• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.335-340
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• 2002

In this study procedure for finding out additional viscous damping required to meet a performance target of an asymmetric nonlinear structure is developed based on the design concept of Pauly. The behavior of an asymmetric nonlinear structure after yielding is investigated. Finally the required amount of equivalent damping is obtained using the direct-displacement-based design method without carrying out time-consuming nonlinear dynamic time history analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.437-442
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• 2002

The purpose of this study is to investigate nonlinear behavior and estimate ultimate resistance of the wall structure against seismic loading. Experimental data for RC coupling elements are used for specifying the strength deterioration and stiffness degradation factor of hysteretic model. Modified coupling element models are used in the push over analysis and time history analysis. In the time history analysis, three earthquake waves are used in the analysis and their peak ground accelerations are changed to be 0.2g. The conclusions of this study are as follows : (1) In the push over analysis, yielding of coupling elements occurred at lower story with small story drift ratio as 0.3%. (2) In the time history analysis, the story drift ratio is sufficient for the requirement of Korean Code, But coupling elements at most stories of the buildings occurred yielding. i. e. the earthquake resistant capacity of shear wall structures is not sufficient at 0.2g.

• International Journal of Concrete Structures and Materials
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• v.7 no.2
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• pp.135-153
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• 2013

This study investigates the direct displacement based design (DDBD) approach for different types of reinforced concrete structural systems including single moment-resisting, dual wall-frame and dual steel-braced systems. In this methodology, the displacement profile is calculated and the equivalent single degree of freedom system is then modeled considering the damping characteristics of each member. Having calculated the effective period and secant stiffness of the structure, the base shear is obtained, based on which the design process can be carried out. For each system three frames are designed using DDBD approach. The frames are then analyzed using nonlinear time-history analysis with 7 earthquake accelerograms and the damage index is investigated through lateral drift profile of the models. Results of the analyses and comparison of the nonlinear time-history analysis results indicate efficiency of the DDBD approach for different reinforced concrete structural systems.

• Earthquakes and Structures
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• v.17 no.1
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• pp.91-99
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• 2019

Fragility analysis is an effective tool that is frequently used for seismic risk assessment of bridges. There are three different approaches to derive a fragility curve: experimental, empirical and analytical. Both experimental and empirical methods to derive fragility curve are based on past earthquake reports and expert opinions which are not suitable for all bridges. Therefore, analytical fragility analysis becomes important. Nonlinear time history analysis is commonly used which is the most reliable method for determining probabilistic demand models. In this study, to determine the probabilistic demand models of bridges, time history analyses were performed considering both material and geometrical nonlinearities. Serviceability limit states for three different service velocities were considered as a performance goal. Also, support displacements, component yielding and collapse limits were taken into account. Both serviceability and component fragility were derived by using maximum likely hood methods. Finally, the seismic performance and critical members of the bridge were probabilistically determined and clearly presented.

• Journal of Mechanical Science and Technology
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• v.19 no.7
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• pp.1517-1525
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• 2005

Liquid sloshing displays the highly nonlinear free surface fluctuation when either the external excitation is of large amplitude or its frequency approaches natural sloshing frequencies. Naturally, the accurate tracking of time-varying free surface configuration becomes a key task for the reliable prediction of the sloshing time-history response. However, the numerical instability and dissipation may occur in the nonlinear sloshing analysis, particularly in the long-time beating simulation, when two simulation parameters, the relative time-increment parameter a and the fluid mesh pattern, are not elaborately chosen. This paper intends to examine the effects of these two parameters on the potential-based nonlinear finite element method introduced for the large amplitude sloshing flow.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1220-1226
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• 2011

The purpose of this study is to assess the seismic performance of a reinforced concrete pier using ductility demand-based seismic design method and nonlinear earthquake analysis. A computer program named MIDAS/Civil(MIDAS IT,2009) for the analysis of the reinforced concrete pier was used. The bridge pier was designed by the ductility demand-based seismic design. In addition, a seismic performance was evaluated through both capacity spectrum method and nonlinear time history method. In order to determine the seismic performance of the bridge pier, the maximum response values from the capacity spectrum method and nonlinear time history analysis were compared each other.

• Earthquakes and Structures
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• v.10 no.4
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• pp.811-828
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• 2016

This study aims to present nonlinear time history analysis results of double leaf cavity wall (DLCW) reinforced concrete structure exposed to shake table tests. Simulation of the model was done by a Finite Element (FE) program. Shake table experiment was performed at the National Civil Engineering Laboratory in Lisbon, Portugal. The results of the experiment were compared with numeric DLCW model and numeric model of reinforced concrete structure with unreinforced masonry wall (URM). Both DLCW and URM models have two bays and two stories. Dimensions of the tested structure and finite element models are 1:1.5 scaled according to Cauchy Froude similitude law. The URM model has no experimental results but the purpose is to compare their performance level with the DLCW model. Results of the analysis were compared with experimental response and were evaluated according to ASCE/SEI 41-06 code.

• International Journal of Concrete Structures and Materials
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• v.10 no.1
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• pp.99-112
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• 2016

During earthquake, reinforced concrete walls show complicated post-yield behavior varying with shear span-to-depth ratio, re-bar detail, and loading condition. In the present study, a macro-model for the nonlinear analysis of multi-story wall structures was developed. To conveniently describe the coupled flexure-compression and shear responses, a reinforced concrete wall was idealized with longitudinal and diagonal uniaxial elements. Simplified cyclic material models were used to describe the cyclic behavior of concrete and re-bars. For verification, the proposed method was applied to various existing test specimens of isolated and coupled walls. The results showed that the predictions agreed well with the test results including the load-carrying capacity, deformation capacity, and failure mode. Further the proposed model was applied to an existing wall structure tested on a shaking table. Three-dimensional nonlinear time history analyses using the proposed model were performed for the test specimen. The time history responses of the proposed method agreed with the test results including the lateral displacements and base shear.

• Computers and Concrete
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• v.16 no.5
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• pp.723-740
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• 2015

In this study, the seismic performance of skewed highway bridges has been assessed by using fragility function methodology. Incremental Dynamic Analysis (IDA) has been used to prepare complete information about the different damage states of a 30 degree skewed highway bridge. A three dimensional model of a skewed highway bridge is presented and incremental dynamic analysis has been applied. The details of the full nonlinear procedures have also been presented. Different spectral intensity measures are studied and the effects of the period on the fragility curves are shown in different figures. The efficiency, practicality and proficiency of these different spectral intensity measures are compared. A suite of 20 earthquake ground motions are considered for nonlinear time history analysis. It has been shown that, considering different intensity measures (IM) leads us to overestimate or low estimate the damage probability which has been discussed completely.

• Steel and Composite Structures
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• v.20 no.2
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• pp.399-412
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• 2016

This paper evaluates the seismic response of three dimensional steel space buildings using the spread plastic hinge approach. A numerical study was carried out in which a sample steel space building was selected for pushover analysis and incremental nonlinear dynamic time history analysis. For the nonlinear analysis, three earthquake acceleration records were selected to ensure compatibility with the design spectrum defined in the Turkish Earthquake Code. The interstorey drift, capacity curve, maximum responses and dynamic pushover curves of the building were obtained. The analysis results were compared and good correlation was obtained between the idealized dynamic analyses envelopes with and static pushover curves for the selected building. As a result to more accurately account response of steel buildings, dynamic pushover envelopes can be obtained and compared with static pushover curve of the building.