PERILAKU DINAMIS STRUKTUR BETON BERTULANG DARI GEDUNG BERATURAN DENGAN DAKTILITAS (Nilai R) SUBSISTEM STRUKTUR YANG BERBEDA

Abstract

In the SNI 03-1726-2002 Standard Clause 4.3.5 it is stated that “When a
structural system parallel to the direction of nominal earthquake load, consists of
some sub-structural systems, the representative reduction factor (Rr) of the
earthquake load for this structure in the direction of the earthquake load can be
calculated as an average of weighting values with each sub-structural system base
shear as its weighting factors”. With the representative reduction factor (Rr), the
base shear acting on the structure does not consider the weakest sub-system which
reaches its yielding capacity first, whereas base on stiffness concept, sub-system
with a different ductility will resist a different base shear. In order to investigate
dynamic behavior of a structure due to this both earthquake loading condition,
analysis was done on a reinforced concrete structure of a regular building consisted
of structural sub-systems of shear walls and frames which have each different
ductility. This both loading conditions are the earthquake with reduction factor of
Rr and Rs.
Dynamic behavior of the structure is obtained from the results of modeling and
analysis of the structure using finite element software (SAP 2000). The calculation
was done in two stages in which the first stage, the structure was designed to resist
both gravity load and earthquake load. In the design process, earthquake load was
treated as static equivalent earthquake load with a reduction factor calculated
according to SNI 03-1726-2002 requirements. The second stage, the structure that
has been designed, its dynamic behavior was evaluated using nonlinear static
pushover analysis including period, base shear, horizontal drift, stiffness, damping
and other dynamic properties of the structures.
The results of analysis show that dynamic behaviors of the structure subjected to
earthquake load with representative reduction factor (Rr) differ from those of the
earthquake load with reduction factor each sub-system (Rs). For earthquake load
with reduction factor Rs, the actual ductility factor, actual earthquake reduction
factor, effective period of the structure are bigger than those of the structure with
reduction factor Rr. However, it has smaller base shear, less number of plastic
hinges and smaller effective damping.