Issue 1: Jan.-Apr. 2021

Milad Bahrami, Michel Guillot

Abstract:Metal Inert Gas (MIG) welding is a versatile gas metal arc welding (GMAW) process that uses a continuous solid wire electrode and a shielded gas to assemble both thin sheet and thick section components. As welding distortion and residual stress have negative effect on welding assembly, it is necessary to select the proper welding parameters. This study focuses on the optimization parameters for Metal Inert Gas (MIG) welding, Aluminum 6061 samples have been welded in V-groove butt joint configuration, with 60 degree angle and 6.35 mm thickness. Taguchi technique based Orthogonal Array (L4 and L8) is used for Design of Experiments (DOE) and artificial neural network (ANN) modeling is utilized to predict the distortion and Ultimate Tensile Strength (UTS). The 3d surface graphs and contour plots were generated for the results to elucidate the relationship between welding parameters, lack of penetration(LOP), ultimate tensile strength (UTS) and distortion. Afterward optimum process parameters are identified to maximize the UTS as well as minimize distortion and lack of penetration for the weld joint. The ideal range of process parameters such as voltage, wire feed speed, gun angle, distance between nozzle to weld, travel speed, root gap and root face have been found.

International Journal of Bridge Engineering, Vol. 9, No. 1, 2021: pp. 1-13

Osama Mohammed Elmardi Suleiman Khayal

Abstract:From the point of view of mechanics of engineering materials, the deformation of a plate subjected to transverse loading consists of two components: flexural deformation due to rotation of cross-sections, and shear deformation due to sliding of sections or layers. The resulting deformation depends on two parameters: the thickness to length ratio and the ratio of elastic to shear moduli. When the thickness to length ratio is small, the plate is considered thin, and it deforms mainly by flexure or bending; whereas when the thickness to length and the modular ratios are both large, the plate deforms mainly through shear. Due to the high ratio of in-plane modulus to transverse shear modulus, the shear deformation effects are more pronounced in the composite laminates subjected to transverse loads than in the isotropic plates under similar loading conditions. Mathematical models for rectangular laminated plates in bending need to determine the real stress‐strain state in the laminated plate, which requires the application of more accurate theories. In addition, it is important to find a balance between the desired accuracy and calculation costs. Different theories for rectangular plate analysis have been reviewed. These theories can be divided into two major categories, the individual layer theories (IL), and the equivalent single layer (ESL) theories. These categories are further divided into sub – theories by the introduction of different assumptions.

International Journal of Bridge Engineering, Vol. 9, No. 1, 2021: pp. 15-34

Saman Mansouri

Abstract:The seismic design of structures depends on the selection of suitable earthquakes according to the realistic conditions of the structure and its site, which is not possible except by accurately recognizing the characteristics of the earthquakes. For this purpose, in this paper, the characteristics of near and far-fault earthquakes have been studied in detail in order to the seismic design of the structures. Directivity, fling-step, asperity, types of the faults, the duration of strong ground motion and its maximum values (PGA, PGV, and PGD) are some characters of the earthquakes which are investigated in this study. At the end, a flowchart based on the characteristics of the earthquakes in order to select them for the design of structures according to the realistic conditions of the structure and its site is presented.

International Journal of Bridge Engineering, Vol. 9, No. 1, 2021: pp. 35-48

Osama Mohammed Elmardi Suleiman Khayal

Abstract:In materials science, a composite laminate used in decks industry, is an assembly of layers of fibrous materials. The individual layers consist of high-modulus, high-strength fibers impregnated in an appropriate polymeric, metallic, or ceramic matrix material. Layers of different materials may be used, resulting in a hybrid laminate. The individual layers generally are orthotropic or transversely isotropic with the laminate then exhibi-ting anisotropic , orthotropic, or quasi-isotropic properties. Quasi-isotropic laminates exhibit isotropic in plane response but are not restricted to isotropic out-of-plane response. Depending upon the stacking sequence of the individual layers, the laminate may exhibit coupling between in plane and out of plane response. An example of bending-stretching coupling is the presence of curvature developing as a result of in-plane loading. The properties of a composite laminate depend on the geometrical arrangement and the properties of its constituents. The exact analysis of such structure – property relationship is rather complex because of many variables involved. Therefore, a few simplifying assumptions regarding the structural details and the state of stress within the composite have been introduced. The deformation of a plate subjected to transverse loading is caused either by flexural deformation due to rotation of cross-sections, or shear deformation due to sliding of sections or layers. The resulting deformation depends on the thickness to length ratio and the ratio of elastic to shear moduli. When the thickness to length ratio is small, the plate is considered thin, and it deforms mainly by flexure or bending; whereas when the thickness to length and the modular ratios are both large, the plate deforms mainly through shear. Due to the high ratio of in-plane modulus to transverse shear modulus, the shear deformation effects are more pronounced in the composite laminates subjected to transverse loads than in the isotropic plates under similar loading conditions.

International Journal of Bridge Engineering, Vol. 9, No. 1, 2021: pp. 49-63