This research is carried out to study the effect of the external post-tensioning technique on the flexural capacity of simply supported composite castellated beam experimentally. In this research, seven composite castellated beams having the same dimensions and material properties were cast and tested up to failure by applied two concentrated loads at 700 mm from each end. Two external strands of 12.7 mm diameter were fixed at each side of the web of strengthening beams and located at depth 180 mm from top fiber of the section (dps) at each end of the beam. The strands have been tensioned by using a hydraulic jack with a constant stress of 100 MPa. This research aims to study the effect of the strengthening by different shapes of strand profiles of external post-tensioning techniques on the flexural capacity of the composite castellated beam. These beams were divided into three groups. Each group contained two composite castellated beams while 7th composite castellated beam kept without strengthening by external post-tensioning technique As control beam. The first group included two beams with straight strand profile of external Post-tensioning. The second group included two beams with a triangular strand profile of external post-tensioning. The third group included two beams with a trapezoidal strand profile of external post-tensioning. All composite castellated beams were simply supported, and all of them were fully shear connections between the concrete slab and steel girder. All beams included the 16 castellated openings and were stiffened by six stiffener plates welded on the web of castellated beams. Three stiffener plates are welded on each side of the web. Two of these stiffener plates welded at the middle of the beam, and four of them welded at locations under the loads. The experimental results of this research were increasing 5.43% in load capacity of an average of the straight profile of composite castellated beams, increasing 18.92% in load capacity of an average of triangular profile composite castellated beams, and increasing 20.71% in load capacity of the trapezoidal profile of composite castellated beams. All the above results were compared with control beams.
The purpose of this study is to avoid delays and cost changes that occur in emergency reconstruction projects especially in post disaster circumstances. This study is aimed to identify the factors that affect the real construction period and the real cost of a project against the estimated period of construction and the estimated cost of the project. The case study is related to the construction projects in Iraq. Thirty projects in different areas of construction in Iraq were selected as a sample for this study. Project participants from the projects authorities provided data about the projects through a data collection distributed survey made by the authors. Mathematical data analysis was used to construct a model to predict change
... Show MoreIn this research, a simple experiment in the field of agriculture was studied, in terms of the effect of out-of-control noise as a result of several reasons, including the effect of environmental conditions on the observations of agricultural experiments, through the use of Discrete Wavelet transformation, specifically (The Coiflets transform of wavelength 1 to 2 and the Daubechies transform of wavelength 2 To 3) based on two levels of transform (J-4) and (J-5), and applying the hard threshold rules, soft and non-negative, and comparing the wavelet transformation methods using real data for an experiment with a size of 26 observations. The application was carried out through a program in the language of MATLAB. The researcher concluded that
... Show MoreAbstract:
The aim of the current study was to investigate the possible protective effect of graded doses (5, 10, and 15mg/kg) of pyridoxine hydrochloride intraperitoneally injected against (15mg/kg) doxorubicin-induced cardiotoxicity in female rats. Fifty-six (56) Wistar albino female rats were utilized weighing 180-200 gm allocated into eight groups, seven rats each; Group I: negative control distilled water; Group II: Pyridoxine (5mg/kg); Group III: Pyridoxine (10mg/kg); Group IV: Pyridoxine (15mg/kg); Group V: doxorubicin (15 mg/kg); Group VI: Pyridoxine (5 mg/kg) prior to
... Show MoreIn this study, a Hydroxyapatite (HA) coating was prepared on a titanium implant by an electrochemical deposition process. The titanium pre-treatment by anodizing in 1.65 mol/L sulfuric acid with (10V) at room temperature. The deposition was all conducted at a constant voltage of 6.0 V, for 1 h at room temperature. The coatings thus prepared were characterized with Fourier transform infrared spectroscopy (FTIR) and thickness of the coated layer.The electrochemical deposition of HA occurred on the titanium as a cathode. Coated titanium by HA after anodizing revealed a good corrosion protection efficiency even at a temperature ranged (293-323) K in artificial saliva. Activation energy and pre-exponential factor (kinetic parameters) were calcul
... Show MoreThis study deals with the serviceability of reinforced concrete solid and perforated rafters with openings of different shapes and sizes based on an experimental study that includes 12 post-fire non-prismatic reinforced concrete beams (solid and perforated). Three groups were formed based on heating temperature (room temperature, 400 °C, and 700 °C), each group consisting of four rafters (solid, rafters with 6 and 8 trapezoidal openings, and rafter with eight circular openings) under static loading. A developed unified calculation technique for deflection and crack widths under static loading at the service stage has been provided, which comprises non-prismatic beams with or without opening exposed to flexure concentra
... Show MoreBackground: with the advent of new postmaterial in dentistry, it has become important to measure fitness of post restoration along the horizontal plane of the root space.This study aimed to measure and compare, the cement film thickness of conventional zinc phosphate cement in micrometer between the post and root dentin along horizontal plane at different post space regions (coronal, middle and apical) of four types of posts, by using stereomicroscopy. Material and methods: Thirty-two extracted human maxillary canines, mandibular canines and maxillary central incisors (n=32) were instrumented with ProTaper system files (hand use) and obturated with gutta-percha for ProTaper and AH26® root canal sealer. After 24hrs of incubation at 37ºC, p
... Show MoreCantilever beams are used in many crucial applications in machinery and construction. For example, the airplane wing, the microscopic probe for atomic force measurement, the tower crane overhang and twin overhang folding bridge are typical examples of cantilever beams. The current research aims to develop an analytical solution for the free vibration problem of cantilever beams. The dynamic response of AISI 304 beam represented by the natural frequencies was determined under different working surrounding temperatures ((-100 ℃ to 400 ℃)). A Matlab code was developed to achieve the analytical solution results, considering the effect of some beam geometrical dimensions. The developed analytical solution has been verified successful
... Show MoreActive vibration control is the main problem in different structure. Smart material like piezoelectric make a structure smart, adaptive and self-controlling so, they are effective in active vibration control. In this paper piezoelectric elements are used as sensors and actuators in flexible structures for sensing and actuating purposes, and to control the vibration of a cantilever beam by using sliding mode control. The sliding mode controller (SMC) is designed to attenuate the vibration induced by initial tip displacement which is equal to 15 mm. It is designed based on the balance realization reduction method where three states are selected for the reduced model from the 24th states that describe the c
... Show More