Positive Moment Research Articles

Live music in the intensive care unit – a beautiful experience

ABSTRACT Background The growing number of lightly or non-sedated patients who are critically ill means that more patients experience the noisy and stressful environment. Live music may create positive and meaningful moments. Purpose To explore non-sedated patients’ experiences of patient-tailored live music interventions in the intensive care unit. Design A qualitative study using a phenomenological-hermeneutic approach. Data were collected at two intensive care units from September 2019 to February 2020 exploring 18 live music interventions performed by music students from The Royal Academy of Music, Aarhus, Denmark. Methods Observations of live music interventions followed by patient interviews. All data together were analysed using Ricoeur’s theory of interpretation. The Consolidated Criteria for Reporting Qualitative Research (COREQ) checklist was used. Results Five themes emerged: 1) A break from everyday life, 2) A room with beautiful sounds and emotions, 3) Too tired to participate, 4) Knowing the music makes it meaningful and 5) A calm and beautiful moment. Conclusion Patient-tailored live music to awake patients is both feasible and acceptable and perceived as a break from every-day life in the ICU. Implications for practice Supporting health and well-being by bringing a humanizing resource into the intensive care setting for patients and nurses to enjoy.

СТАН ТА ЦИФРОВІ ВЕКТОРИ РОЗВИТКУ РИНКУ СТРАХУВАННЯ УКРАЇНИ

The article examines the current state and digital vectors of the development of the insurance market of Ukraine and identifies promising directions for the digitalization of insurance. The essence of the insurance category is revealed. It is noted that the insurance market in Ukraine lags far behind developed countries. An analysis of the dynamics of the number of participants in the insurance market, the amount of assets of insurance companies, the structure of the insurance portfolio by types of insurance was carried out, and the main trends of the insurance market in Ukraine were revealed. The keys to the stable development of insurance activity in Ukraine have been defined as: quick response to new conditions and customer requests; the ability to adapt, accumulate positive experience, analyze and correct negative moments; develop harmoniously, find a balance between the accumulation of new knowledge and their practical application. Factors influencing and functioning of the domestic insurance market are determined. The features of modern trends in digital insurance tools, as an important mechanism for the growth of the insurance market, are revealed. It was found InsurTech that modern technologies are important for insurance companies. These InsurTech nclude artificial intelligence technologies, new inventions in the field of cyber security, big data analysis («bigdata), blockchain technologies, the Internet of Things (LoT ) and smartphone applications.

Digitalization of services in the field of patients’ rights protection: current state and prospects for the development of legislation

This scientific article is devoted to the current problems of digital transformation in the field of health care and the introduction of electronic medical services. The main directions of introduction of the digitalization process in the sphere of medicines circulation in Ukraine are revealed, the attention is focused on the positive and negative moments of digitalization in the sphere of medicines circulation in Ukraine. Possible areas for improving digitalization in the field of circulation of medicines in Ukraine are identified, as well as the need to improve the legal regulation of digitalization in the field of circulation of medicines in Ukraine in order to protect the rights and interests of patients in the field of medicines. The article analyses the current state of legal regulation of digitalisation in the healthcare sector of Ukraine and the readiness to provide quality electronic healthcare services to patients. The authors have identified the need to adopt and amend regulations that would regulate the development of the electronic healthcare system, in particular, the introduction of an electronic public health system; electronic document management in the field of healthcare; implementation of measures to ensure the safety of medicines and the creation of an electronic prescription; expansion of the functions of the electronic system of state registers; automation of medical services; and legalisation of medical cannabis.
 The article examines the problems of legalisation of cannabis for medical purposes in Ukraine. International legal acts and standards in the field of narcotic drugs and psychotropic substances are analysed. The authors review national legislative acts regulating the production and trafficking of narcotic drugs, psychotropic substances and precursors.
 The article examines the German experience of legal support for patients’ access to the necessary medical cannabis treatment for various diseases and post-traumatic stress disorders. The article identifies the specifics of legal regulation of medical cannabis treatment services. The authors outline two types of medical cannabis treatment services - general and special, which differ in procedural features.

Study on Numerical Simulation of Surrounding Rock Structure Safety of Urban Underwater Shield Tunnel: A Case in Chongqing

Based on the engineering background of shield construction of a subway section in Chongqing, which needs to pass through a park and there is a lake inside this park, this paper adopts theoretical analysis methods and numerical simulation calculation methods to explore the distribution law of the seepage field and the characteristics of water pressure in lining segments during shield tunneling. The results show that, during the whole excavation of a double-track tunnel with EPB shield, the maximum vertical effective stress is about 4.24 MPa, which is located at the arch foot of the tunnel. The maximum effective stress in the horizontal direction is about 3.61 MPa, which is located on both side walls of the tunnel in the horizontal direction; after the left and right tunnels are excavated in sequence, a “double precipitation funnel-shaped” pore pressure distribution is formed around the tunnel; during the construction of the shield tunnel, the vertical displacement and horizontal displacement of the surrounding rock show an increasing trend and gradually tend to be stable values of 24.09 mm and 25.28 mm; the segment vault has settlement, the maximum settlement is 21.8 mm, the arch bottom has uplift, and the maximum uplift is 24.4 mm. The maximum horizontal displacement of the segment appears on both sides of the arch waist, and the maximum horizontal displacement decreases with the increase of excavation steps; the positive bending moment of the lining segment is mainly distributed on both sides of the arch crown, and the negative bending moment is mainly distributed on both sides of the arch bottom. The axial force of the lining segment is compressive stress, and the maximum axial force is mainly distributed on both sides of the arch waist. The maximum normal shear stress occurs on both sides of the segment arch bottom. The study conclusions provide theoretical foundation and a new guidance for long-term safety evaluation of underwater tunnel structures.

Insights into performance enhancement mechanism of GaAs(100) photocathode by Cs/Li/O and Cs/Li/NF3 co-deposition

To verify the effects of additional Li introduction on the Cs-O and Cs-NF3 activation processes of GaAs(100) photocathodes, Cs-Li-O and Cs-Li-NF3 co-adsorption models of GaAs(100) β2(2 × 4) surfaces with different Cs/Li ratios are investigated, on the basis of pristine Cs-O and Cs-NF3 adsorption models. Residual gases including CO2, H2O, CO and H2 are introduced to the Cs-Li-O and Cs-Li-NF3 co-adsorption models to compare the damaging effects of typical residual gases. Simulation results show that the optimal Cs/Li ratio is 3:1, wherein 6Cs-2Li-1NF3 surface model exhibits smaller work function and 6Cs-2Li-1O surface model has better immunity to residual gases. Meanwhile, 6Cs-2Li-1O surface has better resistance abilities to CO2, CO and H2 than 6Cs-1O surface, while the resistances of 6Cs-2Li-1NF3 surface to H2O, CO and H2 are worse than those of 6Cs-1NF3 surface. From the perspective of charge transfer, a reverse dipole moment [Cs/Li-gas] and two positive dipole moments, i.e., [Cs/Li-surface] and [Cs/Li-O/NF3] are formed. Therefore, it is inferred that, the Cs-Li-O activation recipe, in comparison to the Cs-O activation recipe, can improve the photoemission stability of GaAs photocathodes, whereas the Cs-Li-NF3 activation recipe can increase quantum efficiency but is more sensitive to residual gases.

Kinematic Afterslip Patterns

AbstractNon‐inertial afterslip has been inferred to occur following large earthquakes. An explanation for this slow slip phenomenon is that coseismically generated stresses induce sliding on parts of a fault surface with velocity‐strengthening frictional properties. Here we develop an alternative mesoscale heuristic explanation for afterslip based on the idea that afterslip may occur on any portion of a fault that exhibits positive residual geometric moment following an earthquake, including sections that ruptured coseismically. Following a large earthquake, this model exhibits exponential time decay of afterslip and allows for variable sensitivity to coseismic event magnitude and residual geometric moment. This model provides a partial explanation for the spatial relationship of co‐ and post‐seismic slip associated with the 2011 MW = 9 Tohoku‐oki earthquake.

The effect of unequal load values on reinforced concrete deep beams

One of the most important problems facing the behavior and strength of deep beams is the asymmetry of the load in terms of magnitude despite its presence in the center of the beam span. It is known that the compression paths (struts) that transfer the load from the support points to the load points are usually symmetrical in deep beams when the 2-point load is central and equal, but in the current research work these struts are asymmetrical as a result of the inequality of load. This led to the strut with the higher load failing before that with the lower load. Therefore, the deep beam fails early. Twelve deep beam specimens were analyzed using SAP2000 software, which is based on the finite element method. Unequal 2-point loads of 33%-67%, 25%-75%, and 12.5%-87.5% were adopted. This case was studied using different values of concrete's compressive strength of 20, 30, and 40 MPa. Accordingly, the load capacity, midspan deflection, positive moments, and shear stresses decreased by about 24-13%, 22-8%, 11-10%, and 15-13.5%, respectively.

THE (IN)EFFICIENCY OF USA EDUCATION GROUP STOCKS: BEFORE, DURING AND AFTER COVID-19

This paper represents a pioneering effort to investigate multifractal dynamics that exclusively encompass the return time series of USA Education Group Stocks concerning two non-overlapping periods (before, during, and after COVID-19). Given this, we employ the Multifractal Detrended Fluctuations Analysis (MF-DFA). In this sense, we investigate the generalized Hurst exponent [Formula: see text] and the Rényi exponent [Formula: see text] for each asset and quantify their statistical properties, which allowed us to observe separately the contributing small scale (primarily via the negative moments [Formula: see text]) and the large scale (via the positive moments [Formula: see text]). We perform a fourth-degree polynomial regression fit to estimate the complexity parameters that describe the degree of multifractality of the underlying process. Also, we shall apply the inefficiency multifractal index to assess the COVID-19 shock for both periods. Our findings show that for both periods, the majority of these assets are marked by multifractal dynamics associated with persistent behavior [Formula: see text], a higher degree of multifractality and the dominance of large fluctuations. At the same time, most of these assets show asymmetry parameter [Formula: see text] for both periods, indicating that large fluctuations contributed more to multifractality in the time series of returns.

ОСНОВНЫЕ ПРИОРИТЕТЫ БЮДЖЕТНОЙ ПОЛИТИКИ РОССИЙСКОЙ ФЕДЕРАЦИИ В УСЛОВИЯХ МЕНЯЮЩЕГОСЯ МЕСТА РОССИИ В СОВРЕМЕННОМ МИРЕ

The article examines statistical data on the volumes of revenues and expenditures of the federal budget of the Russian Federation, as well as expenditures on national defense, national secu-rity and social policy for 2023-2026. A conclusion is made about the stability of budgetary resource spending. An analysis of changes in tax legislation from 2025, the implementation of which determines the implementation of budget policy in Russia, is carried out. The main innovations boil down to an increase in tax rates and an expansion of the list of taxable items. This will increase tax collection and the revenue side of the budget. An analysis of budget expenditures for the implementation of state pro-grams in the considered priority areas of activity of the Russian Federation showed that quite large vol-umes of budget financing are allocated for these purposes. The level and dynamics of the allocation of financial support are different. There will be no significant decrease or increase in the volume of budget financing in the next two-year period for all analyzed state programs. This is a positive moment, indicating the stability of the budget policy in the Russian Federation. The negative aspects include the potential existence of a situation in which a significant increase in budget expenditures is possible, their significant redistribution across industries and areas of activity, and a reduction in budget financing for a number of expenditure items. These are objective reasons that are currently associated with great difficulties in forecasting the development of events. The paper examines the regulatory framework concerning the pri-orities of budget policy in the medium term. The main areas include increasing the openness of budget procedures, the level of tax collection, the quality of tax administration, developing the institute of "pref-erential taxation", focusing on the most complete long-term forecasting and budget planning, optimizing budget financing with maximum focus on "goals-costs-results", focusing on the development of scientific research, radio-electronic, machine-tool industries, expanding the possibilities for using information technologies in the budget sector and strengthening control over the expenditure of budget financing.

Running Mechanics After Training on Sand in Runners With Pronated Feet: A Randomized Controlled Trial

Purpose: Pronation in the foot is a normal rolling movement occurring at the subtalar joint during running. The human foot, as the primary interface with our environment, presents morphological and postural changes following prolonged running. This study aims to identify running mechanics while training on the sand in runners with pronated feet. Methods: Thirty runners with pronated feet were in the control group, and 30 runners with pronated feet were in the experimental group. An experimental group conducted an 8-week corrective exercise program, while a control group did not exercise. A force plate was included to collect ground reaction forces in the walkway. An analysis of variance (ANOVA) with repeated measures test was conducted to identify the presence of an interaction between the within-and between-subject factors on the dependent variables. The significance level was set at P<0.05. Results: The experimental group displayed lower first peak vertical ground reaction force (P=0.026), peak mediolateral ground reaction force (P=0.000), anterior-posterior impulse (P=0.032), loading rate (P=0.004) and a larger last peak vertical ground reaction force (P=0.000) during training on the sand. Irrespective of the group under consideration, a lower first peak mediolateral ground reaction force (P=0.000), peak positive free moment amplitude (P=0.001), and a larger last peak mediolateral ground reaction force (P=0.003) observed in the post-test compared to the pre-test. Conclusion: We suggest that training on sand may be a suitable intervention to change running mechanics in male runners with pronated feet.

An Exploratory Study on Motivations and Outcomes of Academic Achievement Capitalization on Social Media

Capitalization, the process of sharing positive events to savor and relive positive moments, brings intrapersonal and interpersonal benefits to the sharer. In students' academic lives, academic achievements represent significant positive events that offer opportunities for capitalization. With the rise of social media, capitalizing on academic achievements has transitioned from traditional face-to-face interactions to digital platforms, where students increasingly share and celebrate their achievements. Given the significance of capitalization for well-being and the scarcity of research in this area, this study seeks to advance the understanding of the significance of capitalization within the context of a student's academic achievements and social media. Specifically, it aims to explore the practice of academic achievement capitalization on social media by examining the reasons for using these platforms, the motivations driving this practice, and the associated outcomes. Utilizing a qualitative exploratory research design, one-on-one semi-structured interviews were conducted with ten college students who frequently capitalize on their academic achievements. Content analysis of the interviews revealed that social media features are instrumental in facilitating the capitalization of academic achievements. Moreover, the study identified five key motivations driving this behavior: seeking validation, self-presentation, inspiring others, seeking support, and emotional expression. Consistent with existing research on capitalization, students experience predominantly positive outcomes, both interpersonal and intrapersonal, from sharing their academic achievements on social media, highlighting how digital platforms and capitalization help maximize the positive impact of these experiences. The findings provide an understanding of how and why students celebrate and showcase their academic achievements on social media, emphasizing how the capitalization of these achievements and the social media responses they receive influence their personal and social well-being

Digital Pedagogy: Challenges and Readiness for Learning in Digital Environment

Introduction. The article outlines the development trends of digital pedagogy and learning conditions in the new educational environment. The urgency of the study is justified through changes in technology and methods of providing education, as well as implications in the education sector with digital technologies and digital landscape. All of this helps improve the efficiency of educational activity and its outcome. However, it also requires digital literacy from its users. The novelty lies in identification of digital pedagogy problems and assessment of students' readiness for the implementation of digital tools in learning.Purpose. In our study, we will consider capabilities, challenges, and risks of education in a digital environment in an integrated way.Materials and Methods. We used theoretical methods for the analysis of digitalization state in the Russian and foreign education systems, and current requirements for digital skills of educational process participants. In the empirical part, the questionnaire method regarding teachers’ and students’ readiness level for the digital shift and ability to fully operate with digital educational environment was taken on the broad matter.Results. Various strategies and practices, models, and pedagogical innovations in the didactics development area were analyzed. We have revealed strengths and weaknesses, positive and problematic moments, organizational and didactic issues of learning in the digital landscape. Theoretical and methodological foundations of didactics under the conditions of digital transformation were structured. We analyzed the responses of teachers and students and draw a conclusion about their readiness for the digital shift in education.Discussion. The main factors that impact effective leaning in the digital landscape are stressed. It is proposed that digital pedagogy, as a new direction in science, is bound to answer plenty of questions regarding the digital shift. We have to enrich traditional methodology capabilities with a new content, modern tools and methods of teaching using digital technologies, as well as information and communications means, leaving the best to its side.

Seismic performance and damage control of large-span prestressed concrete rigid-frame bridges with high piers crossing strike-slip faults

Post-earthquake surveys show that fault-crossing simply supported beam bridges or continuous beam bridges suffer from severe seismic damage, such as falling beams and even collapse. Currently, there is a lack of understanding of the seismic performance of fault-crossing prestressed concrete rigid-frame bridges (PCRFBs). In this study, a representative PCRFB was used as a case study, and typical strike-slip fault cases were discussed, including fault-crossing angles and permanent displacement. The results revealed that different from other bridge structure types, the mid-span section was prone to yield failure because of the significant plastic deformation demands when the fault crossed the middle span. Positive and negative moment failures of the mid-span girder occurred when the fault-crossing angle was greater than or less than 90°, respectively. The fault-crossing angle is an important factor that affects the seismic performance of PCRFBs. A value of 90° is a favorable fault-crossing angle with minimal damage. The deformation demands of the mid-span were larger than the internal force effects when there was an increase in the permanent ground displacement of the fault. The proposed shock-absorbing hinge system (SAHS) can effectively reduce the vertical displacement of the girder and can significantly avoid the occurrence of plastic hinges, so the main girder is protected.

A Relationship-Based Resilience Program for Promotores: Protocol for a Randomized Controlled Waitlist Trial.

Community service providers (CSPs) play an integral role in the health care of low-income Hispanic or Latinx (HL) communities. CSPs have high-stress frontline jobs and share the high-risk demographics of their communities. Relational savoring (RS) has been associated with lower cardiovascular reactivity and psychosocial benefits, with particular promise among HL participants. In this study, we aim to identify RS's potential in promoting CSPs' cardiometabolic health and, in so doing, having broader impacts on the community they serve. This randomized controlled waitlist study aims to examine the effect of an RS intervention on (1) CSPs' cardiometabolic health (cardiometabolic risk factors and outcomes) and (2) CSPs' threats to leaving the workforce. We will recruit a sample of 80 CSPs from community health agencies serving low-income HL populations. Participating CSPs will be randomized into an experimental or a waitlist control. Participants will complete 1 or 2 baseline assessment batteries (before the intervention), depending on the assigned group, and then complete 2 more assessment batteries following the 4-week RS intervention (after the intervention and at a 3-mo follow-up). The RS intervention consists of guided reflections on positive moments of connection with others. Electrocardiogram data will be obtained from a wearable device (Polar Verity Sense or Movisens) to measure heart rate variability. The primary outcome is cardiometabolic health, consisting of cardiometabolic risk (obtained from heart rate variability) and cardiometabolic health behaviors. The secondary outcomes include CSPs' threats to leaving the workforce (assessed via psychological well-being), intervention acceptability, and CSPs' delivery of cardiometabolic health programming to the community (exploratory). Analyses of covariance will be used to examine the effects of RS on cardiometabolic health and on CSPs' threats to leaving the workforce, comparing outcomes at baseline, postintervention, and at follow-up across participants in the experimental versus waitlist group. The study has been approved by the University of California, Irvine, Institutional Review Board and is currently in the data collection phase. By May 2023, 37 HL CSPs have been recruited: 34 have completed the baseline assessment, 28 have completed the 4 intervention sessions, 27 have completed the posttreatment assessment, and 10 have completed all assessments (including the 3-mo follow-up). This study will provide valuable information on the potential of RS to support cardiometabolic health in HL CSPs and, indirectly, in the communities they serve. ClinicalTrials.gov NCT05560893; https://clinicaltrials.gov/study/NCT05560893. DERR1-10.2196/51427.

Seismic fragility of reinforced concrete buildings with hollow-core flooring systems

Hollow-core flooring systems were damaged in Wellington buildings during the 2016 Kaikoura earthquake (7.8 Mw) and have been shown to be susceptible to undesirable failure mechanisms (loss of seating, negative moment, and positive moment failure modes) at low drift demands. These undesirable damage mechanisms have also been observed in sub-assembly and super-assembly laboratory testing of hollow-core flooring systems and the test data obtained has enhanced the state-of-the-art knowledge of the probable seismic behaviour of hollow-core floor units. In this study, using currently available sub-assembly test data, fragility functions are defined for hollow-core flooring systems. Furthermore, the proposed fragility functions are combined with fragility information derived from nonlinear dynamic analyses for two eight-storey bare-frame reinforced concrete (RC) buildings designed based on New Zealand standards. This study shows that, in comparison with RC buildings with flooring systems that are not susceptible to gravity load failures, RC buildings with vulnerable hollow-core floors have a significantly higher likelihood of exceeding the collapse prevention limit state, as defined in this study.

Software Tools for Digitalizing the Basic Processes and Services in the Higher Schools of the Republic of Bulgaria

The article examines the issues of the application of modern software tools and technologies for digitization of the main processes and services in the higher education institutions of the Republic of Bulgaria. The topic is complex and debatable, both from the point of view of the applied methods and technologies, and in terms of reporting the effectiveness of these services. The acceleration of the digitization processes necessitates and requires the taking of specific measures to ensure the level of cyber security of the organization. One of the measures in this direction is for the developed web applications to be based on the latest technologies, as well as to carry out specific vulnerability tests before launching the services. As a result of the analyzed theoretical statements, as well as on the basis of the specific software implementation, some of the positive moments in expanding students’ access to modern digital services have been outlined.

Change in reactive pressures and bending moments under the action of various external loads on the strip

The problem of changing the reactive pressures acting on the strip interacting with the soil base is considered when using different soil models: a linear-deformable half-plane, a linear-deformable layer of finite thickness and the Winkler model. The goal is to compare the obtained results with the results of calculating the strip without taking into account its joint work with the soil. The methodology for calculating the "strip - soil" system is based on the method of B.M. Zhemochkin, for which the strip is divided into five equal length sections with a length of s=l/5=10/5=2 m. As a result of calculations it is proved that when any soil model is introduced, the reactive pressure curves will have a curvilinear shape with the highest values under the ends of the strip. The shape of the diagrams of bending moments both when using different soil models and when ignoring the joint work of the strip with the soil is identical. Positive bending moments when introducing a model of a linear-deformable layer of finite thickness are significantly greater than when calculating the strip without taking into account its joint work with the soil. The absolute values ​​of the negative bending moments in this case are significantly smaller than the similar moments obtained by ignoring the joint work of the strip and the soil. If Winkler models are included in the calculations, then the mentioned bending moments differ slightly from the moments obtained in the calculations of the strip in a primitive way. The originality of the work lies in the application of a unified approach to determining the stress-strain state of a strip located on soils described by various models of the "strip-soil" system. It is shown that if the model is applied incorrectly, it is possible to get false ideas about the stress-strain state of the system. For example, if the strip is considered as a strip on a linear-deformation plane, a stretched zone is obtained almost along the entire length of the strip in the lower zone, and in other cases both in the lower and upper zones, and this requires different reinforcement of the strip if it is designed with reinforced concrete. The practical value lies in the need for a serious justification for the use of a certain soil model, depending on soil conditions.

CONSTRUCTION PLANNING OF THE UPPER STRUCTURE OF THE PKP-PK BUILDING AT HUSEIN SASTRANEGARA AIRPORT BANDUNG

The PKP-PK building is one of the facilities located at an airport to visually monitor aircraft movements. In connection with this, at Husein Sastranegara Airport Bandung there is a PKP-PK building. In this study, it is intended to plan the PKP-PK building structure in accordance with SNI. so that in analyzing the structure, the SRPMK (Special Moment Bearing Frame System) method is used. In the calculation of the structure used SRPMK (Special Moment Bearing Frame System) and Strong Column Weak Beam which refers to SNI 1726: 2019 concerning earthquakes. In planning the building structure, SNI 2847: 2019 concerning reinforced concrete and SNI 1727: 2018 for loading are used. In this research, the SAP 2000 auxiliary program is used for 3D building modeling, PCAColumn for column interaction diagram calculation, and Autocad 2018 for reinforcement details. In the planning, 400/600mm main beam, with 5 D 19 flexural reinforcement at positive moment, at 7 D 19 flexural reinforcement at negative moment, 300/500mm sub-beam, with 3 D 16 flexural reinforcement at positive moment, at 5 D 16 flexural reinforcement at negative moment, 200/300 sub-beam with 3 D 13 flexural reinforcement at positive moment, at 5 D 13 flexural reinforcement at negative moment 600/600 column and 100 mm plate thickness and structural reinforcement details are included in the engineering drawings. In addition, the PKP-PK structural design control check based on SNI 1726: 2019 has met the requirements and fulfills the Strong Column Weak Beam concept and the cost required for the PKP-PK building construction planning is Rp1,324,860,000.00 (One Billion Three Hundred Twenty Four Million Eight Hundred Sixty Thousand Rupiah).

Numerical and experimental study of a segmentally prefabricated orthotropic steel–ultra-high-performance concrete composite deck for long-span cable-stayed bridges

Utilizing the high strengths, toughness, and durability of ultra-high-performance concrete (UHPC), a segmentally prefabricated orthotropic steel–UHPC composite deck (POSUCD) system has been developed for long-span cable-stayed bridges. The deck system combines an orthotropic steel deck (OSD) with a reinforced UHPC layer using notched perfobond strips (NPBLs). The UHPC layer is prefabricated onto the OSD of the girder segment in the factory to form the POSUCD. After the precast UHPC layer is cured, the girder segments are transported to the bridge site and assembled. The precast UHPC layers are then connected via transverse wet joints before tensioning stay cables. Against the background of the Danjiangkou Reservoir Bridge with a main span of 760 m, finite element (FE) analysis was conducted to examine the stress state and flexural tests were carried out on local full-scale models to verify the feasibility of POSUCD. The results show that the prefabricated UHPC layer reduces the maximum static compressive stress of the steel deck in the girder system by 21%, and the stress ranges at fatigue-prone details of the steel deck are decreased by 28%–90% compared to traditional OSDs with asphalt overlay. Since the prefabricated UHPC layer helps withstand dead axial load in the main girder, the high compressive strengths of UHPC can be utilized more effectively than in deck systems with UHPC only used as a cast-in-situ overlay to resist vehicular wheel loads. The transverse wet joint interfaces were identified as the weakest aspect of the POSUCD, whether under tension or compression; however, their nominal flexural strengths along the longitudinal direction meet the required design standards. The shear resistance of NPBLs was also well confirmed by the minimal interfacial slip on the specimen when it reached the ultimate capacity under positive bending moment.

The Effect of Asynchronous Grouting Pressure Distribution on Ultra-Large-Diameter Shield Tunnel Segmental Response

The complex distribution of synchronous grouting pressure results in excessive tunnel deformation and various structural diseases, especially for ultra-large-diameter shield tunnels. In this study, to reduce the risk of tunnel failure, a three-dimensional refined finite element model was established for the Wuhan Lianghu highway tunnel project, taking into account the non-uniform distribution of synchronous grouting pressure. This study focuses on investigating the development patterns of internal forces, deformations, and damages in segment structures under varying grouting pressure ratios. The results indicate that the primary failure mode of a segment is tensile failure occurring at the outer edge of the arch. Moreover, an increased ratio of grouting pressure between the arch bottom and top leads to a higher positive bending moment value and greater tensile damage at the arch waist. The tunnel ring gradually exhibits distinct “horizontal duck egg” shape deformation. When the grouting pressure ratio is 2.8, there is a risk of tensile cracking at the outer edge of the arch waist. At this time, the segment convergence deformation is 39.71 mm, and the overall floating amount reaches 43.12 mm. This research offers engineering reference for the prediction of internal forces and deformations in ultra-large-diameter shield tunnels during grouting construction, thereby facilitating their application in the development of resilient cities.