• Title/Summary/Keyword: civil engineering

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The effect of local topography on the seismic response of a coupled train-bridge system

  • Qiao, Hong;Du, Xianting;Xia, He;De Roeck, Guido;Lombaert, Geert;Long, Peiheng
    • Structural Engineering and Mechanics
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    • v.69 no.2
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    • pp.177-191
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    • 2019
  • The local topography has a significant effect on the characteristics of seismic ground motion. This paper investigates the influence of topographic effects on the seismic response of a train-bridge system. A 3-D finite element model with local absorbing boundary conditions is established for the local site. The time histories of seismic ground motion are converted into equivalent loads on the artificial boundary, to obtain the seismic input at the bridge supports. The analysis of the train-bridge system subjected to multi-support seismic excitations is performed, by applying the displacement time histories of the seismic ground motion to the bridge supports. In a case study considering a bridge with a span of 466 m crossing a valley, the seismic response of the train-bridge system is analyzed. The results show that the local topography and the incident angle of seismic waves have a significant effect on the seismic response of the train-bridge system. Leaving these effects out of consideration may lead to unsafe analysis results.

Comparison of support vector machines enabled WAVELET algorithm, ANN and GP in construction of steel pallet rack beam to column connections: Experimental and numerical investigation

  • Hossein Hasanvand;Tohid Pourrostam;Javad Majrouhi Sardroud;Mohammad Hasan Ramasht
    • Structural Engineering and Mechanics
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    • v.87 no.1
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    • pp.19-28
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    • 2023
  • This paper describes the experimental investigation of steel pallet rack beam-to-column connec-tions. Total behavior of moment-rotation (M-φ) curve and the effect of particular characteristics on the behavior of connection were studied and the associated load strain relationship and corre-sponding failure modes are presented. In this respect, an estimation of SPRBCCs moment and rotation are highly recommended in early stages of design and construction. In this study, a new approach based on Support Vector Machines (SVMs) coupled with discrete wavelet transform (DWT) is designed and adapted to estimate SPRBCCs moment and rotation according to four input parameters (column thickness, depth of connector and load, beam depth,). Results of SVM-WAVELET model was compared with genetic programming (GP) and artificial neural networks (ANNs) models. Following the results, SVM-WAVELET algorithm is helpful in order to enhance the accuracy compared to GP and ANN. It was conclusively observed that application of SVM-WAVELET is especially promising as an alternative approach to estimate the SPRBCCs moment and rotation.

Seismic performance of Bujian Puzuo considering scale ratio and vertical load effects

  • Yong-Hui Jiang;Jun-Xiao He;Lei Zhu;Lin-Lin Xie;Shuo Fang
    • Structural Engineering and Mechanics
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    • v.90 no.5
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    • pp.447-458
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    • 2024
  • This study investigated the influence of scale ratio and vertical load on the seismic performance of Puzuo joints in traditional Chinese timber structures. Three low-cyclic reversed loading tests were conducted on three scaled specimens of Bujian Puzuo in Yingxian Wooden Pagoda. This study focused on the deformation patterns and analyzed seismic performance under varying scale ratios and vertical loads. The results indicated that the slip and rotational deformations of Bujian Puzuo were the primary deformations. The scale of the specimen did not affect the layer where the maximum interlayer slip occurred, but it did decrease the proportion of slip deformation. Conversely, the reducing vertical load caused the layer with the maximum slippage and the position of the damaged Dou components to shift upward, and the proportion of slip deformation increased. When the vertical load was decreased by 3.7 times, the maximum horizontal bearing capacity under positive and negative loadings, initial stiffness, and energy dissipation of the specimen decreased by approximately 60%, 58.79%, 69.62%, and 57.93%, respectively. The horizontal bearing capacity under positive loading and energy dissipation of the specimen increased by 35.63% and 131.54%, when the specimen scale was doubled and the vertical load was increased by 15 times.

Seismic train-bridge coupled system sensitivity analysis considering random aftershock intensity and residual track deformation

  • Jincheng Tan;Manman Chen;Xiang Liu;Han Zhao;Lizhong Jiang;Peidong Guo;Wangbao Zhou;Ping Xiang
    • Structural Engineering and Mechanics
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    • v.91 no.1
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    • pp.25-38
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    • 2024
  • After the mainshock, whether the train can be allowed to pass the bridges plays an important role in ensuring the transport of supplies and rescue works for example, in the "12 May" earthquake in China, after evaluation, the bridge was still used for transportation in rescue at a very slow speed, engineers usually evaluate whether the train can pass the bridge safely based on the experience, lacks sufficient calculation basis and does not fully consider the risk caused by aftershocks. To address this issue, this paper comprehensively considers the randomness of track irregularity, the randomness of aftershock intensity and other multiple random sources in train-bridge interaction system (TBIS). The sensitivity of train to various random parameters after earthquake is analyzed from the perspective of probability, the most sensitive random variable in this paper is PGA of aftershocks, both for bridge and trailer car, With the increase of epicentral distance, the sensitivity of PGA will decrease, and correspondingly, for trailer car, the sensitivity of other random variables will increase, research in this paper provides a basis for the subsequent random analysis of post-earthquake driving safety.