scholarly journals Seismic Behavior of Turbine-Generator Foundation under Strong Earthquake Action in Different Directions

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Dong An ◽  
Tie-jun Qu
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Seismic Behavior ◽  
Turbine Generator ◽  
Maximum Displacement ◽  
Scaled Model ◽  
Seismic Displacement ◽  
Limit Value ◽  
Seismic Design Code ◽  
Story Drift

In order to study seismic behavior of half-speed turbine-generator foundation under horizontal earthquake loading in different directions, the 1/10 scaled model was designed and fabricated. The rigid foundation of half-speed turbine-generator sets can be seen as a complex space frame system. The tests were conducted under eight earthquake waves in two directions separately. The loading directions were along the axis of longitudinal and transverse. The seismic response of displacement and story drift was investigated by a pseudodynamic test. The hysteresis behavior and crack propagation were analyzed. From the research, it is shown that the maximum displacement of the foundation under the earthquake of intensity 7 is 15.20 mm (longitudinal), basically in the range of elastic deformation. The seismic response of earthquake input in different directions is obviously different. Under the same earthquake input, the seismic displacement along the axis of longitudinal is larger than that of transverse. Under the rarely earthquake of intensity 8, the foundation still keeps good working condition. The maximum elastic-plastic story drift is 1/191 under the limit value 1/50 provided in the Code for Seismic Design of Buildings. The deformation capacity of the structure meets the requirements of the current seismic design code of China.

scholarly journals Seismic Behavior of a Class of Mixed Reinforced Concrete-Steel Buildings Subjected to Near-Fault Motions

2021 ◽  
Vol 6 (12) ◽  
pp. 172
Author(s):  
Paraskevi K. Askouni ◽  
George A. Papagiannopoulos
Keyword(s):  
Reinforced Concrete ◽  
Seismic Response ◽  
Seismic Design ◽  
Seismic Behavior ◽  
Time History ◽  
Steel Buildings ◽  
Seismic Codes ◽  
Near Fault ◽  
Non Linear ◽  
Story Drift

This paper investigates the seismic behavior of a class of mixed reinforced concrete­–­steel buildings. In particular, mixed buildings constructed by r/c (reinforced concrete) at their lower story(ies) and structural steel at their upper story(ies) are studied from the viewpoint of their wide application in engineering praxis. The need to investigate the seismic behavior for this type of mixed buildings arises from the fact that the existent literature is small and that modern seismic codes do not offer specific seismic design recommendations for them. To study the seismic behavior of mixed r/c-steel buildings, a 3-D numerical model is employed and five realistic r/c-steel mixed buildings are simulated. Two cases of the support condition, i.e., fixed or pinned, of the lowest steel story to the upper r/c one are examined. The r/c and steel parts of the mixed buildings are initially designed as separate structures by making use of the relevant seismic design guidelines of Eurocode 8, and then the seismic response of these buildings is computed through non-linear time-history analyses. The special category of near-fault seismic motions is selected in these time-history analyses to force the mixed r/c-steel buildings under study to exhibit a strong non-linear response. Seismic response indices in terms of inter-story drift ratio, residual inter-story drift ratio and peak floor absolute accelerations are computed. The maximum values of these indices are discussed by comparing the two aforementioned kinds of support conditions and checking the satisfaction of specific seismic performance limits. Conclusions regarding the expected seismic behavior of mixed r/c-steel buildings under near-fault seismic motions are drawn. Finally, the need to introduce specific design recommendations for mixed r/c-steel buildings in modern seismic codes is stressed.

Analysis for Seismic Response of Compacted Soil-Cement Pile Composite Foundations

2011 ◽  
Vol 368-373 ◽  
pp. 456-460
Author(s):  
Hong Huan Cui ◽  
Li Qun Zhang ◽  
Hai Long Wang
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Seismic Behavior ◽  
Composite Foundation ◽  
Response Analysis ◽  
Compacted Soil ◽  
Rigid Pile ◽  
Soil Cement ◽  
Earthquake Load ◽  
Rigid Pile Composite Foundation

Compacted soil-cement pile possess the excellences both flexible pile and rigid pile. The composite foundation of compacted soil-cement pile are getting more and more applicable to construction． However, the research on their response under dynamic load, especially under earthquake load，is quite limited．Now the seismic response analysis in time domain is performed with finite element method(ABAQUS).Some parameters influencing the anti-seismic behavior of half-rigid pile composite foundation are studied． Based on these research , some conclusions which may be of some value for anti-seismic design of this type of composite foundations are drawn．

Seismic Displacement Design Method Comparison between Chinese, American, European and Japanese Seismic Design Codes

2013 ◽  
Vol 859 ◽  
pp. 43-47
Author(s):  
Gui Ming Zhang ◽  
Wen Feng Liu ◽  
Zhi Hong Chen
Keyword(s):  
Seismic Design ◽  
Design Method ◽  
Method Comparison ◽  
Chinese American ◽  
Frame Structure ◽  
Design Codes ◽  
Reinforced Concrete Frame ◽  
Seismic Displacement ◽  
Story Drift ◽  
Earthquake Action

Seismic displacement design method and allowable values of story drift are compared between Chinese, American, European and Japanese seismic design codes. An engineering example's seismic displacement is calculated in the methods given by the four codes, and story drift are compared. Researches show that allowable story drift of Chinese code under rare earthquake action is approximately close to that of American with a 10% probability of exceedance in 50 years, and allowable story drift of Japanese code is more rigorous than other three codes. For three-story three-span reinforced concrete frame structure, in the condition of same intensity, displacement of Chinese under the earthquake action with 2~3% exceeding probability of 50-year is greater than that of American and European with 10% exceeding probability of 50-year. However, intensity plays no role in Japan's displacement calculation, and the calculation result of displacement of Japanese code is less than other three codes.

scholarly journals Influence of Superior Vibration Modes on the Seismic Response of Reinforced Concrete Structures with Eigen-Periods Near Code Control Periods

2020 ◽  
Vol 9 (1) ◽  
pp. 108-122
Author(s):  
Savu Adrian-Alexandru
Keyword(s):  
Reinforced Concrete ◽  
Seismic Response ◽  
Seismic Design ◽  
Structural Design ◽  
Control Period ◽  
Three Dimensional ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Base Shear ◽  
Seismic Design Code

Abstract The current paper studies the effect of superior eigen-modes on the seismic response for a series of reinforced concrete structures having eigen-periods near code control periods. Although the structural design is based on Romanian seismic design codes (“P100-1/2013 - Seismic design code - Part 1 - Design provisions for buildings” and “SR-EN 1998/2004 - Design of structures for earthquake resistance”), it carries some importance for other countries with similar seismic design spectra. A total of twenty-four models for structures were considered by varying their location (through control period values), three-dimensional regularity, overall dimensions and height regime. Results were compared and conclusions were drawn based on percentage values of relative displacements (storey drifts) and base shear forces.

scholarly journals Dynamic Characteristics and Seismic Response Analysis of Self-Anchored Suspension Bridge

2012 ◽  
Vol 5 ◽  
pp. 183-188
Author(s):  
Lian Zhen Zhang ◽  
Tian Liang Chen
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Dynamic Characteristics ◽  
Response Spectrum ◽  
Time History ◽  
Suspension Bridge ◽  
Bridge Engineering ◽  
Response Analysis ◽  
Seismic Response Analysis ◽  
Seismic Design Code

Self-anchored suspension bridge is widely used in Chinese City bridge engineering for the past few years. Because the anchorage system of main cable has been changed from anchorage blocks to the ends of the girder, its’ dynamic mechanics behavior is greatly distinguished with the traditional earth anchored suspension bridge. This paper studies the dynamic characteristics and seismic response of one large-span self-anchored suspension bridge which is located in China/Shenyang city. Using a spatial dynamic analysis finite element mode, the dynamic characteristics are calculated out. An artificial seismic wave is adopted as the ground motion input which is fitted with acceleration response spectrum according to the Chinese bridge anti-seismic design code. Time-integration method is used to get the seismic time-history response. Geometry nonlinear effect is considered during the time-history analysis. At last, the dynamic characteristics and the behavior of earthquake response of this type bridge structure are discussed clearly. The research results can be used as the reference of seismic response analysis and anti-seismic design for the same type of bridge.

Comments about the Seismic Behavior of “Inverted Y”- Braced Frames

2018 ◽  
Vol 763 ◽  
pp. 106-115
Author(s):  
Helmuth Köber ◽  
Marina Stoian
Keyword(s):  
Seismic Design ◽  
Cross Sections ◽  
Seismic Behavior ◽  
Braced Frames ◽  
Design Code ◽  
Nonlinear Analyses ◽  
Braced Frame ◽  
Seismic Design Code ◽  
Steel Consumption ◽  
Plastic Zones

Four configurations were analyzed for a ten storey “inverted Y-braced” frame with rigid and/or pined beam/column and diagonal/column connections. All considered frame configurations were sized for the forces produced by the same code seismic design force evaluated according to the in charge Romanian seismic design code. In case of two of the considered configurations, additional potentially plastic zones with reduced member cross-sections were provided along the girders and diagonals of the frame (in order to size clearly by design a global plastic failure mechanism for the “inverted Y-braced” frame). The behavior of each frame configuration during dynamic nonlinear analyses was observed. The steel consumption was estimated for each considered configuration.

scholarly journals Seismic Behavior of Concentrically Braced Steel Frames with Out-of-Plane Offset Irregularity

2017 ◽  
Vol 11 (1) ◽  
pp. 485-495 ◽  
Author(s):  
Amin Mohebkhah ◽  
Marzieh Akefi
Keyword(s):  
Seismic Design ◽  
Seismic Behavior ◽  
Steel Frames ◽  
Design Parameters ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Overstrength Factor ◽  
Concentrically Braced ◽  
Out Of Plane ◽  
Story Drift

Braced steel frames are sometimes designed with out-of-plane shifted bracing members on the first story due to architectural or functional considerations. Such frames are classified and designated as frames having the Type-4 horizontal structural irregularity entitled “frames with out-of-plane offset irregularity” as per theMinimum Design Loads for Building and Other Structures(ASCE 7-10). The purpose of this study is to investigate the nonlinear seismic behavior of ordinary steel concentrically braced frames with out-of-plane offset irregularity and evaluate their seismic design parameters. To this end, two 3-story and 6-story three-dimensional ordinary concentrically braced frames (OCBFs) with and without out-of-plane offset of one of the vertical elements on the first story were considered (i.e. irregular and regular configurations). The seismic design parameters considered in this study includes: frame overall overstrength factor, column overstrength factor and the inelastic dynamic inter-story drift demands. Nonlinear time-history dynamic analysis of the frames showed that overall overstrength factor of the low- and mid-rise irregular frames studied in this research is lower than that of the regular ones. Moreover, it was found that theSeismic Provisionsprescribed overstrength factor (i.e. Ωo=2.0) to amplify columns axial seismic forces in OCBFs is not conservative for the studied regular frames’ columns as well as the columns in the vicinity of the shifted bracing members on the first story of the irregular frames. Also, it was shown that the studied low- and mid-rise regular and irregular concentrically braced frames experience greater inter-story drift demands than predicted by the amplified elastic analysis proposed in the codes.

scholarly journals The effect of story drift in a multi-story building under the influence of an earthquake

2021 ◽  
Vol 17 (3) ◽  
pp. 270-277
Author(s):  
Dmitriy A. Sharapov ◽  
Tesfaldet H. Gebre ◽  
Yusuf M. Ali
Keyword(s):  
Reinforced Concrete ◽  
Horizontal Plane ◽  
Seismic Behavior ◽  
Lateral Force ◽  
Seismic Loads ◽  
Reinforced Concrete Structure ◽  
Maximum Displacement ◽  
Concrete Building ◽  
Story Drift ◽  
Story Building

This paper content is structure subjected sudden story drift as a result from earthquakes, forming hinges and eventually collapsing. The aim of this paper is to develop building thirty story building for seismic in Khartoum using finite element method (FEM) and the equivalent lateral force (ELF) procedure of American code ASCE 7-16. In current work the thirty-story reinforced concrete building was considered is to analyze the seismic behavior of the reinforced concrete structure to find the drift between the story by finding the maximum displacement from the program that causes the building to collapse, by choosing the shear wall as the support system to resist the lateral load and by looking to model the building inclined to the horizontal plane. Calculations were also made on the drift between the story to compare with the allowable drift. It is implemented in the Robot structural program - an ingenious program for designing and analyzing lateral (seismic) loads.

scholarly journals Probabilistic seismic response analysis of coastal highway bridges under scour and liquefaction conditions: does the hydrodynamic effect matter?

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Xiaowei Wang ◽  
Yutao Pang ◽  
Aijun Ye
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Highway Bridges ◽  
Element Model ◽  
Response Analysis ◽  
Hydrodynamic Effect ◽  
Strong Earthquakes ◽  
Influence Of Water ◽  
Scour Hazard ◽  
Ground Motion Records

AbstractCoastal highway bridges are usually supported by pile foundations that are submerged in water and embedded into saturated soils. Such sites have been reported susceptible to scour hazard and probably liquefied under strong earthquakes. Existing studies on seismic response analyses of such bridges often ignore the influence of water-induced hydrodynamic effect. This study assesses quantitative impacts of the hydrodynamic effect on seismic responses of coastal highway bridges under scour and liquefaction potential in a probabilistic manner. A coupled soil-bridge finite element model that represents typical coastal highway bridges is excited by two sets of ground motion records that represent two seismic design levels (i.e., low versus high in terms of 10%-50 years versus 2%-50 years). Modeled by the added mass method, the hydrodynamic effect on responses of bridge key components including the bearing deformation, column curvature, and pile curvature is systematically quantified for scenarios with and without liquefaction across different scour depths. It is found that the influence of hydrodynamic effect becomes more noticeable with the increase of scour depths. Nevertheless, it has minor influence on the bearing deformation and column curvature (i.e., percentage changes of the responses are within 5%), regardless of the liquefiable or nonliquefiable scenario under the low or high seismic design level. As for the pile curvature, the hydrodynamic effect under the low seismic design level may remarkably increase the response by as large as 15%–20%, whereas under the high seismic design level, it has ignorable influence on the pile curvature.

scholarly journals Experimental Study on the Behavior of Existing Reinforced Concrete Multi-Column Piers under Earthquake Loading

2021 ◽  
Vol 11 (6) ◽  
pp. 2652
Author(s):  
Jung Han Kim ◽  
Ick-Hyun Kim ◽  
Jin Ho Lee
Keyword(s):  
Seismic Performance ◽  
Seismic Design ◽  
Bridge Piers ◽  
Scale Model ◽  
Inertia Force ◽  
Small Scale ◽  
Lap Splice ◽  
Existing Structures ◽  
Seismic Design Code ◽  
Seismic Force

When a seismic force acts on bridges, the pier can be damaged by the horizontal inertia force of the superstructure. To prevent this failure, criteria for seismic reinforcement details have been developed in many design codes. However, in moderate seismicity regions, many existing bridges were constructed without considering seismic detail because the detailed seismic design code was only applied recently. These existing structures should be retrofitted by evaluating their seismic performance. Even if the seismic design criteria are not applied, it cannot be concluded that the structure does not have adequate seismic performance. In particular, the performance of a lap-spliced reinforcement bar at a construction joint applied by past practices cannot be easily evaluated analytically. Therefore, experimental tests on the bridge piers considering a non-seismic detail of existing structures need to be performed to evaluate the seismic performance. For this reason, six small scale specimens according to existing bridge piers were constructed and seismic performances were evaluated experimentally. The three types of reinforcement detail were adjusted, including a lap-splice for construction joints. Quasi-static loading tests were performed for three types of scale model with two-column piers in both the longitudinal and transverse directions. From the test results, the effect on the failure mechanism of the lap-splice and transverse reinforcement ratio were investigated. The difference in failure characteristics according to the loading direction was investigated by the location of plastic hinges. Finally, the seismic capacity related to the displacement ductility factor and the absorbed energy by hysteresis behavior for each test were obtained and discussed.

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