The basis of capacity design has been explicitly or implicitly regulated in most bridge design specifications. It is to guarantee ductile failure of entire bridge system by preventing brittle failure of pier members and any other structural members until the columns provides fully enough plastic rotation capacity. Brittle shear is regarded as a mode of failure that should be avoided in reinforced concrete bridge pier design. To provide ductility behavior of column, the one of important factors is that flexural hinge of column must be detailed to ensure adequate and dependable shear strength and deformation capacity. In particular, this study focused on assessing transverse reinforcement contribution to the column shear strength. Transverse reinforcement contribution measured during test. Each three components of transverse reinforcement contribution, axial force contribution and concrete contribution were investigated and compared. It was assessed that the concrete stresses of all specimen were larger than stress limit of Korea Bridge Design Specifications.

A deflection of a RC structure increases when sustained loads are applied in it. In this paper, a parametric study of long-term deflection was performed according to concrete strength, creep coefficient and ratio of sustained load for each design provisions. Results show that a long-term deflection in KSCDC is able to apply an effect of creep using an effective modulus of elasticity.

This research was an attempt to design a new structural concept of non-uniform reinforced and super concrete truss members applying by super concrete which has the compressive strength of 80-200MPa, the tensile strength of 8-20MPa, and the tensile strain of 1.0-5.0%. The super concrete truss members were designed by the Strut-Tie approach as well as aesthetic design concept. The structural performance of designed superconcrete truss was evaluated with the conventional reinforced concrete members.

In this research, new structural design and manufacturing method of atypical irregular UHPC structural members were newly introduced. The atypical irregular UHPC member was optimized to design from the conventional rectangular section and a method of nonuniform formwork system was newly created to manufacture the irregular member. The specimens were evaluated by analysis and the newly designed member was improved in bending performance by 2.6 times compared to conventional rectangular concrete beams.

In this study, the purpose of the study is to determine the depth of damage caused by early frost damage in concrete slab structures under the conditions of external temperature during winter. In other words, we intend to analyze the depth variation of the early frost damage as the thickness of the concrete slab member changes under the condition of the 3-component binder frequently used in practice. As a result, the thinner the component, the significantly reduced the overall temperature of the concrete. In addition, the thinner the component thickness, the higher the delay in increasing the brightness of the core collected from the concrete member, and the greater the effect on the depth of the early frost damage was on the thinner the component thickness.

이 연구는 CRC기둥강도곡선의 비탄성영역에 대한 해석적 고찰이다. CRC기둥강도곡선의 비탄성영역은 최대 잔류응력 크기 0.5σy 와 Bleich이론을 기초로 하고 있다. 이는 실제로 알려진 최대 압축 잔류응력의 크기가 0.3σy 인 경우 보다 다소 보수적이다. 본 연구는 열압연강재의 최대 압축 잔류응력의 크기를 0.3σy 으로 고려하여 그에 따른 기둥강도곡선과 접선탄성계수 Et를 제안하고 이를 CRC에서 제안하고 있는 값들과 각각 비교 고찰한다. 축 압축력을 받는 비탄성 기둥의 응력은 기둥에 작용하는 하중이 좌굴을 일으키기 전에 재료의 비례한도를 넘어 항복점에 도달할 것이다. 따라서 점차적인 단면의 항복 상태에 따른 기둥강도곡선을 검토할 필요가 있다. 본 연구는 최대 압축 잔류응력 σr = 0.5σy 을 사용하여 재료의 항복에 따른 임계하중 곡선식을 유도하고 이를 CRC기둥강도곡선과 비교 고찰한다.

콘크리트는 장기수명이 요구되는 구조물에 적합한 건설재료로 내구성이 우수하지만 장기간 지하수에 노출되어 발생하는 칼슘용출 현상에 대한 이해 및 이에 따른 RC 부재의 휨 거동 특성을 평가할 필요가 있다. 실험결과에 따르면, 광물질 혼화재는 RC 부재의 장기강도 개선에 효과적이지만, 칼슘용출이 발생하면 RC 부재의 항복하중 및 휨 강성이 감소하고 중립축깊이와 처짐량이 증가하는 것으로 나타났다. 따라서 칼슘용출에 의한 열화는 RC 부재의 성능 저하를 유발하므로 칼슘용출 환경에 노출되는 지하구조물에 광물질 혼화재가 적용될 경우에는, 광물질 혼화재 종류에 따른 최적 혼입 비율이 마련되어야할 것으로 사료된다.

본 연구의 목적은 볼접합부를 갖는 원형강관의 좌굴실험 결과를 토대로 하여 국내외 압축재 설계규준과 비교 평가함으로써 부재의 좌굴내력 및 좌굴길이 계수의 안전성과 합리성을 조사하는 것이다. 좌굴성능 평가를 위해 선정된 원형강관은 ∅48.6×2.8t와 ∅60.5×3.2t 및 ∅ 76.3×3.2t이다. 국내외 압축재 설계를 위해 우리나라의 하중저항계수 설계법(LRFD), 일본의 한계상태 설계법(LSD) 및 영국의 BS5950 규준을 적용하였다. 본 연구에서는 선행연구의 실험결과와 국내외 설계규준과의 좌굴성능을 비교 분석하였다. 그 결과를 요약해 보면 다음과 같다. 각 국의 압축재 설계규준에서 부재의 전체길이를 좌굴길이로 적용한 결과 실험에 의한 좌굴내력의 64%∽89% 정도로 나타났다. 따라서 안전을 위해 현재 설계 규준식에 준하여 부재설계를 수행하는 것이 바람직하다고 판단되었다. 실험결과 측정된 좌굴내력은 우리나라, 일본 및 영국의 압축재 설계규준에서 좌굴길이를 순수 원형강관만으로 고려한 좌굴내력 값에 비해 1.02배∽1.43배 높은 것으로 나타났다. 따라서 스페이스 프 레임 구조물 설계에 있어 개별부재 좌굴내력은 절점 간 길이가 아닌 순수 원형강관의 길이로 좌굴계수를 고려할 필요가 있을 것으로 보여진다.

The minimum reinforcement ratio is an important design factor to prevent a brittle failure in RC flexural members. A minimum reinforcement ratio is presented by assuming an effective depth of cross-section and moment arm lever in CDC and KHBDC. In this study, it suggests that a rational method for minimum reinforcement ratio is calculated by material model and force equilibrium. As results, a minimum reinforcement ratio using a p-r curve in KHBDC is evaluated about 52~80% of recent design code’s value and it induces an economical design. And also, a ductility capacity in case of placing this minimum reinforcement amount is evaluated about 89% of recent design code’s value, but ductility in a member is 7 or more, so it has a sufficient ductility capacity. Therefore, it is judged that a minimum reinforcement ratio using p-r curve has a theoretical rationality, safety and economy in a flexural member design.

강교량은 유지관리가 충분히 이루어지지 않거나 , 해안 과 같이 가설위치의 환경이 고온 다습한 경우 단면에 국부적인 부식손상이 발생할 수 있다. 특히 강거더 교량 의 지점부에서는 교대부와 강거더 단부의 공간이 협소하여 상대적으로 습도가 높고 신축이음부로부터의 강 우 및 동결 방지제가 누수되어 침전물을 습윤상태로 유지하게 되므로, 복부판과 지점부 보강재에 집중적으로 부식이 발생되고 있으므로 이로 인한 구조성능 변화를 확인하여야 한다. 따라서 본 연구에서는 실제 발생할 수 있는 강거더 단부 복부판과 보강재의 국부부식손상을 모사한 강 재 실험체를 제작하고 이에 대한 단부 지압강도 변화를 실험적으로 평가하였다. 실험결과, 국부적 부식손상은 강거더 단부의 지압강도에 영향 을 주며, 특히 수직 보강재에 의한 영향이 크게 나타남을 확인하였다.

To examine the practical potentials of V-ties to provide a confinement to a strengthening jacket section of existing reinforced concrete members, direct bond tests were conducted under a parameter of the V-tie details. Test results showed that V-ties with headed-end had a higher bond strength than those with the other details.

It was studied structural design of nonuniform UHPC concrete structural members. UHPC concrete has the compressive strength of 120-200MPa, the tensile strength of 8-20MPa, and the tensile strain of 1.0-5.0%. There are two types of specimens of nonuniform members improved in bending and shear performances. The specimens were evaluated by beam load test induced by bending and shear failures.

In this paper, the flexural test of concrete member damaged due to Calcium leaching were performed to evaluate the characteristics of structural behavior. From the results, yield load, maximum load and flexural rigidity of RC member damaged by calcium leaching were decreased and the depth of the neutral axis was increased.

Due to recent climate changes, damage to the soundproof wall due to typhoons and strong winds is on the rise. This study determine the fragility curve of aluminum frame, which is a weak member of the soundproofing wall, due to strong wind. The fragility was analyzed in term of aluminum frame thickness variation. Finite element analysis of the wall was performed with ABAQUS, a commercial program. Random wind loads applied to the structures were generated using the Monte Carlo simulation technique. Also, the limit state was set based on the analysis results. The fragility curves were developed with consideration of three influential factors which are installation location, wind exposure and thickness aluminium frame of soundproof wall.

본 연구에서는 휨을 받는 압축강도 80 MPa 수준의 고강도 콘크리트 부재의 구조거동 실험 연구를 수행하였다. 실험변수는 보통(SD 400) 및 고강도(SD 600)철근, 0.98~1.58%의 종방향 철근비, 200×250, 200×300 mm의 단면크기를 고려하였다. 9개의 보 부재를 제작하여 휨 실 험을 수행하였으며 극한휨강도, 하중-처짐 관계, 균열 형태, 파괴형상 및 연성을 파악하였다. 실험결과는 철근비가 증가함에 따라 휨강도는 증 가하고 연성은 감소한다. 또한, 철근비가 증가함에 따라 균열의 개수가 증가하며 균열폭은 감소하는 경향을 나타내었다. 철근의 강도 등급에 따른 하중-균열폭 관계는 뚜렷한 차이를 나타내지 않는다. 콘크리트 비선형거동 해석을 수행하였으며, 극한하중 예측값과 측정값을 비교하였 다. 고강도 콘크리트의 휨거동 예측 결과는 실험부재의 휨강도를 전반적으로 과소평가하고 있다.

This study examined the effects of the embedded auxetic grating structures by design on numerical analysis. Compressive tests were performed and the results showed the effectiveness of auxetic grating structures for the enhancements of stiffness.

The reinforcement effect of buckling resistance steel damper on member with two-column and beam is evaluated by investigating the relationship of lateral load and displacement

A steel tubular member has been generally used for the offshore structure. Its stucutral performance can be decreased due to corrosion damage under severe corrosion environment In this study, to examine the compression performance of steel tubular member depending on corrosion thickness, damaged ratio, FE analyses were conducted and compared.

A minimum reinforcement ratio is an important factor to prevent a brittle failure for RC flexural members. In this paper, a parametric study of minimum reinforcement ratio is performed according to concrete strength, steel yield strength and cover depth ratio for each design provisions. A minimum reinforcement ratio using a stress-strain model is suggested. And results show that this mode is able to reflect material strength and cross-section properties properly.

Studies on the lattice girder of the cross sectional form and construction works through laboratory experiments have been performed. The numerical analysis for structural behavior such as deflection and stresses on the lattice girder, however, are insufficient. In this study the stiffness of a lattice girder was examined by using MIDAS.