on the sum of the spring coefficients taken as design variables and passive constraints on each of them as the upper and lower bounds. Optimality criteria are derived using the Lagrange Multipliers method. The gradient information required for solving the optimization problem is analytically derived. Numerical results show that the aimed method is quite effective in finding optimum spring stiffness coefficients.
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    Optimal damper distribution for seismic rehabilitation of planar building structures
    (ELSEVIER SCI LTD, 2007) Aydin, E.; Boduroglu, M. H.; Guney, D.
    In this study, the variations of optimal damper placement using different objective functions are presented. Instead of the usual choice of transfer function amplitude of the top displacement of the structure, the transfer function amplitude of the base shear force evaluated at the undamped fundamental natural frequency of the structure is chosen as an objective function. In the optimization procedure, the damping coefficients of the added dampers are treated as design variables. An active constraint on the sum of the damping coefficients of added dampers and the upper and lower bounds for each damper are taken into consideration. The new objective function based on transfer function amplitude of the base shear force is compared with the transfer function amplitudes of top displacement. The response of the structure is investigated for both of the objective functions in terms of the transfer function. The time history analysis is performed using the Kobe earthquake ground motion records to demonstrate the validity of the proposed design method. The results of the numerical procedure show that the proposed procedure based on the transfer function of the base shear force can also be beneficial in the rehabilitation of seismic response of the structures. (c) 2006 Elsevier Ltd. All rights reserved.
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    OPTIMAL PASSIVE CONTROL OF SHEAR BUILDINGS
    (Acad Sci Czech Republic, Inst Thermomechanics, 2017) Aydin, E.; Ozturk, B.; Dutkiewicz, M.
    In the paper, the analysis of damping parameters for vibration reduction of buildings with use of optimization algorithm is presented. Optimal values of damping coefficients are determined at fundamental structural mode of shear buildings in order to attain desired added damping ratios. The cost function is defined as the sum of damping coefficients of the dampers to be minimized. Proposed optimization problem is solved by using three different numerical algorithms that are namely: Simulated Annealing, Nelder Mead and Differential Evolution algorithms, respectively. Numerical example is presented to prove the validity of the proposed method. The changes of optimal distributions of the dampers with respect to target damping ratios and structural periods in a particular range are investigated for two-story shear building model. The numerical results show that the proposed damper optimization method is easy to apply and efficient to find optimal damper distribution for a target damping ratio.
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    Optimal placement of elastic steel diagonal braces using artificial bee colony algorithm
    (TECHNO-PRESS, 2015) Aydin, E.; Sonmez, M.; Karabork, T.
    This paper presents a new algorithm to find the optimal distribution of steel diagonal braces (SDB) using artificial bee colony optimization technique. The four different objective functions are employed based on the transfer function amplitude of; the top displacement, the top absolute acceleration, the base shear and the base moment. The stiffness parameter of SDB at each floor level is taken into account as design variables and the sum of the stiffness parameter of the SDB is accepted as an active constraint. An optimization algorithm based on the Artificial Bee Colony (ABC) algorithm is proposed to minimize the objective functions. The proposed ABC algorithm is applied to determine the optimal SDB distribution for planar buildings in order to rehabilitate existing planar steel buildings or to design new steel buildings. Three planar building models are chosen as numerical examples to demonstrate the validity of the proposed method. The optimal SDB designs are compared with a uniform SDB design that uniformly distributes the total stiffness across the structure. The results of the analysis clearly show that each optimal SDB placement, which is determined based on different performance objectives, performs well for its own design aim.
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    Optimal placement of steel diagonal braces for upgrading the seismic capacity of existing structures and its comparison with optimal dampers
    (ELSEVIER SCI LTD, 2008) Aydin, E.; Boduroglu, M. H.
    In this study, the optimal placement of X steel diagonal braces (SDBs) is presented to upgrade the seismic response of a planar building frame. The optimal placement is defined as the optimal size and location of the SDBs in a frame structure. Steady state response of the structure evaluated at the undamped fundamental natural frequency is defined by means of transfer functions that are independent of initial values and the input excitation. The objective functions are chosen as the amplitude of transfer function of the top displacement and the amplitude of transfer function of the base shear force evaluated at the undamped fundamental natural frequency of the structure. In the optimization procedure, the stiffness parameters of the added braces are described as the design variables. Principal optimality criteria are derived using Lagrange Multipliers Procedure. The obtained nonlinear equations are solved with "Steepest Direction Search Algorithm". Sensitivities of the objective functions are determined analytically. A simplified algorithm for the state of the base shear force as the objective function is also proposed. The response of the structure is examined for both of the objective functions in terms of the transfer function. Seismic rehabilitation with SDBs is compared to the rehabilitation with viscous dampers. Therefore, a total equivalent stiffness parameter is defined so that the transfer function amplitude of the top displacement of building structure with SDB attains the same value with the transfer function amplitude of the top displacement of building structure with optimal dampers based on the top displacement. The time history analysis is performed using E1 Centro earthquake around motion records to demonstrate the validity of the proposed design method. The results of the numerical procedure point out that the proposed procedure based on the transfer function of the base shear force and the top displacement can also be beneficial in the rehabilitation of seismic response of the structures. (C) 2007 Elsevier Ltd. All rights reserved.
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    The evaluation of damage mechanism of unreinforced masonry buildings after Van (2011) and Elazig (2010) Earthquakes
    (IOP PUBLISHING LTD, 2015) Guney, D.; Aydin, E.; Ozturk, B.
    On March 8th, 2010 Karakocan-Elazig earthquake of magnitude 6.0 occurred at a region where masonry and adobe construction is very common Karakocan-Elazig is located in a high seismicity region on Eastern Anatolian Fault System (EAFS). Due to the earthquake, 42 people were killed and 14'113 buildings were damaged. Another city, Van located at South east of Turkey is hit by earthquakes with M = 7.2 occurred on October 23rd, 2011 at 13:41 (local time), whose epicenter was about 16 km north of Van (Tabanli village) and M = 5.6 on November 9th, 2011 with an epicenter near the town of Edremit, south of Van and caused the loss of life and heavy damages. Both earthquakes killed 644 people and 2608 people were injured. Approximately 10'000 buildings were seriously damaged. There are many traditional types of structures existing in the region hit by earthquakes (both Van and Elazig). These buildings were built as adobe, unreinforced masonry or mixed type. These types of buildings are very common in rural areas (especially south and east) of Turkey because of easy workmanship and cheap construction cost. Many of those traditional type structures experienced serious damages. The use of masonry is very common in some of the world's most hazard-prone regions, such as in Latin America, Africa, the Indian subcontinent and other parts of Asia, the Middle East, and southern Europe. Based on damage and failure mechanism of those buildings, the parameters affecting the seismic performance of those traditional buildings are analyzed in this paper. The foundation type, soil conditions, production method of the masonry blocks, construction method, the geometry of the masonry walls, workmanship quality, existence of wooden beams, type of roof, mortar between adobe blocks are studied in order to understand the reason of damage for these types of buildings.
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    Using an artificial bee colony algorithm for the optimal placement of viscous dampers in planar building frames
    (SPRINGER, 2013) Sonmez, M.; Aydin, E.; Karabork, T.
    In this study, an Artificial Bee Colony Algorithm (ABCA) is used to obtain the optimal size and location of viscous dampers in planar buildings to reduce the damage to the frame systems during an earthquake. The transfer function amplitude of the top displacement and the elastic base shear force evaluated at the first natural circular frequency of structures are chosen as objective functions. The damper coefficients of the added viscous dampers are taken into consideration as design variables in a planar building frame. Transfer function amplitude of the top displacement and the amplitude of the elastic base shear force at the fundamental natural frequency are minimized under an active constraint on sum of the damper coefficients of the added dampers. According to two specified objective functions, an optimization algorithm based on the ABCA is proposed. The proposed method is verified by a gradient-based algorithm; steepest direction search algorithm (SDSA). The proposed ABCA and the SDSA are applied to find the optimal damper distribution for a nine-storey planar building then the optimal damper allocation obtained from the ABCA is investigated to rehabilitate models of irregular planar buildings. The validity of the proposed method was demonstrated through a time history analysis of the optimal damper designs, which were determined based on the frequency domain using the ABCA. The numerical results of the proposed optimal damper design method show that the use of the ABCA can be a practical and powerful tool to determine the optimal damper allocation in planar building structures.