• Earthquakes and Structures
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• v.16 no.4
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• pp.487-499
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• 2019

Energy-based seismic design of structures has gradually become prominent in today's structural engineering investigations because of being more rational and reliable when it is compared to traditional force-based and displacement-based methods. Energy-based approaches have widely taken place in many previous studies and investigations and undoubtedly, they are going to play more important role in future seismic design codes, too. This paper aims to compute the maximum earthquake energy input to elastic single-degree-of-freedom (SDOF) systems for selected real ground motion records. A data set containing 100 real ground motion records which have the same site soil profiles has been selected from Pacific Earthquake Research (PEER) database. Response time history (RTH) analyses have been conducted for elastic SDOF systems having a constant damping ratio and natural periods of 0.1 s to 3.0 s. Totally 3000 RTH analyses have been performed and the maximum mass normalized earthquake input energy values for all records have been computed. Previous researchers' approaches have been compared to the results of RTH analyses and an approach which considers the pseudo-spectral velocity with Arias Intensity has been proposed. Graphs of the maximum earthquake input energy versus the maximum pseudo-spectral velocity have been obtained. The results show that there is a good agreement between the maximum input energy demands of RTH analysis and the other approaches and the maximum earthquake input energy is a relatively stable response parameter to be used for further seismic design and evaluations.

• Smart Structures and Systems
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• v.21 no.1
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• pp.53-64
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• 2018

Nondestructive testing methods are required to assess the condition of civil structures and formulate their maintenance programs. Axial force identification is required for several structural members of truss bridges, pipe racks, and space roof trusses. An accurate evaluation of in situ axial forces supports the safety assessment of the entire truss. A considerable redistribution of internal forces may indicate structural damage. In this paper, a novel compressive force identification method for prismatic members implemented using static deflections is applied to steel beams. The procedure uses the Euler-Bernoulli beam model and estimates the compressive load by using the measured displacement along the beam's length. Knowledge of flexural rigidity of the member under investigation is required. In this study, the deflected shape of a compressed steel beam is subjected to an additional vertical load that was short-term measured in several laboratory tests by using fiber Bragg grating-differential settlement measurement (FBG-DSM) sensors at specific cross sections along the beam's length. The accuracy of midspan deflections offered by the FBG-DSM sensors provided excellent force estimations. Compressive load detection accuracy can be improved if substantial second-order effects are induced in the tests. In conclusion, the proposed method can be successfully applied to steel beams with low slenderness under real conditions.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.5
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• pp.245-254
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• 2017

The building which are essential for disaster recovery is classified as a special seismic use group. Especially, achievement of seismic performance is very important for the hospital, so the hospital should be able to maintain its function during and right after an earthquake without significant damage on both structural and non-structural elements. Therefore, this study aimed at checking the seismic performance of a hospital building, but which was limited to structural elements. For the goal, a plan with a configuration of general hospitals in Korea was selected and designed by two different seismic-force-resisting systems. In analytical modeling, the shear behavior of the wall was represented by three inelastic properties as well as elastic. Nonlinear dynamic analyses were conducted to evaluate the performance of structural members. The result showed that the performance of shear walls in the hospital buildings was not satisfied regardless of the seismic-force-resisting systems, while the demands on the beams and columns did not exceed the capacities. This is the result of only considering the shear of the wall as the force-controlled action. When the shear of the wall was modeled as inelastic, the walls were yielded in shear, and as the result, the demands for frames were increased. However, the increase did not exceed the capacities of the frames members. Consequently, since the performance of walls is significant to determine the seismic performance of a hospital building, it will be essential to establish a definite method of modeling shear behavior of walls and judging their performance.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.5
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• pp.299-309
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• 2018

Now that problems with force-based seismic design have been clearly identified, design is inclined toward displacement-based methods. One such widely used method is Direct-Displacement-Based Design (DDBD). Yet, one of the shortcomings of DDBD is considering higher-mode amplification of story shear, moments, and displacements using equations obtained from limited parametric studies of regular planar frames. In this paper, a different approach to account for higher-mode effects is proposed. This approach determines the lateral secant stiffness of the building frames that fulfill the allowable inter-story drift without exceeding the desired story displacements. Using the stiffness, an elastic response spectrum analysis is carried out to determine elastic higher-mode force effects. These force effects are then combined with DDBD-obtained first-mode force effects using the appropriate modal superposition method so that design can be performed. The proposed design procedure is verified using Nonlinear Time History Analysis (NTHA) of twelve planar frames in four categories accounting for mass and stiffness irregularity along the height. In general, the NTHA response outputs compared well with the allowable limits of the performance objective. Thus, it fulfills the aim of minimizing the use of NTHA for planar frame buildings, thereby saving computational resources and effort.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.6 s.46
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• pp.1-12
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• 2005

For a shear-deformable beam-column element subjected io non-conservative forces, equations of motion and a finite element formulation are presented applying extended Hamilton's principle. The influence of non-conservative force's direction parameter, internal and external damping forces, and shear deformation and rotary inertia effects on divergence and flutter loads of Beck's columns are intensively investigated based on element stiffness, damping and mass matrixes derived for the non-conservative system.

• Structural Engineering and Mechanics
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• v.59 no.4
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• pp.719-737
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• 2016

The present study investigated the earthquake behavior of R/C structures considering the vertical earthquake motion with the help of a comparative study. For this aim, the linear time-history analyses of a high-rise R/C structure designed according to TSC-2007 requirements were conducted including and excluding the vertical earthquake motion. Earthquake records used in the analyses were selected based on the ratio of vertical peak acceleration to horizontal peak acceleration (V/H). The frequency-domain analyses of the earthquake records were also performed to compare the dominant frequency of the records with that of the structure. Based on the results obtained from the time-history analyses under the earthquake loading with (H+V) and without the vertical earthquake motion (H), the value of the overturning moment and the top-story vertical displacement were found to relatively increase when considering the vertical earthquake motion. The base shear force was also affected by this motion; however, its increase was lower compared to the overturning moment and the top-story vertical displacement. The other two parameters, the top-story lateral displacement and the top-story rotation angle, barely changed under H and H+V loading cases. Modal damping ratios and their variations in horizontal and vertical directions were also estimated using response acceleration records. No significant change in the horizontal damping ratio was observed whereas the vertical modal damping ratio noticeably increased under H+V loading. The results obtained from this study indicate that the desired structural earthquake performance cannot be provided under H+V loading due to the excessive increase in the overturning moment, and that the vertical damping ratio should be estimated considering the vertical earthquake motion.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.2
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• pp.23-31
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• 2008

Dynamic earth pressure acting on geotechnical structures can be driving force or resisting force for the displacement of the structure according to the phase relation between the dynamic earth pressure and inertia force of structures. In this research, the evaluation procedure of the phase relation between the dynamic earth pressure and the inertia force was proposed. According to the procedure, numerical analyses on caisson foundation of bridges were performed and the phase relation was analyzed. The analysis results showed that the dynamic earth pressure becomes the driving force, which increases the displacement of the structure, if the displacement amplitude of ground is larger than that of structure due to the low stiffness of the ground, and the dynamic earth pressure becomes the resisting force against the displacement of the structure if the displacement amplitude of ground is smaller than that of structure due to the high stiffness of the ground.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.445-453
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• 2013

This paper was calculated the earthquake load using ELFP(Equivalent Lateral Force Procedure) and RSA(Response Spectrum Analysis) for PSC Box Girder representative bridges by the Phase of KTX designed by ELFP and verified the difference of these analyses. It have been modeled 3 dimensional FE model of 5 bridges using a commercial FEM program for the comparison of these analyses using a commercial FEM program and were compared the earthquake load. It has been to confirm the increase of the difference ELFP of RSA calculated to seismic ground acceleration according to the ground condition and natural period. It is mean that the necessity of seismic reinforcement due to the application of a larger of earthquake load than designed earthquake load form the seismic performance evaluation result according to the difference of calculated earthquake loads.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.527-534
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• 2006

A real-time hybrid method, in which the experimental implementation and the numerical computation of a structure are simultaneously carried out in real-time and combined on-line, has been used as a dynamic testing technique of structure to investigate its dynamic behaviors. In this paper, an experimental hybrid method, which implements the earthquake response control of a building structure with a TLD by using only a TLD as an experimental part, is proposed and is experimentally verified through a shaking table test. In the proposed methodology, the whole building structure with a TLD is divided into the upper TLD and the lower structural parts as experimental and numerical substructures, respectively. At the moment, the control force acting between their interface is measured from the experimental TLD with shear-type load-cell which is mounted on shaking table. Shaking table vibrates the upper experimental TLD with the response calculated from the numerical substructure, which is subjected to the excitations of the measured interface control force at its top story and an earthquake input at its base. The experimental results show that the conventional method, in which both a TLD and a building model are physically manufactured and are tested, can be replaced by the proposed methodology with a simple experimental installation and a good accuracy for evaluating the control performance of a TLD.

• Advances in Computational Design
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• v.7 no.3
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• pp.229-251
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• 2022

In 2017, an intraplate earthquake of Mw 7.1 occurred 120 km from Mexico City (CDMX). Most collapsed structural buildings stroked by the earthquake were flat slab systems joined to reinforced concrete (RC) columns, unreinforced masonry, confined masonry, and dual systems. This article presents the simulated response of an actual six-story RC frame building with masonry infill walls that did not collapse during the 2017 earthquake. It has a structural system similar to that of many of the collapsed buildings and is located in a high seismic amplification zone. Five 3D numerical models were used in the study to model the seismic response of the building. The building dynamic properties were identified using an ambient vibration test (AVT), enabling validation of the building's finite element models. Several assumptions were made to calibrate the numerical model to the properties identified from the AVT, such as the presence of adjacent buildings, variations in masonry properties, soil-foundation-structure interaction, and the contribution of non-structural elements. The results showed that the infill masonry wall would act as a compression strut and crack along the transverse direction because the shear stresses in the original model (0.85 MPa) exceeded the shear strength (0.38 MPa). In compression, the strut presents lower stresses (3.42 MPa) well below its capacity (6.8 MPa). Although the non-structural elements were not considered to be part of the lateral resistant system, the results showed that these elements could contribute by resisting part of the base shear force, reaching a force of 82 kN.