Ersin AYDIN, M. Hasan BODUROĞLU

Yapıların deprem davranışlarının iyileştirilmesi için çelik çapraz elemanların optimum yerleşimi

Bu çalışmada, düzlem çerçeveler için X tipi çelik diyagonallerin optimum yerleşimi gösterildi. Optimum yerleşim diyagonallerin optimum yer ve büyüklükleri tanımlandı. Birinci mod etkisindeki kararlı yapısal davranış, başlangıç durumlarından ve giriş hareketinden bağımsız olan transfer fonksiyonları ile ifade edildi. Amaç fonksiyonları yapının birinci moduna karşı gelen transfer fonksiyonu tepe deplasmanı ve taban kesme kuvveti olarak seçildi. Optimizasyon yönteminde, tasarım değişkenleri olarak eklenen diyagonallere ait olan rijitlik parametreleri tanımlandı. Lagrange çarpanları yöntemi kullanılarak optimumluk kriterleri türetildi. Ortaya çıkan doğrusal olmayan denklem takımı en dik yön algoritması (Steepest Direction Search Algorithm) ile çözüldü. Yapının davranışı hem transfer fonksiyonlarına bağlı olarak hem de El Centro deprem kuvvetleri altında araştırıldı.

Optimal placement of steel diagonal braces for the rehabilitation of the earth-puake response of the structures

The different rehabilitation systems have been used to upgrade the seismic response of the structures. Common rehabilitation techniques were based on two basic approximations; to rehabilitate with adding new elements such as steel bracing and shear walls or to upgrade with selectively strengthening the deficient structural elements of the buildings. In this study, the optimal placement of X steel braces is presented for a planar building frame. The optimal placement is defined as the optimal size and location of the braces. Steady state response of the structure evaluated first undamped natural frequency is defined transfer functions that are independent on initial values and input excitation. The objective functions are chosen as the transfer function amplitude of the top displacement and the transfer function amplitude 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 defined as the design variables. Principal optimality criteria are derived using Lagrange Multipliers Procedure. Obtained nonlinear equations are solved with “Steepest Direction Search” algorithm. Sensitivities of the objective function are derived analytically. A simplified algorithm for the state of the base shear force as objective function is shown. The response of the structure is investigated both the transfer function amplitude and the time history analysis values under El Centro earthquake forces.

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