• Structural Engineering and Mechanics
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• v.85 no.2
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• pp.265-274
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• 2023

The spherical steel bearings (SSBs) has been gradually replaced traditional rubber bearings and extensively applied to high-speed railway (HSR) bridges in China, due to their durability and serviceability. Nevertheless, SSB is generally simplified to the ordinary constraints in the finite element model, which cannot reflect its detailed mechanical characteristics, especially its seismic performance. To provide a more precisely simulation, an innovative and simplified finite element simulation method is proposed and the combined element group is developed in ANSYS. The primary parameters were determined by means of the performance test of SSB. The finite element model of SSB applied to a single-span HSR simply supported girder bridge was established through the proposed method. The seismic performance of the SSB was further investigated. A shake table test was conducted to evaluate the accuracy of the proposed simulation method. It is found that the numerical results could have a good agreement with the experiment, namely, the proposed method is feasible and efficient.

• Earthquakes and Structures
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• v.14 no.4
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• pp.337-347
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• 2018

This paper presents some shaking table tests conducted on a 1/4-scaled model with 5-story steel reinforced concrete (SRC) spatial frame with irregular section columns under a series of base excitations with gradually increasing acceleration peaks. The test frame was subjected to a sequence of seismic simulation tests including 10 white noise vibrations and 51 seismic simulations. Each seismic simulation was associated with a different level of seismic disaster. Dynamic characteristic, strain response, acceleration response, displacement response, base shear and hysteretic behavior were analyzed. The test results demonstrate that at the end of the loading process, the failure mechanism of SRC frame with irregular section columns is the beam-hinged failure mechanism, which satisfies the seismic code of "strong column-weak beam". With the increase of acceleration peaks, accumulated damage of the frame increases gradually, which induces that the intrinsic frequency decreases whereas the damping ratio increases, and the peaks of acceleration and displacement occur later. During the loading process, torsion deformation appears and the base shear grows fast firstly and then slowly. The hysteretic curves are symmetric and plump, which shows a good capacity of energy dissipation. In summary, SRC frame with irregular section columns can satisfy the seismic requirements of "no collapse under seldom earthquake", which indicates that this structural system is suitable for the construction in the high seismic intensity zone.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.43-48
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• 2022

In order to evaluate the seismic performance of the modular expansion joint known for its large expansion allowance and remarkable durability, this study conducts seismic response analysis and seismic simulation test. The bridge selected for the seismic response analysis is a cable stayed bridge with main span length of 1,000m. Three artificial earthquake were generated with respect to the design response spectra of the Korean Standards (KS), AASHTO LRFD and Eurocode, and applied to the selected bridge. The seismic simulation tests reproduced the artificial earthquakes using dynamic hydraulic actuators in the longitudinal and transverse directions. The test results verified the durability and safety of the expansion joint in view of its seismic behavior since abnormal behavior or failure of the expansion joint was not observed when the artificial earthquake waves were applied in the longitudinal direction, transverse direction and both directions.

• Computers and Concrete
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• v.32 no.1
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• pp.15-26
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• 2023

In order to study the anti-seismic performance of full light-weight concrete utility tunnel, EL Centro seismic waves were input, and the seismic simulation shaking table test was carried out on the four utility tunnel models. The dynamic characteristics and acceleration response of the system consisting of the utility tunnel structure and the soil, and the interlayer displacement response of the structure were analyzed. The influence law of different construction methods, haunch heights and concrete types on the dynamic response of the utility tunnel structure was studied. And the experimental results were compared with the finite element calculation results. The results indicated that with the increase of seismic wave intensity, the natural frequency of the utility tunnel structure system decreased and the damping ratio increased. The assembling composite construction method could be equivalent to replace the integral cast-in-place construction method. The haunch height of the assembling composite full light-weight concrete utility tunnel was increased from 30 mm to 50 mm to enhance the anti-seismic performance during large earthquakes. The anti-seismic performance of the full light-weight concrete utility tunnel was better than that of the ordinary concrete utility tunnel. The peak acceleration of the structure was reduced by 21.8% and the interlayer displacement was reduced by 45.8% by using full light-weight concrete. The finite element simulation results were in good agreement with the experimental results, which could provide reference for practical engineering design and application.

• Steel and Composite Structures
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• v.34 no.5
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• pp.715-732
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• 2020

High-strength steel composite Y-eccentrically braced frame (Y-HSS-EBF) is a novel structural system. In this study, the spatial substructure hybrid simulation test (SHST) method is used to further study the seismic performance of Y-HSS-EBF. Firstly, based on the cyclic loading tests of two single-story single-span Y-HSS-EBF planar specimens, a finite element model in OpenSees was verified to provide a reference for the numerical substructure analysis model for the later SHST. Then, the SHST was carried out on the OpenFresco test platform. A three-story spatial Y-HSS-EBF model was taken as the prototype, the top story was taken as the experimental substructure, and the remaining two stories were taken as the numerical substructure to be simulated in OpenSees. According to the test results, the validity of the SHST was verified, and the main seismic performance indexes of the SHST model were analyzed. The results show that, the SHST based on the OpenFresco platform has good stability and accuracy, and the results of the SHST agree well with the global numerical model of the structure. Under strong seismic action, the plastic deformation of Y-HSS-EBF mainly occurs in the shear link, and the beam, beam-columns and braces can basically remain in the elastic state, which is conducive to post-earthquake repair.

• Structural Engineering and Mechanics
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• v.73 no.4
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• pp.447-454
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• 2020

Seismic isolation technology has a wide application to protect bridges from earthquake damage, a new designed bridge pier with seismic isolation are provided for railways in seismic regions of China. The pier with rocking isolation is a self-centering system under small and moderate earthquakes, and the unbonded prestressed tendons are used to prevent overturning under strong earthquakes. A numerical model based on pseudo-static testing results is presented to evaluate the seismic performance of isolation bridge piers, and is validated by the shaking table test. It is found that the rocking response and the loss of prestressing for the bridge pier increase with the increase of earthquake intensity. Besides, the intensity and spectral characteristics of input ground motion have great influence on displacement of the top and bottom of the bridge pier, while have less influence on the bending moment of the pier bottom. Experimental and numerical results show that the rocking-isolated piers presented in this study have good seismic performance, and it provides an alternative way for the railway bridge in the regions with high occurrence of earthquakes. Therefore, we provide the detailed procedures for seismic design of the rocking-isolated bridge pier, and a case study of the seismic isolation design with rocking piers is carried out to popularize the seismic isolation methods.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.2
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• pp.35-42
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• 2021

In this study, a steel frame that realized the second floor of a structure was fabricated in referring to NFPA 13. In addition, a riser pipe system with groove joints was installed, and a seismic simulation test was performed using static cyclic loading. Cyclic loading tests on the maximum allowable side sway of seismic design standards for buildings in Korea were conducted using actuators to analyze the seismic behavior of the riser pipe system and major piping elements due to the deformation of the steel frame structure or the displacement-dominant behavior caused by the relative displacement between the structural members in the event of a seismic load. Moreover, the deformation angle of the riser pipe system was measured using an image measurement system because it is difficult to measure using the conventional sensors.

• Computers and Concrete
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• v.27 no.2
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• pp.163-173
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• 2021

In this paper, the parameters of haunch height, reinforcement ratio and site condition were evaluated for the influence on the seismic performance of a composite precast fabricated utility tunnel by shaking table test and numerical simulation. The dynamic response laws of acceleration, interlayer displacement and steel strain under unidirectional horizontal seismic excitation were analyzed through four specimens with a similarity ratio of 1:6 in the test. And a numerical model was established and analyzed by the finite element software ABAQUS based on the structure of utility tunnel. The results indicated that composite precast fabricated utility tunnel with the good anti-seismic performance. In a certain range, increasing the height of haunch or the ratio of reinforcement could reduce the influence of seismic wave on the utility tunnel structure, which was beneficial to the structure earthquake resistance. The clay field containing the interlayer of liquefied sandy soil has a certain damping effect on the structure of the utility tunnel, and the displacement response could be reduced by 14.1%. Under the excitation of strong earthquake, the reinforcement strain at the side wall upper end and haunches of the utility tunnel was the biggest, which is the key part of the structure. The experimental results were in good agreement with the fitting results, and the results could provide a reference value for the anti-seismic design and application of composite precast fabricated utility tunnel.

• Earthquakes and Structures
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• v.26 no.3
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• pp.239-249
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• 2024

A new layered shear continuum model box was developed to address the dynamic response issues of buried oil and gas pipelines under multi-point excitation. Vibration table tests were conducted to investigate the seismic response of buried pipelines and the surrounding soil under longitudinal multi-point excitation. A nonlinear model of the pipeline-soil interaction was established using ABAQUS finite element software for simulation and analysis. The seismic response characteristics of the pipeline and soil under longitudinal multi-point excitation were clarified through vibration table tests and simulation. The results showed good consistency between the simulation and tests. The acceleration of the soil and pipeline exhibited amplification effects at loading levels of 0.1 g and 0.2 g, which significantly reduced at loading levels of 0.4 g and 0.62 g. The peak acceleration increased with increasing loading levels, and the peak frequency was in the low-frequency range of 0 Hz to 10 Hz. The amplitude in the frequency range of 10 Hz to 50 Hz showed a significant decreasing trend. The displacement peak curve of the soil increased with the loading level, and the nonlinearity of the soil resulted in a slower growth rate of displacement. The strain curve of the pipeline exhibited a parabolic shape, with the strain in the middle of the pipeline about 3 to 3.5 times larger than that on both sides. This study provides an effective theoretical basis and test basis for improving the seismic resistance of buried oil and gas pipelines.

• Earthquakes and Structures
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• v.23 no.3
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• pp.245-257
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• 2022

This study is a basic study on the seismic reinforcement method of anchors of fixed parts in order to reduce the effect of seismic motion that affects the facilities in the event of an earthquake. By applying the test method of ICC ES AC 156, a seismic simulation experiment was performed on the vibration table with three axes simultaneously using the number of connecting bolts between cabinets and channels as a parameter. In addition, the reliability of the experiment was verified using numerical analysis, and the part about the dynamic characteristics that could not be performed according to the experimental limit was investigated through numerical analysis. As a result of the experiment, it was confirmed that the natural frequency of the main body was increased due to the increase in the number of connecting bolts between the cabinet-channel. Accordingly, it was judged that the rigidity of the lower part of the cabinet was increased due to seismic reinforcement. It was analyzed that the impact delivered to the body was effectively reduced. In the future, if the reinforcement of the connection parts mentioned in this study is added to the existing seismic reinforcement of the electrical cabinets, it is expected that the damage to the electrical cabinets of the power plant equipment caused by an earthquake will be effectively reduced.