Seismic Analysis of Regular and Irregular Reinforced Concrete Framed Building Using Lead Rubber Bearing

Abstract

A seismic base isolation technique is used to
resist damage against earthquakes and
decreases seismic forces and accelerations for
rigid structures. The main objective of this work
is to design of base isolator. In the present study,
four models were studied, namely square (with
and without isolator) and C-shaped model (with
and without isolator). Square-shaped model has
6 bays each in X-direction and Y-direction, each
bay spacing 6 m of plan size 36  36 m and 15
storeys in the Z-direction. The C-shaped model
has 4  6 bays with 15 storeys having a plan
dimension of 24  36 m that has been taken for
seismic analysis. The equivalent static lateral
force and response spectrum method are
adopted for zone-V, soil type-II as per IS
1893:2016, part-1 using ETABS 2017 software.
The building models were designed using IS:
456-2000. There is no specific IS codes for the
design of isolators, hence the UBC 1997 code is
adopted. Lead rubber bearing is designed
manually for two models based on Design Basis
Earthquake (DBE) and Maximum Considered
Earthquake (MCE) and the following
properties, namely vertical stiffness, initial
stiffness for bearing, post-yield stiffness ratio
were assessed and fed as an input to the isolator
to analyse the frame with isolator. The following
response quantities, namely mode period, base
shear, storey displacement, and storey
acceleration were assessed, and comparative
study is made for the frame with and without
isolator. A comparative study is made to assess
the suitability of the model for structural
response.