**Fall
2001
**

**
Nonlinear
Seismic Analysis of R.C.C. Buildings**

Zebun
Nessa Shoma

Reinforced Cement Concrete (commonly known as
Reinforced Concrete and referred to as R.C.C., RCC or RC) is a complex composite
material that provides a unique coupling of two materials (concrete and steel).
When subjected to high stresses, it behaves like an elasto-plastic material.
This behavior is particularly observed when the structure is subjected to
dynamic loads. Considering the nonlinear behavior of R.C.C., parametric studies
are performed in this thesis to investigate some important details of the
behavior of R.C.C. Simple two-dimensional frames are taken for static structural
analysis under increasing vertical load and nonlinear dynamic analysis under
combined vertical load and seismic vibrations. Three known earthquake data (El
Centro, Kobe and Northridge) are applied in the long and short directions of a
number of buildings (2, 5, 10 storied) to study their responses. Various aspects
of the nonlinear response of R.C.C. are studied. These include the effect of
axial force on the Moment-Curvature (M-f) relationship, the mode of failure and the
importance of increasing shear strength. From the analysis it is found that the
failure of all the structures are due to excessive shear force in beam or
column. In case of Kobe earthquake all the buildings taken into consideration
failed (both long and short direction) and no failure occurred in the short
direction due to El Centro earthquake. For Northridge earthquake low rise (2
storied) building frames failed due to excessive shear in the columns. But
results of 5 and 10 storied frames showed that shear failure of beams occurs
rather than the columns. Finally a study is carried out which include increasing
the shear strength of beam, column and footing (1.7, 2 and 2.5 times) in order
to improve the shear capacity of the structure. |