Strengthening of reinforced masonry walls subjected to out-of-plane pseudo-static cyclic load using advanced composite

A number of researchers have conducted experimental tests on unreinforced masonry walls (URM) strengthened with advanced composite materials. Consequently, the strengthening design guidelines are limited in their scope to URM. This research aimed to investigate the behavior of reinforced masonry walls strengthened with advanced composite and subjected to out-of-plane pseudo-static cyclic load. Experimental and analytical studies were conducted to evaluate the performance of different techniques such as near surface mounted (NSM) and externally bonded (EB) fiber reinforced polymer (FRP) with epoxy resin, in addition to NSM with cementitious adhesive and fiber reinforced cementitious material (FRCM). The experimental part included three phases. In the first phase, a series of 42 reinforced masonry walls were tested to study the effectiveness of advanced composites in enhancing out-of-plane flexural capacity. The effect of long-term environmental exposure on strengthening systems was investigated in the second phase of study by testing 10 reinforced masonry walls. The third phase focused on bond behavior between the advanced composite and the concrete masonry unit at different temperatures; 56 specimens were used for this purpose. The results indicated that the non-arching strengthened reinforced masonry wall\u27s behavior was significantly dependent on the type of fiber and fiber reinforcement ratio. The specimens strengthened with glass under combined environmental cycles exhibited an insignificant change in terms of ultimate strength as compared to laboratory conditioned specimens. The theoretical part included the investigation of bond reduction factors, seismic performance, and the nonlinear analysis of strengthened reinforced masonry wall using moment-curvature analysis. As a result of this study, the proposed model for predicting debonding strain and the moment-curvature relation presented an excellent prediction compared to the experimental results --Abstract, page iv

Some improved two-stage shrinkage testimators for the mean of normal distribution

In this paper, we introduced some two-stage shrinkage testimators (TSST) for the mean µ when a prior estimate µ0 of the mean µ is available from the past, by considering a feasible form of the shrinkage weight function which is used in both of the estimation stages with different quantities. The expressions for the bias, mean squared error, expected sample size and relative efficiency for the both cases when o2 known or unknown, are derived and studied. The discussion regarding the usefulness of these testimators under different situations is provided as conclusions from various numerical tables obtained from simulation results

Correlation between field and laboratory measurements on earth dams

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Trace element anomalies in the igneous wall rocks of hydrothermal veins in the Searchlight District, Nevada

Two hundred and fifty vein and wall rock samples were collected from Chief of the Hill and the Duplex Mines of Searchlight District, Nevada. The samples were collected along lines approximately normal to the veins. They were analyzed for lead, copper, zinc, silver, gold, arsenic, selenium, and molybdenum using neutron actication analysis and atomic absorption spectrophotometry. Gold, silver, copper, lead and zinc show well-developed anomalies in the wall rocks. In most cases, the concentration of these elements decreases gradually with increasing distance from the vein and reaches background values at a distance of 40-120 feet from the vein. Molybdenum and selenium did not show a significant difference in concentration between vein material and wall rock. The arsenic concentration was below the detection limit of the used analytical method. The available results indicate that the concentration of metal in the vein strongly influences the extent of the wall rock anomaly. The results also indicate that anomalies are better developed in the hanging wall than in the footwall of a vein --Abstract, page ii

Some improved two-stage shrinkage testimators for the mean of normal distribution

In this paper, we introduced some two-stage shrinkage testimators (TSST) for the mean μ when a prior estimate μ0 of the mean μ is available from the past, by considering a feasible form of the shrinkage weight function which is used in both of the estimation stages with different quantities. The expressions for the bias, mean squared error, expected sample size and relative efficiency for the both cases when 2 known or unknown, are derived and studied. The discussion regarding the usefulness of these testimators under different situations is provided as conclusions from various numerical tables obtained from simulation results.Peer Reviewe

Geochemical anomalies in the igneous wall rock at Mayflower Mine, Park City District, Utah

Approximately 500 samples were collected from the igneous wall rock of the Mayflower Mine, Park City District, Utah. The mine is the sixth largest gold producer in the United States. The samples were analyzed for copper lead, zinc silver, manganese, sodium, potassium, calcium, magnesium and iron by atomic absorption spectrophotometry. Gold was determined by neutron activation analysis, silicon and sulfur by x-ray fluorescence spectrometery. The calculation of the mineral norm from the chemical analysis showed the wall rock to be of granodioritic composition. A study of selected vein samples indicates that the copper, silver and gold content in the veins increases to the eastern and northern part of the mine while lead and zinc show the opposite pattern. The trace element distribution in the wall rock was found to reflect this distribution. The lead and zinc aureoles were found to be confined to the immediate vein area. This indicates low mobility of the two elements. Copper, gold and silver show narrow aureoles in the western part of the mine. The aureoles become much wider in the eastern part where the concentrations in the veins are higher. The manganese aureole is most extensive in the western part where the manganese content of the vein is highest. High anomalous values of copper, lead and zinc in the wall rock coincide with the presence of the minerals chalcopyrite, galena and sphalerite respectively. The results indicate that the size of the trace element aureoles is affected mainly by the mobility of these elements and their concentration in the ore forming solution. Analysis of the wall rock for major elements shows addition of silica in the vein area and some leaching in the immediate wall rock. Aluminum and potassium are enriched in a zone extending 20 to 60 feet away from the vein. In this zone, calcium and sodium are leached. Magnesium and iron show an enrichment zone at some distance from the vein. In the eastern part of the mine alumino-silicate minerals are to some extent replaced by anhydrite, an observation which is also indicated by the very high sulfur values in the eastern wall rock traverses. Factor analysis of the major elements shows clearly the grouping of major elements into two major alteration zones, a potassium rich sericitic zone and a magnesium-iron rich chloritic zone --Abstract, pages ii-iii

Investigation into laser re-melting of inconel 625 HVOF coating blended with WC

High velocity oxy-fuel (HVOF) spraying of Diamalloy 1005 powders mixed with WC particles onto steel (304) is considered and laser re-melting of the resulting coatings is examined. Laser re-melting process is modeled to determine the melt layer thickness while temperature increase is formulated using the Fourier heating law. The morphological and metallurgical analyses prior and post laser re-melting process are carried out using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). X-ray diffraction (XRD) technique is used to determine the residual stress developed in the coating while the analytical formulation is adopted to predict the residual stress levels at the coating base material interface. The indentation tests are carried out to determine the Young’s modulus and fracture toughness of the coating prior to laser re-melting. Corrosion resistance of coating is measured using potentiodynamic polarization technique prior and post laser treatment process. The predictions of the melt layer thickness are in good agreement with experimental results. The presence of WC particles modifies temperature rise and its gradient in the coating while affecting the Young’s modulus, residual stress levels, and fracture toughness of the coating. The differences in the thermal properties of Inconel 625 powders and WC particles result in formation of small size cellular structure through polyphase solidification. WC dissolution in the central region of the large polycrystalline cells is observed due to the loss of carbon through carbonic gas formation. The results of corrosion tests prevail that significant improvement of corrosion resistance can be achieved after laser treatment process