Abstract:
Dhaka, the capital of Bangladesh, is one of the world's most seismically
vulnerable cities due to its proximity to the convergent boundary of the Eurasian
and Indian tectonic plates. This vulnerability is exacerbated by factors such as
uncontrolled urban expansion, non-engineered construction practices, high
population density, and a weak emergency response system. The city is situated
on an elevated Pleistocene terrace surrounded by Holocene floodplains, with the
terrace comprising Pleistocene clayey soils and the floodplains consisting of
alluvial sandy and clayey deposits. To conduct site-specific seismic hazard
analysis, it is crucial to estimate the amplification factors of seismic waves, which
requires determining the average shear wave velocity of the near-surface soils up
to a depth of 30 meters. In Dhaka, Vs30 has been estimated using techniques such
as multichannel analysis of surface waves (MASW), microtremor array
measurement (MAM) survey, and empirical correlations between shear wave
velocity and standard penetration test blow count. Another important concept in
earthquake studies is liquefaction, which refers to the loss of strength and stiffness
in saturated, loose sandy soils during ground shaking, leading to severe structural
damage. The correlation between shear wave velocity and SPT-N has been
analyzed using field test data. Nonlinear site response analysis has been
performed with DEEPSOIL software to evaluate potential seismic hazards at the
ground. The Peak Ground Acceleration has been obtained to assess the likelihood
of liquefaction based on the ground condition. Using borehole data, the research
area has been divided into three different groups to account for local site impacts
and calculate seismicity characteristics using the Bangladesh National Building
Code. Ground motions on specific site classes recorded in other regions with
similar magnitude earthquakes were included in this analysis. A hyperbolic model
was used to fit the shear modulus and damping curves to represent ground
motions under high-strain conditions. The PGA forecasted in this study will
inform the safe design of structures and the proper planning of significant
infrastructure projects
Description:
Supervised by
Prof. Dr. Hossain Md. Shahin,
Head of the Department,
Department of Civil and Environmental Engineering(CEE),
Islamic University of Technology(IUT),
Board Bazar, Gazipur-1704, Bangladesh.
This thesis is submitted in partial fulfillment of the requirements for the degree of Bachelor of Civil and Environmental Engineering, 2024
