Soil-structure interaction plays an important role in the behavior of structure under static or dynamic loading. It influences the behavior of soil, as well as the response of pile under loading. The analysis is highly essential for predicting a more accurate structural behavior so as to improve the safety of structures under extreme loading conditions. The soil-pile system behavior is predominantly nonlinear and this makes the problem complicated. In a laterally loaded pile the load is resisted by the soil-pile interaction effect, which in turn depends on soil properties, pile material, pile diameter, loading type and bed slope of ground. The difficulty in the accountability of the influencing factors necessitates a careful study on soil-structure interaction problem. The analysis became easier with the debut of powerful computers and simulation tools such as finite element analysis software. A detailed literature review on soil-structure interaction analysis of laterally loaded piles is presented in this paper.

Conventional analytical and numerical methods for the mechanical properties of helical threads are relied on many assumptions and approximations and thus hardly yield satisfactory results. In this paper, an effective mesh generation scheme is used which can provide accurate helical thread model to analyse specific characteristics of stress concentrations and contact pressure distributions caused by the helical thread geometry. Sector model of bolted flange joint has been analysed for pretension alone and combination of pretension and axial load. Using the finite element (FE) model with accurate thread geometry with pretension, the thread root stresses, contact pressure along the helix and at the nut loaded surface in the circumferential direction have been studied. The peak stress occurs at the first engaged bolt thread root from nut loaded surface. This stress at the thread root gradually decreases towards the free face of the nut. The contact pressure at nut bearing surface varies in the circumferential direction because of the circumferential variation of the stiffness of engaged threads adjacent to the nut loaded surface. The axial load along the engaged threads gradually decreases from nut loaded surface to zero towards the free surface of the nut. Results from analysis with pretension and axial load indicate that the contact separation starts at the inner radius of flange and grows towards outer diameter of flange as the axial load is increased in the bolted flange joint. It is observed from the analyses that the load is shared by flanges when the external applied axial load is up to 15% of preload, and beyond this, bolt starts sharing external load. The maximum stress occurs at the first engaged bolt thread root. Most of the bolt failures are at the first engaged thread. The study suggests that it is necessary to consider threads in FE model to obtain accurate contact pressure, thread stress, stiffness and bolt load predictions. These critical observations provide insight for optimization of bolted flange joint to meet the structural requirements and weight optimisation.

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Friction welding is a solid state joining process that produces coalescence in materials, using the heat developed between surfaces through a combination of mechanical induced rubbing motion and applied load. In rotary friction welding technique heat is generated by the conversion of mechanical energy into thermal energy at the interface of the work pieces in contact during rotation under pressure. Recent studies revealed that one of the strong influencing factors which affect the tensile characteristics of the friction welded joints is the shape of interface geometry of the mating surfaces. The various interface geometry considered for those studies are Flat-Flat combination, Taper-Taper combination and Concex-Convex combination. It is reported that the Ultimate tensile tensile characteristics of friction welded joints with taper-taper and convex-convex combinations are higher than that obtained with flat-flat combination. Present study investigates the influence of these geometry on the other physical characteristics like hardness and mechanical properties like torsion. Attempts were made to analyze the variations in such properties from flat-flat combination based up on the microstructure studies carried out. The Taper angle considered for taper-taper combination is 30° and the radius of the convex-convex geometry considered is 20mm. The speed for the rotating specimen here is 775 rpm. The welding pressure was kept in the range 0.7-1.73 N/mm2. The forging pressure was kept in the range 1.73-2.76 N/mm2. The hardness and the Modulus of rigidity was found higher for the joints with taper-taper combination. Convex-Convex geometry also showed better modulus of rigidity than Flat-Flat combination, but less in the case of hardness value