As a eco-friendly material, Hwangtoh (red clay) has been studied for complete or partial replacement of portland cement consisted in concrete. In this research, the experimental works were conducted to study the initial quality control for the compressive strength of Hwangtoh concrete (24MPa) using the ultrasonic pulse velocity method and the impact echo method of nondestructive test methods.

In this research, the experimental works were conducted to study the lap strength of the headed reinforcements with confinement provided by stirrups or tie-down bars. Eleven lap splice specimens were tested. The variables in this study were: confinement details and lap length. The initial crack of the specimens lapped developed at the heads of reinforcements. Bearing stress and confinement details contributed to increase strength and deformation.

In this paper, we proposed visual information to provide a highly maneuverable system for a tele-operator. The visual information image is bird’s eye view from UFR(Unmanned Flying Robot) shows around UGR(Unmanned Ground Robot). We need UGV detection and tracking method for UFR following UGR always. The proposed system uses TLD(Tracking Learning Detection) method to rapidly and robustly estimate the motion of the new detected UGR between consecutive frames. The TLD system trains an on-line UGR detector for the tracked UGR. The proposed system uses the extended Kalman filter in order to enhance the performance of the tracker. As a result, we provided the tele-operator with the visual information for convenient control.

Existing nondestructive test methods used to measure reinforcement corrosion is based on qualitative measurement of corrosion, and it has many difficulties of use because many equipment and measurement stages are required for application at actual sites. Accordingly, this study was conducted to estimate reinforcement corrosion of concrete structures using infrared thermography method as a method of measuring reinforcement corrosion in concrete. As for the specimen was to measure reinforcement corrosion, D13 reinforcement with size of 200×150×180mm was buried at length of 250mm for covering depth of 20mm and 40mm. Accelerated reinforcement corrosion test was carried out after placement of concrete. As a result of measuring reinforcement corrosion using infrared thermography method, temperature difference of 1~3°C was shown depending on the corrosion stage. There was a correlation in which temperature decreased according to chloride content. Infrared thermography method was confirmed as a useful method for measurement of reinforcement corrosion inside concrete.

KCI 2012 and ACI318-11 contains development length provisions for the use of headed deformed bars in tension and does not allow their tension lap splices. In ACI318-11, the confinement factor, such as transverse reinforcement factor, is not used to calculate the development length of headed bars. The purpose of this experimental study is to evaluate the effect of confinement details to the lap splice performance of headed deformed reinforcing bars in grade SD400 and SD500. The confinement details are stirrups and tie-down bars in lap zone. Test results showed that specimens with only stirrups had the brittle failure and could not increase lap strengths, and that specimens with composite confinements by stirrups and tie-down bars had the flexural strengths over than nominal flexural strengths. Stirrups with tie-down bars can have an effect on improvement in lap splice of headed bars in grade SD400 and SD500.

In this study, analyzed of the correlation UPVand the compressive strength of structural timber. As a result, increased of UPV in accordance with the compressive strength increases. Though more experiments, judgment to be possible to estimate the compressive strength of the structural timber with UPV

The purpose of this experimental study is to evaluate that KCI2012 equation for the development length, ldt, of headed bars can be used to calculate the lap length of headed deformed bars in grade SD400~500 for high strength concrete. Test results showed that specimens with lap lengths equal to 1.3ldt had maximum flexural strengths as 0.84~0.90 times as the nominal flexural strengths. These observations indicate that 1.3 is unsuitable to the tensile lap length of headed deformed bars in grade SD400~500 for high strength concrete.

현행 콘크리트구조기준 (KCI2012) 및 ACI318-11에서 B급이음된 일자형 이형철근에 대하여 인장력에 대한 겹침이음길이를 정착길이의 1.3배로 산정하고 있다. 동일 기준에서 확대머리 이형철근의 정착길이를 제시하고 있지만 겹침이음상세에 대한 규정은 없다. 이에 본연구에서는 400MPa과 500MPa 설계기준항복강도를 가지는 확대머리 이형철근의 겹침이음실험을 실시함으로써, 기준의 정착길이식을 겹침이음설계에 적용가능한 지를 평가하고자 하였다. 실험결과, SD400과 SD500의 설계기준항복강도를 적용한 확대머리 이형철근에 대하여 겹침이음길이를 정착길이의 1.3배로 산정할 경우, 실험 최대휨강도가 공칭휨강도에 비하여 16~31% 크게 평가되었고 연성적인 휨파괴 거동을 나타내었다. 따라서, 이들 철근에 대해 정착길이 1.3배의 겹침이음길이로 설계함으로써 강도 및 변형성능 측면에서 겹침이음 성능을확보할 수 있는 것으로 사료된다.

The purpose of this study was to analyze flexural behavior of concrete beams with steel bar and FRP reinforcement. An investigation was performed on the influence of the flexural stiffness, cracking, deflection behavior. Specimen with FRP reinforcement showed a higher strength than specimen with only steel bar. Concrete strength had an effect on improvement in flexural strength and ductile deformation.

In this study, the experiments were carried out in order that flexural behavior evaluated High-strength Concrete Beams reinfrced with FRP plates according ro replacement ration of recycled aggregate. As a result, maximum load was higher than existiong of unreinforced when the reinforced with FRP plates and no decrease in load about increased fo replacement ration of recycled aggregate. Some specimens was greater than ACI 440-2R referemce value.

Recently, as increasing interests in Korean-style house, the government has promoted the policy that encourage constructing Korea-style house fabricated timber though the improvement of the related law and administration system. Also, the perception for historic preservation has been increased in respond to heightened interest. In this paper, External bond and Near surface mounted was used as the way to reinforce timber structure’s durability. bond strength for specimens with different bond length was investigated.

본 연구는 순환굵은골재 콘크리트의 활용성 증대 및 규준 정립에 관한 연구의 일환으로 순환굵은골재 치환율에 따른 고강도 철근콘크리트 보의 휨 특성을 검토하고자 한다. 실험은 콘크리트 설계강도 40MPa, 50MPa, 60MPa 순환굵은골재 치환율 0%, 30%, 50%, 100%를변수로 총 12개의 실험체를 제작하여 최종 파괴 시까지 변위제어 방식에 의해 2점 가력하였다. 실험결과 천연골재를 사용한 실험체와 비교시 균열발생 및 파괴양상의 경우, 순환굵은골재를 사용한 철근콘크리트 보의 실험체는 천연골재 철근콘크리트 보 실험체에 비해 균열이 비교적 압축측까지 진전하는 특성을 보였으나 전반적으로 균열양상은 유사하게 나타났으며, KCI 설계기준식에 의한 계산값 및 실험결과의 비교결과 순환굵은골재 치환율에 관계없이 1.08~1.29로 기준값을 상회하는 것으로 나타나 순환굵은골재를 사용한 콘크리트 보의 휨 부재설계에 적용 가능할 것으로 판단된다. 따라서 순환굵은골재 활용성 증대를 위해 추가적인 실험을 통하여 순환굵은골재의 구조적 기준정립이 필요할 것으로 판단된다.

In this study, the amount of construction waste created from Demolition and reconstruction of old buildings by environmental contamination by construction waste has been raised as a social problem, according as a means to settle problems the government is being encouraged the use Recycled aggregate. However recycled aggregate has not yet been applied to structures in many cases. Due to uncertain technical verification of long-term durability, the use of recycled aggregate is being limited. Accordingly in this study, High Strength Concrete Beams use Recycled coarse Aggregate to evaluate the performance of the bending and establish national standards for structural design of recycled aggregates aims to provide the basic data.

In the case of cultural properties, each member has a cultural value and replacing of damaged wood is not easy. In addition, state of our country research for repair and reinforcement of timber are still incomplete. since 2008, research of the reinforcement method using CFRP plate has started. in this study, experiment for the adhesion strength along attachment length of surface bonded and NSM using CFRP plate. As a result, the adhesive strength is increased depend on increased of the adhesion area, measured the change of intensity according to the species of the wood.

A new precast concrete (PC) beam and column connection system using non-prestressed wire strands was recently developed. The system is composed of one unit of two-storied PC-column and PC-beams with U-shaped ends. The connection part of the column and beams is reinforced by deformed bars and non-prestressed wire strands in combination for the improvement of workability. Structural performance of this system was verified by several experimental studies. The purpose of this study is developing a design concept of the beam reinforced by deformed bars and non-prestressed wire strands in combination, in terms of the cross-sectional analysis, based on the preceded experiment. A minimum and maximum reinforcement ratio and the calculation formula for the strength of flexural member reinforced by reinforcements having different yield strengths are derived based on KBC2009. Under consideration existing research results for the application of high strength reinforcement bars, the design yield strength of the non-prestressed wire strand is suggested. An example for the cross section design, satisfying the serviceability requirements, demonstrates the applicability of the design concept developed in the study.

FRP has higher design tensile strength than steel bar and outstanding characteristics such as light-weight, non-corrosion, and lower conductivity. And, current researchers evaluated flexural performances of flexural members using FRP and suggested the development length and splice length by using bonding failure test. This Researchers has the main purpose to examine the quality of bonding failure in the lap spliced FRP and deformed bar. Variables in this test with total 208 specimens planned are re-bar location, embedment length, covering depth, re-bar diameter. And, this study describes the result of our review on the bonding strength of the lap-spliced FRP and the deformed bar located at the bottom.

In this study, we aimed to consider the inspection without destroying the specimen using the Impact Echo Method of nondestructive test using stress wave in an objective manner for detecting defects in concrete members. As a result of estimating the thickness of the concrete slab member using Impact Echo Method under the influence of the result of the stress wave, the average error in the 7.49% confirmed the applicability. In addition, we can check the possibility of data acquisition and construction of concrete structures for the construction of the diagnosis system

In this study, I tried to derive the expression intensity estimation through analyzing the correlation between wave velocity and compressive strength of high-strength concrete and normal-strength one, using ultrasonic pulse velocity which is one of the non-destructive tests which do not damage the structure. By producing a material age strength and body separate experiment which is applied to the ultrasonic pulse velocity, we have derived the estimating compressive strength such as a formula strength of normal-strength concrete : Fc=0.0841vp3.6018, R2=0.82 high strength concrete : Fc=0.0008vp6.9287, R2=0.88. As a result of this verification experiment, the estimated error rate of the compressive strength of normal strength concrete is 16.32%, in the case of high-strength concrete is now 7.58 percent.

Part of the domestic construction practice and non-destructive inspection technology world level is often inadequate to provide the test results to serve as a basis for evaluating the safety of the structure. Therefore, in this study, is intended to provide basic data for legislation nondestructive inspection in Japan, estimates the size of the column using a technique reverberation impact manufactured column member or this purpose. 3% maximum error rate, the result was 1% minimum error rate. The average error rate is 1.6%, revealed as well as the size of the columns that have been measured