Costal Margin Research Articles

Surgical management of costal margin rupture associated with intercostal hernia: Evolution of techniques

INTRODUCTION Costal margin rupture (CMR) injuries in association with intercostal hernia (IH) are rare and symptomatic and provide a significant surgical challenge. Surgical failure rates up to 60% are reported, and optimal techniques are unclear. We have characterized these injuries and describe the evolution of our surgical management techniques. METHODS Patients characterized by the Sheffield Classification where CMR and IH were both present, either CMR-IH or transdiaphragmatic intercostal hernia (TDIH), were identified prospectively, and injury characteristics, patient management, and follow-up data were recorded. Surgical techniques evolved according to patient outcomes from suture repair without and then with extrathoracic mesh, to three iterations of double-layer mesh repair (DLMR). The third iteration involved DLMR with biologic mesh, titanium buttress plates applied to the ribs adjacent to the IH with intercostal nerve-sparing suture placement. Associated surgical stabilization of rib fractures, or surgical stabilization of nonunited rib fractures, was performed when required, with costal margin plate fixation where possible. RESULTS Of 25 patients with CMR-IH and 11 with TDIH, 25 patients underwent surgery, with 6 reoperations in 5 patients. There were 8 suture repairs and 3 extrathoracic mesh repairs: DLMR was performed in 14 patients (3 Mark [Mk] 1, 5 Mk 2, and 6 Mk 3) with 2, 1, and 0 reoperations, respectively. Costal margin stabilization with titanium plates was successful twice at the level of the seventh but failed twice out of three times at the ninth costal cartilage. Reoperation after a failed mesh repair is particularly challenging and may require the placement of titanium buttress plates, surgical stabilization of rib fractures, and the use of stainless steel wire sutures. CONCLUSION Repair of CMR-IH/TDIH is challenging, but experience-based evolution of techniques has led to a durable and reproducible Mk 3 repair. LEVEL OF EVIDENCE Observational; Level III.

Research on the cross-sectional geometric parameters and rigid skeleton length of reinforced concrete arch bridges: A case study of Yelanghu Bridge

To investigate the influence of cross-sectional parameters and the rigid skeleton length on the structural mechanics behavior of reinforced concrete arch bridges, this study focused on the Yelanghu Bridge with a span of 210 m. The sensitivity of the main arch rib's instability mode to cross-sectional parameters such as width, spacing between adjacent webs, height, and concrete thickness was examined by combining the finite element method and the theoretical derivation. Subsequently, research was conducted on the impact of the rigid skeleton length during construction on the static and dynamic performance of the structure relying on the Midas Civil software. The findings indicate that for the Yelanghu Bridge, the risk of in-plane instability is greater than that of out-of-plane and local instabilities. In-plane instability is most sensitive to the section height and the out-plane instability is most sensitive to the thickness of the roof and floor concrete. Under ultimate load-bearing conditions, the axial force in the critical sections of the bridge increases with the length of the rigid skeleton. The fundamental frequency of the Yelanghu Bridge is approximately 0.32, which is significantly lower than that of more rigid arch bridges but higher than those of structurally softer structures such as cable-stayed or suspension bridges. This indicates that large-span reinforced concrete arch bridges exhibit unique dynamic characteristics and belong to moderately flexible structures.

Out-of-plane cyclic behavior of steel box-section twin arch ribs for bridges

Out-of-plane cyclic behavior of steel box-section twin arch ribs for bridges

Visceral leishmaniasis complicated with hemophagocytic lymphohistiocytosis and resistant to amphotericin B: a case report

IntroductionHemophagocytic lymphohistiocytosis characterized by hemophagocytosis leading to uncontrolled inflammation; the most common etiology in secondary cases of hemophagocytic lymphohistiocytosis is viral infections, especially Epstein–Barr virus. Visceral leishmaniasis is a vectorborne protozoal disease caused by Leishmania donovani complex. It is common in tropical and subtropical regions, with 50,000–90,000 new cases annually.Case presentationA 15-month-old Arab female was admitted to our hospital with 15 days of fever and decreased weight. On clinical examination, she had a markedly enlarged liver and spleen that were palpable 4 cm and 6 cm below the costal margin, respectively. The peripheral blood smear showed hypochromic microcytic anemia, poikilocytosis, reactive lymphocytosis, and mild thrombocytopenia. Bone marrow aspiration did not show malignancy or any other pathological findings. The patient was put on antibiotic therapy without improvement. Repeated bone marrow aspiration showed erythrophagocytosis; intracellular small round organisms looked like the amastigote form of Leishmania (Donovan bodies) with no evidence of malignancies. Her lab values showed ferritin greater than 500 ug/L, pancytopenia, and hypertriglyceridemia. The patient was diagnosed with hemophagocytic lymphohistiocytosis secondary to visceral leishmaniasis.ConclusionHemophagocytic lymphohistiocytosis secondary to visceral leishmaniasis is an extensively rare phenomenon in the medical literature that causes challenges in diagnosis and management. Steroids should be used wisely to not cover the symptoms of infections or malignancy, and amphotericin B resistance should be kept in mind in unresponsive Leishmania cases.

Steel Arch Structures with Prestressed Concrete Deck

AbstractFootbridges with prestressed concrete deck, which are suspended on steel arch ribs, are described in terms of the structural arrangement, static function and erection. These bridges create stiff structural systems which guarantee the bridges' favourable dynamic response. While steel arch ribs allow easy erections, the concrete deck guarantees structural integrity. The footbridges are structurally efficient, they are light and transparent, corresponds to the scale of the landscape and all structural members have human dimensions. They were erected with a minimum impact on the environment. Their structural arrangement is illustrated on examples of four bridges.

An Investigation into the Impact of Time-Varying Non-Conservative Loads on the Seismic Stability of Concrete-Filled Steel-Tube Arch Bridges

When the arch rib of the mid-bearing through and lower-bearing through arch bridges undergoes out-of-plane deformation, it is usually subject to the resilience force provided by the flexible hanger, which is known as the “non-conservative force effect” of the suspender. In contrast to the static condition, in the dynamic scenario, the time-varying non-conservative force exerted by the flexible suspender becomes more complex due to dynamic changes in external load. Moreover, the difference in fundamental frequency and vibration period between the bridge system and arch rib may influence the stress distribution within the arch rib during ground motion. This paper investigates the impact of time-varying non-conservative forces on the dynamic stability of arch ribs in concrete-filled steel tube (CFST) bridges under seismic loads. Specifically, it examines the influence of different seismic waveforms, frequency disparities between bridge slabs and arch ribs, and suspender stiffness on the non-conservative effect. The results reveal significant disparities in the impact of non-conservative forces exerted by the suspender during seismic events with identical intensity but varying frequency characteristics. The influence of non-conservative forces on the dynamic stability of bridges escalates as deck stiffness increases, while it remains relatively unaffected by changes in suspender stiffness.

Active Control for Construction Stability of Suspension Arch Rib Segments Based on ARID System

In response to the issues of vibrations affecting the construction safety, speed, and accuracy of suspended structures due to dynamic disturbances during lifting, environmental disturbances, and improper operator actions, this paper investigates the application of the Active Rotary Inertia Driver (ARID) system for double-rope suspended structures, namely analyzes, and applies control to the vibration response of double-rope suspended structures under external excitations. Taking the double-rope suspended structure as an example, a dynamic analytical model of the double-rope suspended structure is established based on D’Alembert’s principle. Through shake table tests, the dynamic response characteristics and vibration control effects of the double-rope suspended structure under various external excitations are studied, and the influence of the twisting radius of the suspended structure on the control effect is analyzed. The experimental results show that the ARID control system achieves significant control effects on the swing and torsional vibrations of the suspended structure, which validates the accuracy of the theoretical model for the ARID control system and demonstrates its feasibility for practical applications.

Bracing systems for three-ribbed arch bridges against out-of-plane buckling

This paper is concerned with the design of bracing systems for three-ribbed parabolic arch bridges against out-of-plane buckling. Typical bracing systems for the three-ribbed arch bridges include K-bracing system and X-bracing system as well as transverse bracing system. The buckling criterion of the braced funicular three-ribbed arch bridge is derived from an exact matrix stiffness method (MSM) with a 14 × 14 s-order element stiffness matrix of three-dimensional beam-column elements that allows for torsional and warping deformations. The lateral torsional buckling load and mode are given by the lowest eigenvalue and eigenvector associated with the assembled structural stability stiffness matrix. A comparison study between different bracing system configurations suggests that the three-ribbed arches with the integral K- or X-bracing system (a K/X-bracing across the three arch ribs) have lower lateral torsional buckling loads than their arch counterparts with the independent K- or X-bracing system (the adjacent arch ribs are connected by K/X-bracing respectively), because the latter ones could provide more restraint on the middle arch rib to avoid early lateral torsional instability. Further, a bracing utilization efficiency index (defined as the normalized buckling capacity over material usage for bracing system) is proposed to quantify the effect of bracing systems in improving the lateral torsional buckling capacity of arch bridges. Highly efficient bracing systems that maximize the lateral torsional buckling load of three-ribbed arch structures with the lowest bracing material usage are then recommended.

Graphical poly-arch model for the ultimate limit state verification of RC deep beams under hanging loads

The structural behavior of RC deep beams under hanging loads differs from that of conventional top-loaded beams. The hanging loads that are applied at the bottom of beams impose a remaining arch action and an intersecting tension field below such indirect load-carrying mechanism can be recognized, which are not dealt well with existing design approaches. Correspondingly, a graphical poly-arch model is developed for the ultimate limit state verification of RC deep beams under hanging loads, in which the function of interior inclined ties linking the arch rib and the longitudinal tie is acknowledged. Based on the connection between graphic statics and strut-and-tie models, the graphical analysis of proposed poly-arch models using reciprocal diagrams is also presented. After that, the proposed graphical poly-arch model is examined by two case studies, in which the predictions have a fairly good agreement with test results with different span-length-to-depth ratios. Furthermore, the advantages and limitations of the graphical poly-arch model are discussed. As an upgrade over existing strut-and-tie models, it can be seen that the graphical poly-arch model is highly valuable for organizing the load paths within RC deep beams under hanging loads and provides a clear mechanical explanation of how the inclined ties and the longitudinal ties interact, and what failure patterns govern.

Experimental investigations on the flexural behavior of UHPC wet joints for UHPC light-weight rigid frame arch bridges

Wet joints are critical parts of prefabricated ultra-high-performance concrete (UHPC) light-weight rigid frame arch bridges (LWRFAGs), so their mechanical behavior is important to the structural design and applications of these arch bridges. To explore suitable joint configurations and reinforcement arrangements for connecting UHPC components or arch ribs of a practical UHPC LWRFAG, this paper experimentally investigated flexural behavior of several prefabricated UHPC joint beams with various kinds of wet joints through four-point bending tests. Firstly, four different UHPC joint beams with different joint configurations were designed, including (i) vertical joint; (ii) rhombus joint; (iii) vertical joint with top and bottom strips; and (iv) rhombus joint with top and bottom strips, and their flexural performance were compared with a complete UHPC beam. The experimental results revealed that UHPC joint beam employing the rhombus joint with top and bottom strips exhibited superior flexural behavior and cracking resistance among four UHPC joint beams. Subsequently, to achieve optimal and robust joint configurations, bending performance of one complete UHPC beam and three large-scale UHPC joint beams with rhombus joints but different reinforcement arrangements were experimentally studied. It is observed that the beam with the welded twist reinforcements (specimen V-4) shown optimal flexural performance and cracking resistance. Finally, to explore the load transfer mechanism and effects of reinforcement parameters on flexural behavior of specimen V-4, the parametric studies were comprehensively performed using finite element analyses (FEA). This study could serve as both the experimental and theoretical reference for flexural design of UHPC beams with the rhombus wet joints.

An analytical method for out-of-plane stability assessment of network arch bridges

Network arch bridges typically feature inclined cables with a net configuration to support the bridge deck, therefore, improving the bridge's stiffness and reducing bending moments along the arch elements. Given their relatively slender cross-sections and large compression stresses, properly evaluating stability safety is crucial to the integrity of network arch bridges. However, because of the unique design of cable configuration, current design specifications mostly do not provide specific methods for such stability assessments. To address this gap, the study proposes a new analytical methodology that elucidates the mechanical relationship between basic design parameters and the stability performance of network arch bridges. A numerical example is conducted using finite element analysis to validate the performance of the proposed method. In addition, the influence of several design parameters on the stability factor and buckling length factor is investigated. This research further proposes a practical expression for the buckling length factor of arch ribs with nonlinear regression analysis. The results exhibit that the proposed method can efficiently and accurately evaluate the buckling stability performance of network arch bridges, and the established practical expression can facilitate designers in easily estimating the critical buckling load during the design process.

Clinical outcomes of ruxolitinib treatment in 595 intermediate-1 risk patients with myelofibrosis: The RUX-MF Real-World Study.

Ruxolitinib (RUX) is a JAK1/2 inhibitor approved for the therapy of myelofibrosis (MF) based on clinical trials including only intermediate2-high risk (INT2/HIGH) patients. However, RUX is commonly used in intermediate-1 (INT1) patients, with scarce information on responses and outcome. The authors investigated the benefit of RUX in 1055 MF patients, included in the "RUX-MF" retrospective study. At baseline (BL), 595 (56.2%) patients were at INT1-risk according to DIPSS (PMF) or MYSEC-PM (SMF). The spleen was palpable at <5 cm, between 5 and 10 cm, and >10 cm below costal margin in 5.9%, 47.4%, and 39.7% of patients, respectively; 300 (54.1%) were highly symptomatic (total symptom score ≥20). High-molecular-risk (HMR) mutations (IDH1/2, ASXL-1, SRSF2, EZH2, U2AF1Q157) were detected in 77/167 patients. A total of 101 (19.2%) patients had ≥1 cytopenia (Hb<10 g/dL: n.36; PLT <100 x 109/L: n = 43; white blood cells <4 x 109/L: n = 40). After 6 months on RUX, IWG-MRT-defined spleen and symptoms response rates were 26.8% and 67.9%, respectively. In univariate analysis, predictors of SR at 6 months were no HMR mutations odds ratio [OR], 2.0, p=.05], no cytopenia (OR, 2.10; p=.01), and blasts <1% (OR, 1.91; p=.01). In multivariate analysis, absence of HMR maintained a significant association (OR, 2.1 [1.12-3.76]; p=.01). In INT1 patients, responses were more frequent and durable, whereas toxicity rates were lower compared to INT2/high-risk patients. Presence of HMR mutations, cytopenia, and peripheral blasts identified less-responsive INT1 patients, who may benefit for alternative therapeutic strategies.

Sliding connectors for cyclic construction of steel-UHPC composite truss arch bridges: design method and feasibility study

To break through the three major technical bottlenecks of traditional long-span arch bridges, which are excessive self-weight, high cost and difficult construction, a new steel-ultra high performance concrete (UHPC) composite truss arch bridge scheme and a matching cyclic construction method were proposed. The main arch can be divided into several times for closure from the inside out. Special transverse connection devices need to be installed between the arch ribs constructed with successive closures by step. The devices can not only ensure the stability of the arch ribs constructed subsequently, but also do not cause serious stress superposition on the already closed arch ribs. Therefore, sliding connectors for the cyclic construction of new arch bridges and the corresponding simplified modeling method were proposed in this paper. Subsequently, the working mechanism was analyzed, and the design method was proposed. Finally, the feasibility of sliding connectors and the correctness of the corresponding design method were verified by the experiment. The results indicate that it is necessary to install a transverse sleeve structure in the sliding connector, which plays a key role in transverse adjustment. The design of key dimensions in sliding connectors is controlled by the maximum vertical and longitudinal displacements of the inner arch. The outer arch could slide freely under the premise of ensuring stability, and the mechanical superposition response of the inner arch was relatively small. For the inner arch, the vertical displacement at the crown only increased by 10.94 %, and the maximum compressive stress in the UHPC arch ribs only increased by 16.3 %. The sliding connector also has the potential for further optimization to achieve smaller stress superposition.

A Comparative Study Between Ultrasound-Guided Ilioingunial/Iliohypogastric Nerve Block versus Transverse Abdominis Plane Block in Patients Undergoing Oblique Inguinal Hernia Repair

Abstract Background Poorly controlled acute pain after abdominal surgery is related to somatic pain signals derived from the abdominal wall and is associated with a variety of unwanted post-operative consequences, including patient suffering, distress, respiratory complications, delirium, myocardial ischemia and prolonged hospital stay. Objective Regional anesthesia by (Ultrasound guided (US) Transversus abdominis plane block (TAP) or Ultrasound guided ilioinguinal and iliohypogastric nerves (IIN+IHN) block may be used as components of multimodal anesthesia with a comparable effect. In the present study, Bupivacaine is used to compare between them following inguinal hernia repair. Patients and Methods The study was conducted on 60 randomly chosen patients aged above 18 years, American Society of Anesthesiologists (ASA) class I or II scheduled for elective unilateral open inguinal hernia repair under general anesthesia, in Ain Shams University Hospitals after approval of the medical ethical committee. They were allocated in two groups. TAP block Group: received general anesthesia and (0.2 mL/kg of 0.25% bupivacaine per side), by midaxillary approach, under ultrasound guidance, the probe was placed transversely between the iliac crest and costal margin. Ilioinguinal/ iliohypogastric nerves block group: received general anesthesia, with (0.2 mL/kg of 0.25% bupivacaine per side). The inferior portion of linear ultrasound transducer will be placed over the anterior superior iliac spine with the superior margin of the transducer pointed directly in an oblique plane toward the umbilicus. The superior margin of the ultrasound transducer was slowly rotated superiorly and inferiorly until the fascial plane between the internal oblique and transverse abdominis muscle is identified. Results The results of the study revealed that patients received IIN+IHN block had significantly lower pain scores at 8, 12, 16, 20, and 24 hrs after operation, delayed time for rescue analgesia and decreased total need of analgesic in the first 24hrs post-operative compared to patients who received TAP nerves block. Conclusion IIN+IHN block was effective in reducing postoperative pain scores for 4-6 hours, lowering total 24-h postoperative opioid and analgesic consumption and delaying the need for rescue analgesia after inguinal hernia repair under general anesthesia, compared to TAP nerves block. It will be more useful to study in high-risk hypertensive and cardiac patients and to correlate with plasma catecholamine levels, which reflect the stress response and it is necessary to evaluate postoperative pain on movement in farther studies.

565 Robot-Assisted Surgery for Thoracic Endometriosis Syndrome – a Single-Centre, Retrospective Review of the First Fifty Cases

Abstract Aim Thoracic endometriosis syndrome (TES) is underdiagnosed, due to cyclical thoracic symptoms being underreported. Management of TES also remains controversial, with abdominal and thoracic approaches proposed, both laparoscopically and robotically, and no guidelines available. We aimed to characterise our experience with a multidisciplinary, robot-assisted approach, with a focus on symptom prevalence and surgical outcomes. Method A retrospective review of all consecutive procedures for TES between July 2020 and March 2023 surgery was performed. Robot-assisted removal of endometriosis from the underside of the diaphragm, from the pleura or superior diaphragm, or wedge resection of the lung through videoscope-assisted thoracic surgery, in any combination with or without pelvic endometriosis removal, were included. Presenting symptoms, intra-operative, and histological outcomes were analysed. Results Fifty robotic TES procedures, on forty-six patients were undertaken; median age was 32 (IQR 26–36). Cyclical shoulder tip pain (n = 29, 63%), costal margin pain (n=18, 39.1%), and scapular pain (n=11, 23.9%). There were no major Clavien-Dindo complications. Median blood loss was 10ml (IQR 6.25–27.25), and median length of stay was 1 day (IQR 1–2 ). The majority of the underside of the diaphragm specimen (n=35, 77.8%), and the pleural, and lung specimens (n=17, 85%) were either histologically positive for endometriosis or showed inflammation consistent with endometriosis. Conclusions Robotic-assisted surgery can be safely used for TES. Management of TES should involve an MDT including gynaecologic, hepato-pancreatico-billary, and thoracic surgeons, with minimally invasive experience. Going forward, long-term, patient-reported outcomes need to be analysed to ensure the effectiveness of robot-assisted surgery in TES.

A Practical Approach to Alignment and Error Feedback Control for Long-Span Arch Bridges

The accurate installation of long-span arch bridges’ arch ribs remains a challenge due to the complex calculations required for cable forces and arch rib displacements, as well as the significant influence of environmental and construction loads. In this study, we propose a practical approach to alignment and error feedback control for long-span arch bridges. Cable forces were optimized using multiple control objectives based on influence matrix principles. The impact of temperature on the next segment to be installed was analyzed using the metastatic GM(1, 1) model and fitting results. Several tunable parameters were employed to account for parameter errors and environmental interference. These parameters were adjusted based on the deviations between practical and theoretical alignments for different arch rib segments, achieving a model output of an offset-free-tracking arch rib structure. This technology was applied to monitor the construction of the Tian’e Longtan Grand Bridge. Compared to conventional alignment control approaches, the proposed method achieved excellent arch ring alignment after the closure of the high-accuracy arch rib and cable release, as well as effective control of cable force uniformity and tower deviation. Field measurement data indicate that the closing deviation of the arch ring is only 3 mm. This study provides a valuable reference for the construction control of long-span arch bridges.

Вторинні порушення форми грудної клітки після корекції лійкоподібної деформації за методом Nuss

Aim - studying the influence of the elasticity of the chest on the formation of secondary pectus carinatum and secondary protrusion of costal arches after Nuss procedure in order to determine the risk groups for the occurrence of data of secondary postoperative deformations in order to optimize a surgical intervention in these groups . Materials and methods. We analysed the data of 6 patients with pectus carinatum and 5 children with rib arches protrusion, which were formed as a result of Nuss funnel chest correction. The elasticity of the chest was studied by determining the ratio of its circumference during maximum inhalation and exhalation (mobility index - MI) as well as the ratio of the distance between the support plane in the supine position and the front surface of the chest in a neutral position and at the moment of compression (compliance index - CI). To calibrate the indicators, the data were calculated in a group of 30 healthy children. Depending on the obtained values, 3 degrees of chest elasticity are distinguished: high, medium and rigid chest. Results. 3 degrees of chest elasticity were determined in children without chest deformity: high (MI - 9.1±0.9%; CI - 28.1±1.8%), medium (MI - 6.8±0.2%; CI - 22.7±2.1%) and a low or rigid chest (MI - 4.9±0.2%; CI - 15.6±1.8%). The following data were recorded in patients with secondary deformities: 80% of patients with secondary pectus carinatum had a high degree of elasticity of the chest, 20% - average degree. In 83.33% of cases, patients with secondary rib arches protrusion had a high degree of elasticity of the chest, and 16.67% had an average degree. Secondary rib arches protrusion in 80% of cases is combined with the use of one horizontal bar. All cases of occurrence of secondary deformations are associated with a symmetric local type of funnel chest with or without deformations of costal arches or with an asymmetric local type. Conclusions. Using the Nuss operation technique with short plates in patients in the period of rapid growth with a high degree of elasticity of the chest with type IA and IIA1 of funnel chest can reduce the risk of secondary pectus carinatum; and in cases of high level risk of secondary protrusion of the rib arches the "flare buster" technique can help avoid this complication. The vast majority of secondary deformations are prone to spontaneous regression. The research was adhered to the principles of the Declaration of Helsinki. The research protocol was agreed by the Local Ethics Committee of the mentioned institution. The patients' informed consent was obtained for the study. No conflict of interests was declared by the authors.

Mechanical response of long-span CFST arch bridges based on the hydration heat temperature effect

As the span of concrete-filled steel tube (CFST) arch bridges increases, the hydration heat temperature effect of concrete inside steel tube becomes more severe, which increases the safety risk during the construction process. Therefore, a numerical simulation of the mechanical response of a long-span CFST arch bridge under the influence of hydration heat was carried out. First, based on the hydration heat conduction theory, a finite element model of the transient temperature field of a CFST arch rib was established. The temperature distribution of the CFST arch rib and its variation with time were revealed, and an approximate formula for the distribution of the hydration heat temperature along the radial direction of the CFST was provided. Subsequently, the variation law of the thermal stress of a CFST during hydration heat release was investigated. Finally, based on the principle of temperature equivalence, a finite element model of the overall CFST arch rib was established to examine the effect of hydration heat on the deformation of the arch rib. The results reveal that the hydration heat temperature field of the CFST arch rib exhibits nonlinear and axisymmetric characteristics. The maximum temperature of the section and the maximum temperature difference can reach 73.5 °C and 33.2 °C, respectively. Because of the influence of the hydration heat, there is a significant stress gradient in the cross section of the arch rib. A maximum radial stress of 2.08 MPa is attained, indicating a risk of concrete cracking. Additionally, the displacement along the transverse and vertical directions of the chord tube exhibits an initial increase, followed by a decrease over time. The maximum transverse displacement of the chord tube reaches 70.6 mm, while the vertical displacement reaches 117.8 mm.

Strength Optimisation and Static Performance Analysis of Arch Ribs of Steel-tube Concrete Arch Bridge

By means of finite element simulation, the axial compressive stiffness of different steel-tube concrete short columns was imported into the finite element model, and the effects of adopting new steel-tube concrete arch ribs on the mechanical properties of the key components of steel-tube concrete arch bridges, such as internal forces and displacements, were analyzed. The results show that: with the increase of the axial compressive stiffness of the arch rib chord, under different load combinations, the vertical displacement of the arch rib chord will increase, and the structure will be lifted up, with a maximum of 31.85%; the vertical displacement of the deck slab will also increase, with a maximum increase of 6.8%, which is smaller than the vertical displacement of the arch rib chord; the absolute value of the downward and transverse displacements of the arch rib chord will be reduced, with a maximum reduction of 7.1% respectively. The absolute values of the transverse and crossover displacements of the arch rib chord tube will be reduced, with the maximum reduction of 7.1% and 6.8%, respectively. In the project of arch bridge, the deflection and deformation of the arch rib, deck plate and other components of the more stringent restrictions, especially the vertical displacement, it is recommended to use the higher axial compressive stiffness of the steel pipe concrete arch rib.

Recent Construction Technology Innovations and Practices for Large-Span Arch Bridges in China

Arch bridges provide significant technical and economic benefits under suitable conditions. In particular, concrete-filled steel tubular (CFST) arch bridges and steel-reinforced concrete (SRC) arch bridges are two types of arch bridges that have gained great economic competitiveness and span growth potential due to advancements in construction technology, engineering materials, and construction equipment over the past 30 years. Under the leadership of the author, two record-breaking arch bridges—that is, the Pingnan Third Bridge (a CFST arch bridge), with a span of 560 m, and the Tian’e Longtan Bridge (an SRC arch bridge), with a span of 600 m—have been built in the past five years, embodying great technological breakthroughs in the construction of these two types of arch bridges. This paper takes these two arch bridges as examples to systematically summarize the latest technological innovations and practices in the construction of CFST arch bridges and SRC arch bridges in China. The technological innovations of CFST arch bridges include cable-stayed fastening-hanging cantilevered assembly methods, new in-tube concrete materials, in-tube concrete pouring techniques, a novel thrust abutment foundation for non-rocky terrain, and measures to reduce the quantity of temporary facilities. The technological innovations of SRC arch bridges involve arch skeleton stiffness selection, the development of encasing concrete materials, encasing concrete pouring, arch rib stress mitigation, and longitudinal reinforcement optimization. To conclude, future research focuses and development directions for these two types of arch bridges are proposed.