Improved definition of dynamic load allowance factor for highway bridges

Yongjun Zhou,Zhongguo John Ma,Yu Zhao,Xiongwei Shi,Shuanhai He 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.3

The main objective of this paper is to study the dynamic load allowance (DLA) calculationmethods for bridges according to the dynamic response curve. A simply-supported concrete bridge with asmooth road surface was taken as an example. A half-vehicle model was employed to calculate the dynamicresponse of deflection and bending moment in the mid-span section under different vehicle speeds using thevehicle-bridge coupling method. Firstly, DLAs from the conventional methods and code provisions wereanalyzed and critically evaluated. Then, two improved computing approaches for DLA were proposed. Inthe first approach, the maximum dynamic response and its corresponding static response or itscorresponding minimum response were selected to calculate DLA. The second approach utilized weightedaverage method to take account of multi-local DLAs. Finally, the DLAs from two approaches werecompared with those from other methods. The results show that DLAs obtained from the proposedapproaches are greater than those from the conventional methods, which indicate that the currentconventional methods underestimate the dynamic response of the structure. The authors recommend that theweighted average method based on experiments be used to compute DLAs because it can reflect thevehicle’s whole impact on the bridge.

Unified calculation model for the longitudinal fundamental frequency of continuous rigid frame bridge

Yongjun Zhou,Yu Zha,Jiang Liu,Yuan Jing 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.3

The frequencies formulas of the bridge are of great importance in the design process since these formulas provide insight dynamic characteristics of the structure, which guides the designers to parametric analyses and the layout of the bridge in conceptual or preliminary design. Continuous rigid frame bridge is popular in the mountainous area. Mostly, this type of bridge was simplified either as a girder or cantilever when calculating the frequency, however, studies showed that the different configuration of the bridge made the problem more complex, and there is no unified fundamental calculation pattern for this kind of bridge. In this study, an empirical frequency equation is proposed as a function of pier’s height, stiffness of pier and the weight of the structure. A unified fundamental frequency formula is presented based on the energy principle, then the typical continuous rigid frame bridge is investigated by finite element method (FEM) to study the dynamic characteristics of the structure, and then several key parameters are investigated on the effect of structural frequency. These parameters include the number, position and stiffness of the tie beam. Nonlinear regression analyses are conducted with a comprehensive statistical study from plenty of engineering structures. Finally, the proposed frequency equation is validated by field test results. The results show that the fundamental frequency of the continuous rigid frame bridge increases more than 15% when the tie beams are set, and it increases with the stiffness ratio of tie beam to pier. The results also show that the presented unified fundamental frequency has an error of 4.6% compared with the measured results. The investigation can predicate the approximate longitudinal fundamental frequency of continuous ridged frame bridge, which can provide reference for the seismic response and dynamic impact factor design of the pier.

Leadership Development in Students as Part of Attitude Development

Zhou Yongjun,Viktoriia O. Anishchenko,Olena V. Vasylenko,Nataliia V. Iaremenko,Mykhailo V. Fomin International Journal of Computer ScienceNetwork S 2023 International journal of computer science and netw Vol.23 No.7

Leadership development corresponds to the focus on the individual's success and competitiveness strategy. This is the optimal direction of the organization of attitude development because it covers two aspects of the student's personality development, professionally-oriented and self-centric. The aim of the study is to identify and compare the leadership level in second-and fourth-year students to see dynamics of development and implementation of the leadership phenomenon in the professional and personal making up of future specialists. Based on the theoretical analysis of the issue, the authors developed an objective and subjective diagnostic model for leadership skills. In this study, data of the objective diagnostic technique are the key. Subjective diagnostic technique for leadership skills provides insights for problem interpretation. At the level of the first group of respondents, the average Leadership Skills Level of the second-year students was quite low and was found within the medium level. The second group of respondents consisting of the fourth-year students showed a slight but effective improvement. The Leadership Skills of this group were found at a sufficient level. Positive dynamics was revealed for all criteria of leadership skills as a result of applying objective diagnostic methods: decreased percentage of students with negative and relatively low markers of Leadership Skills Level and corresponding increase in percentage of applicants with positive markers of Leadership Skills Level. Further research can be organized in the direction of identifying and developing successful universal and professionally-oriented tactics for leadership development in students as part of attitude development.

Improved definition of dynamic load allowance factor for highway bridges

Zhou, Yongjun,Ma, Zhongguo John,Zhao, Yu,Shi, Xiongwei,He, Shuanhai Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.3

The main objective of this paper is to study the dynamic load allowance (DLA) calculation methods for bridges according to the dynamic response curve. A simply-supported concrete bridge with a smooth road surface was taken as an example. A half-vehicle model was employed to calculate the dynamic response of deflection and bending moment in the mid-span section under different vehicle speeds using the vehicle-bridge coupling method. Firstly, DLAs from the conventional methods and code provisions were analyzed and critically evaluated. Then, two improved computing approaches for DLA were proposed. In the first approach, the maximum dynamic response and its corresponding static response or its corresponding minimum response were selected to calculate DLA. The second approach utilized weighted average method to take account of multi-local DLAs. Finally, the DLAs from two approaches were compared with those from other methods. The results show that DLAs obtained from the proposed approaches are greater than those from the conventional methods, which indicate that the current conventional methods underestimate the dynamic response of the structure. The authors recommend that the weighted average method based on experiments be used to compute DLAs because it can reflect the vehicle's whole impact on the bridge.

Correlation between Vitamin B12 and Mental Health in Children and Adolescents: A Systematic Review and Meta-analysis

Yongjun Tan,Li Zhou,Kaiqi Gu,Caihong Xie,Yuhan Wang,Lijun Cha,Youlin Wu,Jiani Wang,Xiaosong Song,Xia Chen,Hua Hu,Qin Yang 대한정신약물학회 2023 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.21 No.4

To conduct the association between vitamin B12 and mental health in children and adolescents. Five databases were searched for observational studies in any language reporting on mental health and vitamin B12 levels or intake in children and adolescents from inception to March 18, 2022. Two authors independently extracted data and assessed study quality. Qualitative and quantitative analysis of data were performed. The review was registered in the PROSPERO database (CRD42022345476). Fifty six studies containing 37,932 participants were identified in the review. Vitamin B12 levels were lower in participants with autism spectrum disorders (ASD) (standardized mean difference [SMD], −1.61; 95% confidence interval [95% CI], −2.44 to −0.79; p < 0.001), attention deficit hyperactivity disorders (SMD, −0.39; 95% CI, −0.78 to −0.00; p = 0.049) compared with control group. Vitamin B12 intake were lower in participants with ASDs (SMD, −0.86; 95% CI, −1.48 to −0.24; p = 0.006) compared with control group, but showed no difference between depression group (SMD, −0.06; 95% CI, −0.15 to 0.03; p = 0.17) and the control group. Higher vitamin B12 intake were associated with lower risk of depression (odds ratio [OR], 0.79; 95% CI, 0.63−0.98; p = 0.034) and behavioral problems (OR, 0.83; 95% CI, 0.69−0.99; p = 0.04). The vast majority of included studies supported potential positive influence of vitamin B12 on mental health, and vitamin B12 deficiency may be a reversible cause for some mental health disorders in children and adolescents.

Identifying Topic-Sensitive Influential Spreaders in Social Networks

Donghao Zhou,Wenbao Han,Yongjun Wang 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.2

Identifying influential spreaders is an important issue in understanding the dynamics of information diffusion in social networks. It is to find a small subset of nodes, which can spread the information or influence to the largest number of nodes. The conventional approaches consider information diffusion through the network in a coarse-grained manner, without taking into account the topical features of information content and users. However, for messages with different topics, the target influential spreaders may vary largely. In this paper, we propose to harness historical propagation data to learn the information diffusion probabilities on topic-level, based on which we use a greedy algorithm to iteratively select a set of influential nodes for a given topic. Specially, we design a three-stage algorithm named TopicRank to mine the most influential spreaders with respect to a specific topic. Given observed propagation data, we first use Latent Dirichlet Allocation (LDA) model to learn a topic mixture for each propagation message. Then, the topic-level diffusion probability of an edge is computed by exploiting the propagation actions occurred to it and the topic distribution of these propagation messages. Last, based on the learned topic-level diffusion probabilities, we apply optimized greedy algorithm CLEF to identify influential nodes with respect to a specific topic. Experimental results show that our method significantly outperforms state-of-the-art methods when used for topic-sensitive information spread maximization.

Exploiting Historical Diffusion Data to Maximize Information Spread in Social Networks

Donghao Zhou,Wenbao Han,Yongjun Wang 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.2

Information spread maximization is to find a small subset of nodes in social network such that they can maximize the expected spread of information. In this paper, we attempt harnessing historical information cascades data to learn how information propagates in social networks and how to maximize its spread. In particular, we proposed a voting algorithm to learn diffusion probabilities of edges from cascades data. Then a pruning method is developed to remove trivial edges whose weights are smaller than a threshold. Moreover, motivated by the social influence locality, we propose a Local Influence Model to evaluate node's influence within a local area instead of the whole network, which can effectively reduce the computational complexity. Based on Local Influence Model, we use greedy algorithm to find an approximate optimal solution. Experimental results show that our method significantly outperforms state-of-the-art models both in terms of information spread and algorithm runtime.

Experiment on the Behavior of a Self-Anchored Suspension and Cable-Stayed Hybrid Bridge during Structural Transformation

Yu Zhao,Yongjun Zhou,Lingling Wu,Changchang Li,Zhongguo John Ma 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.6

The Longgang Bridge in Shaanxi, China, is a complex continuous hybrid structure composed of two cable-stayed self-anchored suspension parts and one single-pylon cable-stayed part. A 1:20-scaled model was established due to the effect of multiple structural transformation, frequent internal force changes during the construction process, and differences between actual material parameters and theoretical calculation parameters. In this paper, the design, materials, counterweight, experimental instrumentation, and construction stages of the scaled model are introduced. Based on the experimental data, the nonlinear behavior of the self-anchored suspension and cable-stayed hybrid bridge during the structural transformation of the construction process is systematically and comprehensively studied. The evolutions of the hanger force and stayed cable force, the variation in the subcable and back-cable forces, the displacement characteristics of the suspension cable and the deflection of the stiffened girder are analyzed, and the relationships among these variables in different states of the structural system are discussed. This paper will serve as a technical reference for the construction of similar bridges in the future.

Postthrombolytic Antiplatelet Use for Patients with Intercerebral Hemorrhage without Extensive Parenchymal Involvement Does Not Worsen Outcome

Weihua Jia,Lichun Zhou,Xiaoling Liao,Yuesong Pan,Yongjun Wang 대한신경과학회 2015 Journal of Clinical Neurology Vol.11 No.4

Background and Purpose It is unclear whether postthrombolytic antiplatelet (AP) therapy after thrombolytic-related hemorrhage without extensive parenchymal involvement (THEPI) afects the clinical outcome. Tis study explored whether AP administration in patients with THEPI afects short- and long-term outcomes. Methods All of the data for this study were collected from the Trombolysis Implementation and Monitor of Acute Ischemic Stroke in China (TIMS-China) registry. Patients with THEPI were assigned to either the AP (AP therapy should be commenced 24 h afer intravenous thrombolysis) or AP-naïve groups. THEPI was defned according to European-Australasian Acute Stroke Study II criteria. Te 90-day functional outcome, 7-day National Institutes of Health Stroke Scale (NIHSS) score, and 7-day and 90-day mortalities were compared between the AP and AP-naïve groups. Logistic regression analysis was used to evaluate the effects of AP therapy on the short- and long-term clinical outcomes. Results Of the 928 patients enrolled from those in the TIMS-China registry (n=1,440), 89 (9.6%) had nonsymptomatic intracerebral hemorrhage (ICH) within 24–36 h afer thrombolysis; 33 (37%) of these patients were given AP therapy (AP group) and 56 (63%) were not (APnaïve group). No significant differences were found for the risk of 7-day aggravated ICH (p=0.998), 7-day NIHSS score (p=0.5491), 7-day mortality [odds ratio (OR)=3.427; 95% confdence interval (95% CI)=0.344–34.160; p=0.294], 90-day mortality (OR=0.788, 95% CI=0.154– 4.040, p=0.775), or modifed Rankin score 5 or 6 at 90-days (OR=1.108, 95% CI=0.249–4.928, p=0.893) between the AP and AP-naïve groups afer THEPI. Conclusions Early administration of postthrombolytic AP therapy afer THEPI does not worsen either the short- or long-term outcome. AP therapy may be a reasonable treatment option for patients with THEPI to reduce the risk of ischemic stroke recurrence.

Lateral Load Distribution for Hollow Slab Bridge: Field Test Investigation

Yu Zhao,Xiaozhe Cao,Yongjun Zhou,Gangqiang Wang,Ruixin Tian 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.3

Distribution factors (DFs) for one typical cross-section as specified in the AASHTO LRFD specification can be varied when the bridge parameters such as span length, loading lanes and skew are changed. The diversity between design and actual DFs may be varied as the bridge parameters changed. To study this diversity, this paper presents an evaluation of lateral load DFs for prefabricated hollow slab bridges. The response of the bridge was recorded during the field test. This field test was divided into two stages: a concentrated force loading test on the prefabricated girder that settled on the bridge supports before the girders were connected transversely and a vehicle loading test after the girders were connected transversely. The instruments used to record the response of the bridge were strain gauges and dial indicators. The measured data in the multi-stages of the field test could be used to calibrate the support condition of the bridge and transverse connection between adjacent girders in the finite element model (FEM) using beam and plate elements. From the FEM, DFs for this hollow slab bridge were determined and compared with the DFs in the AASHTO LRFD specification. A parametric study using the calibrated FEM was then used to investigate the effect of various parameters including span length, skew and bridge deck thickness on the DFs. It was found that AASHTO LRFD specification is conservative compared with the analysis in the FEM, while this conservatism decreased as the span length and skew of the hollow slab bridge increased.