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Seismic running safety assessment for stochastic vibration of train–bridge coupled system

Zhao Han, Wei Biao, Jiang Lizhong, Xiang Ping

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e180, 2022

EN

With the rapid development of high-speed railway, the seismic running safety problem of high-speed train passing on bridge is becoming increasingly prominent. Since different wheel–rail contact states including uplifting, climbing up, detachment, recontact and derailment have been introduced into the simulation of train–bridge coupled (TBC) system, there are many problems arising for the mainstream derailment index in evaluating seismic running safety and stochastic analysis of train. To this end, a seismic running safety assessment for stochastic response of TBC system was first proposed in this paper. In this system, a detailed wheel–rail contact model was built to calculate the time-varying contact point and the contact force, which can be applied to simulate the detachment and recontact between the wheel flange and rail. Meanwhile, a stochastic analysis framework for derailment of the TBC system is developed. The stochastic vibration of a high-speed train traversing a multi-span prestressed simply supported box-girder bridge under earthquake with random magnitude was studied. In addition, an improved train running safety index, lateral wheel–rail relative displacement, was proposed and compared with the derailment factor and the offload factor to verify its feasibility. It shows an intuitive result as a derailment index in a stochastic train running safety analysis under earthquake. Furthermore, the lateral wheel–rail relative displacement and pertinent derailment probability were significantly affected by the intensity of the earthquake. The methodology herein can be helpful in seismic running safety assessment of high-speed train.

2

Seismic behavior of corroded reinforced concrete column joints under low-cyclic repeated loading

Luo Xiaoyong, Cheng Junfeng, Xiang Ping, Long Hao

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 2

138--157

EN

To investigate the influence of corroded steel bars on seismic performance of reinforced concrete (RC) columns, eight full-scale RC columns were designed and fabricated, which were composed of one uncorroded RC column, three RC columns with longitudinal reinforcement corrosion and four stirrup-corroded RC columns. The electrochemical test was conducted to accelerate the corrosion of steel bars in RC columns, and the low-cyclic repeated loading tests on RC columns with corrosion-damaged steel bars were carried out. The seismic behavior indicators, including the hysteretic curves, skeleton curves, displacement ductility coefficient, stiffness degradation curves and energy dissipation capacity of corroded RC columns and uncorroded columns, were compared and discussed. The experimental results show that with the increase in steel bars corrosion degree, the pinch phenomenon of the hysteretic curve gradually increases, and the energy dissipation capacity, stiffness and plastic deformation capacity of specimen reduce significantly. The ductility and energy dissipation coefficient decreased by 20% and 36%, respectively, when the stirrups corrosion ratio of specimen reaches 15.2%, and a shear failure surface was formed in the plastic hinge zone at the foot of the columns, which leads to the change of failure mode from ductile bending failure to shear failure with poor ductility under the ultimate load for corroded columns. The influence of stirrup corrosion on the failure mode of specimens is remarkable, but the effect of longitudinal reinforcement corrosion is negligible for specimens with the corrosion ratio within 14.7%. The adverse effects caused by over 15.2% stirrup corrosion should be considered in seismic design of structures in seismic zone.

3

Mechanical performance of overlap connections with grout-filled anchor reinforcements in embedded metal corrugated pipe

Chen Jun, Chen Xulin, Ding Fa-xing, Xiang Ping, Yang Cai-qian, Liu Yilong, Xu Fu

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 4

456--467

EN

To study the mechanical performances of a new kind of overlapping connection with grouted anchor reinforcements in embedded metal corrugated pipes, a total of 24 groups of 72 specimens were prepared and tested. The overlap connection performance of grouting anchor reinforcements in embedded metal corrugated pipes was studied by bi-directional tension test. The factors such as the diameter of anchor reinforcements, anchor length and location of reinforcements were taken into account. The results show that the bi-directional tension test method can effectively reflect the actual stress state of the overlap connection. When the connection satisfies the structural requirements, the location of the reinforcement has little influence on the anchorage performance of the connection. Under the same conditions, the failure load of the specimens will increase with the increase of the diameter of reinforcements and the anchorage length. Meanwhile, under the same conditions, the average bond stress decreases with the increase of the reinforcement diameter and the anchorage length. Experimental results and analysis show that overlap connection with grout-filled anchor reinforcements in embedded metal corrugated pipe has good anchoring performances, and also has the advantages of simple structure and convenient construction.