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Go to Editorial ManagerA theoretical and experimental investigation pertaining to the buckling behavior of slender fiber reinforced polymer columns subjected to axial loading under varying temperatures (from room temperature to 50?). Two groups of composite materials were used for manufacturing of test specimens, the first consist of perlon fiber as a reinforcement and acrylic resin as a bonding matrix, while the second consists of a combination of perlon and carbon fibers as reinforcement. The composite specimens were fabricated by vacuum molding technique and cut according to ASTM D-638 for conducting tensile test. The data from tensile test were used to calculate the effective slenderness ratio and defining the column as Euler buckling column. An experimental rig was designed, manufactured and calibrated to study the effect of thermal and buckling load subjected to columns.Numerical analyses pertaining the buckling behavior for both groups were conducted. The results show that the temperature has a considerable effect on properties of fiberreinforced polymer composites where the value ofcritical load and Young's Modules decrease withthe increase of temperature for both groups.Perlon & Carbon reinforcement composites gavebest mechanical properties, which make them thebest candidate to improve the buckling resistancecharacteristics of composite materials.
This research deals with the extent to which corrosion affects the behavior of buckling for 6061-T4 aluminum alloy under increasing compressive dynamic loads. Two types of columns, long, and intermediate were used.1% of the length column is the allowable lateral deflection. This is called the critical buckling of the columns. For the purpose of calculating the critical deflection, a digital dial gauge was used and set at a distance of 0.7 of column length from the fixed end condition for the column. The experimental analysis revealed that the corrosion time negatively affects the mechanical properties of materials such as the corroded specimens of 60 days (The least time to observe the corrosion of aluminum in the soil) which have approximately 2.7 % reduction in ultimate strength compared with the non-corroded specimen. Increasing the corrosion time reduces the critical load such as the maximum reduction will be 4.24% in critical buckling load for 60 days’ corrosion time. The results obtained were experimentally compared with the theoretical formulas of the Perry-Robertson and Euler-Johnson formula with the results of the ANSYS. It was found that the Perry-Robertson formula has a good agreement with the experimental results with a safety factor of 1.2, while the Euler-Johnson formula agreed with the experimental results taking a safety factor of 1.5. The ANSYS results showed a good agreement between the measured and calculated values by taking 1.1 factor of safety.
In this research the behavior of cylindrical shells under axial load have been studied. The experimental program is included two groups: the first consists of nine cylinders; each has a diameter of 150 mm, while the height varies from 100 to 500 mm and thickness of 1.5 mm, test results show that the optimum height to achieve the maximum strength is 300 mm with L/D equal to 2. The second group consists of two cylinders with diameter of 150 mm and height of 300 and 500 mm strengthened with stiffeners plate welding from inside at four quarters with thickness of 1.5 mm and width 20 mm fabricated from the same metal of the cylinders. After testing these two cylinders were gain an increase in the strength reached to 42% for 300 mm cylinder and 26.4% for 500 mm cylinder. The failure modes for these two groups are: the buckling at bottom like “elephant’s foot” for cylinders height from 100 to 300 mm and “inelastic buckling” for cylinders height from 350 to 500 mm for the first group, and the ” inelastic buckling” for the second group.
This paper deals with the elastic stability of a column bolted at its mid-height to a simply supported square plate and subjected to a concentrated load, using energy method. A uniform homogeneous column is assumed to be pinned at both ends. From symmetry considerations, half of the column is modeled by making the plate acting as a torsion spring on the column at its mid-height. The column length and cross-section, plate dimensions and thickness, and the material properties for the column and the plate catch the interest of the author. The problem is solved by using energy method and ultimately, the elastic buckling load is found. The analytical elastic buckling load is compared with a numerical solution obtained from finite element method using SAP2000. The numerical results agree with the analytical solution. The finite element model is refined to catch the actual effect of the bolted plate on the elastic buckling load. It has been found that the elastic buckling load is increased due to the increase in the rotational stiffness provided from the plate.
The aim of this work is to investigate the effect of soil corrosion on the critical buckling load of circular columns made of 2014-T4 aluminum alloy. In this work, 24 specimens were used and buried in the soil for 120 days. The samples divided into two groups (12 columns with corrosion before shot penning (SP) and ultrasonic impact treatment (UIT), and 12 columns with corrosion after combined surface treatments (SP+UIT)). The experimental1results revealed1that the corrosion negatively1affects the mechanical properties1of the material, and the1reduction percentage (R%) for1ultimate tensile strength (UTS) and1yield strength (YS) was (1.95% and 4.57%) respectively. After combined surface treatments (SP+UIT) for the corroded columns, the ultimate1tensile strength (UTS) and yield1strength (YS) were improved with (2.42%, and 2.87%) respectively. Perry-Robertson, Rankine, and ANSYS were used to estimate the critical buckling load (Pcr) and compare it with the experimental results. Rankine and Perry's formulas have been achieved a good agreement with the experimental without and with (1.5) factor of safety respectively. While ANSYS gave satisfactory prediction with a safety factor of (2.2, and 2.7) and (1.9, and 2.7) for long and intermediate columns before and after (SP+UIP) respectively.
Double skin composite (DSC) construction or Steel/concrete/steel sandwich construction (SCSS) is an innovative and relatively new form of composite construction that can be used in submerged tube tunnels, bridges deck, nuclear structures, liquid and gas containment structures, offshore and onshore structures, military shelters, and shear walls in buildings. The system consists of a plain concrete core sandwiched between two steel plates interconnected together by various types of mechanical shear connectors. The DSC construction perceives advantages that the external steel plates act as both formwork and primary reinforcement, and also as impermeable, blast and impact resistant membranes. The major duty of the shear connectors is to withstand longitudinal shear force and beam/slab separation, while in the bi-steel type where shear connectors are friction welded at both their two ends to two parallel steel plates, the longitudinal and transverse shear force, as well as plate buckling are resisted. The present paper highlights the previous prime researches concerning the subjects of SCSS composite construction, specifically on the conducted tests (push-out tests, tensile, direct shear tests, and bending tests) in which the components of partial interaction (uplift and slip forces) are resisted by various types of shear connectors.