Application of Performance-Based Plastic Design (PBPD) Method for 3D Steel Brace Frames

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Application of Performance-Based Plastic Design (PBPD) Method for 3D Steel Brace Frames

ارائه دهنده: Provider: Ali Mirzaei

اساتید راهنما: Supervisors: Mohammad Shushtari (Ph.D)

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: دکتر فریدون رضایی - دکتر مصطفی مقدسی

زمان و تاریخ ارائه: Time and date of presentation: September, 14, 2020

مکان ارائه: Place of presentation:

چکیده: Abstract: Performance-Based Plastic Design (PBPD) method is a new seismic design method of structures. The PBPD method applies structural drift and yield mechanism to the designing process from the beginning, furthermore it could control the behavior of the structure before starting the design process, it has been able to enter the structural energy, which is the index of structural damage, into the design process. This method provides design forces directly and without trial and error cycles on the other hand, the performance of the structure corresponding to the initial forecast requires less calculation. The PBPD method has been successfully applied in various structural systems, and this indicates the importance and position of this design method. To design the structure, the energy equilibrium equation is used, the term of which are originally obtained for a two-dimensional frame. Energy is a scalar quantity and is independent of direction, therefore writing the energy equilibrium equation independently for each direction is not without mistake. Also, in the equilibrium equation used in this method, the effects of adjacent frames and orthogonal frames in a three-dimensional state have been ignored. In addition, in 2D modeling, the interaction of 3D forces, such as biaxial bending, is neglected, which could be one of the reasons why this method is not responsive for 3D cases. In this research, to apply the effect of adjacent frames and orthogonal frames on each other, base shear nonlinear distribution in the plan was used. Based on nonlinear time-history analysis results of six 3D steel structures, with surrounding bracing frames and internal moment frames, the base shear of the two orthogonal directions has been linked to each other and also the two adjacent frames has been linked to each other. In this research, the artificial neural networks have been used to fit the functions. In the new method presented in this research, the yielding base shear of a 2D frame is calculated independently using the energy equilibrium equation and then, the base shear of the other frames is calculated through the base shear nonlinear distribution. Three 3D structures have been designed using two-dimensional PBPD method and the proposed method. The results of time history analysis showed that the structures designed with the used method, are not able to provide the desired target mechanism (strong column-weak beam), Also, the method used in this study estimates the yield base shear of the frames less than the conventional method, As a result, it can be said that the energy equilibrium equation for calculating the base shear has some drawbacks and needs to be modified in further research. Key Words: Performance-Based Plastic Design, Base Shear Nonlinear Distribution, Energy of Structures, 3D Designing of Steel Structures, Artificial Neural Networks

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