• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.67-74
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• 2002

An experimental assessment on the dynamic behavior of saturated sand which can consider the irregular characteristics of earthquakes was proposed. The equivalent uniform stress concept presented by Seed and Idriss has been applied to evaluate the liquefaction resistance strength to simplify earthquake loading. However, it was known that the liquefaction resistance strength of soil based on the equivalent uniform stress concept can't exactly mirror the dynamic characteristics of the irregular earthquake motion. In this study, estimation of the criterion of the liquefaction resistance strength was determined by applying real earthquake loading to the cyclic triaxial test. From the test results, relationships between excess pore water pressure and the earthquake characteristics such as magnitude or duration were determined. Magnitude scaling factors to determine the soil liquefaction resistance strength in seismic design were also proposed.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.13-18
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• 2008

The 2005 west off Fukuoka earthquake with Mjma 7.0 occurred in the vicinity of Fukuoka city with 1.4 million populations, which had been regarded as rather seismically inactive in Japan. The strong motion records by K-net indicated PGV of 64 cm/s in Fukuoka city and some condominium buildings sustained extensive non-structural damages. In this study, we conducted a questionnaire survey for residents of 8 condominium buildings located in the downtown area of Fukuoka city after the earthquake. The results indicate that damaged nonstructural walls and distorted doors disrupted evacuation route for many occupants, and furniture and content damage on upper floors became severer resulting in higher rates of human casualty. Earthquake preparedness for indoor safety was raised after the earthquake, though further safety measures can be advised. In the phase of post-earthquake emergency and restoration period, residents' management organizations play important roles, so that neighborhood activities to promote communication networks are important in urban environment with aging population.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.4
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• pp.67-74
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• 2001

Structural engineers lately have an interest in the safety for equipments and facility in buildings subjected to earthquake. The stability of cultural assets was not considered for the earthquake induced vibration, while the integrity of structure has been considered through the resistant earthquake design. The purpose of this study aimed to analyze the behavior of isolation device named as \"Isolation table system\" and to evaluate its isolation performance through the experiment study. Isolation table is one of isolation systems to reduce the vibration which was transferred from slab to exhibition table. Experimental result shows that isolation table can reduce the vibration by 80-90% and its behavior is very stable within its maximal stroke.al stroke.

• Structural Engineering and Mechanics
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• v.27 no.5
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• pp.589-607
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• 2007

Two series of tests were conducted to investigate the behavior of local thin jacketing for the retrofitting of reinforced concrete (RC) columns. In the first series, four full-scale RC columns with a height of 400 cm and a 30 cm square cross-section were tested under constant axial load and reversed cyclic lateral displacements. The heavily damaged columns were retrofitted with local thin jacketing. Self-compacting concrete (SCC) was used in the production of 7.5 cm thick, four-sided jacketing. The height of the jacketing was 100 cm for one specimen and 200 cm for all others. In the second series, the retrofitted columns were retested with the same axial load and displacement history. The effectiveness of local thin jacketing in the retrofitting of RC columns was examined with respect to lateral strength, stiffness, inelastic load-deformation behavior and energy dissipation.

• Smart Structures and Systems
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• v.29 no.3
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• pp.485-498
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• 2022

In near-fault earthquake prone areas, the velocity pulse-like seismic waves often results in excessive horizontal displacement for structures, which may result in severe structural failure during large or near-fault earthquakes. The recently developed isolator-gap damper (IGD) systems provide a solution for the large horizontal displacement of long period base-isolated structures. However, the hysteresis characteristics of the IGD system are significantly different from the traditional hysteretic behavior. At present, the hysteretic behavior is difficult to be reflected in the structural analysis and performance evaluation especially under random earthquake excitations for lacking of effective analysis models which prevent the application of this kind of IGD system. In this paper, we propose a mathematical hysteretic model for the IGD system that presents its nonlinear hysteretic characteristics. The equivalent linearization is conducted on this nonlinear model, which requires the variances of the IGD responses. The covariance matrix for the responses of the structure and the IGD system is obtained for random earthquake excitations represented by the Kanai-Tajimi spectrum by solving the Lyapunov equation. The responses obtained by the equivalent linearization are verified in comparison with the nonlinear responses by the Monte Carlo simulation (MCS) analysis for random earthquake excitations.

• Earthquakes and Structures
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• v.6 no.2
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• pp.181-199
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• 2014

The infill walls, whose contribution to the earthquake resistance of a structure is generally ignored due to their limited lateral rigidities, constitute a part of the lateral load bearing system of an RC frame structure. A common method for improving the earthquake behavior of RC frame structures is increasing the contribution of the infill walls to the overall lateral rigidity by strengthening them through different techniques. The present study investigates the influence of externally bonded perforated steel plates on the load capacities, rigidities, and ductilities of hollow brick infill walls. For this purpose, a reference (unstrengthened) and twelve strengthened specimens were subjected to monotonic diagonal compression. The experiments indicated that the spacing of the bolts, connecting the plates to the wall, have a more profound effect on the behavior of a brick wall compared to the thickness of the strengthening plates. Furthermore, an increase in the plate thickness was shown to result in a considerable improvement in the behavior of the wall only if the plates are connected to the wall with closely-spaced bolts. This strengthening technique was found to increase the energy absorption capacities of the walls between 4 and 14 times the capacity of the reference wall. The strengthened walls reached ultimate loads 30-160% greater than the reference wall and all strengthened walls remained intact till the end of the test.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.2
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• pp.95-101
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• 2018

Diagonally reinforced concrete coupling beams (DRCB) play an important role in coupled shear wall systems since these elements dissipate most of seismic input energy under earthquake loading. For reliable seismic performance evaluation using nonlinear response history analysis, it is important to use an accurate analytical model for DRCBs. In this study, the Pinching4 model is used as a base model to simulate the cyclic behavior of DRCBs. For simulating the cyclic behavior of DRCBs using the Pinching4 model, the analytical parameters for backbone curve, pinching and cyclic deterioration in strength and stiffness should be computed. To determine the proper values of the constituent analytical parameters efficiently and accurately, this study proposes the empirical equations for the analytical parameters using regression analyses. It is shown that the hysteretic behavior of coupling beams can be simulated efficiently and accurately using the proposed numerical model with the proposed empirical equations of model parameters.

• Earthquakes and Structures
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• v.14 no.2
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• pp.179-186
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• 2018

We present the accurate investigation the seismic behavior of the gravity retaining wall built near rock face based on numerical method. The retaining wall is a useful structure in geotechnical engineering, where the earthquake is a common phenomenon; therefore, the evaluation of the behavior of the retaining wall during an earthquake is essential. However, in all previous studies, the backfill behind the wall was usually approximated by a homogeneous region, while in contrast, in practice, in many cases retaining walls are used to support the soil pressure in, inhomogeneous, mountainous area. This suggests an accurate investigation of the problem, i.e., numerical analysis. The numerical results will be compared with some of recently proposed analytical methods to show the accuracy of the proposed method. We show that increasing the volume of the rock face yields decreasing the permanent horizontal displacement of the gravity retaining wall built near rock face. Besides, we see that the permanent horizontal displacement of the gravity retaining wall with homogenous backfill is more than permanent horizontal displacement of the gravity retaining wall case of the built near rock face in different frequency contents.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.5
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• pp.301-310
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• 2016

There are differences in seismic behavior between non-skewed bridges and skewed bridges due to in-plane rotations caused by pounding between the skewed deck and its abutments during strong earthquake. Many advances have been made in developing design codes and guidelines for dynamic analyses of non-skewed bridges. However, there remain significant uncertainties with regard to the structural response of skewed bridges caused by unusual seismic response characteristics. The purpose of this study is performing non-linear time history analysis of the bridges using abutment-soil interaction model considering pounding between the skewed deck and its abutments, and analyzing global seismic behavior characteristics of the skewed bridges to assess the possibility of unseating. Refined bridge model with abutment back fill, shear key and elastomeric bearing was developed using non-linear spring element. In order to evaluate the amplification of longitudinal and transverse displacement response, non-linear time history analysis was performed for single span bridges. Far-fault and near-fault ground motions were used as input ground motions. According to each parameter, seismic behavior of skewed bridges was evaluated.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.389-396
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• 2001

This paper presents an analytical prediction of the fatigue behavior of reinforced concrete bridge piers under earthquake. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected, local discontinuous deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel. The proposed numerical method for fatigue behavior of reinforced concrete bridge piers under earthquake will be verified by comparison with reliable experimental results.