Deep Embedment Research Articles

Lost and found: the late discovery of a migrated intrauterine device after 15 years - a case report

Intrauterine devices (IUDs) are a preferred reversible contraceptive choice for about 159 million women worldwide. While generally safe, they pose risks like uterine perforation and device migration, which happen in about 1 in 1000 insertions. Other common issues include insertion failure, pain, infection, and menstrual changes. This report details a rare case of IUD migration in a 40-year-old woman, discussing the diagnostic challenges and the approaches used to manage such complications. IUD migration to the bladder is uncommon but can lead to serious, often undetected issues, thus underscoring the necessity for regular follow-up after placement. Early diagnosis with imaging is critical for proper treatment, with the World Health Organization recommending surgical removal in symptom-free cases. The rarity of uterine perforation during IUD use highlights the vital need for vigilant monitoring and patient follow-ups to prevent and quickly address such complications. The uncertain timing and cause of IUD migration further stress the importance of comprehensive counseling and regular patient check-ups. Abdominal discomfort may indicate an IUD has migrated, emphasizing the need for patient awareness and routine self-monitoring after placement. CT imaging is crucial for identifying and pinpointing the location of migrated IUDs, facilitating their removal using minimally invasive methods like colonoscopy and laparoscopy. For more complicated scenarios, such as those involving deep embedment, laparotomy may be necessary.

Research on Reduction Coefficients of Water Pressure on Outer Surfaces of Linings of Inclined Shaft Tunnels in Deep Embedment

Research on Reduction Coefficients of Water Pressure on Outer Surfaces of Linings of Inclined Shaft Tunnels in Deep Embedment

Shear Reinforcement of Existing Reinforced Concrete Beam Using Deep Embedment Method

The load capacity of old reinforced concrete structures must be increased to meet current standards. This might be due to increased load needs, inadequate shear provisions in the original design, material degradation, or rising demands for shear capacity related to flexural strengthening. This research demonstrates a method that effectively repairs RC beams using embedded steel bars. Loading history was reproduced in the form of cracking within the elastic range in 2000 x 150 x 200 mm beam. The beam was repaired and then reloaded to failure in the experimental test. The results show that the contribution of steel bars embedded in the core of the RC beam to the load capacity can be significant. The highest initial stiffness of the strengthened beam was 13,07 kN/mm, which was 69% higher than the control beam, while the maximum load of the strengthened beam was 43 kN with the deflection at 13,00 mm, 43% higher than the control beam. The cracks developed during the reinforced beam’s second load phase were identical to the first, and the shear capacity increased more than the control beam.

Various Methods of Strengthening Reinforced Concrete Beam-Column Joint Subjected Earthquake-Type Loading Using Fibre-Reinforced Polymers: A Critical Review

Fibre-reinforced polymer (FRP) composites are extensively employed in concrete technology due to their exceptional mechanical strength and durability. They serve a dual purpose, not only reinforcing damaged elements but also supporting heavier service loads and addressing long-term concerns in new infrastructure projects. Consequently, the objective of this review is to establish a comprehensive research database that focuses on evaluating the strengthening behaviour of reinforced concrete (RC) beam-column joints (BCJ) under earthquake loads through diverse types and application methods of FRP composites. The efficacy of these strengthening techniques is assessed by considering factors such as the loading capacity and dissipated energy of RC BCJ versus the joint confinement index provided by the fibre in the joint area. Through this state-of-the-art review, it becomes evident that FRP composites effectively enhanced the normalized load of specimens up to 27 kN/?MPa and enhanced the dissipated energy until 558.6 kN-mm for the case of specimens with a lower confinement index, less than 0.3. Additionally, the specimen strengthened with the deep embedment (DE) method resulted in a moderate normalized load and dissipated energy compared to those strengthened with the external bonded (EB) method. The test results indicated that the average normalized load and dissipated energy of the DE-strengthening method was 93% and 28.5% compared to that of the EB-strengthening method. These findings reveal that FRP composites offer distinct advantages in terms of load capacity and dissipated energy when used for strengthening earthquake-affected RC BCJ. Finally, based on the compilation of the previous works, this research proposes several techniques for utilizing FRP composites to enhance RC BCJ subjected to earthquake load.

Pullout Capacity of Single and Biwing Anchors in a Soft Clay Deposit: Model Investigation in a Centrifuge and FEM Predictions

One of the ways to install plate anchors in deep seabed is to drop the anchor system from the sea level and allow it to initially embed in the seabed under its own weight. Further dragging would cause the anchor to rotate and embed further into the seabed. There could be difficulties of getting the anchor plate horizontal or mooring line to be perpendicular to the plate where the maximum pullout capacity could be achieved. As part of the investigations, various aspects of the plate performance were examined through centrifuge testing in which the plate orientation and pullout angles were varied. It was presumed that dynamic stability of the anchor (during field installation) can be achieved by having the plate in biwing configuration. Therefore, the performance of the biwing anchors having different spacing between the plates was also examined in the centrifuge testing program and the findings were compared with predictions obtained through finite-element modeling (FEM). Both pullout directions and the plate angles considerably influenced the pullout capacity factors. The comparison between the predicted pullout capacity using FEM and measured pullout capacity for biwing anchors at shallow embedment depths was excellent. However, the FEM-predicted pullout capacity was noticeably lower than the measured ones for deep anchors. Pullout capacity of biwing anchors at shallow embedment depth increased as the spacing between the plates S increased from 0 to 0.5B. However, there appears to be a slight reduction in the performance in deep embedment anchors. This is also reflected in FEM findings.

Perkuatan Balok Beton Bertulang Yang Mengalami Kegagalan Geser Menggunakan Metode Deep Embedment

Bridges are infrastructure buildings that are commonly used and very functional in everyday. One of the structural components of the bridge is a reinforced concrete beam as a load bearer that will be forwarded to the foundation. The shear capacity of reinforced concrete beam structures sometimes cannot meet the existing requirements. This can be caused by increased loads, inadequate shear strength in the initial design and material damage due to natural factors. There are several methods that have been carried out to overcome the decrease in shear strength in beam structures, namely reinforcement methods by externally bonded (EB) and near-surface mounted (NSM). In reality, shear reinforcement with EB and NSM methods in implementation only relies on epoxy adhesion and concrete blankets, which still causes structural failure. The deep embedment strengthening method (DE) can be proposed as a shear reinforcement for reinforced concrete beams to overcome the previous problems. Reinforcement with DE method is a shear reinforcement that is reinforced in the core of reinforced concrete beams. This research was conducted by embedding 8 reinforcements vertically with a distance of 200 mm along the shear span. In this study, finite element modeling was carried out using ABAQUS. The results of finite element modeling with the DE method showed that the maximum load was 30.646 kN and the maximum deflection was 13.00 mm. The collapse model that occurs from finite element modeling on test specimens with DE reinforcement experiencing flexural failure.

Pemodelan Elemen Hingga Terhadap Pembebanan Geser Pada Balok Beton Bertulang Tanpa Sengkang yang Diperkuat dengan Metode Deep Embedment

Beams are a rigid part of the structure of a building. This beam is specifically designed to be able to withstand and transfer loads to column. Beams without shear reinforcement will experience changes in behavior both in terms of strength and failure patterns.The shear capacity of existing reinforced concrete structures is often unable to meet existing requirements.This decrease in strength can be caused by increased load, strong shear that is inadequate in initial design and material damage due to natural factors. Many methods that have been done are by means of external bonded (EB) method and near-surface mounted (NSM) method. However, shear resistance using the EB and NSM methods is prone to structural failures due to the magnification of this method only to contain an epoxy attachment and its blanket. To overcome this problem the resistance method using deep embedment (DE) method have been proposed to reinforcement the shear capacity of existing reinforced concentrate structures.The purpose of this study was to analyze the shear behavior of reinforced concrete beams without shear reinforcement strenghtned by the DE method through finite element modeling.In this research, the existing reinforced concentrate structures put up the reinforcement by implant three kinds of steel carcass with 200 mm each gaps spread out shear beam. The maximum load result obtained from finite element analysis on reinforced concrete beams reinforced by the DE method was 29.09 kN. While the maximum deflection results obtained in finite element analysis was 10.1 mm. The failure model that occurs in the beam which is strengthened from the results of finite element analysis is the shear collapse.

Analisis Elemen Hingga Terhadap Perilaku Balok Beton Bertulang Yang Diperkuat Dengan Menggunakan Metode Deep Embedment

Bridges are infrastructure buildings that are affected by technological developments. Beam structures on bridges often experience a decrease in strength, one of which is shear strength. Sometimes the shear capacity of reinforced concrete beam structures cannot meet the requirements at this time. This can be caused by increased loads, inadequate shear provisions in the initial design and material damage due to natural factors. Reinforcement methods by means of externally bonded (EB) and near-surfaced mounted (NSM) are methods that have been carried out to overcome the decrease in shear strength in beam structures. Shear reinforcement using the EB and NSM methods in practice only relies on epoxy bonding and concrete covers, this makes it susceptible to structural failure. Reinforcement method deep embedment (DE) can be used as a suggestion as shear reinforcement in reinforced concrete beams to overcome the previous problems. Reinforcement using the DE method is shear reinforcement which is reinforced at the core of reinforced concrete beams. The aim of this research is to analyzq the behaviour of reinforced concrete beams resulting from finite element modelling using ABAQUS software. This research was carried out by embedding 20 bars vertically with a distance of 100 mm along the shear span. The results of finite element modelling with ABAQUS software show that the maximum load obtained is 28,12 kN and the maximum deflection that occurs is 14,10 mm. The final result of the beam failure model is flexural failure. This is indicated by the initial crack pattern that occurs vertically in the middle of the beam span. The crack continues to propagate towards the compression area of the beam until the beam collapses.

Deep embedment and NSM techniques for shear strengthening of reinforced concrete slender beams with cFRP ropes

Shear failure is catastrophic and occurs usually without advance warning, thus it is desirable that the beam fails in flexure rather than in shear. Many existing reinforced concrete beams are found to be deficient in shear strength and need to be strengthened. Reinforced concrete beams can be strengthened against shear failure by using polymer composites reinforced with fibres in many different techniques. This study aims to the most efficient shear strengthening of beams with carbon fibre reinforced polymer (cFRP) between near-surface mounted (NSM) technique and the deep embedment (DE) technique. Reinforced concrete beams with dimensions 15x15x70 cm, with the use of classified C30/37 concrete were constructed, each of which was reinforced with 3Ø10 B500c steel bars, only under bending. The specimens were tested in shear under two-point bending loading conditions, after having been strengthened with NSM or DE technique with cFRP rope by various reinforcing arrangements. As main conclusion, it appears that the NSM strengthening technique gives lower values than DE strengthening technique in correspondingly schemes.

Numerical investigation on DE-strengthened-RC beams without steel shear reinforcement

This study presents a two-dimensional nonlinear finite element (FE) model for Deep Embedment (DE) strengthened reinforced concrete (RC) beams without existing steel shear links. The FE model was developed and validated against experimental results reported in published literature. The parametric study was thereafter conducted to examine important parameters influencing the strengthened behavior. The parameters were concrete compressive strength, beam width, beam size, and tension reinforcement ratio. The FE model accurately predicted experimental results with a mean predicted-to-experimental value of 1.04. The FE results showed that the percentage of shear strength provided by embedded steel bars was almost constant once both concrete strength and tension reinforcement ratio were increased. However, an increase in the beam width resulted in a decrease in the percentage of shear strength gain due to embedded steel bars. Shear stress at failure decreased once beam size was increased for both unstrengthened (control) and DE-strengthened beams. The percentage of shear strength provided by embedded steel bars decreased from 47.9% to 27.6% as effective depth was increased from 261.5 mm to 523 mm.

Nonlinear Fe Model for Shear Strengthening of Simply Supported RC Beams with FRP DE Bars

Deep embedment (DE) is emerging as a potential and effective shear strengthening approach for existing reinforced concrete (RC) structures. A two-dimensional nonlinear finite element (NLFE) model for simply supported RC T-beams strengthened in shear with embedded carbon fibre reinforced polymer (CFRP) and steel bars is presented in this study. VecTor2, version 4.2, was used to create a two-dimensional NLFE model. To validate the nonlinear FE models, three sets of six simply supported RC T-beams from Breveglieri et al. (2015) are employedEach set consists of two beams with vertical and inclined (45) DE bars. Set one strengthens the beams with steel DE bars without vertical steel stirrups in the shear span. In the shear span, the beams of Sets two and three are reinforced with CFRP DE bars with vertical steel stirrups @180 mm c/c and @300 mm c/c, respectively. The above-mentioned NLFE model is validated by comparing experimental and predicted results for failure load, deflection, and failure mode. For both experimental and simulated beams, the fracture pattern is diagonal, and the failure mode is shear failure. The overall mean predicted/experimental loads at failure and deflection at failure ratios are 1.09 and 1.00, respectively, with corresponding standard deviations of 0.03 and 0.04. Following the validation of the proposed NLFE model's correctness, numerical parametric tests are conducted to determine the influence of concrete compressive strength and effective depth of RC T-beams on shear capacity of simply supported RC T-beams. The parametric analysis findings reveal that enhancing the cylinder compressive strength increases the predicted failure load while increasing the effective beam depth decreases it

Numerical simulation of damaged RC half-joint beams: towards appraisal and retrofitting

Concrete half-joint beams (HJB) are characterised by local reductions in the overall beam depth at the support and are ideal for structural connections. However, the beam joint region is vulnerable to deterioration and design/detailing shortcomings. Non-linear numerical modelling of the behaviour of a series of impaired reinforced concrete HJBs was conducted in this study. The major defects considered were unavailability of diagonal bars/U bars, shear reinforcement inadequacy and reinforcement corrosion. The numerical simulations captured global and local behaviours of the beams. The load capacity prediction discrepancy was in an impressive range of −16.7% to +1.5%, in contrast to the predictions of the commonly used strut-and-tie model in the range of −39.2% to 16.9%. Subsequently, an experimental study was established using finite-element modelling to explore the retrofitting potential of defective HJBs using the deep embedment (DE) technique. The strength enhancement was almost 30% and the internal load paths and the failure mode of the defective beam were favourably altered with the post-installation of the retrofitting element. The DE technique was thus identified as an ideal option for the retrofitting of impaired HJBs.

Making (Critical) Meaning of Meaning-making: Complicating the Racialization of Asian Indian American Youth

ABSTRACT This article examines the racializing processes throughlining the meaning-making of a Guru Vandana—an annual teacher appreciation event organized by many Asian Indian communities across the U.S.—that took place in a Midwestern city in 2019. Guided by a framework of transmodalities (a novel lens for the analysis of multimodal semiosis) and critical bifocality (a methodological approach to connect discursive and lived practices with broader structural arrangements), the author drew on interview and observational data of a set of Indian American parents and children and white teachers who attended the event to trace and analyze meanings intended, made, and missed of featured performances (e.g., dance, chants, and yoga demonstrations by the children). Indexing the deep embedment of Indian American positioning within multiple translocal and transnational hierarchies, findings reveal Guru Vandana’s tacit operation as a space wherein varied framings and understandings of Indianness circulate to both contest and (re)produce racialization, stereotypes, and caste subjectivity.

Molecularly imprinted polydopamine coated CdTe@SiO2 as a ratiometric fluorescent probe for ultrafast and visual p-nitrophenol monitoring

Molecular imprinted ratiometric fluorescent analysis method has been a popular method for the quantitative and qualitative tests of target analysis yet encounters low detection efficiency caused by the deep embedment and uneven distribution of fluorescent monomers, even the embedding rate of fluorescent monomer directly affects the visual detection effect. Herein, the ratiometric fluorescent molecularly imprinted polymers (F-PDA/CdTe QDs@SiO2@MIPs) based fluorescent polydopamine (F-PDA) and CdTe quantum dots (CdTe QDs) was successfully synthesized to detect p-nitrophenol (p-NP) selectively and visually. F-PDA was firstly used in the synthesis of ratiometric fluorescent molecularly imprinted polymers to serve as both fluorescent monomer and functional monomer, which greatly shorten the detection time while reducing the fluorescence loss caused by polymer coating. The test results showed that the p-NP quenched the fluorescent of F-PDA via electron transfer. Meanwhile, F-PDA/CdTe QDs@SiO2@MIPs enabled to visually detect a low detection limit of p-NP (56.68 nM) within 2.0 min by naked eyes. The detection time was as fast as quantum dots detect targets directly and the detection limit was well below the standard concentration of p-NP in drinking water. Finally, the F-PDA/CdTe QDs@SiO2@MIPs realize the detection of p-NP in the drinking and wastewater respectively.

Large‐diameter post‐installed bonded fasteners in very low compressive strength concrete

AbstractThis paper describes tests performed with large, post‐installed bonded fasteners installed in concrete of very low compressive strength. Concrete with several strengths were studied, including strength classes under C20/25. The goal was to determine whether such connections could be designed according to EN 1992‐4, as they deviate from the scope of this standard by the fact that the concrete is outside the permissible compressive strength range. Additionally, these tests aimed to cover the knowledge gap regarding bonded fasteners installed with large‐diameter threaded rods, deep embedment depths, and reduced edge distances, since little research has been done in this area. Tests on single fasteners and on a group of four anchors were performed, and the results were compared with the design values calculated according to EN 1992‐4. Conclusions have been drawn, and possible underestimation of the load‐bearing capacity of such anchorages has been quantified.

Efficient shear retrofitting of reinforced concrete beams using prestressed deep embedded bars

The Deep Embedment (DE) technique is a promising reinforced concrete (RC) shear strengthening scheme. When compared with the other retrofitting systems, the DE approach is impressive in many ways. Particularly, since the DE element is installed to the beam core, the truss mechanism is enhanced and that enables achieving high shear enhancements. Due to the internal application of the DE reinforcement, steel can also be utilized as the retrofitting material without reservations on corrosion. It is however identified that the tensile capacity of the DE bar is partially utilized. In this context, the potential of using prestress in the DE system as an improvement was explored through a non-linear numerical study and an experimental study. Two DE reinforcement types of normal steel and high-tensile steel were considered and the prestress level was set to 40%. Both approaches showed that the use of prestress in the DE system was capable of enhancing the beam shear capacity significantly, where the extra strength gain in one case was almost 26%. The serviceability performance of the beams was also improved due to the prestress application. Meanwhile, the numerical predictions showed good correlations with the global and local behaviours of the experimental beams.

Interpreting strength parameters of strain-softening clay from shallow to deep embedment using ball and T-bar penetrometers

Full-flow penetrometers (ball and T-bar) are widely used for measurements of strength characteristics of clayey soils in offshore field investigations and laboratory tests. However, the accuracy of the estimated undrained shear strength is hampered by: (1) the drastic variation of the bearing factor for the penetrometer at shallow and transitional penetration depths where full-flow mechanisms are not achieved; and (2) the strain-softening of the soil, which results in a degradation of the estimated strength. This study conducted LDFE analyses to simulate the entire penetration process of full-flow penetrometers in strain-softening soils from shallow to deep embedment depths. Parametric studies were performed to investigate the effects of varied factors on the bearing factor and failure mechanism during the penetrometer penetration. Based on the LDFE analyses, empirical formulas are established to represent the critical penetration depths in the strain-softening soil, which are used to correct the bearing factor at shallow penetration depths. The discrepancies of the transitional failure mechanism and the trapped cavity bearing factor between ball and T-bar are emphasized. Finally, a back-analyses framework is proposed to estimate the strength parameters (including the original undrained shear strength prior to any strain-softening, and the strain-softening parameters) based on the measurements of the penetrometer during the first penetration from shallow to deep embedment depths. Through a series of model tests, the reliability of the back-analyses framework is validated.

Undrained bearing capacity of spudcan in soft-over-stiff clay after penetration

As the boundary condition of jack-up systems, the foundation model of offshore structures affects the vibration mode and structural behavior of leg structure. Typical simple foundation models such as pinned and linear spring do not reflect either plastic failure or the resulting plastic behavior of the soil. Alternatives, for example Model B for clay, derived for consideration of the nonlinear behavior of soil, have been studied continuously improved until recently. Additionally, research on the foundation models has been continued in multi-layered soils, especially stiff-over-soft layer soils that present a risk of punch-through. In the present study, a yield envelope analysis is performed for the situation wherein the jack-up leg penetrates deeply through the soft clay and meets the stiff clay. In such soft-over-stiff clays, both the upper soft clay and the lower stiff clay affect the spudcan, thereby complicating the use of a foundation model of single clay. The numerical analysis used in this study is based on the Coupled Eulerian-Lagrangian (CEL) analysis with strain-dependent nonlinear soil properties. Installation effect and corresponding soil disturbance are considered in the following yield envelope analysis. Undrained bearing capacities of the single clay are calculated at the deep embedment for checking the suitability of the analysis, and continuous results have shown to the existing theories of single clay. In the soft-over-stiff clay case, the lower stiff clay has a significant effect on the capacities in the vertical, horizontal and rotational directions. The squeezing effect does not affect the vertical tensile capacity but increases the compressive vertical, horizontal, and rotational capacities. The stronger the underlying clay and the deeper the embedment, the asymmetrically larger the yield envelope becomes. The calculated yield envelopes are normalized to the increased capacities, and a yield envelope expression for the soft-over-stiff clay is suggested for the normalized shape. The effect of the maximum capacity on the yield envelope equation is examined, and it is found that the largely calculated capacity can make the yield envelope close to the paraboloid.

Interpreting strength parameters in soft clays from a new free-fall penetrometer

Free-fall penetrometers (FFP) are time-efficient and cost-effective tools for estimation of seabed strength parameters. However, the accuracy of strength parameters are coupled affected by the strain-rate effect, the strain-softening effect and the hydrodynamic drag on the FFP. A modified free-fall ball penetrometer with a booster (FFBPB) was put forward in the present study for the convenience of measuring the strength of soils with deep embedment depth. Numerical analyses based on the computational fluid dynamics (CFD) approach were conducted in the present study to investigate the complex ball-soil interaction, from which the expressions of the strain-rate factor, drag coefficient, and added mass were established. Then a back-analyses framework was developed to estimate the strength parameters, including the original undrained shear strength, strain-rate parameter, and strain-softening parameters, based on the measurements from the FFBPB. Finally, a series of model tests were performed to validate the back-analyses framework. The back-analysed strength parameters are considerably consistent with that from quasi-static tests, indicating the reliability of the back-analyses framework.

Shear strengthening of existing reinforced concrete beams with embedded bars – an overview

This paper presents an overview of the deep embedment (DE) method – also referred to as the embedded through-section method – a promising technique for concrete shear strengthening. The aim of this work was to collate pull-out and beam test results with a view to identifying existing gaps in knowledge. A careful evaluation of pull-out test results showed that, except for the effect of embedded length, the bond performance of DE bars epoxy-bonded into concrete is not fully understood. Analysis of beam test results identified significant gaps in knowledge, particularly with regard to the effect of concrete strength, loading type, shear span-to-effective depth ratio, size effect and DE bar surface coating. Moreover, the analysis of beam test results revealed a novel interaction between steel tension and DE shear reinforcement. Finally, yet importantly, the paper summarises the research required for robust implementation of the DE technique.