Al-Qadisiyah Journal for Engineering Sciences

This paper introduced a strengthening technique for flat plates using steel stiffeners. In this paper, the
effectiveness of steel stiffeners with different arrangements and numbers on the punching shear strength.
The strengthening steel plates were extended from column to the slab and acted as a column capital of an
equivalent concrete column capital. The study was divided into two parts, the first part was the experimental
study involves the molding three reinforced concrete flat slab strengthening with different dimensions and
numbers of steel stiffeners, with changed the dimensions of steel plates for specimens (SS1 (100×100mm),
SS2 (200×200mm), and SS3 (300×300mm)) in addition to reference model without strengthening. The loadcapacity of the strengthened slabs was increased by (39.84%, 57%, and 99.2%) respectively over that of the
control specimen with slabs (SS1, SS2, and SS3). The second part that numerical modeling through the
ABAQUS finite element program was introduced. Effect of the steel stiffeners\' size and the effect of the
column\'s shape (rectangular and circular) that\'s deal with steel stiffeners were studied experimentally and
numerically. A good agreement was obtained between the experimental and theoretical results

Gypseous soils are common in several regions in the world including Iraq, where more than 28.6% of the
Iraq surface is covered with this type of soil. This soil, with high gypsum content, causes different problems
for construction and strategic projects. As a result of water flow through the soil mass, the permeability and
chemical arrangement of these soils varies with time due to the solubility and leaching of gypsum. In this
study, the soil of 36% gypsum content, was taken from one location, which is about 100 km southwest
of Baghdad. The samples were taken from depths of 0.5 and 1 m below the natural ground and mixed with
3%, 6% and 9% of Copolymer and Novolac polymer to improve the collapsibility, permeability and
compaction parameters. The results of the experimental work showed a noticeable improvement of the
collapsibility and permeability of the soil treated with polymer materials compared to the untreated soil.
Furthermore, adding 3% of polymer (copolymer and novolac polymer) materials gave the best improvement
in collapsibility which reached a 44.5 and 46%, respectively, in 3 hours. The improvement in permeability
reached 98.6% copolymer and 86.2% novolac polymer in 1 day.

Solid waste management is one of the big challenges facing most countries around the world. Reusing these
wastes in construction project represent one of the most efficient ways to consume these wastes and reduces
the demand on natural sources. The Crumb Rubber (CR) of tires is a source of a huge amount of solid waste
that can be reused in construction projects such as paving of roads. The current research presents an
experimental investigation for the dowel bars performance in rubberized concrete pavement. The research
involves conducted pullout tests for dowel bars cast in concrete pavement contains a different percentage
of CR particle (2%, 4%, and 6% of total aggregate) as partial or total replacement to aggregate on sieves
No. 16 and No. 50. Four cases of dowel bars surface were investigated. The results of the study showed that
adding CR particles to concrete can significantly reduce the bond between the dowel bars and surrounding
concrete pavement which allows for more free movement of dowel bars and reduce joint lockup. The use
of treated CR by NaOH solution with standard dowel bars (epoxy coated lubricant steel dowels) can give a
superior reduction in pullout load. The reductions were 45%, 66%, and 83% in pullout load for the
percentages of 2%, 4%, and 6% crumb rubber respectively compared with the reference mix.

Utilization of local accessible materials is an important stage for sustainability nowadays. Brick units are
the most commonly used construction material around Jimma town due to the availability of clayed
soil. In comparison with the traditional method, brick produced by small micros un-skill enterprises is
mainly specified by less quantity and lower quality The purpose of this study was to improve the
properties of clayed soil adopted in manufacturing of masonry brick units using Literate soil . In
order to achieve this, non-probability sampling technique was used to collect samples from Jimma
area. The collected samples were then prepared for running different laboratory tests. The samples were
formulated through partially replacing literate soil by 5%, 10%, 15% and 20%, respectively. The test results
showed that the procedure adopted in this study can produce lightweight brick units without any
deterioration in the quality of bricks. The maximum compressive strength value was noted for the brick
units formulated with lateritic soil of 15% replacing. The optimum firing furnace temperature was observed
at 1000°C for 5hrs. The brick units prepared at this temperature level exhibited the highest resistance to the
applied loads.

This study presents an experimental investigation for push-out tests in order to evaluate the performance
of continuous perfobond connectors. A total of five specimens composed of light-weight concrete-filled
steel tubes (square and circle sections) with two reinforced blocks were tested. The measured parameters
are the compressive strength of the concrete blocks and the type of the section. The specimens were tested
under a concentric load applied on the steel tube filled with lightweight concrete; the corresponding slip
value was measured using two LVDTs. The experimental results showed that the ultimate shear strength
and stiffness of the square steel tube filled with concrete were higher than that of circular samples. The
ultimate shear strength and stiffness increased with an increase of concrete compressive strength, while
the corresponding slips showed decreasing in their values with increase of the compressive strength of
the concrete.

Activated carbon is a porous material that has a great character to be used for drug delivery system as a
carrier. It is agreed that drug carriers maintain the concentration of drugs within the required range for a
long period and undetermined toxicity resulting from the use of overdoses. They have the ability to direct
the drug to the affected area, immunity, biophysics, and drug efficacy. Activated carbon was used at two
different particle sizes (0.6µm size with surface area 544.4704 m2/g and 11.042 nm size with surface area
985.6013m2/g ) and Naproxen was used as a drug model. This research studied the effect of several
parameters, including particle size (11.042 nm and 0.6µm), weight of drug to carrier weight ratio (0.5,1 and
1.5) on loading efficiency, and temperature (35, 37 and 39 ºC), time (1,3 and 5 hr), pH of the solution (1.5
and 6.5) on mass transfer coefficient in release drug. The result of experiments showed that maximum
loading efficiency can be obtained when the particle size of activated carbon was in Nano-size and the ratio
of drug weight to AC weight was 1.5. The release process was studied by studying the mass transfer
coefficient, the highest value of the mass transfer coefficient was obtained at the beginning of the unloading
time, at temperature 37 ºC and solution in pH 6.5.

At the present time and as a result to the recent developed technology demand for higher data rate and
capacity has been increased. For the wireless networks, the combination of radio over fiber (RoF) with
(XGPON) Gigabit-capable PON techniques produce a high data rate at lower cost. Thus, this paper
illustrates that the performance of RoF-XGPON optical link has been analyzed for multi-channel through
combining two multiplexing techniques, such as; Subcarrier Multiplexing (SCM) and Wavelength Division
Multiplexing (WDM). The proposed system utilizes WDM-xGPON and SCM-XGPON architecture
combined with RoF technology with 10 Gpbs data rate and (2.4, 5.8, 10 and 15) GHz radio frequency (RF),
when change the optical fiber length between (10 to 80) km. The network performance is compared with
various digital quadrate amplitude modulation schemes, like ; 4 - QAM, 16 - QAM and 64 - QAM for
various input power (-2, 2, and 6) dB. The performance analysis is based on the optical spectrum of
transmitted and received signals for 4-channel, constellation diagram, eye diagram, bit error rate (BER),
power received, and quality factor. The result explain that the WDM-XGPON-Rof performs better than
SCM-XGPON-Rof for different modulation schemes. The bit error rate for WDM-XGPON less than the
SCM-XGPON while the power received recorded to the WDM-XGPON greater than SCM-XGPON and
the quality factor for SCM-XGPON less than the WDM-XGPON. Therefore The simulation results show
that the WDM-XGPON-RoF gives better performance from SCM-XGPON-RoF. The software optisystem
version 15 has been used to simulate this system

This paper presents a numerical simulation of the structural response of reinforced concrete (RC) beams
under elevated temperature using the commercial finite element package ABAQUS. A numerical model is
firstly suggested by selecting the appropriate geometrical and material properties of the RC beam model at
elevated temperature. Thereafter, the suggested numerical model was validated against the experimental
tests conducted in this study. The validation results in terms of temperatures- time histories; load-mid span
deflection of the RC beams have confirmed the accuracy of the suggested numerical model. The validated
numerical model was implemented in conducting a parametric study to investigate the effects of two
important parameters on the behavior and failure of RC beams under elevated temperature. These
parameters are the effect of the high ranges of elevated temperatures; and the effect of heating rate. The
parametric study results have revealed that the failure load and the ductility of RC beams under elevated
temperature are not considerably influenced by changing the heating rate. It has also been concluded that
the ultimate load capacities of RC beams have considerably decreased by 55.49%, 74.72%, and 81.31%
comparing with the control RC beam when they exposed to temperature values of 600 ºC, 700 ºC, and 800ºC
respectively. These conclusions may be used in the design of RC beams subjected to fire induced
temperature.

The use of electroless Ni-P plating (EN) coating has attracted a surprising interest in the most recent years.
Many useful characteristics of the electroless-plating method have created many benefits in different
industries such as oil, gas, electronic, automotive, aerospace, and chemical. Some of the highlighted
properties of such a method are superior corrosion resistance, superior mechanical properties, and uniform
thickness of the coating as well as good surface finish properties, good adhesion characteristics, and a wide
range of thickness. In this paper, electroless plating has been applied in a (Ni-P) bath at two different times
of 2 and 3 hr respectively. After the plating, a heat treatment at 400 °C for an hour under vacuum 10-4 torr
has been done. The prepared samples were characterized by energy dispersive spectroscopy, X-ray
diffraction, and scanning electron microscopy (SEM). In addition, micro-hardness and corrosion rate
following Tafel extrapolation in two acidic solutions (1M HCl and 1M H2SO4) were also determined.
Vickers hardness values for specimens, coated by Ni -P at 2 and 3 hr have increased by 47 % and 32 %
respectively. X-ray diffraction analysis for the coated surfaces showed two phases of Ni3P and NiP,
presented before and after heat treatment. The SEM images of the cross sectional coated specimens revealed
that the thickness of the coating is 68.43 and 92.71 µm for 2 and 3 hr coating time, respectively. Tafel
analysis showed that the coated specimens had a lower corrosion current density compared to that for the
bare specimens. The corrosion current density for the coated specimens in 1M H2SO4 increased by 57 %
with 2 hr and 69 % at 3 hr coating time. While, the corrosion current density for the coated specimens in
1M HCl increased by 37 % and 83 % at 2 and 3 hr coating time respectively.