Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Parametric Study on the Factors Effecting the Foundation Input

Ground Motion
Earthquake waves-soil layers and structural elements (i.e. foundation, piles and the building itself) interact each other during a seismic event. In the recent years, researches have been carried out to investigate the influence of this detrimental interaction, using either field or centrifuge tests combined with numerical analyses. Several numerical methods are available to model earthquake wave-soil-structure interaction with different levels of accuracy. Input ground motion and more specifically the foundation input motion has a key role in the design. In the free-field case (no structural elements), one dimensional analysis (SHAKE, EERA) provides satisfactory results to estimate the local site effects. However, the kinematic interaction between the seismic waves and the foundation may drastically change the characteristic of the seismic wave. Thus the input motion to be exerted to the superstructure from the raft must include the local site effects, existence of foundation depth and the piles.
In order to consider the influence of several parameters on the foundation input motion, the bedrock ground motion propagation thorough the soil layers were investigated in this study. The main focus was on three factors that affect foundation input motion: (i) existence of the structural elements such as piled raft foundation (ii) soil stratification by means of soil stiffness (iii) different earthquake acceleration records.
Three-dimensional numerical analysis were performed by using FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions) software. Behavior of piles and soil layers under seismic loads were analyzed by using equivalent linear method. With this method, soil shear modulus reduction curves and damping curves depending on the increase of shear strain were taken into account. Numerical results clearly revealed that, for piled raft foundation case, the form of spectral acceleration change and the maximum spectral acceleration increase, particularly for soils both with low soil stiffness and stratified layers. In order to investigate the effect of damping, damping functions which represent the shear modulus reduction and local damping were used in analyses. As expected, it was found that, damping model has a major impact on the shape response spectrum and calculated forces/moments on structural elements.
  

SELEK Muharrem

Tez Adı : Ortak Bir İzolasyon Tabanına Sahip Olan Binaların Sismik Davranışı

Danışman : Doç. Dr. Cenk ALHAN

Anabilim Dalı : İnşaat Mühendisliği

Programı : -

Mezuniyet Yılı : 2013

Tez Savunma Jürisi : Doç. Dr. Cenk ALHAN

Prof. Dr. Namık Kemal ÖZTORUN

Doç. Dr. Sadık ÖZTOPRAK

Doç Dr. Ümit ÖZER

Yrd. Doç. Dr. Fatih YALÇIN