• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.249-256
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• 1999

This study is intended to propose a systematic procedure for the development of the reliability-based seismic safety and cost-effective Performance criteria for design and upgrading of long span PC bridges. In the paper, a set of cost function models for life cycle cost analysis of bridges is proposed. The total life cycle cost functions consist of initial cost and direct/indirect damage costs considering repair/replacement costs, human losses and property damage costs, road user costs, and indirect regional economic losses. The damage costs are successfully expressed in terms of Park-Ang median global damage indices and damage probabilities. The proposed approach is successfully applied to model bridges in both regions of a moderate seismicity area like Seoul, Korea and a high one like Tokyo, Japan. It may be expected that the proposed approach can be effectively utilized for the development of cost-effective performance criteria for design and upgrading of various types of bridges as well as long span PC bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.591-594
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• 2004

Recently, a tendency for development of seismic approach of foreign countries is capacity design development. Capacity design is rational seismic design concept of capacity protection considering not only earthquake magnitude, but also behavior of structure. For that reason, the most bridge seismic design specifications contain capacity protection provisions explicitly or implicitly. The capacity protection is normally related with slenderness effect of the columns, force transfer in connections between columns and adjacent elements, and shear design of columns. It intends to prevent brittle failure of the structural components of bridges, so that the whole bridge system may show ductile behavior and failure during earthquake events. The objectives of this paper are to deduce needed provisions for the moderate seismicity regions such as Korea after studying current seismic design codes and to establish rational criteria provisions of seismic design for future revision of seismic design specifications.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.351-358
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• 1999

The base-isolation technology is to set up LRB between the base of a building and the ground to protect the building from seismic force. As Korea belongs to the region of moderate or weak seismicity it is more resonable to apply the base-isolation technology of LRB in the field of the response reduction of equipments under machine or transportation vibrations than in the field of seismic response reduction of buildings, In this paper small-scale LRB's designed for the response reduction of equipments are manufactured and tested for thier performance. The shaking table test is conducted to analyze the characteristics of LRB such as the variation of natural frequencies damping ratios and equipments responses.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.4 s.44
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• pp.43-54
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• 2005

This paper presents cost-effectiveness evaluation of semi-active control system for cable-stayed bridge under earthquake excitations with various magnitudes and frequency contents. Semi-active control system, which is operated by using Bi-stale control method on the basis of linear quadratic Gaussian (LQG) optimal controller, is designed for the benchmark control problem proposed by Dyke et at. The cost-effectiveness of the proposed control system is defined by the ratio of life-cycle costs between a bridge structure with shock transmission units and a bridge structure with the semi-active control devices. The simulated results show that the damper cost has little influence on the cost-effectiveness of the semi-active control system while the cost-effectiveness is quite sensitive to the damage cost induced by the bridge failure. It is also found that the semi-active control system guarantees relatively high cost-effectiveness for the cable-stayed bridge subject to the ground motions in the regions of moderate seismicity with soft soil condition and strong seismicity with stiff soil condition.

• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.687-696
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• 2004

It has been known that practically unavoidable lap splices of longitudinal reinforcement in the plastic hinge region have a bad effect on the seismic performance of reinforced concrete bridge columns. Lap splices were usually located in the plastic hinge region of most bridge columns designed before the implementation of the new seismic design provisions of 1992 Korea Bridge Design specification. The objective of this research is to evaluate the seismic performance of full-sized reinforced concrete bridge piers with lap splice of longitudinal reinforcement in the plastic hinge region, and to develop an appropriate lateral confinement concept of RC bridge columns with lap-spliced longitudinal steels in low or moderate seismicity region. Eight test specimens in the aspect ratio of 4.0 were made with three types of lap splicing, two levels of confinement steel ratios and two types of tie configurations. It was confirmed from the Quasi-Static test that displacement ductility ratios were significantly reduced for nonseismic test columns with lap spliced longitudinal steels but were satisfied the seismic requirement for limited ductile design specimens. As a conclusion, pertinent lateral confinement content was proposed for the seismic. performance of RC bridge piers with $50\%$ lap-spliced longitudinal reinforcing steels in low or moderate seismicity region.

• Earthquakes and Structures
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• v.1 no.1
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• pp.93-108
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• 2010

This paper investigates the seismic performance of existing reinforced concrete frames with wide beams mainly designed for gravity loads, as typically found in the seismic-prone Mediterranean area before the introduction of modern codes. The seismic capacity is evaluated in terms of the overall amount of input energy that the frame can dissipate/absorb up to collapse. This approach provides a quantitative evaluation that can be useful for selecting and designing an appropriate retrofit strategy. Six prototype frames representative of past construction practices in the southern part of Spain are designed, and the corresponding non-linear numerical models are developed and calibrated with purposely conducted tests on wide beam-column subassemblages. The models are subjected to sixteen earthquake records until collapse by applying the incremental dynamic analysis method. It is found that the ultimate energy dissipation capacity at the story level is markedly low (about 1.36 times the product of the lateral yield strength and yield displacement of the story), giving values for the maximum amount of energy that the frame can dissipate which are from one fourth to half of that required in moderate-seismicity regions.

• Structural Engineering and Mechanics
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• v.33 no.2
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• pp.137-158
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• 2009

This paper investigates the behavior of reinforced concrete (RC) circular columns under combined loading including torsion. The main variables considered in this study are the ratio of torsional moment to bending moment (T/M) and the level of detailing for moderate and high seismicity (low and high transverse reinforcement/spiral ratio). This paper presents the results of tests on seven columns subjected to cyclic bending and shear, cyclic torsion, and various levels of combined cyclic bending, shear, and torsion. Columns under combined loading were tested at T/M ratios of 0.2 and 0.4. These columns were reinforced with two spiral reinforcement ratios of 0.73% and 1.32%. Similarly, the columns subjected to pure torsion were tested with two spiral reinforcement ratios of 0.73% and 1.32%. This study examined the significance of proper detailing, and spiral reinforcement ratio and its effect on the torsional resistance under combined loading. The test results demonstrate that both the flexural and torsional capacities are decreased due to the effect of combined loading. Furthermore, they show a significant change in the failure mode and deformation characteristics depending on the spiral reinforcement ratio. The increase in spiral reinforcement ratio also led to significant improvement in strength and ductility.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.250-257
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• 2002

Pseudo dynamic test is an on-line computer control method to achieve the realism of shaking table test with the economy and versatility of the conventional quasi-static approach Pseudo dynamic tests of six full-size RC bridge piers have been carried out to investigate their seismic performance. For the purpose of precise evaluation, the experimental investigation was conducted to study the seismic performance of the real size specimen, which is constructed for highway bridge piers in Korean peninsula. Since it is believed that Korea belongs to the moderate seismicity region, five test specimens were designed in accordance with limited ductility design concept. Another one test specimen was nonseismically designed according to a conventional code. Important test parameters were transverse reinforcement and lap splicing. Lap splicing was frequently used in the plastic hinge region of many bridge columns. Furthermore, the seismic design code is not present about lap splice in Korean Roadway Bridge Design Code. The results show that specimens designed according to the limited ductility design concept exhibit higher seismic resistance. Specimens with longitudinal steel lap splice in the plastic hinge region appeared to significantly fail at low ductility level.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.885-890
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• 2002

Pseudo dynamic test is an on-line computer control method to achieve the realism of shaking table test with the economy and versatility of the conventional quasi-static approach. Pseudo dynamic tests of four full-size RC bridge piers have been carried out to investigate their seismic performance. For the purpose of precise evaluation, the experimental investigation was conducted to study the seismic performance of the real size specimen, which is constructed for highway bridge piers in Korean peninsula. Since it is believed that Korea belongs to the moderate seismicity region, three test specimens were designed in accordance with limited ductility design concept. Another one test specimen was nonseismically designed according to a conventional code. Important test parameters were transverse reinforcement and lap splicing. Lap splicing was frequently used in the plastic hinge region of many bridge columns. Furthermore, the seismic design code is not present about lap splice in Korean Roadway Bridge Design Code. The results show that specimens designed according to the limited ductility design concept exhibit higher seismic resistance. Specimens with longitudinal steel lap splice in the plastic hinge region appeared to significantly fail at low ductility level.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.19-27
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• 2001

Seismic parameters fur computation of ground motions in Southern Korea are obtained from recently recorded data, and site-independent regional and site-dependent local strong ground motions are predicted using efficient computational techniques. For the computation of ground motions, we devised an efficient procedure to compute site-independent $x_{q}$ and dependent $x_{s}$ values separately. The first step of this procedure is to use the coda normalization method far computation of site independent Q or corresponding $x_{q}$ value. The next step is the computation of $x_{s}$, values fur each site separately using the given $x_{q}$ value. For computation of ground motions the empirical Green's function (EGF) is modified to account fur the depth and distance variations of subevents on a finite fault plane using the theoritical Green's function. It is computed using wavenumber integration technique in layered media. The site dependent ground motions at seismic stations in southeastern local area were properly simulated using the modified empirical Green's function method in layered medium. The proposed method and procedures fur estimation of site dependent seismic parameters and ground motions could be efficiently used in the low and moderate seismicity regions.ons.s.ons.