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This study presents an experimental investigation on composite beams (CB) to explore the effectiveness of adding external post-tensioning (EPT) force, as a strengthening technique, on the monotonic flexural performance of composite samples. Two experiments on CB were conducted under three-point loading. High-strength steel strands post-tensioned to 46% of the ultimate strength were used to apply the EPT. Moreover, a finite element (FE) model is developed to present numerical investigations on the monotonic and fatigue behaviors of the CB with and without EPT by considering the slip between the concrete slabs and steel beams as well as the fatigue deterioration in the concrete slabs. A FE parametric study is conducted using the proposed FE model to investigate the effect of steel beam grade, tendon eccentricity, span-to-depth ratio, and fatigue loading. The optimum span-to-depth ratio to obtain the maximum contribution of the EPT force in improving the CB capacities is 9.0. Key words: steel and concrete composite beams, post-tensioning, monotonic, experimental, finite element. Cette etude presente une verification experimentale sur les poutres composites (PC) afin d'explorer l'efficacite de l'ajout d'une force de precontrainte par post-tension externe (PTE), comme technique de consolidation, sur la performance de flexion monotone des echantillons composites. Deux experiences sur des PC ont ete menees sous charge en trois points. Des torons d'acier a haute resistance precontraints par post-tension jusqu'a 46 % de la resistance ultime ont ete utilises pour appliquer la PTE. En outre, un modele d'elements finis (EF) est developpe pour presenter des investigations numeriques sur les comportements monotones et de fatigue de la PC avec et sans PTE en considerant le glissement entre les dalles de beton et les poutres d'acier ainsi que la deterioration due a la fatigue dans les dalles de beton. Une etude parametrique des EF est menee a l'aide du modele EF propose pour etudier l'effet de la nuance des poutres d'acier, de l'excentricite du tendon, du rapport portee-profondeur et de la charge de fatigue. Le rapport portee-profondeur optimal pour obtenir la contribution maximale de la force PTE dans l'amelioration des capacites PC est de 9,0. Mots-cles : poutres composites en acier et en beton, post tension, monotone, experimental, element fini., Introduction Concrete and steel composite beams (CB) are widely used in the construction of bridges as effective structural members. The ductility of steel in tension combined with the hardness and [...]

This paper gives a mathematical formulation for the transverse resonance of thermoelastic nanobeams that are simply supported and compressed with an initial axial force. The nonlocal elasticity concept is used to analyze the influence of length scale with the dual-phase-lag (DPL) heat transfer theory. The nanobeam is due to a changing thermal load and moves in one direction at a constant speed. The governing motion equation for the nonlocal Euler-Bernoulli (EB) beam hypothesis can also be derived with the help of Hamilton's principle and then solved by means of the Laplace transform technique. The impacts of nonlocal nanoscale and axial velocity on the different responses of the moving beam are investigated. The results reveal that phase delays, as well as the nonlocal parameter and external excitation load, have a substantial impact on the system's behavior. [ABSTRACT FROM AUTHOR]

Unreinforced masonry (URM) is one of the most popular construction materials around the world, but vulnerable during earthquakes. Due to its brittle nature, the URM structures may lead to a possible collapse of the wall of a building during earthquake events causing casualties. In the current research, an attempt is made to enhance the seismic capacity of URM structures by proposing a new innovative composite material that can improve the shear strength and deformation capacity of the URM wall systems. The results revealed that the fiber-reinforced plastic having high tensile and shear stiffness can significantly increase in-plane as well as out-of-plane bending strength of the URM wall. It was recorded that the bending moment of the prism increased up to 549.5% by increasing the bending moment from 490 N*mm to 3183 N*mm per mm deflection of prism upon using glass fibers. Moreover, the ductility ratio amplified up to 5.73 times while the stiffness ratio increased up to 4.16 times with the aid of glass fibers. Since the material used in this research work is low cost, easily available, and no need for any skilled labor, which is economically good. Therefore, the URM walls retrofitted with fiber-reinforced plastic is an economical solution. [ABSTRACT FROM AUTHOR]