TÓM TẮT NGHIÊN CỨU THỰC NGHIỆM Hussein
FLEXURAL BEHAVIOR OF REINFORCED CONCRETE BEAM STRENGTHENED WITH TEXTILE REINFORCED CONCRETE Strengthening of reinforced concrete structures using textile reinforced concrete (TRC) has emerged as a viable technique to retrofit/repair deteriorated structures. In this study, the flexural performance of concrete beams strengthened with TRC has been investigated by means of a finite element analysis on ABAQUS software. The work reported in this paper deals with the analytical models, proposed to predict the behavior of reinforced concrete beam strengthened with externally bonded TRC layers. The surface – based cohesive behavior is also captured to represent the interfacial bonding between TRC and concrete substrate. The results of the numerical simulations are used to validate the experimental results. .
Flexural strengthening of RC beams using textile reinforced mortar – Experimental and numerical study
Abstract In this paper, the effectiveness of textile reinforced mortars (TRMs), as a means of increasing the flexural capacity of reinforced concrete (RC) beams, is experimentally and numerically investigated. A new type of textile (basalt-based textile) was used as strengthening material. The studied parameters included type of mortar, number of TRM layers and type of strengthening material: TRM versus carbon fiber-reinforced polymer (CFRP) composites. A total of six beams were tested under four-point bending till failure. Two beams were used as control specimens. Three beams were externally upgraded by TRM sheets for enhancing their flexural capacity; and one beam was strengthened with CFRP laminates for comparison with its TRM counterpart. Besides the experimental program, a numerical investigation utilizing nonlinear finite element (FE) analysis was carried out using LS-DYNA software. In addition to the six beams tested in this study, another three beams were collected from the literature for the purpose of finite element validation. A comparison was made between the experimental and numerical results and good agreement was obtained. Based on the validation of FE results, the numerical analysis was extended to include additional cases to study the flexural enhancement of RC beams using more TRM layers with different end anchorages.
Numerical tools applied to power reactor noise analysis
In order to be able to calculate the space- and frequency-dependent neutron noise in real inhomogeneous systems in two-group theory, a code was developed for the calculation of the Green's function (dynamic transfer function) of such systems. This paper reports on the development as well as the test and application of the numerical tools employed. The code that was developed yields the space-dependence of the fluctuations of the neutron flux induced by fluctuating properties of the medium in the two-group diffusion approximation and in a two-dimensional representation of heterogeneous systems, for both critical systems and non-critical systems with an external source. Some applications of these tools to power reactor noise analysis are then described, including the unfolding of the parameters of the noise source from the induced neutron noise, measured at a few discrete locations throughout the core. Other concrete applications concern the study of the space-dependence of the Decay Ratio in Boiling Water Reactors, the noise-based estimation of the Moderator Temperature Coefficient of reactivity in Pressurized Water Reactors, the modeling of the beam- and shell-mode core-barrel vibrations in Pressurized Water Reactors, and the investigation of the validity of the point-kinetic approximation in subcritical systems driven by an external source. In most of these applications, calculations performed using the code are compared with at-power plant measurements. Power reactor noise analysis applications of the above type, i.e. core monitoring without disturbing plant operation, is of particular interest in the framework of the extensive program of power uprates worldwide.