For structural concrete members that may expose to serious earthquake, overload or accident impact, the design of ductility must be given the same importance as the flexural strength. The aim of this investigation is to study the change in ductility of structural concrete flexural members during their exposure to limited cycles of repeated loading. Twenty full-scale beam specimens have been fabricated in to two identical groups; each group consisted of ten specimens. The first group was tested under monotonic static loading to failure and regarded as control beams, while the specimens of the second group were subjected to ten cycles of repeated loading with constant load interval, which ranged between 40% and 60% of ultimate load. Specimens in each group were categorized as follows: two traditional reinforced concrete specimens with different intensity of tension reinforcement; three partially prestressed specimens with bonded strands; three partially prestressed specimens with unbonded strands; and two fully prestressed concrete specimens. The main variable, which was considered for all specimens was the partial prestressing ratio (PPR). It was observed that, the ductility of reinforced concrete beams was insignificantly increased during subjecting to limited repeated loading. For fully prestressed and partially prestressed concrete beams with high level of PPR, the ductility was significantly enhanced, while, it was decreased for specimens with small level of PPR.
The need for wireless sensing technology has rapidly increased recently, specifically the usage of electromagnetic waves which becoming more required as a source of information. Silicon carbide (SiC) Nano particles has been used in this study, the material under test (MUT) was exposed directly to a microwave field to examine the electromagnetic behavior. The permittivity and permeability were investigated with different filler materials to approach best and optimal electromagnetic absorbing characteristics to assist engineers to monitor structure-based composite for defects evaluation that may occur during operation conditions or through manufacturing process. XRD, FESEM and both complex permittivity and permeability were measured f
... Show MoreThe idea of using slender Reinforced Concrete (RC) columns with cross-shaped (+-shaped) instead of columns with square-shaped was discussed in this paper. The use of +-shaped columns provides many architectural and structural advantages, such as avoiding prominent columns edges and improved the structural response of member. Therefore, this study explores the structural response of slender +-shaped columns experimentally and numerically by nonlinear finite element analysis using Abaqus simulation tools. The results showed an excellent convergence in strength between numerical and test results with an average standard deviation of 0.05 and 0.07. Besides that, the use of +-shaped column
This study deals with the subject of violence, but from another perspective, it has not been emphasized in contemporary studies of violence in Arabic and raqi universities, which is the structural or institutional aspect of violence. Traditional studies have focused their analysis of violence on the direct side the violence, The other side of the violence is the hidden violence, which is characterized by a lack of clarity of the underlying factors and its effects are not arises, which makes it the most serious violence, which requires a deep research into the social, political, economic, cultural and psychological structure of society (individuals and institutions). This study was based on the theory of the Norwegian scientist (J
... Show MoreThis paper presents the results of experimental investigation carried out on concrete model piles to study the behaviour of defective piles. This was achieved by employing non-destructive tests using ultrasonic waves. It was found that the reduction in pile stiffness factor is found to be about (26%) when the defect ratio increased from (5%) to (15%). The modulus of elasticity reduction factor as well as the dynamic modulus of elasticity reduction factor increase with the defect ratio
In this research work, a new type of concrete based on sulfur-melamine modification was introduced, and its various properties were studied. This new type of concrete was prepared based on the sulfur-melamine modification and various ingredients. The new sulfur-melamine modifier was fabricated, and its fabrication was confirmed by IR spectroscopy and TG analysis. The surface morphology resulted from this modifier was studied by SEM and EDS analysis. The components ratios in concrete, chemical and physical characteristics resulted from sulfur-melamine modifier, chemical and corrosion resistance of concrete, stability of concrete against water adsorption, stability of concrete against freezing, physical and mechanical properties and durabi
... Show MoreThe presence of construction wastes such as clay bricks, glass, wood, plastic, and others in large quantities causes serious environmental problems in the world. Where these wastes can be used to preserve the natural resources used in construction and reduce the impact of this problem on the environment, it also works to reduce the problem of high loads of concrete blocks. Clay bricks aggregate (AB) can be recycled as coarse aggregate and replaced with volumetric proportions of coarse aggregate by ( 5% and 10%), as well as the use of clay brick powder (PB) by replacing its weight of cement (5% and 10%) and reduced in the manufacture of concrete blocks (blocks). Four mixtures will be prepared and tested to learn how to re
... Show MoreOver the last few years, there has been a worldwide increase in the use of composite materials for rehabilitation of deficient reinforced concrete structures. One important application of this technology is the use of Carbon Fiber Reinforced Polymer (CFRP) jacket to provide external confinement of reinforced concrete columns. Square concrete column specimens 100×100×1000 mm with concrete
compressive strength of about 30 and 50 MPa, steel fiber volume fraction 0%, 0.5%, 0.75%, and percentage of longitudinal reinforcement 2.01%, 3.14% and 4.52% were tested until failure in previous research. In this research seven tested columns were repaired and rehabilitated using one layer of CFRP flexible wraps and tested to determine their ultim
Waste materials might be utilized in various applications, such as sustainable roller compacted concrete pavements (RCCP), to lessen the negative environmental consequences of construction waste. The impacts of utilizing (brick, thermostone, granite, and ceramic) powders on the mechanical characteristics of RCCP are investigated in this study. To achieve this, the waste materials were crushed, grounded, and blended before being utilized as filler in the RCCP. After the mixes were prepared, compressive strength, splitting tensile strength, flexural strength, water absorption, density, and porosity were all determined. According to the research results, adding some of these powders, mainly brick and granite powder, enhances the mechanical
... Show MoreThis experimental study demonstrates the gable-reinforced concrete beams’ behavior with several number of openings (six and eight) and posts’ inclination, aimed to find the strength reduction in this type of beam. The major results found are: for the openings extending over similar beam length it is better to increase the number of posts (openings),