• 한국주거학회논문집
• /
• 제13권5호
• /
• pp.9-20
• /
• 2002

The purpose of this study are to evaluate the dwelling quality of rural houses constructed with industrialized wall structures(ALC; Autoclaved Light weight Concrete, SRC; Steel Fiber Reinforced Concrete, ST'L; Steel Framed Insulating Panel), and to establish a method of dwelling quality evaluation. The questionnaire survey by mail was done, for investigating the residents' responses to indoor environment, durability, and economic aspect. The respondents are 118 residents living in rural houses constructed with industrialized wall structures. Physical elements of indoor environment(temperature, humidity, air quality, and noise level) were measured in three sample houses, which were selected considering of architectural characteristics. The findings are as follows; 1) As a result of questionnaire survey, residents' responses to dwelling quality are generally positive. 2) As a result of measurement, indoor environments of sample houses are in relatively comfortable condition. 3) As a summary of research, ALC and ST'L are evaluated as recommendable structures for a rural house.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
• /
• pp.329-332
• /
• 2005

R.C. bridges may require strengthening during the service life. The main cause of durability problem of R.C. bridges is the corrosion of reinforcing steel. For this reason, researches to solve the problem have been conducted but the achievements are just for improving, not the solution. Fiber Reinforced Polymers are recognized as the alternative materials for solving the problem due to the excellent corrosion-resistant property, light-weight and higher strength than steel. This paper presents experimental results and theoretical consideration of bond test for new type GFRP rebar

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
• /
• pp.673-676
• /
• 2006

Steel FibreReinforced Shotcrete(SFRS) is one of the main tunnel support along with the rock bolt during the excavation and after the completion of the tunnel. In the standard qualification of the SFRS defined by Korea Highway Corporation, 28 day core specimen has to meet the compressive strength of 19.6 MPa and over 90 % fibre contents. Furthermore, for the 28 days brick shaped specimen made by shooting, flexural strength should be over 4.4 MPa and flexural toughness ratio which can be calculated from flexural toughness factor has to meet more than 68% of flexural strength. In shotcrete, accelerating agent is added for the rapid strength development. Silicate and aluminate type agents are known to develop shotcrete strength rapidly, however, has such problem to degrade the middle and long term strength. Hence, using poly carboxylic super plasticizer, it was aimed to enhance the quality of the shotcrete with the lower water-cement ratio and the same level of workability. The present paper shows the part of the field test result and its analysis.

• Structural Engineering and Mechanics
• /
• 제83권1호
• /
• pp.109-121
• /
• 2022

Twelve push-out test specimens were conducted with various parameters to study the static and fatigue performance of a new through-bolt shear connector transferring the shear forces of interface between prefabricated hybrid fiber reinforced concrete (HFRC) slabs and steel girders. It was found that the fibers could improve the fatigue life, capacity and initial stiffness of through-bolt shear connector. While the bolt-hole clearance reduced, the initial stiffness, capacity and slippage of through-bolt shear connector increased. After the steel-concrete interface properties were improved, the initial stiffness increased, and the capacity and slippage reduced. Base on the test results, the equation of the load-slip curve and capacity of through-bolt shear connector with prefabricated HFRC slab were obtained by the regression of test results, and the allowable range of shear force under fatigue load was recommended, which could provide the reference in the design of through-bolt shear connector with prefabricated HFRC slabs.

• Structural Engineering and Mechanics
• /
• 제81권4호
• /
• pp.513-522
• /
• 2022

Steel-concrete composite segments replacing the conventional reinforced concrete segments can provide the rectangular shield tunnel superiorities on bearing capacity, ductility and economy. A simplified model with high-efficiency on computation is proposed for investigating the nonlinear response of the rectangular tunnel lining composed of composite segments. The simulation model is developed by an assembly of nonlinear fiber beam elements and spring elements to express the transfer mechanism of forces through components of composite segments, and radial joints. The simulation is conducted with the considerations of material nonlinearity and geometric nonlinearity associated with the whole loading process. The validity of the model is evaluated through comparison of the proposed nonlinear simulation with results obtained from the full-scale test of the segmental tunnel lining. Furthermore, a parameter study is conducted by means of the simplified model. The results show that the stiffness of the radial joint at haunch of the ling and the thickness of inner steel plate of segments have remarkable influence on the behaviour of the lining.

• 콘크리트학회논문집
• /
• 제15권3호
• /
• pp.377-385
• /
• 2003

인장강도와 내방식성이 우수하고 콘크리트 구조물속에서 철근과의 정착성이 양호하여 콘크리트 구조물의 새로운 보강재로 사용되고 있는 탄소격자섬유의 보강효과를 검증하기 위하여 탄소격자섬유보강공법으로 보강한 철근콘크리트 보 시험체를 제작하여 정적 휨 파괴실험을 통해 보강효과 및 휨 파괴특성을 분석하였다. 강판이나 탄소섬유 압착공법에서 나타나는 계면박리(탈락)파괴 보다는 보수 몰탈의 고강도화로 휨균열의 진전에 의해 콘크리트 속에서 철근에 정착된 격자섬유 층에서의 균열이 지점부로 진행되어 파괴되는 내부 계면박리와 지간중앙에서 철근 항복후 격자와 연결된 앵커볼트의 항복으로 인한 탄소격자섬유 파괴, 그리고 격자섬유 항복후 취성적인 콘크리트 압축파괴 양상이 나타났다. 실험결과를 근거로 최소보강재량이 제시되었으며, 강도설계법을 근거로 격자섬유로 보강시 필요한 설계법이 제안되었다.

• Computers and Concrete
• /
• 제16권5호
• /
• pp.683-701
• /
• 2015

When approached using nonlinear finite element (FE) techniques, structural analyses generate, for real RC structures, large complex numerical problems. Damage is a major part of concrete behavior, and the discretization technique is critical to limiting the size of the problem. Based on previous work, the ${\mu}$ damage model has been designed to activate the various damage effects correlated with monotonic and cyclic loading, including unilateral effects. Assumptions are formulated to simplify constitutive relationships while still allowing for a correct description of the main nonlinear effects. After presenting classical 2D finite element applications on structural elements, an enhanced simplified FE description including a damage description and based on the use of multi-fiber beam elements is provided. Improvements to this description are introduced both to prevent dependency on mesh size as damage evolves and to take into account specific phenomena (permanent strains and damping, steel-concrete debonding). Applications on RC structures subjected to cyclic loads are discussed, and results lead to justifying the various concepts and assumptions explained.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
• /
• pp.70-71
• /
• 2019

Glass fiber reinforced concrete (GFRC) is very suitable as a material for free-form concrete panels (FCPs) because of its lightweight, strong, moldable, durable and sustainable properties. GFRC is superior in construction and maintenance compared with materials such as steel, aluminium, titanium, glass and plastic, and is advantageous in cost. However, GFRC is being produced by skilled craftsmen, and still lacks the technology to economically produce high quality FCPs. Currently, there is a technology to automatically and accurately produce FCPs. However, the developed technology can not be applied to the field with simple production technology without production line for mass production. To solve this problem, the purpose of this study is a basic study of production system development of free-form concrete panels. This study introduces the developed FCPs production technology and builds FCP production system for mass production. The results of this study will be used as basic data for the commercial production of FCPs in the future.

• Structural Engineering and Mechanics
• /
• 제5권6호
• /
• pp.679-689
• /
• 1997

The damage of concrete subjected to multiaxial complex loading involves strong anisotropy due to its highly heterogeneous nature and the geometrically anisotropic characteristic of the microcracks. A comprehensive description of concrete damage is proposed by introducing a fourth-order anisotropic damage tenser. The evolution of damage is assumed to be related to the principal components of the current states of stress and damage. The unilateral effect of damage due to the closure and opening of microcracks is taken into account by introducing projection tensors that are also determined by the current state of stress. The proposed damage model considers the different kinds of damage mechanisms that result in different failure modes and different patterns of microdefects that cause different unilateral effects. This damage model is embedded in a thermomechanically consistent constitutive equation in which hardening and the triaxial compression caused shear-enhanced compaction can also be taken into account. The validity of the proposed model is verified by comparing theoretical and experimental results of plain and steel fiber reinforced concrete subjected to complex triaxial stress histories.

• 콘크리트학회논문집
• /
• 제24권5호
• /
• pp.585-596
• /
• 2012

이 연구는 교량이나 주차장 건물 등에 적용이 가능한 GFRP 보강 철근 폴리머 콘크리트 T형 보의 휨 특성에 관한 연구로서 GFRP 보강 수준에 따른 압축파괴(compression failure: CF), 인장파괴(tension failure: TF) 및 GFRP 보강재의 파괴(fiber sheet failure: FF) 등 파괴모드의 판단과 결정방법을 제시하고, 파괴모드별 설계휨강도 산정식을 제시하였다. GFRP 보강 철근콘크리트 보에서는 FF, TF, CF 등 3가지 파괴모드 중에서 철근항복 ${\rightarrow}$ GFRP 파단 ${\rightarrow}$ 압축측 콘크리트 파괴의 순으로 진행되는 FF 파괴모드가 가장 이상적이다. FF 파괴모드의 경우 압축측 폴리머 콘크리트가 극한변형률(${\varepsilon}_{cu}$)에 도달하기 전에 GFRP가 먼저 파단되므로 콘크리트의 극한상태를 기반으로 하는 기존의 등가직사각형 응력블럭의 개념을 적용할 수 없다. 따라서 이 연구에서는 폴리머 콘크리트의 특성에 부합되는 이상화된 폴리머 콘크리트의 압축응력-변형률 곡선을 제안하고, 폴리머 콘크리트의 변형률을 기반으로 하여 응력블럭 매개변수 ${\alpha}$, ${\beta}$를 도출하였다. 또한 T형 보의 형상비에 따른의 압축응력 분포 및 설계휨강도 특성을 규명하고 적정한 형상비를 2.5로 제시하였으며, GFRP 보강재의 두께 및 높이에 따른 설계휨강도 산정식을 제시하고 그 식의 적정성을 실험과 이론해석에 의해 입증하였다.