Search Results (28)

This study established a numerical model for a foundation pit at the Zhongyilu Station of the Wuhan Metro Line 12, using Plaxis3D version 2021 finite element software to examine the horizontal displacement of the diaphragm wall, ground surface settlement, and differential settlement between the diaphragm wall and the lattice columns across various construction stages. A comparison with the cut-and-cover method prompted the adoption of a strategy that integrates segmental pouring of the main structure and the installation of internal supports to optimize the original scheme. The results indicated that as the foundation pit was excavated, both the horizontal displacement of diaphragm wall and the ground surface settlement gradually increased, while the differential settlement between the diaphragm wall and the lattice columns shows exhibited an initial decrease followed by an increase. In comparison to the cut-and-cover method, the cover-and-cut method demonstrated greater efficacy in controlling foundation pit deformation and minimizing disturbances to surrounding environment. As the number of segmental pouring layers and support levels increased, the overall deformation of the foundation pit showed a gradual decreasing trend, and the differential settlement between the diaphragm wall and the lattice columns continued to fluctuate. When each floor slab was poured in three layers with two supports placed in the middle, the maximum horizontal displacement of the diaphragm wall could be reduced by 22.47%, and the maximum ground surface settlement could be decreased by 19.01%. The findings in this research can provide valuable basis and reference for the design and construction of similar projects. Full article

The CORE complex refers to the muscles of the core region of the body, including the abdominal muscles, lower back muscles, and diaphragm. Among the various techniques aimed at improving CORE strength and functionality, abdominal hypopressive techniques have gained popularity. Objectives: To evaluate the available scientific literature on the effects of AHT on the CORE complex. Methods: A systematic search was conducted in January 2025 in PubMed, Web of Science, PEDro, Cochrane, ClinicalTrials.gov and Scopus. Only randomized controlled trials (RCTs) involving adults were included. Two reviewers independently selected studies and extracted data. The review was registered in PROSPERO (CRD-42023424933) and followed PRISMA guidelines. Results: Of 258 studies identified, 13 of them met the eligibility criteria for the final review. Showing the application of abdominal hypopressive techniques could have positive effects on the pelvic floor, transverse abdominis muscle, lumbar region, and diaphragm. The average methodological quality of the articles is 6.6 according to the PEDro scale. The risk of bias was high in 12 articles. Conclusions: Although the results show improvements in the CORE muscles after applying abdominal hypopressive techniques, further research is necessary to confirm these findings, given the insufficient methodological quality of the scientific literature and its high risk of bias. Full article

The behaviour of horizontal floor diaphragms plays a crucial role in ensuring the overall response of a building during earthquakes, as the stiffness of these diaphragms determines whether the structure will act as an integrated system. If the diaphragms do not exhibit sufficient stiffness, differences in the redistribution of forces on wall elements arise, increasing the risk of significant deformations and even local damage, which is commonly observed in earthquake-affected areas. Additionally, flexible diaphragms heighten the risk of torsional effects. Due to these factors, more attention should be given to the response of buildings with flexible diaphragms. Eurocode standard specifies general requirements under which diaphragms should be considered rigid within their plane, depending on the maximum diaphragm moment. However, specific guidelines regarding the geometric and material properties of elements that significantly impact seismic behaviour are not included in the existing European standards. This served as a basis for conducting a numerical study analysing the in-plane behaviour of floor elements made from different materials. This study, limited to a simple box-shaped structure with masonry walls, symmetrical in both orthogonal directions, evaluated and thoroughly analysed the deformations for different types of diaphragms, including prefabricated wooden frame-panel floors, CLT panels, and reinforced concrete slabs. Special emphasis was placed on wooden structural elements due to the increased demand for timber construction, as the behaviour of these elements needs to be properly studied, especially in seismic regions. The study results were obtained through FEM analysis using the SCIA Engineer software, version 22. The modelling of elements was carried out considering the orthotropy of brick wall and wooden ceiling elements, as well as simulating the appropriate shear stiffness of the connecting means. Full article

Taking the foundation pit of the Suzhou Chunshenhu Road Expressway Reconstruction Project as an example, the excavation process of the foundation pit was numerically simulated using a three-dimensional finite element method. The measured data and simulated data of the lateral deformation of the enclosure structure, surface settlement deformation of the ground outside the pit, and settlement deformation of the building were compared to analyze the impact of foundation pit construction on adjacent buildings. The influence of foundation pit floor and diaphragm wall thickness on wall displacement, building settlement, and foundation pit uplift was also discussed. The results showed the following: (1) Adding a foundation pit floor has a significant effect on reducing the lateral displacement of the diaphragm wall, settlement of the building, and uplift of the foundation pit. Increasing the thickness of the foundation pit floor has a limited effect on reducing the displacement, while increasing the thickness of the diaphragm wall has a small effect. (2) The displacement curve of the underground diaphragm wall increases with depth. It reaches a maximum at the excavation surface and then decreases gradually. (3) The surface settlement increases first and then decreases with distance from the foundation pit, showing a concave shape. As the depth of excavation increases, the settlement value increases. (4) Through analysis of the monitoring data of vertical displacement of buildings, it can be seen that during foundation pit excavation, buildings undergo five stages: initial slow descent, steep descent, mid-term slow descent, late steep descent, and stable deformation. The buildings are dominated by settlement deformation. Full article

The COVID-19 pandemic has brought significant attention to the respiratory system, with much focus on lung-related disorders. However, the diaphragm, a crucial component of respiratory physiology, has not been adequately studied, especially in the context of long COVID. This review explores the multipotential role of the diaphragm in both respiratory health and disease, emphasizing its involvement in long-term complications following SARS-CoV-2 infection. The diaphragm’s fundamental role in respiratory physiology and its impact on balance and posture control, breathing patterns, and autonomic nervous system regulation are discussed. This review examines complications arising from COVID-19, highlighting the diaphragm’s involvement in neurological, musculoskeletal, and inflammatory responses. Particular attention is given to the neuroinvasive impact of SARS-CoV-2, the inflammatory response, and the direct viral effects on the diaphragm. The diaphragm’s role in long COVID is explored, with a focus on specific symptoms such as voice disorders, pelvic floor dysfunction, and sleep disturbances. Diagnostic challenges, current methods for assessing diaphragmatic dysfunction, and the complexities of differentiating it from other conditions are also explored. This article is the first to comprehensively address diaphragmatic dysfunction resulting from COVID-19 and long COVID across various physiological and pathological aspects, offering a new perspective on its diagnosis and treatment within a multisystem context. Full article

Lower back pain (LBP) has been the leading cause of disability since 1990. Objectives: The main objective of this observational case–control study was to evaluate, using ultrasound, whether there were differences in the onset and ratio of core muscle contraction between subjects with non-specific chronic lower back pain and healthy subjects. Methods: A total of 60 participants (52% women), split between those with non-specific chronic lower back pain (n = 26) and healthy (n = 34) subjects, were recruited. Initial muscle contraction of the lateral abdominal wall, pelvic floor, lumbar multifidus, and respiratory diaphragm was measured using ultrasound. The abdominal drawing-in maneuver, contralateral arm elevation, the Valsalva maneuver, and voluntary contraction of the pelvic floor in seated and standing positions were performed. The muscle thickness of the lateral abdominal wall and lumbar multifidus and excursion of the pelvic floor and diaphragm at rest and during testing were also analyzed. Results: No differences were found between the groups in the initial contraction. Statistically significant differences were found in the following variables: diaphragm excursion (p = 0.032, r = 0.277) and lumbar multifidus ratio (p = 0.010, r = 0.333) in the standing–abdominal retraction maneuver; pelvic floor excursion (p = 0.012, r = 0.325) in the standing–contralateral arm raise; and transverse abdominis ratio (p = 0.033, r = 0.275) in the sitting–contralateral arm raise. A statistically significant interaction between the groups and body mass index was observed in resting diaphragm excursion (p = 0.018, partial eta squared = 0.096) during sitting–voluntary pelvic floor contraction. Conclusions: It cannot be concluded that there is a specific pattern of core activation in any of the groups. However, statistically significant differences were found in the contraction indexes of the lumbopelvic musculature. Full article

In order to study how to improve the spatial action of precast monolithic composite floor slabs, and examine replacing the cast-in-place surface layer for reducing the weight of structure, we used pseudo-dynamic tests on one-quarter scale models of two-span and three-story frame structures. The lateral load tests compared the stresses and displacements with a cast-in-place floor frame–shear wall structure (SJ1) and a precast monolithic floor frame–shear wall structure with X horizontal braces at the bottom of the floor (SJ2). The results show the X horizontal braces can improve the spatial action. Structural integrity (SJ2) as well as the effective transmission of the horizontal force can be ensured by additional X bracing at the bottom of the rigidity of the floor without a cast-in-place concrete topping. The results show that X horizontal braces more effectively transfer horizontal stress, which provides a beneficial reference for similar research. Full article

An 18-month-old neutered male domestic shorthair cat was presented for an emergency consultation after falling from the second floor. The cat sustained minor traumatic injuries but did not exhibit dyspnea. Routine radiographic examination raised suspicion of a diaphragmatic hernia, but the circumscribed nature of the soft tissues visible in the thorax was atypical for a classic traumatic diaphragmatic hernia. A positive contrast peritoneography highlighted the likely presence of a hernial sac, which strongly suggested a “true diaphragmatic hernia”, also known as “pleuroperitoneal hernia”. This diagnosis was confirmed during laparotomy, which allowed for the visualization of a 3 cm radial diaphragmatic defect in the right ventral quadrant of the pars sternalis. The diaphragm’s edges were rounded. A portion of the falciform ligament and a part of the omentum were protruding through the defect and were contained within a hernial sac. Herniorrhaphy was performed. The cat recovered without complications. Given its presentation and location, ventrally and to the right, this anomaly is analogous to what is described in humans as “Morgagni hernia”. Six other cases of Morgagni hernias have probably been reported in cats but were not identified as such. This case underscores the utility of peritoneography, a straightforward technique useful for diagnosing diaphragmatic hernias, which enables differentiation between acquired traumatic forms and congenital forms, particularly peritoneopericardial hernias and pleuroperitoneal hernias. True diaphragmatic hernias are almost always serendipitous discoveries. Full article

Urban areas in Taiwan are densely populated with limited land. Excavation often takes place near existing buildings, necessitating protective measures for adjacent properties. Among these measures, cross walls or buttress walls are commonly employed, especially in weak foundation soils, which have seen many successful applications. These mechanisms mainly contribute to reducing lateral deformation of the diaphragm walls, ground subsidence, and excavation face uplift. However, the behavior of these walls is essentially three-dimensional, and common engineering analyses employing one-dimensional elastoplastic beam analysis cannot adequately simulate their mechanical behavior. This study utilized the PLAXIS 3D 2018 software to analyze real-life cases of buttress walls and cross walls. Then, the results of the numerical models were validated against actual field measurements, and the outcomes were satisfactory, and within the regulatory allowable values. The primary objective of this study was to find the influence of different buttress wall removal timings on the lateral deformation of the diaphragm wall. The findings suggest that the gradual removal of buttress walls will effectively control the lateral deformation of diaphragm walls during the excavation of deeper floors like mezzanines. Full article

In the modelling of reinforced concrete (RC) buildings, the rigid diaphragm hypothesis to represent the in-plane behavior of floors was and still is very commonly adopted because of its simplicity and computational cheapness. However, since excessive floor in-plane deformability can cause a very different redistribution of lateral forces on vertical resisting elements, it may be necessary to consider floor deformability. This paper investigates the classical yet intriguing question of modeling orthotropic RC floor systems endowed with lightening elements by means of a uniform orthotropic slab in order to describe accurately the building response under seismic loads. The simplified method, commonly adopted by engineers and based on the equivalence between the transverse stiffness of the RC elements of the real floor and those of the orthotropic slab, is presented. A case study in which this simplified method is used is also provided. Then, an advanced finite element (FE)-based method to determine the elastic properties of the equivalent homogenized orthotropic slab is proposed. The novel aspect of this method is that it takes into account the interaction of shell elements with frame elements in the 3D FE model of the building. Based on the results obtained from the application of this method to a case study, a discussion on the adequacy of the simplified method is also provided. Full article

The rigid floor assumption is commonly used in structural design, but it is not applicable to buildings with a large plane aspect ratio. This study designed nine frame-shear wall structures with the story of 3, 6, and 12, with a plane aspect ratio of 2, 3.33, and 4. Based on the design results, the finite element models were set up by ETABS. Both the rigid diaphragm and the flexible diaphragm cases were considered in each model. The effect of elastic diaphragm deformation on structural seismic performance was investigated, including fundamental period, top displacement, inter-story drift, and base shear force. The results indicate that the diaphragm deformation on 3-story structures is more significant than that on 6-story and 12-story structures. The diaphragm in-plane deformation increases with the aspect ratio. On the basis of the analysis results, a simplified formula to calculate the internal force amplification factor and a quantitative assessment method for evaluating the diaphragm flexibility were proposed, which can provide a reference for engineering design. Full article

The solution of timber-to-concrete composite (TCC) floors represents a well-established construction technique, which is consistently used for both the retrofitting of existing timber floors and the realization of new diaphragms. The success of TCC floors relies on the intrinsic effectiveness in increasing both the in-plane (for lateral loads) and the out-of-plane (for gravity loads) performance of existing timber floors. As a widespread retrofit intervention, it is common to use existing floorboards as a permanent formwork for the concrete pouring. Rather few research studies of literature, in this regard, highlighted an overall reduction of load capacity and slip modulus due to the presence of such an interposed interlayer. In this regard, the present paper focuses on the use of screws as efficient mechanical connectors and analyses different configurations and inclination angles for their arrangement. This main goal is achieved by performing parametric Finite Element (FE) numerical analyses, validated on previous experimental tests, in order to specifically investigate the influence of the in-between interlayer, as well as the role of friction phenomena and the influence of the test setup and experimental protocol to achieve the basic mechanical performance indicators. Full article

Low back pain represents the leading cause of disability since 1990. In 90% of cases, it is classified as non-specific low back pain, being chronic in 10% of subjects. Ultrasound has proven to be an effective measurement tool to observe changes in the activity and morphology of the abdominal muscles. This article reviews which core synergies are studied with ultrasound in healthy subjects and with chronic non-specific low back pain. A systematic review was conducted on studies analyzing synergies between two or more core muscles. Publications from 2005 until July 2021 were identified by performing structured searched in Pubmed/MEDLINE, PEDro and WOS. Fifteen studies were eligible for the final systematic review. A total of 56% of the studies established synergies between the core muscles and 44% between the homo and contralateral sides of the core muscles. The most studied core synergies were transversus abdominis, internal oblique and external oblique followed by the rectus abdominis and the lumbar multifidus. No studies establishing synergies with diaphragm and pelvic floor were found. Eight studies were conducted in healthy subjects, five studies in subjects with chronic non-specific low back pain compared to healthy subjects and two studies in subjects with chronic non-specific low back pain. Full article

One of the advances in physiotherapy in recent years is the exploration and treatment by ultrasound imaging. This technique makes it possible to study the relationship between the musculature of the anterolateral wall of the abdomino-pelvic cavity, the pelvic floor muscles and the diaphragm muscle, among others, and thus understand their implication in non-specific low back pain (LBP) in pathological subjects regarding healthy subjects. Objective: To evaluate by RUSI (rehabilitative ultrasound imaging) the muscular thickness at rest of the abdominal wall, the excursion of the pelvic floor and the respiratory diaphragm, as well as to study their activity. Methodology: Two groups of 46 subjects each were established. The variables studied were: non-specific low back pain, thickness and excursion after tidal and forced breathing, pelvic floor (PF) excursion in a contraction and thickness of the external oblique (EO), internal oblique (IO) and transverse (TA) at rest. Design: Cross-sectional observational study. Results: Good-to-excellent reliability for measurements of diaphragm thickness at both tidal volume (TV) (inspiration: 0.763, expiration: 0.788) and expiration at forced volume (FV) (0.763), and good reliability for inspiration at FV (0.631). A correlation was found between the EO muscle and PF musculature with respect to diaphragmatic thickness at TV, inspiration and expiration, and inspiration at FV, in addition to finding significant differences in all these variables in subjects with LBP. Conclusion: Subjects with LBP have less thickness at rest in the OE muscle, less excursion of the pelvic diaphragm, less diaphragmatic thickness at TV, in inspiration and expiration, and in inspiration to FV. Full article

Poplar laminated veneer lumber (poplar LVL) is made of fast-growing poplar veneer and structural adhesive, which owns the advantages of sustainability and stable quality. Here an innovative poplar LVL floor diaphragm is presented, mainly made up of orthogonal rib beams fitted together using L-shape steel connectors. The paper mainly deals with an experimental study on the bending behavior of the floor under transverse uniform load. Full-scale testing on eight 3.6 m × 4.8 m specimens shows that the damage phenomena of the floor mainly exhibited as the separation between the rib beams and pulling out from the rib beam for the tapping screw. Though some local damage phenomena appeared before the preset maximum loading level, the load-deflection curves basically kept linear for most of the specimens. Under the service load level of 2.5 kN/m², the distribution of deflection and strain for the full-length rib beam substantially exhibited the characteristic of a two-way slab. In contrast, for the segmented rib beam, the situation was much more complex. Due to the parametric design of the specimens, testing results illustrated that the rib beam height played the most important role in floor stiffness. Next was the sheathing panel, while the role of segmented rib beam spacing was relatively unremarkable. At last, a revised pseudo-plate method was proposed to evaluate the maximum deflection of the novel floor, which considered the composite action by rigidity factors. Full article