Gowlla, Jyothsna
(2016)
Analytical and Numerical Studies on FRP Strengthened Reinforced Concrete Columns Under Torsional Loading.
Masters thesis, Indian Institute of Technology Hyderabad.
Abstract
Bridges give the impression of being rather simple structural systems. Despite
their structural simplicity, bridges in particular have not performed as expected under
seismic attack. Under earthquake loading, bridge super structures will in general
experience both rotational and translational motions. As a consequence, the supporting
columns may be subjected to significant torsion, which is often ignored in typical design
practice. Torsion results in brittle mode of failure which is undesirable and therefore,
it is necessary to design it properly for avoiding brittle failures. Over the years,
engineers have developed different methods and techniques in order to retrofit or
strengthen the structures. The research carried till now on strengthening techniques of
columns focuses mainly on those which are subjected to uniaxial eccentric loading
under bending, shear and axial loads. However, till now, no previous study has focused
on strengthening of reinforced concrete (RC) columns under torsional loading. The
present study focuses on filling this knowledge gap. Nonlinear FE models are developed
using commercial package ABAQUS and analysis were carried on to understand the
behaviour of RC columns under torsional loading with and without FRP strengthening.
Similarly, analysis is carried on in MATLAB by using Softened Membrane Model for
Torsion with FRP (SMMT-FRP). The FE and analytical results gave a good
agreement when validated with test data. After validation, behaviour of FRP
strengthened RC Columns with under torsional loading is analysed. Analysis included
various parametric studies like varying thickness of FRP laminate, number of layers,
5 | P a g e I I T H
alignment of FRP and increasing the level of applied axial load. Finally, interaction
diagram between axial compression and torsional moment is also predicted.
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