Loading...
| Friend's email | |
| Your name | |
| Your email | |
| enter code | |
This page was sent successfuly
- Type of Document: M.Sc. Thesis
- Language: English
- Document No: 50828 (53)
- University: Sharif University of Technology, International Campus, Kish Island
- Department: Science and Engineering
- Advisor(s): Dolatshahi, Kiarash; Rafiee Dehkharghani, Reza
- Abstract:
- The main goal of partake quake-attenuating in buildings is to absorb energy and to attenuate the exerted forces into structures as a result of ground motions. Notwithstanding achievements and developments in the field of dampers production, applying of dampers in structures is proportional to following complicated technology and subtle engineering. Installation and initiation of dampers depend on educated and expert crew; moreover, such attenuating systems need maintenance and repair during the useful structural life time. Therefore, nowadays civil engineering suffers from the lack of such quake-attenuating systems to be able to respond simply but applicable mechanism at the same time for almost all types of structure. Since seismic waves travel from the source of an earthquake to the ground surface, the final portion of this traveling is often through soil and characteristic of the soil can greatly influence the nature of shaking at the ground surface. Soil acts as a filter for seismic waves by attenuating and amplifying the motion frequencies to the others. Inspired by this natural phenomenon, herein, it is aimed to propose a new idea that encompasses changing soil nature of under base by materials with known specifications deviate seismic waves before entering into structure. Choosing this proposal research is a step forward in this direction which by choosing the damping feature tries to relocate new isolation system from structural element location into underground position that not only can solve mentioned other method defeats but also it reduces super structural demands by changing stress level of material from steel to soil. This new idea is evaluated by considering a 2D plane strain modeling by assumption of 50m width to 30m depth model dimensions. Evaluation of model is considered for two types of isolated ground and pure soil to be compared with each other to find advantages and disadvantage of this new system. Because of material sensitivity to plastic nonlinear behavior, an especial advance constitutive modeling of Manzari-Dafalias (2004), which is known as the latest achievement over this field, is utilized. The model is imposed by seven earthquake records which are selected accordance to FEMA-440a and FEMA-P695 and are applied as uniform base displacement excitation for this model. Numerical evaluation of this research is performed by open source software framework of OpenSees. The final results of this report are performed in the form of spectral acceleration to find a better comparison between pure soil and isolated ground response. This research succeeds to achieve another considerable goal which is satisfied by innovating new artificial boundary returning to initial artificial boundary theory of Smith (1974), which is named Twin-Boundary by the authors. This theory is based on introducing a metaphorical twin space boundary at a same place over each edge sides. One of this Twin Boundaries works as the fixed-end boundary and the other plays the role of the free-end that the resultant of these Twin Boundaries is summation of reflected waves at each sides that is null. Dimensions, rate of accuracy and specific features divide Twin Boundary into three types to overcome vast user expectations.Application, instruction and feature of each one are explained and formulated. Finally, the ability of Twin Boundary for different incident excitation is clarified and a brief comparison of literature methods compare to Twin Boundary is presented
- Keywords:
- Earthquake ; Seismic Wave ; Vibration Isolators ; Mitigation ; Damage Reduction
Digital Object List-
محتواي کتاب - view
Bookmark