• Earthquakes and Structures
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• v.5 no.3
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• pp.297-319
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• 2013

Two destructive earthquakes occurred on October 23 and November 9, 2011 in Van province of Turkey. The damage in residential units shows significant deviation from the expectation of decreasing damage with increasing distance to epicenter. The most damaged settlement Ercis has the same distance to the epicenter with Muradiye, where no damage occurred while relatively less damage observed in Van having half distance. These three cities seem to have resembling soil conditions. If the damages are evaluated: joint failures and insufficient lap splice lengths are observed to be the main causes of the total collapses in RC buildings. Additionally, low concrete strength, reinforcement detailing mistakes, soft story, heavy overhang, pounding and short columns are among other damage reasons. Examples of damages due to non-structural elements are also given. Remarkable points about seismic damages are: collapsed buildings with shear-walls, heavily damaged buildings despite adequate concrete strength due to detailing mistakes, undamaged two-story adobe buildings close to totally collapsed RC ones and undamaged structural system in buildings with heavily damaged non-structural elements. On the contrary of the common belief that buildings with shear-walls are immune to total collapse among civil engineers, collapse of Gedikbulak primary school is a noteworthy example.

• Smart Structures and Systems
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• v.24 no.1
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• pp.67-81
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• 2019

Rows of closely adjacent buildings with similar dynamic characteristics are common building arrangements in residential areas. In this paper, we present a vibration control strategy for the seismic protection of this kind of multibuilding systems. The proposed approach uses an advanced Linear Matrix Inequality (LMI) computational procedure to carry out the integrated design of distributed multiactuation schemes that combine interbuilding linking devices with interstory actuators implemented at different levels of the buildings. The controller designs are formulated as static output-feedback H-infinity control problems that include the interstory drifts, interbuilding approachings and control efforts as controlled-output variables. The advantages of the LMI computational procedure are also exploited to design a fully-decentralized velocity-feedback controller, which can define a passive control system with high-performance characteristics. The main ideas are presented by means of a system of three adjacent five-story identical buildings, and a proper set of numerical simulations are conducted to demonstrate the behavior of the different control configurations. The obtained results indicate that interstory-interbuilding multiactuation schemes can be used to design effective vibration control systems for adjacent buildings with similar dynamic characteristics. Specifically, this kind of control systems is able to mitigate the vibrational response of the individual buildings while maintaining reduced levels of pounding risk.

• Smart Structures and Systems
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• v.26 no.6
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• pp.765-779
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• 2020

Collapse of bridges in recent earthquakes demonstrates the need to deepen the understanding of the behaviour of these structures against seismic actions. This paper presents a highly detailed numerical model of an actual bridge subjected to extreme seismic action which results in its collapse. Normally, nonlinear numerical models have high difficulties to achieve convergence when reinforced concrete is intended to be represented. The main objective of this work is to determine the efficiency of different passive control strategies to prevent the structural collapse of an existing bridge. Metallic dampers and seismic isolation by decoupling the mass were evaluated. The response is evaluated not only in terms of reduction of displacements, but also in increasing of shear force and axial force in key elements, which can be a negative characteristic of the systems studied. It can be concluded that the use of a metallic damper significantly reduces the horizontal displacements and ensures the integrity of the structure from extreme seismic actions. Moreover, the isolation of the deck, which in principle seems to be the most effective solution to protect existing bridges, proves inadequate for the case analysed due to its dynamic characteristics and its particular geometry and an unpredictable type of axial pounding in the columns. This unexpected effect on the isolation system would have been impossible to identify with simplified models.

• Earthquakes and Structures
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• v.23 no.1
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• pp.87-100
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• 2022

Limiting the displacement of seismic isolators causes a pounding phenomenon under severe earthquakes. Therefore, the ASCE 7-16 has provided minimum criteria for the design of the isolated building. In this research the seismic response of isolated buildings by Triple Friction Pendulum Isolator (TFPI) under the impact, expected, and unexpected mass eccentricity was evaluated. Also, the effect of different design parameters on the seismic behavior of structural and nonstructural elements was found. For this, a special steel moment frame structure with a surrounding moat wall was designed according to the criteria, by considering different response modification coefficients (RI), and 20% mass eccentricity in one direction. Then, different values of these parameters and the damping of the base isolation were evaluated. The results show that the structural elements have acceptable behavior after impact, but the nonstructural components are placed in a moderate damage range after impact and the used improved methods could not ameliorate the level of damage. The reduction in the RI and the enhancement of the isolator's damping are beneficial up to a certain point for improving the seismic response after impact. The moat wall reduces torque and maximum absolute acceleration (MAA) due to unexpected enhancement of mass eccentricity. However, drifts of some stories increase. Also, the difference between the response of story drift by expected and unexpected mass eccentricity is less. This indicates that the minimum requirement displacement according to ASCE 7-16 criteria lead to acceptable results under the unexpected enhancement of mass eccentricity.

• Korean Journal of Community Nutrition
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• v.21 no.1
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• pp.37-52
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• 2016

Objectives: This study was performed to develop an assessment tool for middle aged women's health status based on dietary patterns, which will have practical applications in the working field of health and hygiene, aiming at improving the middle aged women's quality of life through their health improvement. Methods: As a first step, a literature review was conducted and the original data of '2008~2009 Korea Health and Nutrition Examination Survey' were reanalyzed. This analysis identified 65 preliminary questions that may be relevant to the study. After verifying the content validity by experts, the 65 questions were reduced into 51 questions. In order to secure higher validity of the candidate items, verification of their clinical validity was conducted among women aged between 45 and 60 years. Finally, an assessment tool was developed by applying weight and scoring. Results: Selected 51 questions were used to verify clinical validity and the results showed that 20 questions were relevant, nine questions ('regular meal time', 'regular amount of meal', 'intake frequency of dairy products', 'intake frequency of fruits', 'intake frequency of meat products', 'intake frequency of high cholesterol foods', 'intake frequency of salty foods', 'appetite', 'eat breakfast everyday') were related to dietary life. Eleven other questions ('self-rated health status', 'deep sleep', 'smoking', 'frequency of drinking', 'stress levels', 'health-related fitness levels', 'pounding of the heart', 'strange feelings on the skin', 'interfere with daily life', 'menopause will bring you a chance to see the life in a different perspective', and 'body mass index') were selected as valid questions. For the response scale for each question, 5 point Likert scale was used to make total 100 point score. Conclusions: This study is the first attempt to develop a health status assessment tool for middle aged women based on their dietary patterns. We conclude that this tool is expected to be a useful and practical tool in the field.

• Polymer(Korea)
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• v.31 no.1
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• pp.80-85
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• 2007

Maleic anhydride (MA) modified ethylene-propylene-diene terpolymer (MEPDM) was pre-pared from solution polymerization. MEPDM-g-PST copolymer was prepared by melt polymerization of male ate d EPDM and quaternary ammonium silyl polydimethylsiloxane -7,7,8,8- tetracyanoquinodimethane (TCNQ) adduct (PST) in internal mixer and MEPDM-g-PST/HDPE/CB (MPEC) was prepared by com-pounding HDPE, MEPDM-g-PST copolymer and carbon black (CB, 5, 10, 15, and 20 phr), and HDPE/ CB (PEC) by compounding HDPE and CB (5, 10, 15, and 20 phr), respectively. The structure of MEPDM-g-PST copolymer was confirmed by measuring the FTIR. The maximum grafting ratio of MA onto EPDM was 2.35%. The thermal and mechanical properties of the composites were measured and dispersion characteristics of CB in matrix show that CB in MPEC was better dispersed than that in PEC composite.

• Research in Community and Public Health Nursing
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• v.13 no.4
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• pp.786-794
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• 2002

Purpose: The aim of the study was to investigate how adolescents' behavior is correlated with child abuse they experience, and how childrearing attitude of mothers perceived by the adolescents is correlated with child abuse experience by the adolescents. Method: A convenient sampling strategy was used. A total of 160 adolescents participated in this study. Of the 160 responses, 116 were used for final analysis. The data were analyzed using K-YSR program and SPSSWIN. Result: The results were as follows. Mild child abuse experiences reported by the subjects were Throwing the object at me (12.9%, N = 15), Clutching and pushing (12.9%, N = 15), and Slapping on the cheek (14.7%, N = 17)'. Severe child abuse experiences reported by the subjects were Kicking, pounding and biting (10.3%, N = 10), Rod, stick, belt, broom beating using various objects (41.4%, N = 38), and Beating all over the body (6.7%, N = 8). Very severe child abuse experiences reported by the subjects were Burning with cigarette (0.4%, N = 1), Threatening me with objects such as a knife, a hammer, an axe, or a gimlet (0.8%, N = 2). Injuring me with the objects (0.4%, N = 1), and Hospitalized by belting (0.4%, N = 1). In terms of correlations among the main study variables, physical child abuse had significant positive correlations with externalizing problem (r=.271, p=.001) and total behavioral problem (r=.288, p=.002). Physical child abuse also had a significant positive correlation with authoritarian childrearing attitude of mother (r=.363, p=.000). Physical child abuse had significant negative correlations with mothers affectionate childrearing attitude (r=-.191, p=.050) and active participative childrearing attitude (r=-.101, p=.035). Conclusion: Mothers childrearing attitude is a salient factor for preventing child abuse. In addition, child abuse is an important factor for preventing adolescent's behavioral problem.

• Structural Engineering and Mechanics
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• v.51 no.2
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• pp.277-297
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• 2014

Since the isolation bearings undergo large displacements in base-isolated structures, impact with adjacent structures is inevitable. Therefore, in this investigation, the effect of impact on seismic response of isolated structures mounted on double concave friction pendulum (DCFP) bearings subjected to near field ground motions is considered. A non-linear viscoelastic model of collision is used to simulate structural pounding more accurately. 2-, 4- and 8-story base-isolated buildings adjacent to fixed-base structures are modeled and the coupled differential equations of motion related to these isolated systems are solved in the MATLAB environment using the SIMULINK toolbox. The variation of seismic responses such as base shear, displacement in the isolation system and superstructure (top floor) is computed to study the impact condition. Also, the effects of variation of system parameters: isolation period, superstructure period, size of seismic gap between two structures, radius of curvature of the sliding surface and friction coefficient of isolator are contemplated in this study. It is concluded that the normalized base shear, bearing and top floor displacement increase due to impact with adjacent structure. When the distance between two structures decreases, the base shear and displacement increase comparing to no impact condition. Besides, the increase in friction coefficient difference also causes the normalized base shear and displacement in isolation system and superstructure increase in comparison with bi-linear hysteretic behavior of base isolation system. Totally, the comparison of results indicates that the changes in values of friction coefficient have more significant effects on 2-story building than 4- and 8-story buildings.

• Structural Engineering and Mechanics
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• v.61 no.5
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• pp.675-684
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• 2017

In this paper, a hybrid seismic response control (HSRC) system was developed to control bridge behavior caused by the seismic load. It was aimed at optimum vibration control, composed of a rubber bearing of passive type and MR-damper of semi-active type. Its mathematical modeling was driven and applied to a bridge model so as to prove its validity. The bridge model was built for the experiment, a two-span bridge of 8.3 meters in length with the HSRC system put up on it. Then, inflicting the EI Centro seismic load on it, shaking table tests were carried out to confirm the system's validity. The experiments were conducted under the basic structure state (without an MR-damper applied) first, and then under the state with an MR-damper applied. It was also done under the basic structure state with a reinforced rubber bearing applied, then the passive on/off state of the HSRC system, and finally the semi-active state where the control algorithm was applied to the system. From the experiments, it was observed that pounding rather increased when the MR-damper alone was applied, and also that the application of the HSRC system effectively prevented it from occurring. That is, the experiments showed that the system successfully mitigated structural behavior by 70% against the basic structure state, and, further, when control algorithm is applied for the operation of the MR-damper, relative displacement was found to be effectively mitigated by 80%. As a result, the HSRC system was proven to be effective in mitigating responses of the two-span bridge under seismic load.

• Journal of Korea Water Resources Association
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• v.40 no.3
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• pp.215-221
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• 2007

The main purpose of this study is to find the appropriate method to prevent the reduction of infiltration capacity due to sealing of soil surface. The study results indicate that installation of gravel or larger soil facilitates the drainage of infiltrated rainwater. However, considering that the infiltration capacity has been reduced since the installation, it seems that the sealing of soil surface is caused by the inflow of suspended soil into the lower sand layer. To promote the infiltration capacity by reducing the pounding of lower natural soil layer, the sand soil should be placed above the natural soil layer with shallow depth just below the larger gravel. Furthermore, the crust generated above the soil surface should be removed regularly and the sand layer above the natural soil layer should be replaced with new one so that the original infiltration capacity can be maintained properly.