Hasil untuk "Bridge engineering"

Sepehr Faridmarandi, Mansoureh Shahabi Ghahfarokhi, Fatemeh Aliakbari et al.

Abstract Utilizing ultra-high performance concrete (UHPC) for strengthening reinforced concrete (RC) columns has emerged as a compelling approach, particularly for retrofitting. Unlike traditional normal strength concrete jacketing methods, UHPC offers a more efficient alternative. These methods often require substantial increases in column size to achieve desired enhancements in axial, shear, and flexural capacities. By quantitatively assessing the volume of material utilized against the resulting benefits in ultimate capacity and service life extension, it becomes evident that UHPC holds significant promise in retrofit and upgrading endeavors. In the present study, a total of four columns were experimentally tested, including one control column in need of retrofitting and three retrofitted columns, one with a fully reinforced normal strength concrete jacket and the other two with fully reinforced UHPC jackets. The experimental results reveal that the UHPC jacket increases the stiffness, strength, and energy absorption of the columns compared to the normal strength concrete jacket. This study evaluates the feasibility and performance of RC columns strengthened using UHPC. It examines hysteresis curves, failure modes, stiffness degradation, and sectional curvature to assess the efficacy of the strengthening and retrofitting methods.

Guochen Zhang, Liqun Xu, Fei Qiu et al.

Earth and rock dams are an important part of the flood control system, and hidden dangers in such dams are a serious threat to project safety. The application of a single geophysical exploration technology is associated with multiple solutions and limitations, and research on an integrated technology is meaningful for the timely detection and management of hidden dangers in earth and rock dams. This paper summarizes the respective advantages and limitations of geophysical exploration techniques for leakage detection in dams by sorting out and analyzing their principles and application characteristics. The principles of the integrated technology are outlined, and a data analysis system for GIS-based integrated geophysical exploration is elaborated. The challenges and shortcomings of the development of integrated geophysical exploration techniques are summarized. The theoretical model of integrated geophysical exploration information fusion technology based on data fusion and joint inversion is proposed. The feasibility of establishing the theoretical model based on data fusion and joint inversion is demonstrated, providing a direction for the development and practical application of integrated geophysical exploration techniques in the field of geotechnical engineering.

Amira T. Mahmoud, Walaa Medhat, Sahar Selim et al.

Code-to-code translation, a critical domain in software engineering, increasingly utilizes trans-compilers to translate between high-level languages. Traditionally, the fidelity of such translations has been evaluated using the BLEU score, which predominantly measures token similarity between the generated output and the ground truth. However, this metric falls short of assessing the methodologies underlying the translation processes and only evaluates the translations that are tested. To bridge this gap, this paper introduces an innovative architecture, “TC-Verifier”, to formally employ the Uppaal Model-checker to verify trans-compiler-based code translators. We applied the proposed architecture to a trans-compiler translating between Swift and Java, providing insights into the verified and unverified aspects of the translation process. Our findings illuminate the strengths and limitations of using Model-checking for formal verification in code translation. Notably, the examined trans-compiler reached a verification success rate of 50.74% for the grammar rules and productions modeled. This study underscores the gaps in trans-compiler-based translations and suggests that these gaps could potentially be addressed by integrating Large Language Models (LLMs) in future work.

YAO Yong, YAN Yu, SUN Bowen et al.

In view of temperature cracks in concrete box girders easily occurring during construction, an inverse analysis method based on uniform design theory and differential evolution back propagation (DE-BP) neural network was proposed to accurately obtain the thermal parameters of concrete box girders and ensure the reliability of temperature analysis of concrete box girders. This method established the nonlinear relationship between the temperature peak of characteristic points and the thermal parameters through the DE-BP neural network. By using the uniform design method and the Abaqus finite element numerical model, 130 sets of sample data were generated. Based on the ratio of 12∶1 for training samples to test samples, the back analysis model was trained. The results show that the mean absolute percentage errors EMAPE of the DE-BP neural network model are all less than 3%, and the relative errors are less than 5%. This indicates that the prediction accuracy of the BP neural network can be effectively improved by the DE algorithm. The maximum error of the temperature peak for the characteristic points based on inversion analysis is 2.05 ℃, and the calculated temperature histories are in good agreement with the actual ones. In a word, the back analysis method of thermal parameters for the concrete box girder based on the DE-BP neural network and uniform design theory demonstrates high accuracy and a stable inversion process with good reliability, which can provide a theoretical basis for temperature control of other similar projects.

Junjie Kong, Cheng Teng, Fenglan Liu et al.

IntroductionPeripheral nerve injuries, especially those involving long-distance deficits, pose significant challenges in clinical repair. This study explores the potential of continuous microcurrent electrical nerve stimulation (cMENS) as an adjunctive strategy to promote regeneration and repair in such cases.MethodsThe study initially optimized cMENS parameters and assessed its impact on Schwann cell activity, neurotrophic factor secretion, and the nerve regeneration microenvironment. Subsequently, a rat sciatic nerve defect-bridge repair model was employed to evaluate the reparative effects of cMENS as an adjuvant treatment. Functional recovery was assessed through gait analysis, motor function tests, and nerve conduction assessments. Additionally, nerve regeneration and denervated muscle atrophy were observed through histological examination.ResultsThe study identified a 10-day regimen of 100uA microcurrent stimulation as optimal. Evaluation focused on Schwann cell activity and the microenvironment, revealing the positive impact of cMENS on maintaining denervated Schwann cell proliferation and enhancing neurotrophic factor secretion. In the rat model of sciatic nerve defect-bridge repair, cMENS demonstrated superior effects compared to control groups, promoting motor function recovery, nerve conduction, and sensory and motor neuron regeneration. Histological examinations revealed enhanced maturation of regenerated nerve fibers and reduced denervated muscle atrophy.DiscussionWhile cMENS shows promise as an adjuvant treatment for long-distance nerve defects, future research should explore extended stimulation durations and potential synergies with tissue engineering grafts to improve outcomes. This study contributes comprehensive evidence supporting the efficacy of cMENS in enhancing peripheral nerve regeneration.

Nurhamidah Nurhamidah, Ahmad Junaidi, Rudy Ferial et al.

Bridge infrastructure is critical in connecting one region with other areas separated by rivers or ravines. In Minangkabau, a type of bridge is built using the Ba Atok Bridge roof. This bridge structure is characterised by pointed roof-like buffalo horns, where the Minangkabau people are known as Gonjong. The remaining Ba Atok Bridge is located in Padang City, specifically in Guo Village, Jalan Lubuak Tampuruang, Kuranji Village, Kuranji District, Padang City, with a bridge length of 16 meters. The community needs the Ba Atok Bridge as a bridge to cross the river to gardens, schools, madrasas, mosques, and other villages. Its unique shape has charm, and this is one of the cultural heritage assets that must be maintained as a characteristic bridge between the nuances of traditional Minangkabau culture. Therefore, the Community Service Team of the Faculty of Engineering, Andalas University, is also collaborating with the Tourism Awareness Group (POKDARWIS), which also has the same initiative, namely carrying out bridge restoration with traditional Minangkabau cultural nuances. Restoration begins with identifying damage, discussing it with community groups, making an architectural design, submitting a proposal to Bank Nagari, and repairing the bridge's upper frame. The Ba Atokini bridge restoration activities impact crossing access and have become characteristic of the Guo Tourism Village, which POKDARWIS manages.

Carolina B. A. Restini, Tracey Weiler, Kirsten A. Porter-Stransky et al.

Institutions training future healthcare professionals in healthcare and community engagement play a crucial role beyond traditional classroom settings. Recognizing their potential to support under-represented groups and minorities, institutions increasingly encourage engagement with schools and community organizations. However, work remains to advance meaningful and impactful educational outreach and service-learning programs. This manuscript synthesizes the perspectives of a group of medical school educators to discuss developing sustainable programs to engage youth in Science, Technology, Engineering, Math, and Medicine (STEMM) education with a focus on biomedical science. Through near-peer education and service-learning, healthcare students can impart knowledge, provide mentorship, promote enthusiasm for STEMM fields, and nurture health-related self-efficacy within individuals and communities. Collaborative efforts through student-as-teacher approaches bridge health-related disparities and cultivate healthier, more empowered futures for all. We advocate for community outreach strategies that target future health professionals early in their education and support the scholarship of teaching and learning and program evaluation. Successful long-term programs must ensure that results are systematically assessed, measured, and perpetuated. This perspective aims to highlight the role of service learning and community outreach in increasing individual health literacy and fostering an enduring interest in STEMM careers, thereby empowering the next generation of elementary and secondary school students.

Wei Du, Zhijian Hu, Zhi Zhou

The cracking of link slabs in jointless bridges presents significant challenges due to the complexity of their stress conditions. This study focused on analyzing the transverse stresses in link slabs of jointless steel–concrete composite bridges. Utilizing linear elasticity theory and partial differential equations of plates, the deflection and stress distribution functions for the link slabs were determined. The validity of these analytical solutions was confirmed through comparisons with finite element models and load tests. Results from both the load tests and the finite element model indicate that the upper face of the girder end link slabs experiences maximum tensile stresses in both transverse and longitudinal directions. The stress values obtained from the analytical method align well with these results, showing that the total stress, when considering transverse stresses, reaches 107% of the longitudinal stresses alone. Furthermore, a 40% reduction in longitudinal girder spacing or a 50% increase in girder end length can lead to link slab stresses of 128% and 145% of the longitudinal stresses, respectively. This finding suggests that even loads lower than those designed based solely on longitudinal stresses can result in cracking. Therefore, it is recommended that transverse stresses be considered in the design of link slabs for jointless bridges. Relying solely on conventional longitudinal stress analyses may underestimate actual stress conditions and contribute to the formation of cracks.

Yuheng Liu, Lihua Gong, Yonghui Zhang et al.

The activity of electrocatalysts can be optimized via constructing heterostructures, while it remains a challenge for the universal synthesis of heterocatalysts with covalent interface. Herein, a universal bifunctional‐S strategy for the preparation of covalently connected metal sulfides yolk–shell nanoreactors with dual components toward enhanced electrochemical hydrogen production in acid, is reported. Specifically, the yolk–shell MoS2‐(CTAB)2Sz host with abundant covalent S22− is first developed by a micelle‐confined microemulsion technology. The preencapsulated S22− in the precursor is utilized to in situ react with the additional M ions (M = Fe, Co, Ni, Cu, Zn, Mn, Cd, Sn), thus creating the covalent microenvironment at the heterointerface, which demonstrates a universal strategy to prepare dual‐component metal sulfides nanoreactors (MoS2/MxSy–BS). The resultant MoS2/CdS–BS nanoreactor exhibits excellent hydrogen evolution activity (27 mV at 10 mA cm−2) among the MoS2‐based heterocatalysts reported in the literature, while representing an improvement of four times than that of as‐prepared traditional MoS2/CdS heterocatalyst. Operando X‐ray diffractometer patterns are performed to study durability. The enhanced mechanism related to the transformation of catalytic center and the establishment of “electronic bridge” at the interface of MoS2/CdS–BS are revealed by theoretical calculations. This study inspires to develop covalently connected electrocatalysts via nanoreactors’ engineering.

Alper ÖZMEN, Erkut SAYIN

A major portion of the cultural heritage consists of old structures that are susceptible to earthquakes. These structures are prone to significant damage from natural disasters, particularly earthquakes. This study's primary goal is to assess the historical masonry bridge's seismic response to strong far-fault ground motions (FFGM) and near-fault ground motions (NFGM). The historical Sultan Suyu Masonry Bridge is used as a case study in this study. It was created with three-dimensional finite element software. The time history response of the bridge model is contrasted with one another in terms of stresses and displacements produced for FFGM and NFGM. The assessments take into account the FFGM and NFGM of the 1999 Düzce, 1999 Kocaeli, and 1992 Erzincan earthquakes, which had nearly equal peak ground accelerations. The results show that FFGM is equally significant as NFGM and that FFGM could be used in conjunction with NFGM to further evaluation of historical masonry arch bridges.

Sun Xiaolong, Zhu Yunchu, Mao Jie et al.

To clarify the effect of Hindered amine light stabilizer (HALS) on ultraviolet (UV) aging behavior of asphalt binder, the evolution history and characteristics of the UV induced micro-structure of modified asphalt were characterized. Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) were used to analyze the microscopic morphology evolution of light stabilizer-modified asphalt during UV aging. By defining the micro-structure of asphalt in aging joints induced by UV, the identification and classification of typical micro-structure are proposed. On this basis, an evaluation method based on the morphology evolution process of modified asphalt aging was proposed to quantitatively analyze the effect of HALS on the UV aging of asphalt binder. The results show that the control effect of HALS on the UV aging behavior of asphalt can be verified by SEM and AFM detection methods. At the same time, the aging interval of the asphalt modified by hindered amine was divided by the method, and it was verified that the HALS could significantly prolong the service life of the asphalt binder. The micro-morphology of asphalt binder undergoes the process of crack generation and propagation during UV aging. The micro-morphological changes of UV aged asphalt were interfered effectively by HALS, which could alleviate and control the development of UV induced micro-cracks, and promote the fusion of micro-cracks. This study provides an effective evaluation method for detecting UV aging microscopic evolution of HALS.

Jianye Li, Qian Fang, Xiang Liu et al.

This article investigates and presents a case study on the Beijing Subway Line 12 excavation beneath the existing Qinghuayuan Tunnel. The composite pre-reinforcement technique was used in conjunction with the shallow tunneling method to control the distortion of the existing large-diameter tunnel. When building twin tunnels underneath, this strategy considerably decreased the impact on the existing large-diameter tunnel. To systematically study the mechanical response of the existing large-diameter tunnel, a variety of sensors was embedded in the prefabricated segments just above the new twin tunnels. During the undercrossing twin tunnels procedure, the earth pressure, tunnel crown settlement, opening width of the segment joint, and the circumferential strain of the large-diameter existing tunnel were all measured. The settlement development of the existing large-diameter tunnel was categorized under six stages: (1) sedimentation, (2) heave, (3) second sedimentation, (4) second heave, (5) third sedimentation, and (6) steady state. The joint opening of the existing large-diameter tunnel changed sharply during the new undercrossing twin tunnels. The earth pressure and concrete stress of the linings rapidly increased during the new undercrossing twin tunnels. The majority of the reinforcement and concrete stresses were compressive and far lower than the yield strength, indicating that the tunnel was in a safe working condition.

Chenggong Wang, Diankai Cao, Xiaoyang Liu et al.

Bolted shear connectors have the advantages of being easily fitted and dismantled during construction, the initial elastic stiffness of which has a great influence on the structural performance of the connected composite structures. In this paper, the initial elastic behaviors of three types of bolted shear connectors used in steel-concrete composite structures (i.e., the bolt with nonembedded nut, the bolt with single-embedded nut, and the bolt with double-embedded nuts) are investigated using finite element analysis (FEA). After the FE models are verified against the experimental results in other literature, an extensive parametric study is carried out to investigate the effects of eight parameters of the composite structures on the initial shear stiffness and tension stiffness as well as coupling stiffness. Empirical formulas are subsequently developed for obtaining the initial elastic stiffness of the bolted shear connectors, based on which further FEA is performed. The FEA results are in good agreement with the experimental results, illustrating the effectiveness of the empirical formulas.

Nicholas Gaddum, Des Dillon-Murphy, Richard Arm et al.

ABSTRACT: Objective: Treatment of aortic coarctation has seen a shift from traditional surgical repair to the use of aortic stents. The aim of this study was to assess the impact upon hemodynamics and arterial strain when aortic coarctation is treated with a stent using an experimental coarctation model, and to confirm any findings in a clinical cohort using MRI. Methods: An experimental patient model included a silicone arterial tree, and ventricular stroke profile was derived from patient MRI data. Pressure, flow and aortic strain was measured before and after stent placement in the model. A clinical study comprised of strain measurements using MRI in two patient cohorts; those treated with a stent, and those treated with surgical repair. Results: Before stent placement, peak strain decreased as the pulse propagated away from the aortic valve. After stent placement however, peak strain was amplified as it approached the stent, despite peak systolic pressure having dropped by 20 mmHg. Introduction of the stent caused an almost three fold increase in aortic strain rate to 150%.s − 1. Echoing these results the stented patient group's strain increased from 28% +/- 14% in the ascending aorta to 43% +/- 24% (p < 0.05) pre-coarctation. This was not seen in those with surgical repair of coarctation, (ascending aorta 40% +/- 22% compared to the pre-coarctation aorta strain 38% +/- 20%, p = 0.81). Conclusions: Despite a reduced systolic pressure gradient through a stented coarctation, dramatic increases in strain and strain rate could attribute subsequent pathologies in the aorta proximally.

Huihui Chen, Bing Xu, Qin Liu et al.

Recently, the light-type pier can be easily observed in urban elevated roads and bridge structures. This type of pier is broadly used in the field of structural engineering. The Thin-Walled Steel-Reinforced Concrete Pier (TSRCP), as the typical pier of the light-type piers, shows a better mechanical performance than the conventional reinforced concrete pier due to the enhancement of the H-shape steel. In terms of the TSRCP, the designed parameters, including the depth–width ratio (<i>DWR</i>) and axial compression ratio (<i>ACR</i>), have been determined in this study as the concerned variables. Then, a low cyclic loading experiment is conducted based on the three test specimens to investigate the effects of the concerned variables on the failure of the specimens. Meanwhile, some comparative studies are carried out based on the failure processes and modes, critical loading values (cracking, yielding and ultimate state), strain and ductility. The obtained experimental results demonstrate that all specimens illustrate a bending failure mode under the vertical and horizontal low cyclic loadings. Furthermore, for the concerned variables, the increasing <i>DWR</i> will reduce the ultimate bearing capacity of the TSRCP but enhance the plastic deformation. For the <i>ACR</i>, the decrease positively affects the cracking load, further improving the ultimate bearing capacity; however, the deformation capacity will be restrained. Finally, Abaqus is adopted to model the failure processes of three specimens; the comparative study has been conducted based on the simulated and experimental results. After that, the effects of the concerned variables on the failure performances are discussed. Meanwhile, the horizontal ultimate bearing capacity calculated equation for the TSRCP was deduced and validated based on the experimental and simulated data; the verification proves that the proposed equation can obtain a good result. In this study, the complex calculated process of the original equation can be simplified, which not only provides a convenient and useful way to design and manufacture this type of component but can serve as a guideline for validating the practical engineering applications.

Randolph C. H. Chan

Abstract Background The underrepresentation of women in science, technology, engineering, and mathematics (STEM) fields is well documented in developed countries, and yet public discussion of gender disparities in STEM in China is still in its nascent stage. Endorsement of traditional gender role beliefs and conformity to social norms are pertinent to Chinese culture, which may even exacerbate the gender disparities in STEM engagement. Grounded in social cognitive career theory, the present study drew on a national sample of secondary school students (N = 3020) in China to estimate gender disparities in self-efficacy, interest, and aspirations in STEM and examine how cultural and gender norms influence STEM engagement. Results The proposed sequential mediation model was supported, in which girls were more likely to show lower levels of self-efficacy than boys; this was associated with lower interest in STEM and lower motivation to pursue STEM careers. The results also supported the moderating effect of traditional gender role beliefs and found that gender differences in self-efficacy, interest, and aspirations in STEM were more apparent among students who strongly endorsed stereotypical views of male and female roles. Conclusions The findings provide important implications for efforts to improve girls’ access to STEM education through curriculum enrichment and out-of-school time programs to bridge the gender gap in STEM. Access to female role models and gender-responsive pedagogy is also essential to boost girls’ self-efficacy in STEM and eradicate traditional gender role beliefs among all students.

Kazem Shakeri, Elahe Khansoltani

In this paper, a modal pushover method is introduced for the assessment of the asymmetric-plan buildings in which, a load pattern is derived based on the story shears and story torque of building due to the simultaneous excitation in x and y directions. The proposed method is a single-run procedure and its significant advantage is its capability in consideration of the structural yielding in one direction on the total responses of the structure due to the simultaneous excitation in two orthogonal directions. In this method, in order to consider the instantaneous changes during the pushover analysis, two capacity curves of the structure are established based on the adaptive capacity spectrum method and the target displacement corresponding to each capacity curve is determined. Then, the structural responses at two pushover steps corresponding to the obtained target displacements are obtained. Eventually, the total responses of the structure are computed by combining the responses corresponding to the x and y directions. In order to evaluate the proposed method, this method has been applied to an irregular 20-story building subjected to the seven pairs of ground motion records and the obtained results are compared with the responses of nonlinear dynamic analysis as the exact responses. The results show the high accuracy of the proposed method in estimating the inter-story drifts of the studied building.

Ruiwei Feng, T. Deng, Tianpeng Lao et al.

Abstract Previous studies have shown that the seismic incidence angle imposes a non-negligible impact on the seismic performance of curved bridges. The computational efficiency of some current methods for determining the critical angle needs to be improved and their applicability in practical engineering projects remains to be examined. For this reason, a resultant response-based (RRB) method is developed herein for assessing the critical excitation direction of curved bridges. To validate the feasibility of this method in an actual seismic design context, a 1/62.5-scale model of a three-span curved bridge is designed and a multi-angle shaking table test is implemented. Meanwhile, the finite-element model of the test specimen is set up, and the RRB method as well as the linear response-history analysis (LRHA) are comparatively assessed. The results indicate that the RRB method can capture the critical excitation direction of curved bridges with sufficient precision (error does not exceed 10% compared to LRHA). The associated computational effort is also substantially reduced given that RRB requires analysis solely along two orthogonal directions as the incidence angles, compared to standard response history analyses where ground motion excitation is applied at multiple ground motion orientations. The above observation is further verified by a well-designed experimental campaign, which demonstrates the accuracy and practicability of the RRB method for the case of realistic bridge configurations.

Li Sun, Zhongxin Su, Yang Xia et al.

AbstractAiming at the large displacement monitoring needs of slope, road, and bridge engineering, a new method concerning the superwide-range fiber Bragg grating (FBG) displacement sensor based on ...

M. Tazarv, Zachary Carnahan, N. Wehbe

Abstract Glued-laminated (glulam) and cross-laminated timbers are gaining interests in bridge engineering community due to their improved strength and enhanced durability compared to sawn lumber. The main bridge type on South Dakota local roads is a precast prestressed double-tee girder bridge, which has only one supplier in the state. In an attempt to provide more bridge type selection options for local governments, the system performance of two types of glulam timber bridges was investigated through full-scale experiments. One glulam girder bridge and one glulam slab bridge were tested under fatigue and strength loading. Both bridge types showed minimal damage during the fatigue testing and the bridge stiffness remained constant. Strength testing of the two bridge systems confirmed that the AASHTO method of design for timber bridges is adequate. Girders of glulam girder bridges should be designed as fully non-composite members. A cost analysis showed that the superstructure cost of glulam timber bridges can be 30–50% lower than the precast prestressed double-tee bridge superstructure cost. Based on the construction, testing, and cost analysis, it is concluded that both types of glulam timber bridges are viable alternatives to precast prestressed double-tee bridges to be used on local roads.