• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.305-308
• /
• 2006

In this paper, the seismic performance of SRC piers for near fault motions was evaluated by shaking table tests on small scale models. Dead load of the superstructures was simulated by axial prestress at the center of the column section. A mass frame linked with steel bars was fabricated to include the effect of superstructure mass. Friction of the mass frame when it moves was minimized by special details and it was proved before tests. Five pier models with 400mm diameter were tested by increasing the acceleration of the near fault motion. Test results were discussed and compared with previous quasi-static tests.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.85-88
• /
• 2006

This paper deals with shaking table tests on RC piers to evaluate the seismic performance under near fault motion. Small scale models were fabricated and axial force was applied by introducing prestress at the centroid of the column section. Mass effect of the superstructures was simulated by mass frame which was linked with a pier model by steel bars because of the limited payload of shaking table. Friction of the mass frame when it moves was minimized by special details and it was proved before tests. Scale factor of the RC piers was 4.25. Main parameters of the test were details of reinforcements. After verifying the results of shaking table tests, seismic performance was evaluated by increasing the acceleration of the near fault motion.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.46 no.1
• /
• pp.61-71
• /
• 2004

The performance evaluation and deflection of 3 spans concrete simplicity slab bridge analyzed by non-destructive and loading test. Compressive strength of slab and pier appeared in the range of each 353∼366 kgf/$cm^2$ and 152∼215 kgf/$cm^2$ in rebound number test. Also, it appeared that concrete quality of slab was good after performance improvement. The average compressive strength of slab by core picking appeared 229 kg/$cm^2$. In reinforcing bar arrangement test of span and member, it appeared that horizontal and vertical reinforcing bar was arranged to fixed interval. The value of calculation deflection that carried structural analysis with deflection analysis wave in static loading test appeared higher than that of experimental deflection and it appeared that hardness of this bridge was good. Maximum impact factor that estimated from deflection by running speed in dynamic loading test appeared by 0.216 in 10 km/hr running speed.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.11 no.3 s.55
• /
• pp.23-31
• /
• 2007

Fast bridge construction has been increasingly needed according to the changed construction environment. This paper deals with quasi-static tests on precast piers for bridge substructures. One of the most crucial aspect of the design of precast prestressed concrete bridge piers is the seismic performance. Seven precast pier elements were fabricated. The amount of prestressing bars, the prestressing force, and the location and number of the joint between segments were the main test parameters. Test results showed that the introduced axial prestress made the restoration of the deformation under small lateral displacement and minor damage. However, there was no effect of the prestress when the plastic hinge region was damaged severely due to large lateral displacement. Judging from the observed damage, the design of the joints in precast piers should be done for the first joint between the foundation and the pier segment. The amount of the necessary prestressing steel may be designed to satisfy the P-M diagram according to the service loads, not by having the same steel ratio as normal RC bridge piers. In order to satisfy the current required displacement ductility, it is necessary to have the same amount of the transverse reinforcements as RC piers. As the steel ratio increases, the energy absorption capacity increases. The number of joints showed a little influence on the energy absorption capacity.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.4 s.56
• /
• pp.116-125
• /
• 2009

Recently, modular system are popular in construction fields, and they are increasing their marcket share. To compare modular units, bolting and welding are most popular methods. However, the temperature around a welded part might be over than 1,300$^{\circ}C and the composite member might be exposed tp the direct welding heat about 20,000$^{\circ}C. This high welding heat makes decrease of the concrete strength. If the concrete strength seriously decreases, it can affect the behavior and safty of a structure. On this study, To prevent of concrete strength decreases by welding heat, we suggested method of to insert between steel and concrete.

• Journal of the Korea Concrete Institute
• /
• v.17 no.1 s.85
• /
• pp.121-128
• /
• 2005

A RC column-bent pier represents one of the most popular piers used in highway bridges. Seismic performance of reinforced concrete (RC) column-bent piers under bidirectional seismic loadings was experimentally investigated. Six column bent-piers were constructed with two circular supporting columns which were made in 400 mm diameter and 2,000 mm height. One single column specimen was additionally made to comparatively evaluate the seismic response of RC column-bent piers. Test parameters are different transverse reinforcement and loading pattern. These piers were tested under lateral load reversals with the axial load of $0.1 f_{ck}A_g$. Three specimens were subjected to bidirectional lateral load cycles which consisted of two main longitudinal loads and two sub transverse loads in one load cycle. Other three specimens were loaded in the opposite way. Test results indicated that lateral strength and ductility of the latter three specimens were generally bigger than those of the former three specimens. Plastic hinges were formed with the spall of cover concrete and the fracture of the longitudinal reinforcing steels in the bottom plastic hinge of two supporting columns for the former three specimens. Similar behavior was observed in the top and bottom parts of two supporting columns for the latter three specimens.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.14 no.4
• /
• pp.505-513
• /
• 2001

In this study, an optimum design algorithm using efficient reanalysis is proposed for seismic design of Reinforced Concrete (RC) piers. The proposed algorithm for optimization of RC piers is based on efficient reanalysis technique. Considering structural behavior of RC piers, the other approximation technique such as artificial constraint deletion is introduced to increase the efficiency of optimization. The efficiency and robustness of the proposed algorithm including the proposed reanalysis technique is demonstrated by comparing it with a conventional optimization algorithm. A few of design examples are optimized to show the applicability of the proposed algorithm.

• Magazine of the Korea Concrete Institute
• /
• v.13 no.5
• /
• pp.77-81
• /
• 2001

부식 열화는 교량 기술자들에게 있어서 지속적인 도전을 요구하는 문제가 되어왔는데, 스텔스 항공기를 개발하게 한 새로운 재료 기술은 교량의 부식을 해결할 수 있게 하였다. 즉, 경량의 고강도 재료로 높은 피로 저항성을 갖고 있고, 부식에 강한 복합체는 교량의 재료로서 아주 바람직한 성질을 갖고 있다 섬유 보강 폴리머(FRP) 복합재료를 교량의 건설에 이용하려는 프로젝트는 1998년 현재 80 여 개가 넘게 진행되고 있는데, 이 중 미국 내에서 31개의 프로젝트가 수행되고 있다. 이 글은 미국 내에서 FRP복합체를 교량 공학 분야에 적용하려는 초기의 성공적인 시도들에 관한 내용으로 복합체의 장점, 특성, 교량 적용시 고려 사항, 그리고 향후 복합재료에 관한 기술을 토목 구조물에 적용하는데 필요한 소요 기술 등에 관하여 정리한 것이다. 이 새로운 재료는 신설 구조물의 건설과 기존 교량의 보수 및 보강에 모두 적용할 수 있으며, FRP복합체 기술을 토목 구조물과 기반 시설물 건설 분야에 적용하는 것은 지금까지 성공적인 결과를 보여 주고 있다 미국연방도로국(FHWA, Federal Highway Administration)은 이 기술을 미국 내 교통 기반 시설물인 신규 교량의 건설은 물론 기즌 교량의 보수 및 보강에 활용하는 방안에 대하여 관심을 갖고 있다.

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

• Structural Engineering and Mechanics
• /
• v.62 no.3
• /
• pp.281-289
• /
• 2017

Damping value has considerable influence on the dynamic and seismic behaviors of bridges. However, currently the constant damping ratios that are prescribed by most bridge seismic design codes can't truly represent the complicated damping character of actual structures. In this paper, a cyclic loading experiment was conducted to study the effect of stress amplitude on material damping of concrete to present an analyzing model of the material damping of concrete. Furthermore, based on the fundamental damping of structure measured under ambient vibration, combined with the presented stress-dependent material damping concrete, the seismic response of a bridge pier was calculated. Comparison between the calculated and experiment results verified the validity of the presented damping model. Finally, a modified design and analysis method for bridge was proposed based on stress-dependent damping theory, and a continuous rigid frame bridge was selected as the example to calculate the actual damping values and the dynamic response of the bridge under different earthquake intensities. The calculation results indicated that using the constant damping given by the Chinese seismic design code of bridges would overestimate the energy dissipation capacity of the bridge.