87,025 research outputs found
Influence of temperature variations on the mechanical behavior of stay cables using a catenary-based approach
No full textThis paper deals with the statical behavior of elastic cables used in cable-stayed
structures, focusing on thermal effects. Starting from a catenary-based approach, cable’s length variation with respect to reference configuration is evaluated by superimposing a uniform distribution
of temperature to standard elastic contributions. The influence of temperature variations on the mechanical behavior of elastic stay cables is highlighted through the example of the Rades La Goulette cable-stayed bridge built recently in Tunisia, confirming the soundness and the effectiveness of the proposed approach
Strengthening of reinforced concrete beams with basalt-based FRP sheets: an analytical assessmen
No full textIn this paper the effectiveness of the flexural strengthening of RC beams through basalt fiber-reinforced sheets is investigated. The non-linear flexural response of RC beams strengthened with FRP composites applied at the traction side is described via an analytical formulation. Validation results and some comparative analyses confirm soundness and consistency of the proposed approach, and highlight the good mechanical performances (in terms of strength and ductility enhancement of the beam) produced by basalt-based reinforcements in comparison with traditional glass or carbon FRPs
Progressive damage in composite bolted joints via a computational micromechanical approach
No full textIn this paper, the pin-induced progressive damage of fiber-reinforced laminates employed in composite bolted joints is addressed. A nonlinear finite-element computational approach is developed, by describing the pin-based load transfer mechanisms via an incremental formulation that accounts for the unilateral contact between pin and laminate. The nonlinear incremental damage problem is faced via a multiscale strategy that couples: the laminate theory; the micromechanical bridging model for describing stress localization at the constituent scale within each ply comprising the laminate; a microscale biaxial strength criterion combined with a local material degradation rule. Some illustrative numerical applications are presented and discussed, highlighting the good agreement of the proposed results with available benchmarking experimental evidence, as well as providing quantitative indications on the influence of some model parameters
A mixed FSDT finite element for monoclinic laminated plates
No full textA 4-node finite element for the analysis of laminated composite plates with monoclinic layers, as it occurs for example in piezoelectric applications, is developed. The element is built through the linked interpolation scheme proposed by Taylor and Auricchio [Int J Numer Meth Eng 1993;36:3057-66] and is a generalization of the element presented in [Auricchio F, Sacco E. A mixed-enhanced finite-element for the analysis of laminated composite plates. Int J Numer Meth Eng 1999;44:1481-1504]. Starting from a first-order shear deformation theory (FSDT), a mixed-enhanced variational formulation is considered. It includes as primary variables the resultant shear stresses as well as enhanced incompatible modes, which are introduced to improve in-plane deformations. Bubble functions for rotation degrees of freedom and functions linking transversal displacement to rotations are employed. The solvability of the variational formulation is proved whereas effectiveness and convergence of the proposed finite element are confirmed through several numerical applications. Finally, numerical results are compared with the corresponding analytical solutions as well as to other finite-element solutions. (c) 2005 Elsevier Ltd. All rights reserved
Experimental investigation on the debonding failure mode of basalt-based FRP sheets from concrete
No full textIn this paper, the debonding failure mode of basalt-based FRP (BFRP) reinforcements from concrete supports is experimentally investigated. In detail, more than 40 push-pull double shear tests on BFRP-concrete specimens with different geometrical configurations were carried out. Results in terms of debonding load and strain patterns arising at the BFRP layer are presented and discussed, furnishing indications about the influence of: composite thickness, width ratio between the BFRP width and the concrete one, anchor length. On the basis of the proposed experienced evidence, the design indications provided by the Italian Technical Document CNR DT200/R1 and addressing the assessment of the debonding load have been critically analysed. Accordingly and as a further result, a novel effective calibration of the corresponding empirical correction parameter kg (introduced to improve the previsional effectiveness of the fracture-mechanics-based theoretical estimate of the debonding force), has been provided. In detail, in order to ensure the best agreement between proposed experimental data and theoretical predictions associated to concrete elements externally strengthened by the in-situ application of BFRP sheets, the value kg=0.117 mm (5% fractiles 0.079) is specifically proposed, resulting very different from the indication by the Italian technical document (kg=0.077 mm, 5% fractiles 0.037 mm)
Rational derivation of a single-layer model for laminated thin-walled beams
No full textIn this paper an equivalent single-layer theory for the analysis of laminated thin-walled beams is rationally deduced from the three-dimensional elasticity theory. Consistent constraints for strain and stress fields are enforced in the Hu-Washizu functional by a non-standard application of the Lagrange multipliers theory. Vlasov-Wagner assumptions on the middle-surface of the beam and Kirchhoff-Love restrictions are enforced as strain constraints together with dual conditions on the constitutive-related stress field. The linearly elastic properties of the equivalent single-layer beam are deduced considering an anisotropic constitutive behaviour for each lamina. The proposed model takes into account high-order effects related to thickness and curvature of the cross-section centerline, usually neglected, allowing to deduce a refined expression of the torsional warping function for open cross-section laminated beams
Anisotropic thin-walled beam models: a rational deduction from three-dimensional elasticity
No full textIn this paper anisotropic thin-walled beam models are rationally deduced from three-dimensional elasticity by means of a constrained approach. Consistent frictionless internal constraints on both stress and strain dual fields are enforced through a modified Hu–Washizu functional obtained by a nonstandard application of Lagrange multipliers. Beam theories accounting for different shear refinement levels are justified, showing that this variational approach enables the development of new refined models, including high-order nonconventional effects and enhancing standard treatments of shear deformation effects. In agreement with the constrained problem, a locally equilibrated approximation of the stress field acting
on beam cross-section is recovered in closed form. Finally, cases of laminated thin-walled beams as well as of unilateral conewise constitutive behavior (with special reference to bimodular materials) are investigated
A Mixed FSDT finite element formulation for the analysis of composite laminates without shear correction factors
No full textA new 4-node finite element for the analysis of laminated plates is developed starting from a partial-mixed FSDT variational
formulation, which considers out-of-plane shear stresses as primary variables. It does not require either the introduction of
shear correction factors or post-processing procedures to obtain transverse shear stress profiles. Presented numerical examples
show that the element exhibits a quadratic convergence rate and it is locking free
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