scholarly journals Shaking Table Tests of Curved Bridge considering Bearing Friction Sliding Isolation

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Lei Yan ◽  
Qingning Li ◽  
Chun Han ◽  
Haotian Jiang
Keyword(s):  
Seismic Design ◽  
Reduction Rate ◽  
Shaking Table ◽  
Seismic Model ◽  
Peak Acceleration ◽  
Curved Bridges ◽  
Curved Bridge ◽  
Maximum Reduction ◽  
Sliding Isolation ◽  
Bearing Friction

Specific to severe damage to curved bridges in earthquakes caused by the excessive force of the fixed bearings and piers, a new seismic design method on curved bridges considering bearing friction sliding isolation is proposed in this paper. Seismic model bridge and isolation model bridge with similarity ratio of 1/20 were made and the shaking table comparison test was conducted. The experimental results show that the isolation model curved bridge suffered less seismic damage than the seismic model curved bridge. The fundamental frequencies of the seismic model bridge and isolation model bridge decreased and the damping ratio increased with the increase of seismic intensity. Compared with seismic curved bridge, the maximum reduction rates of peak acceleration along the radial and tangential directions on the top of pier of the isolation model curved bridge were 47.3% and 55.5%, respectively, and the maximum reduction rate of the peak strain on the bottom of pier of the isolation model curved bridge was 43.4%. For the isolation model curved bridge, the maximum reduction rate of peak acceleration on the top of pier was 24.6% compared with that on the bottom of pier. The study results can provide experimental basis for the seismic design of curved bridges.

scholarly journals Model Test on the Vibration Reduction Characteristics of a Composite Foundation with Gravel Cushion under Different Seismic Wave Amplitudes

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Yingying Zhao ◽  
Weiming Gong ◽  
Xianzhang Ling ◽  
Peng Li ◽  
Ziyu Wang ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Seismic Waves ◽  
Vibration Reduction ◽  
Reduction Rate ◽  
Composite Foundation ◽  
Shaking Table ◽  
Isolation Effect ◽  
Peak Acceleration

Gravel cushions have been introduced as a practical and efficient seismic isolation technology to ensure the safety of nuclear power plants. This study investigated the seismic isolation effect of a gravel cushion by conducting a series of shaking table tests on a model foundation with a cushion built of three different types of graded aggregates (single-sized (2–5 mm), two-sized (2–5 mm:5–10 mm = 3 : 1), and continuously graded) under input El Centro seismic waves with three different peak accelerations (0.1 g, 0.2 g, and 0.3 g). The testing results showed that the seismic isolation effect of the gravel cushion increased with the peak seismic acceleration. The gravel cushion built with single-sized aggregates had better seismic isolation performance than gravel cushions built with two-sized or continuously graded aggregates. Under input seismic waves with 0.1 g peak acceleration, the single-sized aggregate gravel cushion still had a seismic isolation effect with a vibration reduction rate of approximately 11.81%, whereas the other two gravel cushions had no effect. Under input seismic waves with peak accelerations of 0.2 g and 0.3 g, all three gravel cushions had seismic isolation effects with vibration reduction rates of approximately 18.63% and 17.92%, respectively. An empirical model is proposed for predicting the vibration reduction rate of the cushion. Under input seismic waves with 0.3 g peak acceleration, the ultimate vibration reduction rate of the gravel cushion fell between 20.44% and 31.33%. The gravel cushion is an excellent option for nuclear power plant foundations with high requirements for seismic isolation, provided that the required bearing capacity is satisfied.

scholarly journals Analysis of the Effects of Soil on the Seismic Energy Responses of an Equipment-Structure System via Substructure Shaking Table Testing

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Lanfang Luo ◽  
Nan Jiang ◽  
Jihong Bi
Keyword(s):  
Seismic Design ◽  
Seismic Energy ◽  
Shaking Table ◽  
Input Energy ◽  
Test Results ◽  
Element Analysis ◽  
Testing Method ◽  
Shaking Table Testing ◽  
Soil Effects ◽  
Substructure Approach

This study investigated the real-time substructure shaking table testing (RTSSTT) of an equipment-structure-soil (ESS) system and the effects of soil on the seismic energy responses of the equipment-structure (ES) subsystem. First, the branch modal substructure approach was employed to derive the formulas needed for the RTSSTT of the ESS system. Then, individual equations for calculating the energy responses of the equipment and the structure were provided. The ES subsystem was adopted as the experimental substructure, whereas the reduced soil model was treated as the numerical substructure when the RTSSTT was performed on the ESS system. The effectiveness of the proposed testing method was demonstrated by comparing the test results with those of the integrated finite element analysis. The energy responses of the ES subsystem in the case of rigid ground (i.e., the ES system) were compared with those considering the effects of soil (i.e., the ESS system). The input energy responses of the ES subsystem were found to decrease significantly after taking the effects of soil into account. Differences due to the soil effects should be considered in the seismic design for the ES system.

scholarly journals Laboratory Tests for Subgrade Reaction Coefficient in Seismic Design of Underground Engineering Domain

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Kunpeng Xu ◽  
Liping Jing ◽  
Xinjun Cheng ◽  
Haian Liang ◽  
Jia Bin
Keyword(s):  
Seismic Design ◽  
Shaking Table Test ◽  
Free Field ◽  
Deformation Mode ◽  
Shaking Table ◽  
Subgrade Reaction ◽  
Underground Structures ◽  
Testing Methods ◽  
Underground Engineering ◽  
Reaction Coefficient

Subgrade reaction coefficient is commonly considered as the primary challenge in simplified seismic design of underground structures. Carrying out test is the most reliable way to acquire this intrinsic soil property. Owing to the limitations of experimental cost, time consumption, soil deformation mode, size effect, and confined condition, the existing testing methods cannot satisfy the requirements of high-precision subgrade reaction coefficient in seismic design process of underground structures. Accordingly, the present study makes an attempt to provide new laboratory testing methods considering realistic seismic response of soil, based on shaking table test and quasistatic test. Conventional shaking table test for sandy free-field was performed, with the results indicating that the equivalent normal subgrade reaction coefficients derived from the experimental hysteretic curves are reasonable and verifying the deformation mode under seismic excitation. A novel multifunctional quasistatic pushover device was invented, which can simulate the most unfavorable deformation mode of soil during the earthquake. In addition, the first successful application of an innovative quasistatic testing method in evaluating subgrade reaction coefficient was reported. The findings of this study provide preliminary detailed insights into subgrade reaction coefficient evaluation which can benefit seismic design of underground structures.

scholarly journals Seismic Performance of Curved Bridges with Longitudinal Slope

2019 ◽  
Vol 9 (4) ◽  
pp. 771
Author(s):  
Peng Su ◽  
Yanjiang Chen ◽  
Zhongwei Zhao ◽  
Weiming Yan
Keyword(s):  
Ground Motion ◽  
Structural Response ◽  
Seismic Excitation ◽  
Tangential Displacement ◽  
Site Conditions ◽  
Rotation Effect ◽  
Curved Bridges ◽  
Curved Bridge ◽  
Displacement Response ◽  
Main Girder

A curved bridge test model with a scale ratio of 1:10 was constructed to investigate the influence of site conditions on curved bridges with longitudinal slopes based on a similar theory. The natural ground motions of five different groups, namely, Sites A–E, were selected from the Pacific Earthquake Engineering Center (PEER) seismic database, and the shaking table model test was conducted under horizontal unidirectional and bidirectional excitations. Results showed that the structural response of the curved bridge is sensitive to the ground motion of different site conditions. Spatial characteristics are observed in the main girder structural response of the curved bridge. When the curved bridge is parallel to the direction of the principal ground motion, the rotation effect of the main girder is greater than that perpendicular to the direction of the principal ground motion. The rotation effect of the main girder leads to evident beam end and bearing displacements at the low pier. The seismic excitation direction and pier height notably affect the displacement response of the pier, and the tangential displacement response of the fixed pier is sensitive to seismic excitation.

Study on the Suitability of Seismic Isolation Technologies for Rural Buildings

2013 ◽  
Vol 353-356 ◽  
pp. 2221-2227
Author(s):  
Guang Hui Zhang
Keyword(s):  
Friction Coefficient ◽  
Seismic Isolation ◽  
Shaking Table Test ◽  
Shaking Table ◽  
Economic Conditions ◽  
Difficulty Level ◽  
Earthquake Disaster ◽  
Sliding Isolation ◽  
Rural Buildings ◽  
Collapse Ratio

Rural buildings are subject to the most serious damage and the highest collapse ratio in earthquake disaster. It is urgent at present to develop seismic isolation technologies applicable to rural buildings under current rural economic conditions of China. Through comparing the existing domestic seismic isolation technologies in respects of the acquisition difficulty level, price and friction coefficient of material and the placement of sliding material, and analyzing the result of simulated shaking table test respectively with the gravel foundation isolation technology and the gravel sliding isolation technology, this paper points out matters needing attention during the development of seismic isolation technologies for rural buildings.

Shaking Table Test on Unreinforced Stone Masonry Pagoda

2012 ◽  
Vol 166-169 ◽  
pp. 730-733 ◽  
Author(s):  
Fei Zhu ◽  
Feng Lai Wang ◽  
Xu Jie Sun ◽  
Y. Zhao
Keyword(s):  
Dynamic Behavior ◽  
Seismic Performance ◽  
Seismic Design ◽  
Shaking Table Test ◽  
Shaking Table ◽  
Cultural Value ◽  
Scale Model ◽  
Stone Masonry ◽  
Experimental Program ◽  
Ancient China

Unreinforced stone masonry pagodas have great cultural value and should be detailed investigation its mechanical properties. These buildings were not designed to resist earthquakes in ancient China, at least not in the way of current methods. The objectives of this research were to understand the dynamic behavior of unreinforced stone masonry pagoda and its seismic performance. To accomplish these, a 1/12 scale model of China Dinosaurs Pagoda was constructed and tested on shaking table. The octangle model height is 3.96m, with aspect ratio of height to width is 2.93, both parameters exceed the stipulated limit of Code for Seismic Design of Building. The model built with the stones and motars similar to the prototype materials and the arrangements. Its dynamic behavior and seismic performance were tested on the shaking table towards the free vibration and three earthquake waves. The experimental program adopted in the research is explained in this paper.

Experimental Study on the Seismic Response of Subway Station in Soft Ground

2017 ◽  
Vol 11 (05) ◽  
pp. 1750020 ◽  
Author(s):  
Ma Xianfeng ◽  
Wang Guobo ◽  
Wu Jun ◽  
Ji Qianqian
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Shaking Table Test ◽  
Design Method ◽  
Underground Structure ◽  
Response Characteristic ◽  
Shaking Table ◽  
Subway Station ◽  
Soft Ground ◽  
Shaking Table Tests

Shaking table tests were conducted on typical models of subway structures subjected to several seismic shaking time histories to study seismic response of subway structures in soft ground as well as to provide data for validation of seismic design methods for underground structure. Three types of tests were presented herein, namely green field test, subway station test, and test for joint structure between subway station and tunnel. The similitude and modeling aspects of the 1g shaking table test are discussed. The seismic response of Shanghai clay in different depths was examined under different input waves to understand the acceleration amplification feature in both green field and in the presence of underground structure. Damage situation was checked on internal sections of both subway station and tunnels by halving the model structure. Structure deformation was investigated in terms of element strain under different earthquake loadings. The findings from this study provides useful pointers for future shaking table tests on underground structures/facilities, and the seismic response characteristic of underground structure derived from the shaking table test could be helpful for validating seismic design method for subway station.

Study on Piping Response Under Multiple Excitation: Part 2 — Validation for Multiple Excitation Analysis of Piping

2013 ◽  
Author(s):  
Satoru Kai ◽  
Tomoyoshi Watakabe ◽  
Naoaki Kaneko ◽  
Kunihiro Tochiki ◽  
Makoto Moriizumi ◽  
...  
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Nuclear Power ◽  
Response Spectrum ◽  
Time History ◽  
Response Spectra ◽  
Shaking Table ◽  
Response Analysis ◽  
Multiple Time ◽  
Floor Response Spectra

The piping in a nuclear power plant is laid across multiple floors of a single building or two buildings, which are supported at many points. As the piping is excited by multiple-inputs from the supporting points during an earthquake, seismic response analysis by multiple excitations is needed to obtain the exact seismic response of the piping. However, few experiments involving such multiple excitation have been performed to verify the validity of multiple excitation analysis. Therefore, analysis of the seismic design of piping in Japan is performed by the enveloped Floor Response Spectrum (FRS), which covers all floor response spectra at all supporting points. The piping response estimated by enveloped FRS is conservative in most cases compared with the actual seismic response by multiple excitations. To perform rational seismic design and evaluation, it is important to investigate the seismic response by multiple excitations and to verify the validity of the analytical method by multiple excitation test. This paper reports the validation results of the multiple-excitation analysis of piping compared with the results of the multiple excitations shaking test using triple uni-axial shaking table and a 3-dimensional piping model (89.1mm diameter and 5.5mm thickness). Three directional moments from the analysis and the shaking test were compared on the validation. As the result, it is confirmed that the analysis by multiple time history excitation corresponds with the test result.

Dynamic Response of Ceiling System with Light Steel Furring and Gypsum Board under Severe Earthquake

2012 ◽  
Vol 166-169 ◽  
pp. 2221-2225 ◽  
Author(s):  
Duo Zhi Wang ◽  
Jun Wu Dai
Keyword(s):  
Dynamic Response ◽  
Fe Model ◽  
Seismic Model ◽  
Peak Acceleration ◽  
Gypsum Board ◽  
Suspension Point ◽  
Input Acceleration ◽  
Current Code

In order to make sure reliability of ceiling system according to the current code, response acceleration of ceiling suspension points are obtained by seismic model developed by ANSYS/LS-DYNA. Then the FE model of ceiling system according to the current code is also developed in ANSYS/LS-DYNA. The input acceleration is added on ceiling suspension point. The following features are obtained from ceiling system with light steel furring and gypsum board under severe earthquake. These are: 1 Many gypsum boards which are designed according to the current code are failed and drop down，that may result in casualties. 2 The furrings are failed and did not drop down, then may drop for higher peak acceleration. 3 The ceiling system according to the current code is not safe under severe earthquake.

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