Crack cronology of reinforced concrete beam under impact loads
Impact is one of dynamic transient loadings which is contribute to structure damages such as cracks and frequently generate a dangerous effect to reinforced concrete structures. Nowadays, several areas of civil engineering incorporate the need to be able to predict such structural behaviour under...
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| Format: | Thesis |
| Language: | English |
| Published: |
2008
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/3144/1/ZAINORIZUAN%20BIN%20MOHD%20JAINI%20-%2024p.pdf http://eprints.uthm.edu.my/3144/ |
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| Summary: | Impact is one of dynamic transient loadings which is contribute to structure
damages such as cracks and frequently generate a dangerous effect to reinforced
concrete structures. Nowadays, several areas of civil engineering incorporate the
need to be able to predict such structural behaviour under impact loading. Previous
researchers have noted that concrete structures under impact loading show different
behaviour from that under static loading. This study presents a three-dimensional
nonlinear finite element simulation of the reinforced concrete beams subjected lowvelocity
impact loading. The main objective of this study is to determine the crack
chronology specifically in time and location. Beam with geometry 1.5m long, 0.2m
depth and 0.1m width has been modelled by ELFEN. Numerical modelling and
ELFEN code is based on previous study of the reinforced concrete beam under
impact loading conducted by P.J. Thiele (2005). This study has involved 16 models
which are divided into three factors of simulation, that are modelling factors to
determine the most suitable model, support conditions to study crack chronology
caused by the rigid support, support material and support thickness, and impactor
factors to determine the crack chronology caused by various velocities and densities.
From the results, the main crack modes are spalling crack at the top surface of beam
and scabbing crack on the bottom surface of beam. It is found in this study that there
are two categories of crack chronologies. First is crack happens at the bottom
surface of beam recognized as scabbing crack and then followed by the beam crack
at the support area and finally spallation crack. Another category of crack chronology
is occurs as scabbing crack, then spallation crack and finally beam crack at the
support area. Cracks due to impact loading can be described by wave theory.
Scabbing crack caused by the direct impact wave and compression condition at the
rare area of beam. Spallation crack occurs by two reasons, the impact wave
propagate to the support area and the rarefaction wave that reflected from support.
Besides that, spallation crack also occur related to its global deformation. For the
purpose of validation, the results obtained from numerical simulation of the threedimensional
reinforced concrete beam, which is carried out using the finite element
software ELFEN are validated by deeply literature review. There are no comparisons
between experimental results. Final cracks pattern for each model is carried out to
make comparison with previous study of crack behaviour where the results are
obviously similar. |
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