الفهرس 
CHAPTER 1: INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The main objective of this thesis is to study hfferent levels of damage due to close
explosion on reinforced concrete panels. One of challenges in close blast loading is
that when tests are replicate using equal charge size and standoff distance,
significantly different values of impulse positive phase duration, and the response of a
structural element are produced. This is because such loading is rather sensitive to
my small change in clmge or specimens. This is achieved by studying documented
experimental work where reinforced concrete panels were subjected to close
explosion, and comparing observed readings with predicted results using numerical
solution
Implicit and explicit analysis scheme are used to study cracks propagation of
remforced concrete panels subjected to blast load. Predicted central deflection and
failure patterns xe compared with published experimental work The stress-strain
plots in concrete and reinforcement elements were selected as the application of the
local failure that lead to structural progressive collapse. For implicit analysis, the
effect of considering cracking of concrete ~naterial and nonlineasity is investigated,
by compari~ig stress and strain trends for linear and nonlinear models. For explicit
analysis, the strain rate effect is studied by studying the response of models with and
without strain rate effect, and compxes their results with expelimental readings. A
comparison between the results of the analysis using implicit and explicit analysis
schemes is presented. The study includes using UFC 3-340-2014 technical manual to
predict damage level and central deflection, which is based on simple approaches for
the problem.
The response of implicit analysis model due to adding strain rate effect to steel and
concrete materials is investigated, and pasametric study to provide recommendations
for the safe design of the slab using simplified calculations according to UFC 3-340-
2014 manual is conducted. The discussion also includes a parametsic study on two
parameters used in the explicit analysis. The first parameter is concerned with the
effect of changing fractuse energy for concrete material by changing maximum
aggregate size. The second parameter is conceined with the effect of using scalar
damage parameter, d equal to one, and ignoring the co~iditiono f maximum principle
stsain to initiate cracking of the element
The study shows that tlie ovelpressuse blast load on test panels is much higher than
the resistance of the reinforced concrete panel. This results in heavy damage for the
panel. For this reason, the implicit solution using ANSYS program stops before the
time to reach maximum deflection. For explicit analysis using Ls-Dyna program, the
solution continues even if early failure occuned for the panel. This is because explicit
integration method does not require a factorization of tlie stiffness matsix in the step
by step solution. Good agreement is noted between predicted crack patterns of
explicit nonlinear cracked model, and observed cracks patterns for field test slabs.
The study shows that the response of the panel is affected by damage in concrete
material more than nodineaity in the concrete and reinforcement. It was found that
stsain rate effect is vital to get good presentation for the response of the panel under
blast load.
Recommendations for the safe design of reinforced concrete panels under blast load
are included in the study. Recommendations are also presented for the implicit and
explicit solutio~isin cluding material types and parameters used in material modeling.