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Reinforced concrete (RC) deep beams are commonly used in structural design to transfer vertical loads when there is a vertical discontinuity in the load path. Much experimental research has been conducted on simply supported deep beams, but little research has been carried out using monotonic loads. In our study, an experimental investigation was conducted to study fixed-ended reinforced concrete deep beams under cyclic and monotonic loads. Five specimens were experimentally tested. The specimens had similar geometry but different reinforcement details. Four specimens were tested under cyclic loads and one specimen under a monotonic load to observe the deflection of the mid-span where the load was applied, as well as the crack patterns, failure modes, and shear strengths. The results show that web reinforcements are more effective than longitudinal bars at increasing shear capacity in fixed-ended RC deep beams.

Discontinuity in cross-section depth may exist in RC columns. If present in a non-seismically detailed frame, such a discontinuity (termed herein setback in columns, SBC) may trigger unexpected seismic damage. However, this typology of irregularity within connections has long been overlooked. This paper offers initial experimental evidence showing how vulnerable these irregular, non-conforming RC connections would be under earthquake-like loading. Four full-scale exterior beam-column subassemblies with SBC were constructed and cyclically tested, including three “as-built” units and a control one improved with seismic detailing. Results indicated that all the units succumbed to joint shear failure, and exhibited distinctly asymmetric responses in different loading directions. Particularly, when subjected to a positive (sagging) beam moment, the “as-built” units displayed a very steep joint cracking pattern and, hence, remarkably lower peak loads as compared to the case where a negative (hogging) beam moment was applied. Possible causes inducing such a salient failure mode are discussed, and a detailed account of the cyclic behaviors of the four units presented. Moreover, based on the concept of wide and narrow joint panels, existing major code provisions and analytical procedures for regular connections were adapted to evaluate the joint shear capacity of the current irregular subassemblies. A practical modeling approach was also developed through ABAQUS user-defined subroutine for capturing the observed global hysteretic responses. Overall, the outcomes of this study highlight the vulnerability of non-seismically detailed exterior connections with SBC, and provide a reference for future related research.

Joints that represent locations of discontinuity were the prominent factors affecting the overall behavior of precast segmental bridges. In this study, the steel shear key was designed, which was used to transmit the shear stress of the joints. To study the mechanical characteristics of the steel shear keyed joints in the construction and finished states, direct shear experiments and numerical analysis were carried out. The experimental results showed that the steel shear keyed joints had a high bearing capacity and good ductility. Under the action of confining stress, the joints relied on the mechanical occlusion between the steel keys to transmit the shear forces. When the load-displacement curve entered the horizontal stage, it can still bore large relative deformation, and the bearing capacity did not decrease. In the construction state, the inelastic deformation of the steel shear key should be used to control the design value of the temporary load. In the finished state, the bearing capacity of joints should be controlled by the direct shear strength of the steel shear key, which can be calculated according to the shear formula. The shear strength of the material and size of the steel shear key are the main factors affecting the bearing capacity of steel shear keyed joints.

A novel approach for mapping induced fractures and associated lineaments has been introduced based on microseismic data, and thus their contribution towards identification, and prediction of the risk zones which may lead to a collapse or rockburst in a coal mine. By taking Tashan Coal Mine (TCM) in Datong coalfield of China as an example, the real-time microseismic data was acquired for a period of 7 months. The microseismic data was processed using standard processing schemes followed by source location and parameters estimation. The proposed approach utilizes microseismic events, trace them to map the induced fractures, and based on their network to interpret associated lineaments. Based on the configuration, geometry, and network, thousands of fractures were identified which vary in length. Regional lineaments have been interpreted based on the orientation of these fractures. The fractures and lineaments distribution were further correlated with computed microseismic energy distribution. The spatial distribution of microseismic energy helped in identification of a geological discontinuity (fault) that clearly separates the study area into northern and southern parts. The reactivation of this fault may pose significant threats to mass stability, life, and property. The northern half is characterized by more and short length fractures while southern by prolonged and fewer fractures. The upper northern half is dominated by high energy ( ≥ 50, 000 J), while the lower part is characterized by variable energy pattern (22,000 to 40, 000 J). It is inferred from the energy-lineaments correlation figure, the northern half describes relatively stronger rock type in comparison to the southern part suggesting different rock deformational behavior. The fractures and lineaments converging towards a single point define risk zones where future collapse or rockburst can be expected. This identification of risk zones provides a strong basis for the real-time prediction of future catastrophic hazards in the coal mines. This study may benefit global underground engineering researchers for hazards prediction and establishing of the early warning systems.

Any Structure that is designed in today’s world has to be designed not only for aesthetics but also for stability. These days high rise multi storied structures are quiet prominent. These types of structures, should not only be designed for aesthetic point of view but also must be designed to resist earthquake forces which are subjected on these structures. These earthquake forces acting on the structures are also known as seismic forces. Due to architectural purposes, some buildings, have openings, provided in them, this creates structural discontinuities in the building. These openings or discontinuities can change the load transfer path of the structures which may cause significant change in the building behavior, under the application of the seismic forces. In this paper pushover analysis is carried out to study the behavior of the building in case of architectural opening for staircase or cut outs etc which results in discontinuity in the structure. Keywords: Diaphragm, Discontinuity, ETABS, Pushover Analysis, Seismic

Since the failure modes of fully grouted bolts subject to displacements of rock joints are difficult to predict, the joint displacements in this study are categorised into two types: opening displacement and shear displacement. At first, a closed-form solution incorporating the nonlinear constitutive model of interfaces between bolts and grout is developed, which is able to formulate the full-range behaviour of bolts subject to the opening displacements of rock joints. Then, a novel numerical approach considering the nonlinear rock reaction force is proposed, which can analyse stress and displacement conditions on each point along a bolt. The results of the proposed numerical approach are validated by existing test results. Combining the proposed numerical approach with the improved closed-form solution, a comprehensive model for predicting yield and failure patterns of rock bolts is proposed. In this way, decoupling between the bolt and grout, the yield and failure patterns of two potential points along the bolt are also highlighted and discussed. Further discussions about the influences of bolt inclined angles to the discontinuity and the dilatancy effect of the joint face are carried out at last. This work provides a useful tool to evaluate the behaviours and estimate the load-bearing capacity of fully grouted bolts in jointed rock masses.

In order to obtain the accurate mechanical parameters of deep-buried coal goaf rock mass, the limitation of geological strength index (GSI) in concealed rock mass is analyzed. Based on the test result and analysis of the current normative standards, the classification indexes of rock mass structural are optimized based on discontinuity distance d and rock mass integrity index K v . The ratio of rock mass saturated strength to dry strength, η, is introduced, quantization formula of structural surface conditions is proposed, and the influence of groundwater and rock types is included in structural surface condition classification. The GSI system is improved to better suit all types of deep-buried and water-rich rock masses. Furthermore, the rock mass disturbance factor D’s quantitative formula is listed according to the Hoek–Brown (HB) criterion. Taking the goaf roof under railway as an example, the parameters of deep-buried rock mass are obtained based on the improved quantitative GSI system and HB criterion. This research provides a scientific reference for achieving geological parameters and engineering designing in goaf areas.

The article discusses the types of dangerous defects in welded joints. The main methods of non-destructive testing are described, their advantages and disadvantages are briefly reflected. The comparison of the automated ultrasonic testing methods with radiographic ones is given on the example of testing the welded joints of ASME DN350 Py250 pipe fittings with a thickness of the welded edges of 53.9 ÷ 61.3 mm. The comparison results of the methods by the criterion of the accuracy of determining the coordinates of defects are presented, which show the expediency of replacing the automated ultrasonic method with the radiographic one, provided that the thickness of the welded edges is shallow.

In addition to the discontinuity of the rail profile of a normal turnout, the unique S-shaped curve of a crossover significantly affects the negotiation performance of a train. For heavy-haul freig...

Public transportation is a basic everyday activity. Costs imposed by violence might have far-reaching consequences. We conduct a survey and exploit the discontinuity in the hours of operati...

The apparent monolithic behaviour of multi-leaf walls is compromised by the discontinuity planes that the load transfer mechanisms generate for the following reasons: i) difference between mechanical characteristics of layers; ii) lack or weakness of the structural interaction between core and external layers. The goal of this paper is to evaluate through parametric analysis the dimensional ratios by reference to core confinement effects of multileaf masonry walls with several interface and mechanical characteristics of layers. The study was carried out through the finite element analysis performed in non-linear field on two-dimensional plain strain models calibrated on experimental basis and numerical results are presented and discussed. The horizontal interfaces hand the load transfer and structural performances of multi-leaf walls. The behaviour of short specimens is controlled by confinement of external layers while for slender masonry walls the out of plane mechanisms affect the confinement effect.

Background Patients with schizophrenia need continuous integrated healthcare, but many discontinue their treatment, often experiencing adverse outcomes. The first objective of this study is to assess whether patient characteristics or treatment history are associated with discontinuity of psychiatric elective care. The second objective is to assess whether practice variation between providers of psychiatric care contributes to discontinuity of elective care. Methods A large registry-based retrospective cohort of 9194 schizophrenia patients, who were included if they received elective psychiatric care in December 2014–January 2015. Logistic regression models were used to identify predictive factors of discontinuity of care. The dependent variable was the binary variable discontinuity of care in 2016. Potential independent predictive variables were: age, sex, urbanization, and treatment history in 2013–2014. Practice variation between providers was assessed, adjusting for the case mix of patients regarding their demographic and care utilization characteristics. Results 12.9% of the patients showed discontinuity of elective psychiatric care in the follow-up year 2016. The risk of discontinuity of care in 2016 was higher in younger patients (between age 18 and 26), patients with a history of receiving less elective psychiatric care, more acute psychiatric care, more quarters with elective psychiatric care without antipsychotic medication, or receiving no elective treatment at all. No evidence for practice variation between providers was found. Conclusions Our findings show that the pattern of previous care consumption is an important prognostic factor of future discontinuity of elective care. We propose that previous care consumption can be used to design strategies to improve treatment retention and focus resources on those most at risk of dropping out.

Background: Proximal full-thickness free hamstring tendon injury (ie, tendon avulsion or rupture) is a severe injury. Treatment decision making relies on clinical factors and magnetic resonance imaging (MRI) variables; it specifically relies on which tendons are injured as well as the extent of tendon retraction. According to a worldwide evaluation of current practice, discontinuity of both proximal tendons and retraction of >2 cm are used as surgical indications. However, both the diagnosis and the use of MRI variables in decision making may be fraught with uncertainty in clinical practice. A reliable standardized MRI assessment is required. Purpose: To propose an MRI assessment for acute proximal full-thickness free hamstring tendon injury and to evaluate its interater reliability. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: We included 40 MRI scans of patients with acute (≤4 weeks of injury) proximal full-thickness free hamstring tendon injury. Three musculoskeletal radiologists assessed proximal full-thickness free hamstring tendon discontinuity using the novel “dropped ice cream sign” and tendon retraction (in mm). Quantification of tendon retraction (in mm) was performed using 2 different methods: (1) a direct (ie, shortest distance between the center of the hamstring origin and the tendon stump) method and (2) a combined craniocaudal/mediolateral measurement method. Absolute and relative interrater reliability were calculated. Results: We found an almost perfect interrater agreement (kappa = 0.87) for assessment of full-thickness tendon discontinuity using the dropped ice cream sign. Interrater agreement for the direct and craniocaudal retraction measurements was good for both the conjoint (intraclass correlation coefficient [ICC], 0.88 and 0.83) and the semimembranosus tendons (ICC, 0.81 and 0.79). The mediolateral retraction measurement yielded only moderate to poor reliability for the conjoint (ICC, 0.53) and semimembranosus tendons (ICC, 0.41). Conclusion: The standardized MRI assessment to identify proximal hamstring tendon discontinuity and quantify tendon retraction is reliable. We recommend using the novel dropped ice cream sign and the direct retraction measurement in clinical practice and research.

This study investigates the influence of pre-existing discontinuities on the roof breaking behaviors under Longwall (LW) mining condition. Taking the Meiyukou Coal Mine’s 82,002 working face as the engineering background, a series of similar experiments were conducted for the purpose. To be specific, mica powder was schematically set above the coal seam, simulating the angled discontinuities in the overlaying strata (α = 30° and 60°). Markers and gauges were employed to monitor the strata displacement and relevant stress variation. The results show that the prefabricated discontinuity leads to an early first weighting and frequent periodical weightings. Besides, discontinuities provide favorable conditions for the crack formation and propagation in the overlaying strata. As a result, the final roof caving height has almost doubled, which may aggravate the bearing pressure of the hydraulic pillars at the working surfaces if in the real situation. Hopefully, these information from the reduced-scale models could serve as a reference for the future practical designs of LW face supporting system.

Attempts to reconstruct the historical geography of medieval Ghazni are complicated by the scarceness and discontinuity of both textual and material sources. This calls for a cross-check of archaeological and epigraphic data with the testimony of medieval geographers, chroniclers and poets who were conversant with the former capital city of the Ghaznavid sultanate. Such an investigation provides new insights into the growth principles of the town. The close interrelation between secular and religious spaces emerges as one of the main features of Ghaznavid state-sponsored monuments, and may have had an influence on the further developments of the urban fabric.

Ground control failures are one of the main causes of accidents in the underground stone mining industry. Some of the fundamental tools for rockfall hazard identification are related to rock mass characterization and geotechnical discontinuity mapping. Recent technological advances in these methods are related to remote sensing techniques and point cloud processing software for automated discontinuity mapping. Remote sensing techniques, such as LiDAR and photogrammetry, generate multi-million point clouds with millimetric precision, capturing the structure of the rock mass. The automated point cloud processing tools offer alternative algorithm-based methods to characterize and map these discontinuities. However, their applicability is constrained by multiple factors such as site specific conditions of the rock mass and the parameters used within the mapping algorithms. This paper evaluates the performance of automated discontinuity extraction software compared with manual virtual discontinuity mapping. Sampling windows from laser-scanned sections in an underground limestone mine are defined and mapped using discontinuity set extractor (DSE). Results from the virtual discontinuity software are compared with manually extracted fractures from I-Site based on reviewing orientation, trace length, spacing, number of extracted discontinuities, and processing time. The analysis determined that the automated mapping algorithm was able to identify the same discontinuity sets that had been manually mapped. The automated mapping software mapped an excessive amount of smaller fractures, which caused the comparison of both mapping techniques to be unsuccessful in terms of trace length and spacing.

Several in-situ rock mass properties and blasthole parameters can affect the rock fragmentation. Because of the complexity of the variables affecting the fragmentation results of blasted rocks, to predict a proper value of the median fragment size has long been a difficult task. The blastability index (BI) represents the effect of five parameters of rock mass description (RMD), joint plane spacing (JPS), joint plane orientation, specific gravity and uniaxial compressive strength on the rock fragmentation. The median discontinuity spacing significantly varies with varying the scanline direction and an acceptable value of the median discontinuity spacing will not be expected in practice. The JPS rating also has a constant value of 20 for a wide range of joint spacing values between 0.1 and 1 m, whereas joint spacing can be in this range for most cases. A new method using image analysis of the in-situ rock mass was applied to represent JPS and RMD (belonging to one of the cases: friable, blocky and massive) as an alternative solution. The images contain the details of all individual discontinuities and interlocked in-situ small and large rock blocks. BI, rock strength factor, blasthole parameters, powder factor, fragment size distribution of blasted rock and in-situ block size distribution using image analysis technique were assessed in 15 zones of Sungun open pit copper mine, Angouran lead and zinc open pit mine, Bonab silica mine, Soufian limestone mine and Rashakan limestone mine. The results for rock mass properties and blasthole patterns cover a wide range using different mines. The fragment size distribution was assessed by Split Desktop program with proper delineating images using the Pixler software and blasting was carried out with electric delay detonators. The relations between fragment size and parameters such as in-situ block size (F50), σc, rating of joint plane orientation, powder factor (q), ϕh, Q and Lc were analyzed. The relations with high correlations were achieved by applying the new approach for the defined conditions. Not only the problem of assessing discontinuity spacing has been improved using this method but also the lower number of parameters that properly represent the factors affecting the rock fragmentation have been used. The results were also analyzed by the Sanchidrian and Ouchterlony model and modified Kuz–Ram models. The fragment size obtained by the new method in this study, Sanchidrian and Ouchterlony model and extended modified Kuz–Ram model by Cunningham (in: Proceedings of 3rd world conference on explosives and blasting, Brighton, 2005) after using correction factor [c(A)] significantly better fitted to the results than the modified Kuz–Ram models by Cunningham (in: Fourney, Dick (eds) Proceedings of 2nd international symposium on rock fragmentation by blasting, Keystone, 1987) and Gheibie et al. (Int J Rock Mech Min 46(6):967–973, 2009).

There are hierarchies and rankings of power relations between different classes of men in each society. Men of varying ranks of masculinity choose diverse grounds on which to compete with one anoth...

China experienced a 47% expansion in higher education enrolment between 1998 and 1999 and a sixfold expansion in the decade to 2008. Using a fuzzy discontinuity in the months of births, we show tha...

Discontinuous deformation analysis (DDA) method is a discrete element method, presenting a great advantage in modelling deformation and rigid body movements, and it is also an alternative approach for problems involving the fracturing process from continuity to discontinuity if the failure mechanism in DDA is well constituted. This paper presents a new united tensile fracture model (UTFM) for the two-dimensional DDA method to simulate the fracture behaviors of various brittle materials (e.g., rock, soil, and concrete). The new fracture model unifies four classical failure modes, including the maximum normal stress criterion, Tresca criterion, Mohr–Coulomb criterion, and the von Mises criterion, for tensile fracture. By incorporating UTFM into the original DDA frame, the improved DDA (I-DDA) can predict the crack initiation and propagation paths in Brazil disc and simulate rock fracture of various brittle materials. Numerical examples of the direct tensile test and the Brazil disc split tests are investigated to verify the accuracy and validity of the I-DDA method. The simulated results agree well with those obtained from physical tests and other numerical analyses, suggesting that the I-DDA has obvious advantage in simulating the fracture behaviors of the Brazil disc split test. Further, the I-DDA is applied to analyze the failure process of a practical earthquake-induced landslide with consideration of the tensile strength of the rock mass. The results indicate that the I-DDA is more feasible to analyze the slope failure, which can consider both the tensile and shear characteristics simultaneously compared with the original DDA.

Background: Though ossicular discontinuity is more common in cases of cholesteatoma, it may happen in non-cholesteatoma COM. The long process of incus is more frequently involved ossicle. Peroperative assessment of ossicular integrity is the gold standard way. But the discontinuity of the ossicular chain can be assumed before surgery by analyzing perforation edge adherent to medial wall and wide air-bone gap The purpose of the study was to find out the preoperative findings which can predict the ossicular discontinuity in non-cholesteatoma cases. Methods: This cross-sectional study was conducted in the department of Otolaryngology-Head & Neck Surgery, Bangabandhu Sheikh Mujib Medical University from January 2013 to June 2014. 81 patients of COM without cholesteatoma were selected as per inclusion and exclusion criteria. Relevant data were collected in a predesigned data collection sheet and analyzed with standard statistical method. Statistically significant inferred for P value 40 dB was found in 60% cases of ossicular discontinuity, followed by air bone gap 31-40 dB(20%), 21-30 dB(13.33%) and 11-20 dB( 6.67%) respectively. So ossicular discontinuity was more in higher air-bone gap group and it was statistically highly significant (p 40 dB. Ossicular discontinuity was also found more in cases where there is attachment of perforation edge to medial wall, and presence of granulation tissue. If preoperative information can be gathered to determine whether or not the ossicular chain is intact, the patient can be better informed, counseled for ossiculoplasty before surgery. J Dhaka Medical College, Vol. 29, No.1, April, 2020, Page 47-52

The accurate analysis of cracking phenomena in the concrete structures has been a research topic of growing interest over the past few decades, with notable developments in the modeling techniques based on either smeared or discrete fracture approaches. The well-known cohesive zone models, belonging to discrete fracture approaches, are commonly judged as very effective for accurately representing the real crack pattern in quasi-brittle materials. The present work deals with comparing two different finite element-based cohesive fracture models: (i) a novel diffuse interface model, and (ii) an existing embedded crack model, based on an inter- and intra- element fracture approach, respectively. The first one relies on an intrinsic cohesive formulation by which the damage process inside the material is represented as a collection of imperfect interfaces randomly placed at the internal boundaries of a finite element mesh. The second one is based on a strong discontinuity approach according to which the crack is modeled as a discontinuity embedded into the displacement field of a standard continuum, allowing concrete cracking along nonprescribed paths to be correctly simulated. Cracking behavior in concrete specimens subjected to general loading conditions has been simulated by these two models and a detailed comparison between the numerical results is provided. Finally, a critical discussion regarding of computational efficiency and numerical accuracy highlights the efficacy of the newly proposed diffuse interface model.

In multistoreyed RCC framed buildings, critical damages are due to seismic ground excitations, which cause catastrophic failuresat the weaker locations. Buildings with two types of structural irregularities namely diaphragm discontinuity and open ground story are considered. Assessment of seismic vulnerability of these buildings is done by using Nonlinear Static Pushover Analysis (NSPA). Performance Based Seismic Design of masonry infilled RCC buildings with two different shape of openings in the diaphragm is considered here with Design Basis Earthquake(DBE) and Maximum Considered Earthquake(MCE) where by selecting appropriate performance criteria in terms of Inter-story drift ratio(IDR) and Inelastic displacement demand ratio(IDDR) are critically observed. The Equivalent Linearization Procedure of Pushover analysis presented in FEMA 440, which is a modification of Capacity Spectrum Method based on ATC-40 guidelines, is performed in ETABS-2016 to study the performance of R.C.C. buildings with diaphragm discontinuity, designed as per IS-1893-2016.

Strut and Tie Modeling (STM) can be used to simplify intricate states of stresses within reinforced concrete (RC) members with geometric or static discontinuity regions (D-regions). A bottle-shaped strut can thus form when an isolated reinforced concrete compressed member is loaded in a relatively small area of the member or in the presence of an opening. In this category of struts, the resulting compressive stresses spread in a lateral direction as they have to avoid the opening area and the strut axis. In this respect, curving compressive stress trajectories give rise to notable transverse strains in an orthogonal direction to the strut axis and subsequently longitudinal cracks will form if insufficient reinforcement is arranged; which can lead to concrete failure. Therefore, an experimental investigation was conducted in this study to examine the dispersion of compressive stresses in isolated RC struts with openings. The size of the openings were kept constant in all specimens. The major parameters were presence of opening and opening location. Consequently, In the second part of the study (Analytical investigation), on the basis of model presented by Sahoo et al. (2009) [19] and based on the geometrical characteristic of the ILC, an analytical model was proposed to predict the load-carrying capacity of a bottle-shaped strut with an opening. This new proposed model considered the effect of size and position of the opening. To conduct the experimental study, five Isolated RC struts with compressive strength of 40 MPa (5800 psi.) and then different positions of openings were tested. Axial load, axial shortening and lateral strains were measured to determine the effects of the test parameters. The obtained results were also compared with an analytical equation of isostatic line of compression (ILC) and the American Concrete Institute (ACI) 318-11 Provision. These results indicated that the presence of an opening creates a variation on the dispersion of compressive stresses and consequently produce a reduction in load-carrying capacity.

A roller compacted concrete (RCC) dam is a large civil engineering structure that is subject to a permanent load of water hydrostatic thrust, and the construction of such a structure requires enormous human, material and financial resources. It gives rise to a reserve of water upstream in billions of m3; therefore, a problem in its stability will generate a catastrophe at its end. Among the means of controlling the dam body is the detection of abnormalities by infrared thermography. In this communication, we will simulate a structure of a dam containing a defect, and the discontinuity of the concrete gives rise to a contrast in the thermo-gram of the downstream surface. Thus several parameters will be studied in this dam, namely the positioning of the defect with respect to the downstream surface, the thickness of this defect and finally the orientation. The thermal images of the downstream surface are recovered in order to interpret the contrast and to draw explanations of what is inside this dam.

Background The mitral valve is often structurally abnormal in hypertrophic cardiomyopathy (HCM). However, the mechanisms responsible for these abnormalities remain controversial. In 2016 we identified, at myectomy, muscular mitral-aortic discontinuity in 5 young patients with obstructive HCM. Objectives This study sought to confirm our preliminary findings and assess the prevalence of muscular mitral-aortic discontinuity in obstructive HCM. Methods At our center, from January 2017 to April 2018, the area between the anterior mitral leaflet and aortic valve was inspected at myectomy in 106 consecutive patients with HCM. Results Muscular mitral-aortic discontinuity was identified in 28 (26%) patients and was significantly more common in younger than older patients (age 39 ± 13 years vs. 58 ± 11 years; p Conclusions We report, for the first time, muscular mitral-aortic discontinuity in HCM. At myectomy, a long muscular discontinuity displaced the anterior mitral leaflet toward the apex in most young patients, was significantly associated with sarcomere mutations independent of age, and was extremely uncommon in older patients. These findings suggest that a long muscular mitral-aortic discontinuity could predispose to the development of outflow obstruction in young patients with sarcomere mutations.

An improved understanding of pillar strength and pillar failure mechanisms is required to optimize tabular mine layout designs. The paper describes the application of a limit equilibrium model for pillar failure analysis. It is shown that the model is capable of reproducing a hardening or softening response for uniformly compressed strip or square pillars. The stress–strain behavior depends on three non-dimensional parameters Q, M and β. Q represents the ratio of the limit failed uniaxial strength to the intact material strength, M is the ratio of the failed limit strength envelope slope to the intact strength envelope slope and β is proportional to the pillar width to height ratio. The model is implemented in a displacement discontinuity solution scheme using unstructured triangular elements to allow irregular plan-view pillar shapes and mining step increments to be represented. The seam-parallel confining stress distribution in the fracture zone is determined using a fast marching solution algorithm. A case study of an experimental pillar extraction site in a platinum mine is presented to illustrate the capability of the model to simulate the evolution of pillar failure as pillar extraction proceeds. Good qualitative agreement to observed failure trends are obtained but the detailed calibration of the model parameters remains a challenge. Further work is required to enhance the representation of pillar edge spalling processes.

Lap splices and bar cutoffs introduce reinforcement discontinuities in reinforced concrete structures. A two-step approach was used to investigate the effect of longitudinal reinforcement discontinuities on the seismic performance of reinforced concrete structural walls. In the first step, six cyclic tests on small-scale reinforced concrete structural walls were conducted to study the effect of bar cutoffs. Three of the six specimens had web longitudinal reinforcement cutoffs to simulate the effects of a retrofit practice used in Japan. The test results indicated that this discontinuity resulted in approximately 50% increase in the unit tensile strains in the longitudinal reinforcing bars in boundary elements. Larger unit tensile strains caused an increase in permanent strain accumulation, increasing the likelihood of bar buckling. In the second step, the mentioned test results were combined with test results from previous tests (that investigated discontinuities related to lap splices) to calibrate equations for estimating drift capacity of structural walls with and without reinforcement discontinuities.

Concrete is a predominant construction material due to a number of advantages. Disadvantages are given by its limited tensile strength and brittle tensile failure behavior. Fiber reinforced cement composites (FRCC) can improve these weaknesses to a large degree. But a proper composition design especially with respect to fiber and bond properties still follows a trial and error approach. Suitable simulation models can overcome this state whereby a mesoscopic view is chosen for the following. The Finite-Element-Method offers appropriate options due to its high flexibility. But special features are required which exceed standard FEM. This concerns modeling of crack formation in the cement matrix, a large number of fibers with arbitrary random distribution and the interaction of fibers with the cement matrix via bond. The paper addresses these items with (1) a further development of the Strong Discontinuity Approach to model discrete cracking of continuum elements on the element level, (2) discretization of single fibers by truss elements with truss nodes independently placed of continuum nodes, (3) connecting them by special bond elements. This allows for nonlinear behavior with respect to cement matrix, fiber material and bond laws. The contribution addresses theoretical basics, special implementation issues, a validation with simple configurations and a simulation of an FRCC experiment.

2D and 3D imageries can allow the optimization of rock mass exploitation (quarries, roads, rail networks, open pit, potentially tunnels and underground mines networks). The increasingly common use of photogrammetry makes it possible to obtain georeferenced 3D point clouds that are useful for understanding the rock mass. Indeed, new structural analysis solutions have been proposed since the advent of the 3D technologies. These methods are essentially focused on the production of digital stereonet. Production of additional information from 3D point clouds are possible to better define the structure of the rock mass, in particular the quantification of the discontinuities density. The aim of this paper is to test and validate a new method that provides statistics on the distances between the discontinuity planes. This solution is based on exploiting the information previously extracted from the segmentation of the discontinuity planes of a point cloud and their classification in family. In this article, the proposed solution is applied on two multiscale examples, firstly to validate it with a virtual synthetic outcrop and secondly to test it on a real outcrop. To facilitate these analyses, a software called DiscontinuityLab has been developed and used for the treatments.

Underground projects require a realistic understanding of geological, structural and mechanical characteristics of the rock mass. This includes a comprehensive rock mass characterization, assessment to all existing site information and an accurate geological model. However, due to the lack of truly three-dimensional subsurface fracture geometry data, this reality is rendered difficult. Thus, the use of Discrete Fracture Networks (DFNs) arises as an interesting tool. DFN models are statistically generated from discontinuity features mapped in situ. These deterministic data can be obtained by employing various techniques, and more specifically with the use of laser scanning (i.e. Light Detection and Ranging—LiDAR). Complimentary discontinuity data can be obtained through fiber optic sensors coupled to tendon rock support elements, adding structural information from within the rock mass to the DFN model. This paper presents the methodology associated with the implementation of LiDAR data into DFN models for the purpose of application in underground projects and the use of optical sensors to capture three-dimensional loading of tendon support and, in turn, identify intersecting discontinuity planes. The Distributed Optical Strain Sensing technology is demonstrated through double shear laboratory tests, as well as through an in situ application to monitor rock mass movement during a tunnel excavation.

In this article, the computational methodology of the catenary–train–track system vibration analysis is presented and used to estimate the influence of vehicle body vibrations on the pantograph–catenary dynamic interaction. This issue is rarely referred in the literature, although any perturbations appearing at the pantograph–catenary interface are of great importance for high-speed railways. Vehicle body vibrations considered in this article are induced by the passage of train through the track stiffness discontinuity, being a frequent cause of significant dynamic effects. First, the most important assumptions of the computational model are presented, including the general idea of decomposing catenary–train–track dynamic system into two main subsystems and the concept of one-way coupling between them. Then, the pantograph base vibrations calculated for two train speeds (60 m/s, 100 m/s) and two cases of track discontinuity (a sudden increase and a sudden decrease in the stiffness of track substrate) are analyzed. Two cases of the railway vehicle suspension are considered – a typical two-stage suspension and a primary suspension alone. To evaluate catenary–pantograph dynamic interaction, the dynamic uplift of the contact wire at steady arm and the pantograph contact force is computed. It is demonstrated that an efficiency of the two-stage suspension grows with the train speed; hence, such vehicle suspension effectively suppresses strong sudden shocks of vehicle body, appearing while the train passes through the track stiffness discontinuity at a high speed. In a hypothetical case when the one-stage vehicle suspension is used, the pantograph base vibrations may increase the number of contact loss events at the catenary–pantograph interface.

Repair or strengthening of building may be required due to the change of the design codes, adding new floors to the building, changing the purpose of the building etc. There are many methods to retrofit buildings. One of them is to strengthen using steel braces. In this strengthening method one of the important questions that should be answered at the initial stage is what kind of steel brace is to be used and how the steel braces are to be arranged. In this study first, the performance analysis of a three-span (all spans are 4.5m), nine-storey (story height is 3m on each floor) reinforced concrete frame building analysis was performed. As a result of the performance analysis, it was determined that the structure needed to be strengthened. Using centric X braces 5 different reinforcing models were created. In this way, the effect of steel braces on the seismic behavior of the building was determined. In the comparison of the models, the results of the performance evaluation, with the Nonlinear Static Pushover Analysis, were used. As a result of the comparison, the optimum results were obtained from the model where central steel braces were used in each story from the first floor without vertical discontinuity.

This work presents a hybrid discrete fracture-dual porosity model of compressible fluid flow, adsorption and geomechanics during CO2 sequestration in coal seams. An application of the model considers the influence of hydraulic fractures on CO2 transport and the stress field of the coal. The low initial permeability of coal is compounded by the injectivity loss associated with adsorption-induced coal swelling, which is recognised as the major challenge limiting CO2 sequestration in coal seams. In this model, the natural fracture network and coal matrix are described by a dual porosity model, and a discrete fracture model with lower-dimensional interface elements explicitly represents any hydraulic fractures. The two models are coupled using the principle of superposition for fluid continuity with a local enrichment approximation for displacement discontinuity occurring at the surface of hydraulic fractures. The Galerkin finite element method is used to solve the coupled governing equations, with the model being verified against analytical solutions and validated against experimental data. The simulation results show that the presence of a hydraulic fracture influences the distribution of gas pressure and improves the gas flow rate, as expected. The stress field of a coal seam is disturbed by CO2 injection, especially the vertical stress, and the presence of a hydraulic fracture leads to a reduction in stress with permeability recovery starting earlier.

Reinforced Concrete (RC) deep beams are commonly used in structural design to transfer vertical loads when, there is a vertical discontinuity in the load path. Due to their deep geometry, force distribution within the RC deep beams is very different from RC shallow beams. There are some Strut- and- Tie Models (STM) developed for RC deep beams. However, most of these models are developed for RC deep beams with simply supported boundary condition, not applying for RC deep beams with fixed-ended condition. In this paper, a novel curved STM was developed to simulate load capacity and failure mode of fixed-ended RC deep beams subjected to monotonic and cyclic point loads. Curved STM has double main struts and fan-shaped sub struts to simulate force distribution within the RC deep beams. Parameters of curved STM were calibrated using 5 fixed-ended RC deep beams subjected to monotonic and cyclic loads. Then, Calibrated model was compared to responses obtained from 31 additional independent experimental tests. Results showed that newly proposed curved STM is able to simulate load capacity and failure mode of fixed-ended RC deep beams very well.

Background: Chronic Otitis Media (COM) is a common disease in our country. COM with or without cholesteatoma may lead to ossicular discontinuity. However, the discontinuity of the ossicular chain is usually confirmed during operation. The purpose of the study was to find out the correlation between preoperative hearing loss and the status of ossicular chain at surgery. Methods: This cross-sectional study was conducted in the department of otolaryngology- Head & neck surgery, Bangabandhu Sheikh Mujib Medical University from January 2013 to June 2014. At least 113 patients of COM were selected as per inclusion and exclusion criteria. Relevant data were collected in a predesigned data collection sheet and analyzed with standard statistical method. Statistically significant inferred for P value 40 dB was found in 60% cases of ossicular discontinuity, followed by air bone gap 31-40 dB(17.14%), 21-30 dB(14.29%) and 11-20 dB( 8.57%) respectively. So ossicular discontinuity was in higher air-bone gap group and it was statistically significant (p

In this work, we present a model for origami-based sheet metal (OSM) folding that can predict the required bending force. OSM folding is enabled by introducing bending features along the bending line, named material discontinuity (MD). Firstly, the introduced analysis in this work developed a bending setup for OSM that does not require a die then introduced a method to analytically derive the bending force for a regular sheet without any added folding features. The analytical approach is followed using an experimental setup identical to the developed OSM bending configuration. Secondly, the OSM bending experiment is conducted to measure the required bending force and to identify which parameters influence the OSM bending force significantly. Finally, an empirical model is proposed considering the analytical force in the first step and the influencing parameters defined in the second step. Regression analysis is carried out using one portion of experimental force measurement to determine the coefficients of the proposed empirical model. The other measurement set is used to validate the prediction model. The validation results of the proposed prediction model show good agreement between the developed prediction model and the experiment results. The prediction model provided a shape factor that represents the topology of each bending feature, as well.

The study results of the edge zone of more than 300 hot-rolled products of steels 09Г2С, 22ГЮ, 20, К56 produced according to the combined technique of smelting, casting, and subsequent rolling in the conditions of casting and rolling complex are presented. Simulation shows that location of imperfections and defects on the slab serves as a prerequisite for defect formation in coil stock. The most common defects include cracks and scabs. The formation of these defects is often associated with the disclosure of oscillation marks during subsequent hot deformation. In such cases, the defect formation nature is difficult to identify by metallographic methods, since signs of the steelmaking nature of their formation are not observed in the cross section of the discontinuity.

The component failure in the machine parts that affect the function during its operation is due the fatigue failure and stress due to discontinuities. As an initiative of dynamic analysis of the discontinuity in the envelope a metal beam of aluminum of the recommended size is taken and the test of the beam is carried out by fixing as a cantilever and applying the excitation using the hammer excited, and the behaviour of the beam is recorded as the modal analysis to find the natural frequency and the different mode shapes have been observed using the experimental setup, and same have been verified using the ANSYS software in which the theoretical value can be compared to the experimental value and the convergences’ of the results are discussed.

The existing references of Wohler data curves (S-Nf fatigue life) for fully reversed cycling loading fail to incorporate the discontinuities effect on metal sheets fatigue life. Experimental results show that the discontinuities, i.e., holes and notches weaken metal sheets and reduce fatigue life. The notch fatigue strength reduction factor (Kf) cannot incorporate the discontinuity effect into the fatigue life prediction models. This paper investigates a new method to study the discontinuity effect on metals fatigue life by applying the Discontinuity Stress Triaxiality (DST) factor to fatigue life prediction models. Three discontinuity geometries were studied in order to investigate the different effect of different radius. A simulation using ABAQUS FEA was used to export the stress triaxiality at the notch root element. The results show that this new method can help in predicting fatigue life for high-strength metals and metals with sharp notches, unlike the Kf factor. Also, the theoretical results show good correlation with the experimental results.

We discuss the problem of determining optimum thicknesses for the refractory and thermal insulation layers to minimize the total cost of the lining and the fuel used to compensate for thermal losses. The proposed methodology (with the required temperature at the boundary of the lining layers specified as an additional condition) reduces the 2D constrained optimization problem for a cost function with a locus of discontinuity but no unconstrained minima to the problem of determining the minimum of a unimodal 1D cost function. The work described in this paper is highly relevant because a major furnace overhaul may involve the use of new materials and costs can be optimized by using new data on available materials and their pricing.

During construction, reconstruction and technical inspection of vertical steel tanks (VST), all wall butt weld joints are subjected to ultrasonic testing to detect internal defects or flaws. The considerable length of examined welds (it can exceed 3,000 m) necessitates the development and implementation of mechanized and automated inspection systems that can increase the rate of testing and documentation of results. Systems of mechanized and automated ultrasonic echo-testing do not support the detection of all defect types and reliable determination of their geometric parameters. The Time-of-Flight Diffraction (TOFD) technique makes it possible to estimate the height of the defect regardless of its type and orientation. However, the application of TOFD technique for welds with non-equal wall thickness is complicated by the fact that the standard software of flaw detectors (‘depth calculator’) does not consider this non-uniformity. The authors have developed the testing procedure to overcome this limitation and to determine the depth of defects in the welds with non-equal wall thickness by TOFD technique using the standard ‘depth calculator’. An experimental verification of this technology confirmed the correctness of the calculations. The inspection scheme and calculation of the depth of discontinuity boundaries using the TOFD technique were tested using the example of the welded joint of the walls with non-equal thickness of the 10,000-m3 tank under construction. The thickness of the walls was 12 and 14 mm; 8 and 10 mm. The inspection of the real facility has confirmed good detection of defects and high reliability of the results.

Purpose In recent times, the use of steel sections with web openings has become common as slim floor beams because they offer a reduction in weight of the steelwork, accommodate services within the floor depth and provide the composite action. The composite action in these beams is achieved either through the concrete dowels or through concrete plugs. Though these web openings offer several benefits in slim floor beams, they induce the material discontinuity in the steel web, which may affect their shear capacity and/or thermal behaviour. The purpose of this study is to investigate the thermal behaviour of slim floor beams with web openings in fire. Design/methodology/approach This research presents findings from experimental and analytical investigations conducted to study the thermal behaviour of slim floor beams with web openings in fire. For this purpose, an experimental investigation was conducted, which shows that the presence of web openings has a major influence on temperature development across the steel section as well as along the span of these beams. The behaviour of the tested slim floor beam is validated using finite element modelling. The validated finite element model is then used to conduct a sensitivity study to analyse the influence of different opening spacings, sizes and shapes on the thermal performance of slim floor beams in fire. Findings Test results show that the presence of web openings has a major influence on temperature development across the steel section as well as along the span of these beams. Temperatures on the web below the openings are found to be higher as compared to those recorded on the adjacent solid steel web. It is also observed that temperatures on the steel web above the openings are lesser than those on the adjacent solid steel web. Parametric studies conducted using the verified analytical modelling methods show that different opening spacings, sizes and shapes have a variable impact on the thermal behaviour of slim floor beams in fire. Closely spaced and larger opening sizes were found to have a more severe influence on their thermal behaviour in fire as compared to widely spaced and smaller openings. It was also found that the behaviour of these beams is influenced by the shape of the openings with rectangular openings resulting in more severe thermal distributions as compared to circular openings. Originality/value The findings from this research study are highly valuable as they contribute to the existing knowledge database. There is a lack of experimental and analytical investigation on performance of slim floor beams with web openings at elevated temperatures. The results and conclusions from this study will help in developing innovative designs for slim floor beams and will help in reducing the fire related risk associated with structures comprising of slim floor beams with web openings.

The slip and instability mechanisms of coal‐rock parting‐coal structure (CRCS) under coupled dynamic and static loading were investigated using theoretical analysis and numerical simulations, and the fracture and instability processes were described by monitoring the displacement, strain, and acoustic emissions (AEs) of coal and rock parting blocks. Based on the parameters of dynamic load, three different effects on slip and instability characteristics of CRCS were presented, and the effect mechanisms of static stress, as well as amplitude and frequency of dynamic stress wave, were analyzed in detail. Finally, the direct effect on the slip and instability strength of CRCS and the frequency range of dynamic load for generating synchronous slip along two discontinuities sandwiched between coal and rock parting blocks were discussed. This work is relevant for early warning coal‐rock dynamic disasters that are triggered by the slip and fracture instability of CRCS under coupled dynamic and static loading in coal mines.

In this study, the effect of rock bridges on rock slope stability was investigated by incorporating non-persistent joint networks in numerical models, and the critical profiles of an open pit mine were analysed. Parallel deterministic networks of infinite and finite lengths, ubiquitous joint network model and Veneziano joint network model were used in order to simulate the rock fractures. Materials were modelled based on the generalised Hoek―Brown and equivalent Mohr–Coulomb failure criteria. The parallel deterministic infinite and the ubiquitous joint network models produced lower safety factors. The introduction of rock bridges along discontinuity planes in the parallel deterministic network and Veneziano joint network models significantly contributed to the stability and strain distribution, which should be considered in stability analysis of rock mass in open pit by rock slope practitioners. The results show the significance of joints in hard rock behaviour and the joints should be included in order to attain practical and realistic simulations. Keywords: Ubiquitous model, Veneziano model, Parallel deterministic joint network, Numerical modelling, Rock slope stability, Discontinuities, Open pit

Fractures play an important role in the geothermal energy recovery from enhanced geothermal systems (EGS) involving interacted multi-physical fields. A strongly coupled thermo-hydro-mechanical (THM) model is proposed to simulate the process of the long-term geothermal production in three-dimensional geothermal reservoirs containing arbitrary discrete fracture networks (DFNs). By introducing a strong discontinuity concept into the DFN model, the aperture variation of each fracture induced by the fluid pressure, external stresses and thermal expansion in the period of production can be captured. Non-isothermal fluid flow in DFN and the local thermal non-equilibrium (LTNE) between fluid and rock matrix are formulated and coupled with the fracture deformation model. Verification is carried out against an analytical solution, followed by a sensitivity and convergence analysis concerning time step and mesh size. This approach is then applied to Habanero EGS project in Australia to evaluate the geothermal productivity and efficiency for a period of 20 years with different injection and production pressures. The results demonstrate that the proposed model is robust and effective to simulate the THM coupled process in 3D fractured reservoirs.

Prediction of the deformation increment and the final displacement of the rock cutting is a challenging task. Many ambiguities linked with unpredictable nature or rock mass make it difficult to apply the adequate contingency measures. Implementation of common approach, which includes modelling of discontinuity effects with estimated reduction of rock mass strength and modulus of elasticity, usually does not yield satisfactory results. Therefore, a calibration of FEM based numerical model was made by conducting parametric analysis which feeds upon data obtained from extensive on-site monitoring system. A step forward was made in description of numerical parameters of karst discontinuities through consideration of monitoring results, as well as excavation procedures, position, inclination and length of discontinuities and PDC (project design change).

This study presents the results of discontinuity mapping using terrestrial laser scanning (TLS) survey and the kinematic method. The results provide the current site and slope condition of comprehensive geological study using terrestrial laser scanning and discontinuity survey at Simpang Pulai, Perak. From the results obtained, it can be concluded that the major potential failures in this area are wedge and plane failures, but there are some area had the potential of toppling failure. This study, however, constitutes a preliminary design consideration and not intended for use in final design or construction. The final design shall be made by the engineer based on the further detail site investigation (S.I.) and other design factors to be used in the actual design of the project.