The research includes an analytical study using the finite element method for the reinforced concrete beams containing holes in the body. These tested trophies have a rectangular cross-section and without additional armament in the area of the hole,
and two patterns (patterned and simple support) were studied. As for the holes, they are rectangular in shape with variable dimensions, where prizes with one hole and prizes with two holes were chosen.
يستعرض البحث أضرار الانفجارات على المباني والمنشآت الهندسية وآلية توصيف هذه الأضرار ونمذجة المنشآت باستخدام البرامج الحاسوبية لدراسة طرائق الترميم و توقع سلوك المنشأ المتضرر.
يحتوي البحث على دراسة قمنا بها حول تاثير الانفجارات على منشآت البيتون المسح والسلوك الفعلي لهذه المنشآت نتيجة الأضرار الحاصلة.
بالاضافة لعملية تقييم السلوك الحاصل وتوقع المشاكل المستقبلية ودراستها باستخدام النمذجة الرقمية باعتماد برامج النمذجة.
Using high strength concrete made a big step in designing and
constructing reinforced concrete structures. In this research, shear
resistance of high strength concrete beams with average resistance
of (65Mpa) and without shear reinforcement was ca
lculated by
making Experimental tests, also we studied the effect of cross
section shape on shear resistance, and measured the deflection in the
middle of the beams then we compared these results with the
mathematical results and with results from other researchers, finally
we developed a relationship to determine shear capacity in high
strength concrete T beams.
The large increase in the volume of demolition concrete waste and its impact on the
environment has led to reconsider of using concrete demolition rubble as a partial or a
whole alternative of natural aggregates to produce new concrete which has th
e required
properties to use in engineering constructions[1]. With the possibility of improving the
mechanical properties of this concrete by processing this aggregates before using it or
support this concrete with fiber to improve its structural behavior.
This research deals with the study of the replacement the natural aggregates used in
concrete with recycled concrete aggregates resulting from the demolition rubble ,
according to different replacement ratiosranging between 0 % -25 % -50 % -75 % -100%
and the impact on the concrete behavior with a natural aggregates and determine the
optimal replacementpercentage.
The results showed a relative decrease in the concrete resistance on the simple
pressure , limited decrease in the volumetric mass also, and a slight adjustment to the
behavior of concrete under the loading effect by increasing the replacement proportion of
the natural aggregateswith recycled concrete aggregates..
This research presents an experimental study behaviour of high strength concrete, for
evaluation of stress - strain curve and derivation of factors of equivalent compressive
stress block, we depend it in design of high strength concrete elements.
For this purpose, number of cylinders specimens with strength 60 MPa were prepared
and tested in compression, then curve was obtained.
The results showed the possibility of producing high strength concrete from local
materials and with strengths are highest than those were obtained, the resulting diagrams of
curve are shown to be essentially linearly elastic up to failure with a steeper declining
portion of the stress - strain diagram, which agree with the results of global researches, the
failure was almost sudden and rapid with increasing strength which shows that the highstrength
concrete less ductile than normal concrete at the failure. Curve of high strength
concrete differs from that normal concrete, this affects on the properties of rectangular
equivalent stress block which requires modifications on the factors led to optimum represent
for it and with evaluation of curve of the tested specimens, the diagram takes a
trapezoidal shape ( ), its value at the top is and the depth of the compressive
block is and we found and ( is average compression/cylinder
compressive strength of concrete, is ratio of the active depth that defined location of
compression force center), when concrete strength increases up , the diagram
shape will be closer to triangular than trapezoidal and then curve takes the shape of triangle its
value at the top is and the depth is and with replacing triangular diagram to rectangle.
This paper presents structural
analysis in using ANSYS programme for modeling of heat load then
comparison between the analytical results and experimental results is
performed .
This research presents an experimental study about the effect of steel fibers on the
main variables of stress- strain curve for high strength concrete on simple compression,
which are: shape of stress- strain curve, ductility factor, energy absorpt
ion capacity. For
this purpose, series of cylinders concrete specimens were prepared in compressive strength
(70 MPa). the steel fiber with aspect ratio of L/D =70 were added at the volume fractions
of (0-1-1.5-2)%. The cylinders were tested under a monotonic loading at compression, and
as a result of the tests, the total curve of stress- strain was obtained. The experimental
results of research showed a positive effect of steel fibers on the behavior of high strength
concrete, this effect increased with increasing volume fraction of steel fibers. It can be seen
from stress-strain curve, whereas the slope of the ascending branch is not much affected.
The descending branch of the stress- strain curve decreases by the increase in the fiber
volume fraction. This means the ductility and toughness improve with the addition of steel
fibers and as a result the behavior of high strength concrete has gone far away from being
brittle as it is used to be.
This research paper revolves around studding the repairing of reinforced concrete
columns which are subjected to an axial compression load, by using ferrocement jackets
containing two layers of Welded Wire Meshes (WWMs), which are in turn encapsula
ted in
high strength mortar.
The experiments were carried out at the concrete lab in the faculty of civil engineering,
Damascus University. The results were analyzed in order to determine the effects of
repairing technique on Ultimate Compressive Strength, Ductility of the Column and Failure
Modes. Empirical results confirmed the efficiency of using locally available welded
wire meshes in repairing of reinforced concrete columns.
Our subject contains studying criterions which ensuring a durable serving of concrete
frame joints, and then choosing two connections according to its deployment and the
availability of its arithmetic relations and easy to be prepared from local ma
terials, and
discuss experimental results of the resent study which allow us to achieve the next part of
our research,which is a structural designing programme by visual basic language to serve
the work in order to be fast and precise.
the last part of the subject is comprising a number of actualizations which confirm
that the process of programming is correct, and then compare the results of experimental
programs and code with our programme results to achieve many important ameliorations
on this programme to become more easily and better.
