An approach for the modeling of interface-body coupled nonlocal damage

Fiber Reinforced Plastic (FRP) can be used for strengthening concrete or masonry constructions.One of the main problem in the use of FRP is the possible detachment of the reinforcement from the supportmaterial. This paper deals with the modeling of the FRP-concrete or masonry damage interface, accounting forthe coupling occurring between the degradation of the cohesive material and the FRP detachment. To this end,a damage model is considered for the quasi-brittle material. In order to prevent strain localization and strongmesh sensitivity of the solution, an integral-type of nonlocal model based on the weighted spatial averaging of astrain-like quantity is developed. Regarding the interface, the damage is governed by the relative displacementoccurring at bond. A suitable interface model which accounts for the mode I, mode II and mixed mode ofdamage is developed. The coupling between the body damage and the interface damage is performedcomputing the body damage on the bond surface. Numerical examples are presented

A coupled interface-body nonlocal damage model for the analysis of FRP strengthening detachment from cohesive material

In the present work, a new model of the FRP-concrete or masonry interface, which accounts for the coupling occurring between the degradation of the cohesive material and the FRP detachment, is presented; in particular, a coupled interface-body nonlocal damage model is proposed. A nonlocal damage and plasticity model is developed for the quasi-brittle material. For the interface, a model which accounts for the mode I, mode II and mixed mode of damage and for the unilateral contact and friction effects is developed. Two different ways of performing the coupling between the body damage and the interface damage are proposed and compared. Some numerical applications are carried out in order to assess the performances of the proposed model in reproducing the mechanical behavior of the masonry elements strengthened with external FRP reinforcements

An approach for the modeling of interface-body coupled nonlocal damage

Fiber Reinforced Plastic (FRP) can be used for strengthening concrete or masonry constructions. One of the main problem in the use of FRP is the possible detachment of the reinforcement from the support material. This paper deals with the modeling of the FRP-concrete or masonry damage interface, accounting for the coupling occurring between the degradation of the cohesive material and the FRP detachment. To this end, a damage model is considered for the quasi-brittle material. In order to prevent strain localization and strong mesh sensitivity of the solution, an integral-type of nonlocal model based on the weighted spatial averaging of a strain-like quantity is developed. Regarding the interface, the damage is governed by the relative displacement occurring at bond. A suitable interface model which accounts for the mode I, mode II and mixed mode of damage is developed. The coupling between the body damage and the interface damage is performed computing the body damage on the bond surface. Numerical examples are presented

An approach for the modeling of interface-body coupled nonlocal damage

Fiber Reinforced Plastic (FRP) can be used for strengthening concrete or masonry constructions.One of the main problem in the use of FRP is the possible detachment of the reinforcement from the supportmaterial. This paper deals with the modeling of the FRP-concrete or masonry damage interface, accounting forthe coupling occurring between the degradation of the cohesive material and the FRP detachment. To this end,a damage model is considered for the quasi-brittle material. In order to prevent strain localization and strongmesh sensitivity of the solution, an integral-type of nonlocal model based on the weighted spatial averaging of astrain-like quantity is developed. Regarding the interface, the damage is governed by the relative displacementoccurring at bond. A suitable interface model which accounts for the mode I, mode II and mixed mode ofdamage is developed. The coupling between the body damage and the interface damage is performedcomputing the body damage on the bond surface. Numerical examples are presented

A coupled interface-body nonlocal damage model for the analysis of FRP strengthening detachment from cohesive material

In the present work, a new model of the FRP-concrete or masonry interface, which accounts for the coupling occurring between the degradation of the cohesive material and the FRP detachment, is presented; in particular, a coupled interface-body nonlocal damage model is proposed. A nonlocal damage and plasticity model is developed for the quasi-brittle material. For the interface, a model which accounts for the mode I, mode II and mixed mode of damage and for the unilateral contact and friction effects is developed. Two different ways of performing the coupling between the body damage and the interface damage are proposed and compared. Some numerical applications are carried out in order to assess the performances of the proposed model in reproducing the mechanical behavior of the masonry elements strengthened with external FRP reinforcements

Understanding and Managing Environmental Roadblocks to Shale Gas Development: An Analysis of Shallow Gas, NORM, and Trace Metals

The main objective of the project was to document occurrences of shallow gas in fresh-water aquifers in Texas either dissolved or free phase and identify controlling processes. A secondary somewhat independent objective was to contribute to the understanding of the nature and variability of flowback and produced water associated with hydraulic fracturing in the context of rock-water interactions. We undertook a large sampling campaign of aquifers in the footprint of major Texas plays (900+ water samples): Barnett in north-central Texas (555 unique locations), Eagle Ford in South Texas (118 unique locations), Haynesville in East Texas (70 unique locations), and in the Delaware Basin of West Texas (40 unique locations). Most of the wells (2/3) are relatively shallow residential wells sampled at or as close as possible to the wellhead but many wells are irrigation, municipal, or rig-supply wells. All samples were analyzed for major ions, dissolved gases, and, when CH4 > 0.1 mg/L, for methane and light alkanes carbon isotopes and trace elements. The vast majority of wells show some measurable methane and ~100 wells show methane > 0.1 mg/L. A total of ~20 wells have methane concentrations > 10 mg/L, these high concentrations were observed in all plays and present at least a thermogenic component. Some wells, generally with a < 10 mg/L concentration, show a clear microbial origin for methane. A number of samples show mixing between the two origins but also more complex behavior such as methane degradation. Samples with thermogenic methane are generally spatially organized in clusters. Overall the source of the dissolved methane is likely natural sourced from shallow natural gas accumulations in the Barnett Shale, lignite beds associated with a fault in the Haynesville shale, and lignite and degradation of oil and deep organic matter associated with a fractured zone in the Eagle Ford Shale. The Delaware Basin samples show no dissolved methane other than associated to a recent blowout. We also performed autoclave experiments in controlled conditions exposing shale core fragments to various fluids, examining reacted and unreacted rocks and documenting chemical composition of the evolving fluid through time. The experiments demonstrated that shales undergo typical geochemical processes during hydraulic fracturing such as carbonate and feldspar dissolution as well as ion exchange resulting in an increase in dissolved solids. Observations suggest that rock permeability is increased two to three-fold and that porosity is increased by 50%. Baseline sampling as it is currently practiced is not sufficient to resolve ambiguity of the source of the dissolved methane even if of thermogenic origin because it still could be natural. Additional analyses such as noble gases and isotopes are needed to better constrain origin of the methane.Bureau of Economic Geolog

Severe propylthiouracil-induced hepatotoxicity in pregnancy managed successfully by liver transplantation: A case report

<p>Abstract</p> <p>Introduction</p> <p>Propylthiouracil-induced severe hepatotoxicity is a relatively rare occurrence, with very few cases reported in the literature. The management of this complication in pregnancy can be a challenge because of the effects of the various treatment options on the fetus.</p> <p>Case presentation</p> <p>We report a rare case of fulminant hepatic failure in a 36-year-old gravida 2 black woman of African descent that occurred at 17 weeks gestation following propylthiouracil treatment for Graves' disease. Her liver failure was managed by liver transplantation and thyroidectomy. Her pregnancy was continued to term, though with not so favorable early childhood sequelae.</p> <p>Conclusion</p> <p>This case illustrates a very rare complication of treatment with a presumed safe drug during pregnancy followed by adverse neonatal outcomes due to the extensive treatment.</p