004
DETERMINATION OF CHARACTERISTIC SITE PERIOD AND PRELIMINARY
GROUND RESPONCE ANALYSIS ACCORDING TO RESONANCE BY USING GIS
M. Tün”, U. Avdan*, M. Altan*, C. Ayday **
* Anadolu University, Satellite and Space Sciences Research Institute, Iki Eylul Campus, 26470 Eskisehir, Turkey -
(mtun, uavdan, maltan, cayday)@anadolu.edu.tr
Commission VII, WG VII/S
KEY WORDS: Analysis, Building, Earthquakes, GIS, Hazards, Soil
ABSTRACT:
Ground response analyses are mostly used for the development of design response spectra in the modern earthquake engineering.
After 1999 Marmara Earthquake, the damages were mostly related with unavailable soil conditions and this unavailability were
analysed according to liquefaction analysis. The other analyses w
In this study, granular soil which the Eskisehir urban area is loca
city, which would be influenced negatively by the earthquake du
different districts of the Eskisehir municipality were included in
Seismic conic penetration test (SCPT) which is known seism
dynamic soil properties in the Study. The geophone in the se
hich cover the dynamic soil properties were not studied in detail.
ted has been studied according to vibration period. Eskisehir is the
€ to unavailable soil conditions and uncontrolled constructions. Five
this studied area.
ic down hole test results have been used for obtaining low-strain
ismic penetrometer detects the travel time, depth and shear wave
velocity (V,) of the tested horizon have been obtained. The soil thickness of the studied area has been calculated from the seismic
resistivity results of the State Hydraulic Works of Eskisehir. The
raw 60 m seismic resistivity records have been evaluated by using
3 dimensional GIS and 3 dimensional alluvial thickness model have been created. Average shear wave velocity (V4) of each 32
SCPT test points have been calculated by taking average of each SCPT drill log.
Characteristic site period (Ts), which is defined as the period of vibration corresponding to the fundamental frequency has been
obtained for each 32 test points. GIS which is a powerful tool and technique for especially earth science, has been used for the
preparation of characteristic site period map (Tr) of the studied area. After that, the number of story of each building has been
determined by in-situ studies in the studied districts. Fundamental vibration period (T;) of each building has been calculated with
respect to number of story according to building codes. GIS overl
apping analyse technique, has been used with characteristic site
period (T,) map layer and fundamental vibration period map layer of each building. Soil and structure relationship has been searched
in this situation and close T, and T, values have been defined as critical values according to high resonance risk. It has been seen
that, the number of critical buildings which are under the hi
resonance risk in the studied area are 63 and this covers
approximately 5.496 of the total studied area. At the end, ground response of the soil according to resonance risk map has been
prepared by GIS technique.
l. INTRODUCTION
Studies into the earthquake conducted within the applications of
ground studies emphasize that an interaction between the
features of the earthquake and local ground conditions is of
great importance (Ansal, A., 1999; Keceli, A., 2000). Just as the
ground has an impact upon the features of the seismic waves
that it gets exposed to, so the seismic waves have an impact
upon the physical features of the ground as they pass through
the ground layers in such a way that they affect the loss and
softness of the ground. Some of the factors likely to influence
the seismic features over the surface would be stratification of
the ground, type of the ground, the main depth of the rock,
geological structure, level of underground water, thickness,
flexibility and plasticity of the ground layers (Ansal, A., 1999),
Making use of shear wave velocity measured in the upper layers
of the ground has brought a new dimension to earthquake risk
analyses. Through analysing the data obtained from these
Studies, it is possible to determine seismic features of the
regions susceptible to earthquakes and their effects upon
various geologic and ground features. Measuring the speed
rapidity of the seismic waves, which occur as a result of seismic
ground movements, passing through the ground is an essential
variance in determination of a deformation likely to occur in the
ground (Ansal A., 1999; Ersin, A., 1998; Ercan, A., 2000).
Different methods are used for measuring shear wave velocity
in the literature (Luna, R. and Jadi H., 2000). In this study,
shear wave velocity (Vs) was measured in determining the
reactive characteristics of the grounds regarding ground
movements in the regions susceptible to earthquakes.
The aim of this study was to determine the possibility
percentages of structural damage due to earthquakes likely to
occur in the region. A Seismic Conic Penetration Tests (SCPT)
was made at 32 different points situated on new alluvium within
a vicinity of 25 km? area of the city of Eskisehir. Shear wave
velocity (V;av) was determined by using SCPT. This value was
taken as one of the variables used in the process of calculating
the fundamental vibration period. Another variable is the
thickness of alluvium was obtained as a consequence of
geophysical resistivity measurements carried out by Eskisehir
* Can Ayday is with the Anadolu University Satellite and Space Sciences Research Institute, Iki Eylul Campus 26470, Eskisehir,
Turkey (corresponding author to provide phone: 222-321-3550; fax: 222-323-91 29; e-mail: cayday@anadolu.edu.tr).
1137
