• Journal of Korean Society of Steel Construction
• /
• v.12 no.5 s.48
• /
• pp.581-593
• /
• 2000

In this study, vertical dynamic analyses on the suspension bridges under seismic load are developed. Time domain analysis, random vibration analysis, and spectral analysis are formulated theoretically. The random nitration analysis is checked by numerical integration and the mathematical integration with correlation coefficient which include CQC and SRSS method in the conditions of white noise and filtered white noise. Beam, truss and frame elements are used in order to model the suspension bridge. Geometric stiffness due to dead load is considered for cable and tower.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2008.04a
• /
• pp.567-572
• /
• 2008

This paper's purpose is to improve determining of the critical response of curved bridge to multi-component seismic motion. There are several methods to combine responses by multi-component excitation response, 30%, 40% rules and square-root-of-sum (SRSS). These combination rules determine same value of critical response in straight bridges. However, each method has critical response value of different magnitude in curved bridges. Thus a study about critical response of curved bridges is required. This paper presents comparison critical responses value as each combination rule, 30%, 40% rules and SRSS on curved bridges with the different radiuses of curvature. This study was carried out by response spectrum analysis of OO IC steel box girder bridge using SAP2000. It is concluded as follows: 1) In curved bridges, 30% and 40% rules tend to underestimate the critical response relatively to SRSS. 2) When bridges have smaller radiuses than 100m, difference between SRSS and 30% or 40% rules let run errors up as radiuses of curvature decreased.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.12 no.5
• /
• pp.31-38
• /
• 2008

Recently the necessity of time history analyses is increasing for the seismic analyses of a structure, and the seismic design provisions of IBC2003, ASCE and KBC2005 require the use of a minimum of seven earthquake records for the time history analyses. Earthquake records for the time history analyses could be selected from the database of the field-measured earthquake records having similar site conditions with the designed site, or from simulated sites satisfying the design spectrum. However, in this study seven earthquake records were generated using 50 earthquake records, classified as records measured at the rock, in the database of the Pacific Earthquake Research Center (PEER). Seven earthquake records were first selected by the least squares fitting method comparing the scaling factored response spectra with the specified design spectrum, and a family of seven artificial time history earthquake records was ultimately generated by multiplying scaling factors, which were calculated by the least squares fitting method and the SRSS averaging method, to the corresponding selected earthquake records.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.9 no.3 s.43
• /
• pp.51-58
• /
• 2005

Many RC building structures of multiple uses constructed in Korea have the Irregularities of torsion and soft story at bottom stories simultaneously. Seismic design codes generally require dynamic analysis and to take into account the effect or earthquake excitations in the orthogonal direction using the approximate methods of 100/30 and SRSS for type of building structures. And ail buildings should be designed to be safe in any direction of earthquake input. But, most of designers have difficulty in considering the orthogonal and directional effect of earthquake. The objective of the study stated herein is to verily 1) the effect of the choice of the reference axes on the seismic design member forces by comparing the analytical results on member forces using the principal axes suggested by Wilson and the global axes generally adopted in design office, 2) the validity or the 100/30 and SRSS methods by comparing the member forces obtained through linear elastic time history analysis with those obtained through using response spectrum analysis and 100/30 (or SRSS) methods. Based on the observations on the analytical results, it is concluded as follows; 1) The values of member forces by principal axes can be about $15\%$ smaller than those by the global axes in the example structure. 2) Though the values of member forces given by time history analysis are generally within the peak values predicted by 100/30 and SRSS methods, many member force vectors $(P,\;M_y,\;and\;M_z)$ by lime history analysis were located outside the boundaries predicted by the approximate method such as the 100/30 method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1993.10a
• /
• pp.163-168
• /
• 1993

현대 산업사회에서 발전소는 중요한 시설물이다. 특히 원자력발전소는 지진 과 같은 천재지변시 매우 위험하기 때문에 내진설계가 필수적으로 요구되어 진다. 최근 국내 원자력발전소의 증가와 1986년 이후 만들어진 내진관련 법 규에 따라 내진설계가 보편화 되어가고 있다. 본 연구에서는 발전소에서 쓰 이는 입축펌프를 해석대상기종으로하여 구조해석과 내진해석을 수행하엿다. 입축펌프는 큰 질량을 가진 모터가 펌프의 윗부분에 위치하고 있어 진동문 제가 야기되는 기종이다. 펌프의 고유진동수는 기초부의 강성과 수조의 내수 위에 따라 변하며, 펌프의 축계의 진동수에 비하여 구조계의 진동수가 운전 회전수에 가깝기 때문에 구조계의 진동이 문제시된다. 해석에 있어서 펌프는 단면이 변하는 Euler Beam으로 보고 유한요소법을 사용하여 모델링하였고, 물의 저항에 의한 부가질량을 고려하였다. 내진해석은 응답스펙트럼법으로 수행하였으며 GRS는 Housner가 0.2g에 대하여 제작한 것을 OBE 조건 (0.12g)으로 scaling하여 사용하였다. 각 모드에 대한 합성방법은 SRSS 법을 적용하였다. 또한 응답스펙트럼법과 시간이력해석의 결과를 비교하였으며, 시간이력해석에서, 수치해석방법으로는 Newmark법을 적용하였다. 지진자료 는, 1940년, California에서 발생한 Elcentro 지진 자료를 이용하였다. 연구수 행과정에서 기초강성계수와 수조내 물의 수위를 주된 인자로 하여 이들의 값에 따라 변하는 고유진동수를 고찰하고, 지진입력시 예상되는 최대응답을 구하여, 비교 분석하였다.

• Journal of Korean Society of Steel Construction
• /
• v.22 no.1
• /
• pp.1-12
• /
• 2010

According to the capacity design concept which forms the basis of the current steel seismic codes, the braces in concentrically braced frames (CBFs) should dissipate seismic energy through cyclic tension yielding and cyclic compression buckling while the beams and the columns should remain elastic. Brace buckling in inverted V-braced frames induces unbalanced vertical forces which, in turn, impose the additional beam moments and column axial forces. However, due to difficulty in predicting the location of buckling stories, the most conservative approach implied in the design code is to estimate the column axial forces by adding all the unbalanced vertical forces in the upper stories. One alternative approach, less conservative and recommended by the current code, is to estimate the column axial forces based on the amplified seismic load expected at the mechanism-level response. Both are either too conservative or lacking technical foundation. In this paper, three combination rules for a rational estimation of the column axial forces were proposed. The idea central to the three methods is to detect the stories of high buckling potential based on pushover analysis and dynamic behavior. The unbalanced vertical forces in the stories detected as high buckling potential are summed in a linear manner while those in other stories are combined by following the SRSS(square root of sum of squares) rule. The accuracy and design advantage of the three methods were validated by comparing extensive inelastic dynamic analysis results. The mode-shape based method(MSBM), which is both simple and accurate, is recommended as the method of choice for practicing engineers among the three.

• Journal of Korean Association for Spatial Structures
• /
• v.8 no.1
• /
• pp.57-67
• /
• 2008

In general, the response spectrum analysis(RSA) method is wifely used for seismic analysis of building structures, and the time history analysis(THA) is applied for computation of structural vibration caused by equipments, machines and moving loads, etc. However, compared with the RSA method, the THA method is very complex, difficult and time consuming. In this study, the maximum responses for the vertical vibration are calculated conveniently by the RSA method. At first, the process for the RSA in excitation is proposed, and the maximum modal responses are combined by CQC and SRSS methods. Also, the responses obtained by the two modal combination methods are compared to the responses by the THA. And the correlation coefficients for human activities is proposed, and the RSA responses obtained by used to the correlation coefficients are calculated. Finally, results of the proposed method are compared with those of the time history analysis and correlation coefficients should be considered for the RSA of floor structure subjected to group dynamic loads.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.12
• /
• pp.393-403
• /
• 2018

This study was conducted to evaluate the effects of a Motivation Enhancement for Smoking Cessation Program on middle school students' knowledge regarding smoking, self-efficacy, and daily amount of smoking. The study used a nonequivalent control group pre-post-test design and included 47 students who smoke from two middle schools located in city U as subjects. Subjects were separated into two groups, an experimental group with 23 students and a control group with 24 students. Data were collected from February 19, 2018 to May 11, 2018 and analyzed using the IBM SRSS/win 24.0 program to conduct a t-test, ${\chi}^2$-test, Fisher's exact test, and a paired t-test. After subjects went through the Motivation Enhancement for Smoking Cessation Program, their knowledge regarding smoking (t= 3.38, p=0.002), self-efficacy (t= -3.37, p=0.002), and their daily amount of smoking (t=3.38, p=0.002) showed significant changes. The results indicate that the Motivation Enhancement for Smoking Cessation Program is effective at increasing subjects' knowledge regarding smoking and self- efficacy while decreasing their daily amount of smoking. Therefore, to induce cessation of adolescent smoking, Motivation Enhancement for Smoking Cessation Programs tailored to each student should be held.