• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2002.03a
• /
• pp.195-202
• /
• 2002

Lap splices of longitudinal reinforcement steels were practically located in the potential plastic hinge region of most bridge columns that were constructed before the 1992 seismic design provision of Roadway Bridge Design Specification in Korea. The objective of this research is to evaluate the seismic performance of shear-critical reinforced concrete(RC) bridge piers with poor detailing of the starter bars in the plastic hinge region, and to develop the enhancement scheme of their seismic capacity by retrofitting with fiber composites. Seven test specimens in the aspect ratio of 2.5 were made with three confinement ratios and two types of lap splices. Quasi-static test was conducted in a displacement-controlled test mode. A significant reduction of displacement ductility ratios were observed for test columns with lap splices of longitudinal steels.

• Structural Engineering and Mechanics
• /
• v.58 no.2
• /
• pp.259-276
• /
• 2016

Lead-rubber bearings (LRBs) have been used worldwide in seismic design of buildings and bridges owing to their stable mechanical properties and good isolation effect. We have investigated the effectiveness of LRBs in framed underground structures on controlling structural seismic responses. Nonlinear dynamic time history analyses were carried out on the well-documented Daikai Station, which collapsed during the 1995 Hyogoken-Nanbu earthquake. Influences of strength ratio (ratio of yield strength of LRBs to yield strength of central column) and shear modulus of rubber on structural seismic responses were studied. As a displacement-based passive energy dissipation device, LRBs reduce dynamic internal forces of framed underground structures and improve their seismic performance. An optimal range of strength ratios was proposed for the case presented. Within this range, LRBs can dissipate maximum input earthquake energy. The maximum shear and moment of the central column can achieve more than 50% reduction, whereas the maximum shear displacement of LRBs is acceptable.

• Steel and Composite Structures
• /
• v.39 no.1
• /
• pp.65-80
• /
• 2021

Irregularities of a building in plan and elevation, which results in the change in stiffness on different floors highly affect the seismic performance and resistance of a structure. This study motivated to investigate the seismic responses of high-rise steel-frame buildings of twelve stories with various stiffness irregularities. The building has five spans of 3200 mm distance in both X- and Z-directions in the plan. The design package SAP2000 was adopted for the design of beams and columns and resulted in the profile IPE500 for the beams of all floors and box sections for columns. The column cross-section dimensions vary concerning the number of the story; one to three: 0.50×0.50×0.05m, four to seven: 0.45×0.45×0.05 m, and eight to twelve: 0.40×0.40×0.05 m. Real recorded ground accelerations obtained from the Vrancea earthquake in Romania together with dead and live loads corresponding to each story were considered for the applied load. The model was validated by comparing the results of the current method and literature considering a three-bay steel moment-resisting frame of eight-story height subject to seismic load. To investigate the seismic performance of the buildings, the time-history analysis was performed using ABAQUS. Deformed shapes corresponding to negative and positive peaks were provided followed by the story drifts and fragility curves which were used to examine the probability of collapse of the building. From the results, it was concluded that regular buildings provided a seismic performance much better than irregular buildings. Furthermore, it was observed that building with torsional irregularity was more vulnerable to seismic failure.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2005.04a
• /
• pp.652-659
• /
• 2005

Even in moderate to low seismic regions like Korean peninsular where wind loading usually governs the structural design of a tall building, the probable structural impact of the design basis earthquake or the maximum credible earthquake on the selected structural system should be considered at least in finalizing the design. In this study, by using response spectrum analysis and linear time history analysis method, seismic performance evaluation was conducted for wind-designed concentrically braced steel highrise buildings. Both spectrum-compatible artificial accelerograms and recorded accelerograms were used as input ground motions for the time history analysis. The analysis results showed that wind-designed concentrically braced steel highrise buildings possess significantly increased elastic seismic capacity due to the system overstrength resulting from the wind-serviceability criterion and the width-to-thickness ratio limits on steel members. Time history analysis results generally tended to underestimate the seismic response as compared to those of response spectrum analysis.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2005.03a
• /
• pp.177-184
• /
• 2005

Even in moderate to low seismic regions like Korean peninsular where wind loading usually governs the structural design of a tall building, the probable structural impact of the design basis earthquake or the maximum credible earthquake on the selected structural system should be considered at least in finalizing the design. In this study, by using response spectrum analysis and time history analysis method, seismic performance evaluation was conducted for wind-designed concentrically braced steel highrise buildings. Input ensemble was normalized to be compatible with expected peak ground acceleration. The analysis results showed that wind-designed concentrically braced steel highrise buildings possess significantly increased elastic seismic capacity due to the system overstrength resulting from the wind-serviceability criterion and the width-to-thickness ratio limits on steel members. The time history analysis tended to significantly underestimated the seismic response as compared to response spectrum analysis. Further detailed studies regarding selection and scaling scheme of input ground motions is needed.

• Journal of Korean Society of Steel Construction
• /
• v.29 no.5
• /
• pp.369-376
• /
• 2017

This paper is the sequel of a companion paper (I. Seismic Design) for design and assessment of the torsional irregular structure using ASCE 7-10 criteria. This study evaluates the influence of torsional provisions on the performance of the designed steel moment frame with different eccentricity, taking the collapse probability as performance metric using the methodology in FEMA P695. The result show that torsional irregular structure designed according to ASCE 7-10 has an excessive seismic performance and the collapse strength is low as the eccentricity increases. To make the design reasonable, a new design approach is proposed in this study.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1999.04a
• /
• pp.305-312
• /
• 1999

This study is intended to propose a systematic and practical life cycle cost(LCC) model for the development of the reliability-based seismic safety and cost-effective performance criteria for design and upgrading of long-span PC bridges. The LCC models consist of five cost functions such as initial cost, repair/replacement cost, human losses, road user cost, and indirect losses of regional economy. The proposed model Is successfully expressed in temrs of Park-Ang damage indices and life cycle damage probability obtained from SMART-DRAIN-2DX which is an existing algorithm for nonlinear time history analysis. The proposed LCC model is successfully applied to a viaduct constructed by PSM, in Seoul. Based on the observations, the proposed systematic procedure for the formulation of LCC model may be useful for the development of the reliability-based seismic safety and cost-effective performance criteria for design and upgrading of long-span PC bridges.

• Structural Engineering and Mechanics
• /
• v.27 no.5
• /
• pp.541-554
• /
• 2007

A simplified yet effective design procedure for viscous dampers was presented based on improved capacity spectrum method in the context of performance-based seismic design. The amount of added viscous damping required to meet a given performance objective was evaluated from the difference between the total demand for effective damping and inherent damping plus equivalent damping resulting from hysteretic deformation of system. Application of the method is illustrated by means of two examples, using Chinese design response spectrum and mean response spectrum. Nonlinear dynamic analysis results indicate that the maximum displacements of structures installed with supplemental dampers designed in accordance with the proposed method agree well with the given target displacements. The advantage of the presented procedure over the conventional iterative design method is also highlighted.

• Journal of The Korean Digital Architecture Interior Association
• /
• v.11 no.2
• /
• pp.115-121
• /
• 2011

Occurrence of earthquakes have been increased all over the world and also, magnitude of earthquakes have been larger these days. Earthquake can be happened in Korea and is not a safe country any more. Many buildings are exposed at danger without any alternatives against earthquake in Korea. Among various kinds of buildings, school buildings are very important and urgent, because many students stays at school and young students have some difficulty to evacuate. Also, most existing school buildings in Korea were not designed considering earthquake resistant design codes. Thus, in this study, 3 types of braces were applied for seismic retrofits of existing school buildings using commercial structural analysis software and effective seismic retrofits were evaluated and discussed based on results by time history analysis.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2001.04a
• /
• pp.465-474
• /
• 2001

Base Isolation system is an effective design strategy that provides a practical substitute for the seismic design of bridge. In this study, the dynamic tests was performed on HDB (Hysteretic Damping Bearing) and Dynapot. Then, the dynamic analysis was carried out for a bridge using the experimental results to estimate the seismic performance of bearings. Analysis for bridge was performed for four types of earthquake loadings. The result of dynamic test and theoretical analysis indicate that the performance of HDB and Dynapot is appropriate for the earthquake loading.