Masonry Confinement Using Steel Strips
This paper presents the behavior of masonry columns confined with steel strips for increasing the axial capacity and stress-strain relationship. The test specimens are divided into three groups; each consists of three specimens with the variables: amount of reinforcement and cross-section aspect ratio. The cross-sectional aspect ratio of the three groups were 1, 2, 3 respectively. The experimental data and highlights different aspects of confinement. The steel strips enhance the ultimate stress and strain but this increase in strength is dependant on the cross-sectional aspect ratio. It is also concluded that the increase in load-carrying capacity and the deformability of masonry is significantly enhanced due to confinement using steel strips and the increase is linear to the average confining stress. The confinement of masonry with steel strips is quite viable and cheap option for strengthening
A MITC-based procedure for the numerical integration of a continuum elastic-plastic theory of through-the-thickness-jacketed shell structures
Abstract Through-the-Thickness Jacketing (TTJ) is a technique for repairing and retrofitting shell structures by inducing in the shell core a beneficial confining stress state created by a net of broadly distributed retrofitting links crossing the shell thickness and tying externally applied layers. The paper presents the derivation, the algorithmic implementation and the numerical assessment of a predictor-corrector computational strategy for the integration of a shell FE-model obtained by combining a discrete MITC quadrilateral element with a layered continuum-based generalized shell theory of TTJ-reinforced structures, essentially based upon a Winkler-like idealization of TTJ. This theory of Through-the-Thickness-Jacketed Shells (TTJS) captures the onset of complex triaxial stress states originated by the interaction between core and TTJ reinforcements. Results of benchmark numerical applications in OpenSees with flat and curved elastic-plastic shell structures are presented in order to assess and illustrate the consistency and the general modelling features of the proposed TTJS-MITC framework endowed with the Drucker-Prager elastic-perfectly-plastic idealization of the nonlinear behavior of the material composing the shell. Numerical results exhibit quadratic convergence and show that the model captures marked strength increments over the in-plane membrane response, albeit these are lower when the response is predominantly of out-of-plane flexural type.
Ozonation of polycyclic aromatic hydrocarbons in oil/water-emulsions: mass transfer and reaction kinetics.
The ozonation of highly condensed polycyclic aromatic hydrocarbons (PAH) was studied in oil/water-emulsions, which are comparable to poorly water-soluble PAH in industrial wastewaters and at contaminated sites. As there was a lack of knowledge about the ozonation in oil/water-emulsions, first the ozone mass transfer was studied and optimized from the gas to the water phase and from the water to the oil phase. The ratio of mass transfer and oxidation reaction was determined by the Hatta-number and revealed a slow, quasi homogeneous reaction of ozone with PAH inside the oil droplets. Because the ozone gas concentration had no influence under the optimized conditions, the selective PAH-ozonation could be described microkinetically by a direct ozone reaction of pseudo-first order regarding PAH-concentrations. The determined PAH mean reaction rate constants of 1.02 min(-1) in oil/water-emulsions are in the upper range as found for PAH dissolved in water. These results give a new insight into the ozonation in the three-phase systems and into the treatment of highly condensed, hardly biodegradable PAH.