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147 results on '"Zhang, Lianzhen"'

14. Seismic Study of An Isolated Cable-Stayed Bridge under Near-Fault Ground Motions.

Author

Gao, Haoyuan, Li, Liuyang, Ding, Zhigang, Zhang, Lianzhen, Zhang, Kun, and Luo, Zhihao

Subjects
SEISMIC wave velocity, GROUND motion, CABLE-stayed bridges, FINITE element method, SOIL classification, SEISMIC waves
Abstract

During strong earthquakes, pounding may occur on large-span bridges and their approach bridges. The effect and mitigation measures of such pounding have rarely been explored in previous studies. This paper primarily uses finite element models to investigate the pounding effects at the expansion joints between the main cable-stayed bridge and its approach bridge. Friction pendulum bearings (FPBs) and fluid viscous dampers (FVDs) are used to alleviate poundings. Furthermore, a detailed analysis is conducted on how the pounding effect of the isolated main bridge with FPBs and FVDs is affected by the wave passage effect, ground motion type, and soil type. This study reveals that FPBs and FVDs can effectively reduce pounding effects and the associated risks. Even with the installation of FPBs and FVDs, lower seismic wave velocities and near-fault seismic motions with pulse effects can significantly increase the pounding effects between the cable-stayed bridge and its approach bridge. [ABSTRACT FROM AUTHOR]

Published
2024
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15. Interpretable Machine Learning Models for Prediction of UHPC Creep Behavior.

Author

Zhu, Peng, Cao, Wenshuo, Zhang, Lianzhen, Zhou, Yongjun, Wu, Yuching, and Ma, Zhongguo John

Subjects
ARTIFICIAL neural networks, MACHINE learning, CREEP (Materials), ELASTIC modulus, HIGH strength concrete
Abstract

The creep behavior of Ultra-High-Performance Concrete (UHPC) was investigated by machine learning (ML) and SHapley Additive exPlanations (SHAP). Important features were selected by feature importance analysis, including water-to-binder ratio, aggregate-to-cement ratio, compressive strength at loading age, elastic modulus at loading age, loading duration, steel fiber volume content, and curing temperature. Four typical ML models—Random Forest (RF), Artificial Neural Network (ANN), Extreme Gradient Boosting Machine (XGBoost), and Light Gradient Boosting Machine (LGBM)—were studied to predict the creep behavior of UHPC. Via Bayesian optimization and 5-fold cross-validation, the ML models were tuned to achieve high accuracy (R2 = 0.9847, 0.9627, 0.9898, and 0.9933 for RF, ANN, XGBoost, and LGBM, respectively). The contribution of different features to the creep behavior was ranked. Additionally, SHAP was utilized to interpret the predictions by the ML models, and four parameters stood out as the most influential for the creep coefficient: loading duration, curing temperature, compressive strength at loading age, and water-to-binder ratio. The SHAP results were consistent with theoretical understanding. Finally, the UHPC creep curves for three different cases were plotted based on the ML model developed, and the prediction by the ML model was more accurate than that by fib Model Code 2010. [ABSTRACT FROM AUTHOR]

Published
2024
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19. A unified method for parameter optimization and dynamic characteristics analysis of tuned mass damper inerter.

Author

Peng, Sijie, Zhang, Lianzhen, and Zhang, Daguang

Subjects
*TUNED mass dampers, *KRAMERS-Kronig relations
Abstract

To enhance the performance of the tuned mass damper (TMD), an inerter has recently been incorporated into a conventional TMD system to constitute a new type of an inerter-based passive control system, namely, tuned mass damper inerter (TMDI). The present study proposes a unified design idea for the TMDI based on the Kramers–Kronig relations in the complex effective mass. The TMDI is equivalent to a combination of a static mass and a conventional TMD, and the theoretical links between the TMDI and conventional TMD have been established. Based on the proposed method, the performance of the TMDI is investigated combined with the existing dynamic characteristics of the conventional TMD. It is concluded that the proposed design idea is feasible, and the previously reported dynamic characteristics of the TMDI can be well demonstrated. Moreover, the mass ratio of the equivalent TMD can be used to compare the control performance of the TMDI and TMD, and when it is larger than the physical mass ratio, the inerter enhances the control performance of the TMD. [ABSTRACT FROM AUTHOR]

Published
2024
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