Papers by Keyword: Stiffness Reduction

Abstract: This article follows earlier publications dealing with reinforced concrete arch overpasses on the D3 0311 motorway section located near Ceske Budejovice, Czech Republic, close to the Austrian border. While previous work provided a basic overview of the bridge’s structural layout and construction, this article focuses on a detailed static analysis and related assessments. Attention is given to serviceability limit states and stability, as well as to the analysis of the construction stages and its possible alternatives. A detailed description of the results from static load testing, including the monitoring of crack initiation and propagation, is presented. The study also addresses the problem of differential shrinkage in the concrete at the arch-deck interface. The results demonstrate that detailed numerical analysis combined with experimental verification through static load testing provides valuable insight for optimizing design and ensuring long-term reliability of these bridge structures.

Abstract: This study investigates the influence of material nonlinear in slender reinforced concrete (RC) columns dynamic second-order effects under seismic load. The stiffness reduction coefficient is adopted in this paper. To identify the significance of various effects in terms of the dynamic second-order effects of the slender RC columns, nonlinear dynamic analyses are conducted for different periods and stability coefficients of simulated models with rare occurrence earthquake. On the basis of the obtained numerical results, the influence of material nonlinear for dynamic second-order effects are reviewed.

Abstract: An analytical model based on the displacement function of the opening of crack applied by Lundmark and Varna [26] in the internal layers to study the evolution of the decrease of stiffness in a laminate is investigated. The results of axial rigidity versus the crack density are presented for three composite materials. The influences of the temperature and moisture on the mechanical properties of composite material are highlighted. The micromechanical model of the laminates used in present study describes the degradation of the mechanical properties of composite material by the variation in the temperature and moisture. The hygrothermal effect is observed to be harmful for composite materials.

Abstract: Significant stiffness reduction of the plate spring due to delaminations around the interwoven cloths could be prevented by using CFRTP (carbon fiber cloth and Polyethylene Terephthalate (PET)) rather than that by using CFRP (carbon fiber cloth and epoxy), when ultra high cyclic loading was applied to the plate spring under high humidity condition. To explain the result, the prediction model of stiffness reduction was introduced considering time-dependent crack propagation accompanying with creep deformation around the crack tip. Stiffness reduction of CFRP under high humidity condition was not only determined by cyclic crack propagation but also by time-dependent crack propagation accompanying with creep deformation around the crack tip. It was found that CFRTP was effective material of the plate springs on vibration conveyer for the uses under high humidity condition to prevent significant stiffness reduction, where the crack propagation accompanying with creep deformation should be prevented around the crack tip.

Abstract: Based on the experimental results, this paper presents the effects of concrete-filled in chord on the static behavior of rectangular hollow section (RHS) steel tubular trusses, including failure modes, load bearing capacity and structural stiffness. Failure of RHS trusses occurs at joints wether concrete-filled in chord or not, concrete-filled in chord changed the failure mode. Load bearing capacity and stiffness of joints subjected to compression load increased significantly, while it is limited to the tension joints. Concrete-filled in the compression chord tube can increase its stiffness significantly, while tension chord tube, it is not that obvious. Finally, based on the results discussed, failure modes and their formulas of calculating the load bearing capacity are discussed. Meanwhile, two methods, that is, amplified factor method and stiffness discounting method, which calculate the structural displacement when considering the joint deformation effects are presented.

Abstract: This paper investigated the stiffness reduction of the plate spring made of CFRP (Carbon cloth and epoxy) subjected to ultra high cyclic fatigue loading under high relative humidity. For practical uses, this paper proposes a new design which prevents the significant degradation with stiffness change of the plate spring at high humidity. Remarkable stiffness reduction of the plate spring due to cracks and delaminations around inter layer could be prevented by using CFRTP rather than that by using CFRP, when ultra high cyclic loading was applied to the plate spring under high humidity condition.

Abstract: Among Non-Destructive Evaluation, vibration-based methods respond to the current ten- dency which is to integrate into the structure identication and monitoring systems; to this aim transducers and sensors are embedded with the mechanical system and driven by suitably designed electronic controllers. The major limit of this and the other indirect identication techniques based on frequency response measurements turns out to be the small sensitivity to local variations of mechanical characteristics: it re ects on a uncertainty on the identied parameters, since it implies a small curvature of any reasonable identication functional build on these quantities. An enlightening example for the application of the proposed technique is given through a beam- like structure coupled to a network of piezoelectric patches. Although the forces exerted by the piezoelectric transducers are not large, the choice of such a kind of actuators/sensors implies the remarkable advantage of dealing with highly sensitive and easily tunable devices.

Abstract: This paper presents the adaptation of the analytical method for transverse laminacracking in multidirectionally laminated composites to the finite element method. The damageinitiation and extension in a structure made of the laminated composite are evaluated by thedeveloped finite element method. The reduction in the stiffness of the laminated composite thatcaused by the crack growth is evaluated by the total force method. In the present analyses by thedeveloped method, the critical strain of the crack growth is the value of the strain which satisfiesboth energy criterion and stress criterion. To demonstrate the accuracy of the developed method,the analytical results of crack growth in CFRP quasi-isotropic laminate with a circular hole arecompared with experimental results.