Central Column Research Articles

Front face shaping of the inner wall tiles in the COMPASS Upgrade tokamak

The central column of the COMPASS Upgrade tokamak, where the plasma discharges will be started and shut down, is covered by a continuous first wall composed of 8 bulk tungsten guard limiters with recessed Inconel tiles in between. In diverted configurations, the plasma will be limited for a short duration (∼0.2 s–0.4 s) during the plasma current ramp-up and ramp-down phases but high heat fluxes due to short power decay lengths are foreseen. An adapted shaping is therefore needed to spread the heat loads over a maximum area. A novel method taking into account the different magnetic equilibria and the incident angle of the field lines was used to design a roof shape able to ensure a constant heat flux on the toroidal direction, accounting for the λqnear−SOL and λqfar−SOL. Due to the diversity of plasma scenarios considered on COMPASS-U, the optimized shape of the inner wall tiles strongly differs from one scenario to another, thus a compromise has to be found among all foreseen scenarios. The tile shaping also needs to take into account possible short wave misalignments. Calculations with the 3D magnetic field line tracing code PFCFlux validates the design, confirming the constant toroidal profile of deposited heat flux for the COMPASS-U workhorse scenarios, or slightly decreasing or increasing heat flux profiles (from the center to the sides of the tile) for scenarios with smaller or higher λqnear−SOL, respectively, within the expected large range (1.7 mm<λqnear−SOL<5 mm), but still providing acceptable loads. Estimated heat fluxes are in the range of 5 MW/m2 to 35 MW/m2 on the 8 guard limiters, receiving 70%–80% of the power deposited to the inner wall. In case of shortwave misalignments up to 0.5 mm in the radial direction, calculations show that leading edges are still protected, confirming the robustness of the design.

Biomechanical evaluation of a healed acetabulum with internal fixators: finite element analysis

BackgroundTreatment of complicated acetabular fracture with internal fixation usually has high risk of failure because of unbefitting fixation. However, evaluation of the biomechanical effect of internal fixation under physiological loading for fracture healing is still generally rarely performed. The purpose of this study is to analyze the biomechanical characteristics of a healed acetabulum with designed internal fixators under gait and to explore the biomechanical relationship between the healed bone and the internal fixator.MethodsA patient-specific finite element model of whole pelvis with designed internal fixators was constructed based on the tomographic digital images, in which the spring element was used to simulate the main ligaments of the pelvis. And the finite element analysis under both the combination loading of different phases and the individual loading of each phase during the gait cycle was carried out. The displacement, von Mises stress, and strain energy of both the healed bone and the fixation were calculated to evaluate the biomechanical characteristics of the healed pelvis.ResultsUnder the combination loading of gait, the maximum difference of displacement between the left hip bone with serious injury and the right hip bone with minor injury is 0.122 mm, and the maximum stress of the left and right hemi-pelvis is 115.5 MPa and 124.28 MPa, respectively. Moreover, the differences of average stress between the bone and internal fixators are in the range of 2.3–13.7 MPa. During the eight phases of gait, the stress distribution of the left and right hip bone is similar. Meanwhile, based on the acetabular three-column theory, the strain energy ratio of the central column is relatively large in stance phases, while the anterior column and posterior column of the acetabular three-column increase in swing phases.ConclusionsThe acetabular internal fixators designed by according to the anatomical feature of the acetabulum are integrated into the normal physiological stress conduction of the pelvis. The design and placement of the acetabular internal fixation conforming to the biomechanical characteristics of the bone is beneficial to the anatomical reduction and effective fixation of the fracture, especially for complex acetabular fracture.

Ranking method of the severest input ground motion for underground structures based on composite ground motion intensity measures

Underground structure seismic response analyses and structural safety seismic designs are based on the scientific and reasonable selection of ground motion records. Different input ground motions lead to varies seismic response due to the strong randomness of ground motion. The severest input ground motion for the seismic analysis of underground structures cannot be obtained via a single intensity measure (IM). For this purpose, a ranking method is proposed based on composite IM for the severest input ground motion for underground structures. Four composite ground motion IMs constructed using the partial least squares regression (PLSR) method are proposed as representative ground motion IMs of the seismic failure potential of underground structures. These composite ground motion IMs correspond to the evaluation of four engineering demand parameters (EDPs), including the moment, shear force, axial force, and relative displacement of the central column of a subway station. Elastic-plastic time-history analyses of a two-story three-span subway station are performed given 64 ground motion records to provide the necessary data samples. After the construction, a bilinear logarithmic regression analysis is carried out. The results show that the proposed composite ground motion IMs have a higher correlation with the seismic dynamic responses than single IMs with respect to effectiveness, practicability, and proficiency. Finally, a ranking method for the severest input ground motion based on these composite ground motion intensity parameters is proposed. This method can be used to obtain the severest design ground motion of underground structures for seismic design.

Characteristics of the plasma sheath in helium discharge within dielectric tubes

To understand the characteristics of the plasma sheath within small tubes, a 2D numerical model of He discharge within dielectric tubes is developed. During plasma propagation for a tube diameter of 0.05 mm, the sheath thickness in the plasma head is almost equal to the tube radius. It decreases rapidly to several micrometers at an axial distance of 0.05 mm behind the plasma head, and then slightly increases and saturates at the axial position far behind the plasma head. A plasma-gas sheath surrounding the central plasma column is observed for a tube diameter equal to or greater than 0.8 mm. It is replaced by a plasma-wall sheath for smaller tubes. With the decrease in the tube diameter, the sheath thickness far behind the plasma head decreases while the ion flux increases significantly. However, when O2 gas with a proportion of 2% is added, both the sheath thickness and ion flux decrease.

Damage and Failure of a Column-Supported RC Flat Slab Subjected to Impulsive Loading

RC flat slabs supported by an array of columns subjected to the action of impulsive pressure were investigated. The slabs were designed for static loads according to current standards. The dynamic responses of 4 × 4- and 8 × 8-column-supported slabs were similar, as were damage and failure. A simplified model consisting of a tributary area and a central column yielded similar results, demonstrating the accuracy of the simplified model and its reliability. These analyses exhibited modes of damage and failure characterized by large shear distortions in the slab–column connection zone. The rest of the span remained undamaged and in a horizontal position. In all analyses, the slab concrete around the column was fully damaged. The rebars failed within a limited zone at the slab–column connections. The early failure of integrity reinforcement indicated that it could not fulfill its duty; thus, a subsequent progressive collapse scenario was inevitable. All bent-up rebars failed, and their contribution to shear resistance was doubtful. The static analysis was entirely different from the dynamic failure mode. Impulsive loading damage and failure were similar to those in the case of slab-on-slab impact; in both cases, the slab underwent large displacement and severe damage in the narrow slab–column zone, whereas the rest of the slab remained almost completely flat and undamaged.

“RULES-BASED MOTION” REANIMATION OF THE CARPUS

Using a reverse engineering capability to quantify the factors that control the rigid body mechanics of the wrist, a mathematical forward animation capability and model of wrist motion that allows the carpus to move under its own rules is being developed. This characterises the isometric connections, from which was developed the Stable Central Column Theory of Carpal Mechanics - which incorporates the Law of Rules Based Motion.This work has now advanced to the ability to reapply the extracted rules to allow rules-based rigid body reanimation of an individual wrist. As each wrist is unique, there is a given reality that each reanimation must be based on an individual wrist's unique rules, and the aspiration to create a standard or normal wrist is unrealistic.Using True Life Anatomy (Adelaide, Aust) analysis software, the specific rules (morphology / connectivity / interaction / loading) of individual wrists have been characterised, and then reapplied in a rigid body reanimation environment using Adams (MSC Software, U.S.) software.In the preliminary application of this biomechanics environment, by using the reverse engineering / forward reanimation process, wrist motion can be recreated - based purely on the unique rules, extracted from individual wrists. Instability of the proximal scaphoid was evident in several of the animations, and there was confirmation that the spatial attachment points of the isometric constraints are very exacting. The actual attachment and specific morphology of the carpal bones varied between individual wrists.Using a reverse engineering and then forward reanimation process, we have been able to recreate wrist motion using the rigid body mechanics based on the Law of Rules Based Motion. Further work is required, but the potential to apply “what if” virtual surgery options to an individual injured wrist and more precisely characterise and test solutions to wrist dysfunction are becoming realised.

Evaluation of the Failure Probability of a 2D RC Frame Subjected to Column Loss

Abstract: This study regards the evaluation of the failure probability of a symmetrical 2D reinforced concrete frame composed of 4 spans and 5 floors, in case of an accidental event which causes the central base column loss. The frame is an internal one of a typical building designed in a highly seismic area, characterised by a high ductility class. The frame is modelled in the non-linear finite elements software Atena 2D, accounting for both geometrical and material non-linearities. The uncertainties relevant to the problem are included by sampling both material and action variables, adopting the Latin Hypercube Sampling technique. To compute the failure probability associated to the accidental scenario, two sets of analyses are considered: the first set to compute the capacity of the structure against the column removal by means of displacement-controlled pushdown analysis; the second set to evaluate the demand in terms of external loads, properly combined within the accidental combination according to the codes. The external load is then amplified in order to include the dynamic effects characterising a scenario of a structural member loss. Finally, the probability of the demand exceeding the capacity is evaluated.

FOUR-DIMENSIONAL COMPUTED TOMOGRAPHY-DERIVED RADIOLUNATE ARTHROKINEMATICS WITH A CASE STUDY IN FOUR-CORNER ARTHRODESIS

The radiocarpal joint, which includes articulations between the radius and the proximal carpal row, transmits force through the central column of the wrist. Chronic disruptions to radiocarpal biomechanics are associated with the development of scapholunate advanced collapse (SLAC) pattern OA. While the radiolunate joint is thought to be typically spared in SLAC progression, degenerative changes can present on the proximal lunate. An investigation of radiolunate arthrokinematics may improve understanding of posttraumatic and postsurgical outcomes, including salvage procedures for SLAC wrist such as scaphoid excision with four-corner arthrodesis (SEFCA). Four-dimensional CT, which captures CT volumes over time or motion, has enhanced our ability to quantify arthrokinematics during functional tasks. We hypothesize that 4DCT-derived radiolunate arthrokinematics during flexion-extension and radioulnar deviation will differ between healthy, uninjured wrists and a wrist three years post-SEFCA. Data were collected from the uninjured wrists of ten participants enrolled in a prospective study of unilateral wrist injury and one participant following SEFCA (n=11, 36% female). The SEFCA arthrodesis was fixed using Kirschner wires prepositioned in the head of the capitate and subsequently advanced into the lunate. Included participants were aged between 18 and 60 years; exclusion criteria included history of injury, surgery, or congenital variant in the contralateral wrist; rheumatologic disease; or connective tissue disease. Static-neutral and dynamic CT data were collected using a dual-source scanner (SOMATOM Flash, Siemens, DE) and commercially-available cardiac sequential scan protocol. 4DCT data were collected over a 1.5-second period as signaled by an ECG simulator. CT volumes were collected at a temporal resolution of 66 ms as participants moved at a cadence of 70 beats per minute (voxel size: 0.234mm × 0.234mm × 0.600mm). Nearest mesh-vertex distances between vertices on the radius and lunate within distance (2.5 mm) and surface-normal angular (60°) thresholds were calculated to define interosseous proximity distributions. Median interosseous proximities at each time point were calculated. Ten participants were aged mean (SD) 30.3 (6.8) years at the time of imaging; the SEFCA participant was 52 years of age and three years postoperative. Median radiolunate interosseous proximities are presented during flexion-extension and radioulnar deviation (Fig. 1). 4DCT has advanced our understanding of wrist arthrokinematics during functional tasks. The current study reveals that radiolunate interosseous proximities in healthy, uninjured wrists remain relatively constant over wrist flexion-extension and radioulnar deviation, with greatest proximities occurring near the extrema of motion. In the SEFCA participant, interosseous proximities were closest in flexion and ulnar deviation; this may be associated with high articular contact pressures in these positions. Interosseous proximities reveal how restricting midcarpal motion in SEFCA impacts adjacent articulations during wrist motion. This study represents a novel use of 4DCT to assess post-arthrodesis outcomes.

Operation State Evaluation of Miter Gate Based on On-Line Monitoring and Finite Element Analysis

As an essential part of the water conservancy hub, the miter gate undertakes the vital task of navigational operation and works in a complex basin with a high water level drop for a long time; therefore, it is necessary to ensure its safe operation. In this paper, taking the Gezhouba No. 2 ship lock miter gate as an example, the actual gate stress and crack signals are obtained using the online monitoring system. The stress distributions of the gate under different working conditions are studied using finite element simulation analysis. Combining simulation analysis with the collected signal analysis, the operation status of the actual gate under each working condition is evaluated. The results show that the stress analysis of the online monitoring is consistent with the finite element analysis results, which verifies the reasonableness of the sensor arrangement. The stress is more concentrated in the area of the gate shaft column, the middle door seam, and the rear flange plate during the operation of the miter gate, and the maximum stress appears on the central sector shaft column of the gate. The cracks of the miter gate mainly appeared in the lower layer of the gate body, and the cracks expand gradually during the long-term operation of the gate. The crack expansion speed corresponds to the miter gate’s stress magnitude.

Influence of Heave Plate on the Flow-Induced Motions of a Floating Offshore Wind Turbine

Abstract Flow-induce motions (FIM) small-scale model tests were performed for the Jappaku floating offshore wind turbines (JPK), a FOWT developed to operate in Brazilian waters. This paper aims to investigate the presence of FIM on the JPK to show the importance of heave plate (HP) design and to show how HP mitigates FIM. Three different HP dimensions were tested and compared with the condition without HP. In addition, two different incidence angles of the current were tested, namely, 0 deg and 180 deg. The results showed amplitudes in the transverse direction similar to the diameter of the external platform column for the case without HP. These amplitudes are higher than the ones observed for previous deep-draft semi-submersibles found in the literature. Conversely, the largest HP dimensions implied in mitigation of the FIM amplitudes, i.e., very low amplitudes, were observed. The presence of the central column played an essential role in FIM and significantly modified the amplitudes in different current incidences. Due to the different diameters of the external and central columns, the FIM presented two different branches of response related to the vortex-shedding frequency around the columns. The results showed that significant FIM could occur for this specific JPK investigation even with HP. The HP design has a positive effect on reducing dynamic behaviors due to the wave and current incidences. Therefore, its design must be included in the preliminary stages of FOWT developments.

Progressive Collapse of Flat Slab Buildings

Progressive collapse occurs when a local failure triggers successive failures leading to total collapse of the structure. In this project, progressive collapse analysis has been done using a finite element linear static and a non linear static analysis on a 6 storey flat slab building. Though there are dynamic methods also for the analysis but static method has been used owing to its practicality and simplicity in engineering world. Dynamic method is more complicated and involves a number of iteration before it can give any close to accurate result, hence is not in much demand nowadays. The results for the linear static analysis have been compiled in the form of demand capacity ratio at critical section and results for that of the non-linear static analysis have been compiled in the form of support rotation at joints. In both the case the building is not susceptible to progressive collapse both when the central column is removed and the corner column is removed.

An Example-Guide for Rapid Seismic Assessment and FRP Strengthening of Substandard RC Buildings

This paper presents a rapid seismic assessment and Fibre Reinforced Polymer (FRP) retrofit design methodology which relies on the European design guidelines recently published in Chapter 8 of fib Bulletin 90 on the use of externally applied FRP reinforcement in the seismic retrofitting of reinforced concrete (r.c.) structures. For this purpose, an example-guide is developed with step-by-step hand calculations aiming to facilitate engineers of practice and researchers working in the field to easily understand the proposed methodology. A three-storey, pilotis-type residential r.c. building is selected typical of the Mediterranean construction practice in the 1970s. The methodology followed only aims to provide preliminary results on seismic assessment and retrofitting before the implementation of more sophisticated analysis if need be (e.g., in case of irregular buildings). The assessment procedure identified that the columns of the ground storey, being the most critical structural elements for the stability of the structure, are vulnerable to brittle failure modes. To remove all the brittle failure modes attributed to inherent deficiencies and enhance the overall deformation capacity of the building, the strengthening schemes applied in the ground storey (pilotis) is a combination of local strengthening measures, such as FRP wrapping, and global interventions. The latter may refer to the addition of r.c. jacketing to the central column to remove slenderness and of metal X-braces to modify the lateral deflection shape of the building and thus moderate the interstorey displacement demand.

Numerical Simulation Study of Progressive Collapse of Reinforced Concrete Frames with Masonry Infill Walls under Blast Loading

The influence of masonry infill walls on the progressive collapse performance of reinforced concrete (RC) frame structures was investigated in this paper, using a nonlinear dynamic analysis approach. Based on ANSYS/LS-DYNA finite element software, two finite element models of RC frame structures with and without masonry infilled walls were established. Then, the collapse modes of the two RC frame structure models were analyzed for different scaled distance blast loads, different locations of column damage, and different span numbers. The results show that with the increase of explosive amount, the collapse degree of the structure is more serious in the same time. Under the condition of destroying the outermost central column, the degree of progressive collapse of the RC frame model with infilled walls in the same time is lower than that of the RC frame model without infilled walls. The RC frame model with infilled walls is more resistant to collapse when the outermost side columns are damaged. With the increase of span number, the structure is more likely to be damaged and collapsed.

Effect of design factors on drivers’ understanding of variable message signs locating traffic events

BackgroundThis article addresses how to combine three elements (a pictogram, an arrow, a city) in a variable message sign (VMS) to locate temporary events (e.g., “congestion before Milan”). We adopted the G1c stack model as a design template, an Advanced Directional Sign (ADS) recommended by the 1968 Convention to locate cities, which can be easily adapted to modern VMS. However, as most of the VMS in operation are not full-matrix, we have also adapted this design to more restrictive display conditions. This adaptation critically concerned the arrow function on the message that either points up broadly (generically, as in G1c) or connects with the city more specifically (explicit). Although G1c reads top-down like a verbal text, previous studies indicated drivers’ preference for bottom-up landmark order in VMS, so both ordering criteria were compared in the present study. MethodsThe experiment involved 99 people (70 drivers and 29 drivers in training). Participants were informed that they would see various VMS reporting certain events (e.g., congestion) related to one of four cities along the road. Their task was to identify the event location (before, after the city) after seeing blocks of two consecutive messages (first a complementary message, then the target message), limiting their response to the content of the second message. Three design-focused factors were tested: typographical alignment (left or centre), landmark order (bottom-up or top-down), and arrow function (explicit or generic). The rate of correct location answers was the dependent variable. ResultsResults revealed that comprehension varied greatly depending on the arrow’s function and the placing of elements. In the explicit-arrow messages, comprehension was good both in the Top-down and Bottom-up conditions, but in the generic-arrow messages, only in the Bottom-up condition was comprehension good. Likewise, understanding was better in the Before condition than in the After condition in all combinations of Landmark order and Arrow function conditions. In general, left alignment of the central column elements of the VMS improved comprehension respective to centred alignment. Finally, the complementary message factor had an effect under certain circumstances. Practical implicationsThe messages displaying a generic arrow (following the G1c model) were better understood when the landmarks were ordered bottom-up, not top-down. In addition, explicit-arrow messages were better understood per se (in the absence of a complementary message) than generic-arrow messages. Overall, this work suggests that improving our understanding of how thought processes and design features relate to each other can contribute to safer driving nationally and internationally.

A new streamlined bubble‐cap distributor for high gas–liquid ratio and the liquid distribution mechanisms

AbstractThe bubble‐cap distributor is the most commonly used and critical internal for trickle bed reactors but holds the inherited disadvantage of liquid central aggregation when operating at a high gas–liquid ratio. A new bubble‐cap distributor with a streamlined downcomer was developed in this paper to counter back the liquid aggregation and improve its comprehensive performance. The effect of the streamline parameters of the new distributor on liquid distribution was systematically explored by the coupled Euler–Euler‐population balance equation (PBE) model. Compared with the classical and polyline converging–diverging structures, the results showed that the streamlined downcomer was a key to generating radial velocity of two‐phase flow and reducing the liquid central aggregation for the bubble‐cap distributor. The mechanism of well‐distribution was explored for the new distributor. Lower converging and diverging angles enhance the distribution performance. A downcomer with a small converging angle and a 30° diverging angle was recommended for dispersing the central aggregated liquid column and acquiring the high distribution uniformity and spray covering circle. These data would be helpful to the optimal design and scale‐up of the bubble‐cap distributor in further industrial applications.

Lateral Column Midfoot Injury: Do They All Need Fixation?

Category: Trauma; Midfoot/Forefoot Introduction/Purpose: Research on midfoot injuries have primarily concentrated on the central column and the Lisfranc ligament without amassing evidence on lateral column injuries. Lateral column injuries have historically been treated with Kirschner wire fixation when encountered. Our aim in this study was to analyse lateral column injuries to the midfoot and their treatment. Methods: Setting: Multicentre observational study Methods: Data was retrospectively collected from three centres on surgically treated midfoot fracture dislocations between 2011 and 2021. Radiographs were analysed using departmental PACS. All statistics was performed using SPSS 26. Results: A total of 113 cases were diagnosed as having a lateral column injury out of the 242 cases included. On cross tabulation, there was a significant association with having a central column injury (112/113, p&lt;.001) and 70% of cases also had an additional medial column injury. Of the 113 lateral column injuries which underwent fixation of the central column, only 13 had undergone Kirschner wire fixation of the lateral column. There were no reported loss of lateral column alignment in either the temporary fixation or no fixation groups in this study. Conclusion: Lateral column injury occurs in almost half of midfoot fractures in this study. It rarely occurs alone and is most commonly related to three column injuries. Nevertheless, following stabilisation of the central column, injuries to the lateral column are unlikely to require any further stabilisation with no reported loss of alignment in our study without lateral column fixation.

Transverse Nonuniformity of Air–Water Flow and Lateral Wall Effects in Quasi-Two-Dimensional Hydraulic Jump

Flow field characterization in high-aerated flows often involves flow imaging techniques through transparent sidewalls, and the results may be subject to sidewall effects and thus differ from the central flow behaviors. This paper contributes an experimental investigation of the sidewall effects on the air-water flow distributions in quasi-two-dimensional hydraulic jumps in a rectangular flume. The tested hydraulic jumps are characterized by preaerated approach flows and large inflow Froude numbers from 10.6 to 15.1. The air-water flow properties are measured intrusively along the centerline, sidewall, and transverse cross sections to provide a three-dimensional view of the aerated flow structure. Substantial redistribution of the bubbly flow is observed due to the presence of lateral aeration boundary layers in the high-speed jet-shear region, compared to the less affected free-surface roller. The magnitude difference between the central and lateral air-water flow properties is more distinct in terms of bubble count rate and less evident for void fraction and interfacial velocity, while the affected area is broader for void fraction distributions. The results suggest a concentration of high-speed jet flow in the central bottom flow column, where the jet layer is thicker, the recirculation roller is smaller, and the proportion of small-size bubbles is higher. The width of the central flow region free of the sidewall effects is approximately 60% to 80% of the flume width in the present facility, narrower on the bottom, and broader at the free surface. The findings demonstrate that the transverse variation of air-water flow and the difference between the central and lateral flow fields should not be ignored for the high-speed flow regions of hydraulic jump. A correct assessment of the sidewall effects is essential for interpreting imaging-based measurement of highly-aerated flow.

Pattern of Injury in Polytrauma Compared to Single Limb Related Midfoot Fractures

Category: Trauma; Midfoot/Forefoot Introduction/Purpose: Midfoot fractures in polytrauma patients are often an under appreciated injury relative to their other major injuries sustained. In this study, our aim was to explore the mechanisms and patterns of injury in a polytrauma related midfoot fractures as compared to single limb injuries. Methods: Setting: Multicentre observational study Methods: Data was retrospectively collected from three centres on surgically treated midfoot fracture dislocations between 2011 and 2021. Radiographs were analysed using departmental PACS. All statistics was performed using SPSS 26. Results: A total of 212 cases were included in the study. Almost all polytrauma cases had occurred as the result of a fall from height or road traffic collision (RTC) (19/20). In single limb injuries, 32% (61/192) had also occurred as the result of fall from height or RTC. The most common mechanism for single limb midfoot fracture was a trip (79/192). Crush injuries only occurred in the single limb injury group in our cohort (n=21). Regarding patterns of injury, there was no significant difference in prevalence of medial column injury (p=.260), or central column injury (p=.704). There were significantly more lateral column injuries in the polytrauma group (75% vs 44%, p=.008), and the polytrauma group was exclusively fracture related compared to 17% of single limb injury having purely ligamentous injury (p=.047). Conclusion: Polytrauma related midfoot injuries have a higher prevalence of lateral column injury than the single limb injuries. Single limb injuries can however, have an equally significant force involved as polytrauma patients with over 50% occurring as the result of high velocity injury. A high index of suspicion should be maintained for midfoot injuries in high velocity mechanisms, regardless of other injuries sustained.

Determination of individual coefficients on the basis of probabilistic analysis

Introduction. This article presents a method for determining partial liability factors for reliability for individual load-bearing elements based on a probable analysis. An assessment is made of the reliability of a multi-storey reinforced concrete building with a structural scheme in the form of a beamless braced frame.&#x0D; &#x0D; Materials and methods. The study is carried out by the probabilistic method of statistical tests. The excess of the design reinforcement of the design design reinforcement is taken as a failure. As random variables, the following are accepted: reinforcement strength Rarm, concrete strength Rbet, as well as the value of the temporary uniformly distributed load on the floors F. All considered random variables are assumed to be distributed according to the normal law.&#x0D; &#x0D; Results. The results of the study are presented for the corner column, the outer column, the middle column and the central column of the first floor. The results are histograms of the calculated reinforcement area and the distribution density of the reinforcement area for each of the columns, as well as tables of the obtained values of the probability of failure, risk and correction factors to the reliability coefficient on responsibility for the columns in question.&#x0D; &#x0D; Conclusions. The obtained correction factors can be applied to refine the reliability factor for liability γn. The proposed approach makes it possible to optimize the design solutions for reinforced concrete buildings in terms of material consumption while ensuring the required level of reliability and mechanical safety.

The Occurrence Parallelism of the 1st and 2nd Ray in Mid Foot Fracture Dislocations. A Review of 234 Cases

Category: Trauma Introduction/Purpose: The parallel nature of the 1st and 2nd metatarsal has been reported in Lisfranc type injuries to the midfoot, reportedly the result of the lateral and dorsal subluxation of the 2nd metatarsal base. In this study, our aim was to explore the prevalence of parallelism in midfoot injuries and the associated features. Methods: Setting: Multicentre observational study Methods: Data was retrospectively collected from three centres on surgically treated midfoot fracture dislocations between 2011 and 2021. Radiographs were analysed using departmental PACS. Parallelism was defined as a 1/2 intermetatarsal angle of less than 6. All statistics was performed using SPSS 26. Results: A total of 234 cases were included in the study. All 234 had undergone non-weightbearing (NWB) radiographs, with 80 patients who had also undergone (WB) weightbearing radiographs. The prevalence of parallelism was 21.3% (17/80) in the WB radiographs and 20.1% (47/234) in the NWB radiographs. The average IMA in the non-parallel group was 9.45 (95% CI 9.12,9.77) and 4.18 (95% CI 3.78, 4.57) in the parallel group. Concomitant lateral column injury was the only factor with a significant association with parallelism (p=.015). Other factors such as bone or ligamentous injury (p=.657), medial column injury (p=.085) and central column injury (p=.323) did not have a significant association. Conclusion: Parallelism in midfoot fracture dislocations occurs in approximately 20% of cases. If present, a high index of suspicion to the presence of a lateral column injury should be maintained due to its significant association.