Iron based shape memory alloys (Fe-SMA) have recently been used as active flexural strengthening material for reinforced concrete (RC) beams. Fe-SMAs are characterized by a shape memory effect (SME) which allows the recovery of previously induced plastic deformations through heating. If these deformations are restrained a recovery stress is generated by the SME. This recovery stress can be used to prestress a SMA applied as a strengthening material. This paper investigates the performance and the load deformation behavior of RC beams strengthened with mechanical end anchored unbonded Fe-SMA strips activated by sequentially infrared heating. The performance of a single loop loaded and a double loop loaded SMA strengthened RC beam are compared to an un-strengthened beam and a reference beam strengthened with commercially available structural steel. In these tests the SMA strengthened beam had the highest cracking load and the highest ultimate load. It is shown that the serviceability behavior of a concrete beam can be improved by a second thermal activation. The sequential heating procedure causes different temperature and stress states during activation along the SMA strip that have not been researched previously. The possible effect of this different temperature and stress states on metal lattice phase transformation is modeled and discussed. Moreover the role of the martensitic transformation during the cooling process on leveling the inhomogeneity of phase state in the overheated section is pointed out.
Water production control has become a key issue in most mature oil fields worldwide. Several water shut off technologies have been developed during the last two decades, and intensive research work is continuously conducted in this field. Relative permeability modifiers (RPM) have proven to be an effective method to enhance oil recovery, especially under linear flow conditions achieved after fracturing. This technique is being extensively used worldwide, with many successful case histories published in the literature. When adequately design and applied, RPM treatments will increase well profitability, improving water-oil ratio, reducing water management costs and environmental impacts. However, RPM treatments are not always effective, as they depend on several aspects associated to formation and fluid production characteristics, polymer chemistry and the interaction between each other. Many oil and gas zones in Entre Lomas field require hydraulic fracturing for a profitable production. However, the risk of contacting close water layers might jeopardize wells productivity. RPM treatments have been conducted in this field since 2007. In most cases the RPM solution was pumped as part of a fracture conformance job. This paper presents the results from more than 50 wells fractured bull-heading RPM treatments. The field work was supported by a laboratory study based on different experiments performed to evaluate RPM efficiency. Regain permeability (RK), relative permeability curves and nuclear magnetic resonance (NMR) tests were conducted using core plugs and Berea sandstone samples. The RPM polymer washout rate was evaluated by spectrophotometer measurements performed on brine samples collected during the flow test. The NMR spectrums run on treated and untreated cores in the saturated and irreducible water condition provided evidence of the polymer bonding capacity and its ability to retain water. The use of RPM´s allowed fracturing formations with close high water saturation transition zones that otherwise would not be produced. Pre and posfrac formation evaluations tests and production data is provided. Laboratory results show that the RPM polymer under study produced a significant reduction in water permeability, without substantial oil perm modification. Polymer wash out time showed strong flow rate dependence affecting the treatment durability. Introduction Entre Lomas field description The Entre Lomas field is located in the northwest Neuquina Basin, Argentina (seeFigure 1). It was discovered in 1960, being formation Tordillo one of the main oil payzones which is under secondary recovery since 1975. Tordillo is a clustered sandstone present at approximately 2300 m. The bottom part of this formation consists of a sequence of fluvial layers, while the top part presents eolian sedimentation characteristics. The bottom part has thin interspaced clay layers with variable extensions. The clustered layers present strong heterogeneity, with week areal and vertical barriers on the payzones under production (Benito, 1997). These characteristics explain the variable production response of certain wells showing, in some cases, low recovery factors. Several water shut-off treatments were conducted in the fluvial layers during 1995, 1999 and 2001 in order to reduce water cuts. These layers presented heterogeneous permeability's (0.5 to 25 mD) which caused injection water channeling and inefficient water flooding results (Wouterlood, 2002).
<p>In the last years fiber reinforced elastomeric bearings (FREBs) acting as isolation devices have begun to replace bearings with steel reinforcement. To understand the behaviour of FREBs under seismic loads it is essential to investigate their relevant mechanical properties, effective shear modulus and equivalent damping ratio. The experimental investigation yielded some discrepancies between collected data and expected behaviour of the bearings. In order to investigate that disagreement, a numerical simulation approach focusing on capturing the visco- hyperelastic behaviour of the elastomeric material has been investigated. In addition, a method for the calibration of the material model is presented and validated. Moreover, the influence of vertical load, horizontal deflection, number of elastomeric and reinforcement layers and support type on the mechanical properties will be discussed.</p>
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