Recently, because pepople are taking a great interest in the water supply system and the related facilities are getting larger, the surge suppression is very important problem. Accordingly, We carried out both numerical simulation and field tests to confirm the safety of intake pumping station.
In this study, the rahmen bridge damaged by the chloride attack was investigated. According to the investigation, the degraded concretes on cantilever kerb and end part were intensively observed. Thus, the chloride content test and half-cell method were performed to evaluate the degraded parts. As a result, the contents of chloride on degraded parts were C and D grade. On the other hand, the half-cell potential values of rebar in degraded concrete were measured with the minor corrosion. Thus, the freeze-thawing action due to deicing water is more influential than the expansion of rebar corrosion by chloride attack. Consequently, the economical repairs of degraded parts is more favorable than the replacement of the degraded parts. Also, it is necessary to inhibit the corrosion of rebar in concrete.
This paper presents a finite element analysis to evaluate thermal conductivity of FRP (Fiber Reinforced Polymer) retrofit system in reinforced concrete structure. Especially, this paper focused on near-surface-mounted retrofit method; FRP is mounted into the groove after making a groove in concrete. Midias-FEA program was used to analyze the case that the epoxy was covered by various board to resist fire such as, calcium silicate or alumino silicate board.
Analysis results give that the prediction of temperature transition from surface is possible by FE analysis and the result can be used to evaluate fire resistance of certain fire proof materials in FRP retrofit system.
In this study, the silicone-based flame retardant compound is combined in case of fire, the fire-resistance board structure stability and durability, performance, such as the possibility of secure confirmation. For this purpose, a silicon compound ATH, MDH, MC, a flame retardant of ocher made by the weight ratio, the thermal properties of the specimen analysis tests were carried out.
This study is to evaluate compressive behavior of confined concrete cylinders using various materials. Materials are tape, velcro, fishline, frp and scratch film. At compressive strength test result, load of confined concrete cylinder using velcro and fishline was slowly decreased after ultimate strength. Also, confined concrete cylinder using tape and frp seem to increase the compressive strength.
Recently, a lot of problems have occurred in the tunnel by low-temperature freezing phenomenon in winter. Icicles caused by low-temperature freezing phenomenon has caused tunnel maintenance and traffic accident possibility. Therefore, in the study it is analyzed that a case of tunnel freezing occurred in the past
In Korea, the anchor pull-out tests apply overseas standards because there are no suitable standards for domestic. Therefore, according to the standards, parameters of ground and anchor force appear differently. In this study, we've compared the field tests conducted in Korea with the field tests of Europe, Hong Kong and Japan and established a pull-test standards being suitable for domestic. Also, we've proposed a research plan using analysis results.
We plan to run the two-dimensional and three-dimensional finite element analysis to build a tunnel behavior DB along the fracture zone for making the development of behavior characterization method of construction of the destabilizing factors for each of the future.
The needs for consistent maintenance for highway bridge has been increased in nowadays. This study is to investigate fundamental database about in-depth inspection for publishing the repair and strengthening methodology. It is because the maintenance budget should be used effectively for optimal maintenance of infrastructures. In order to investigate the maintenance history of highway bridges, the database of in-depth inspection from 1996 to 2012 was analyzed. For the superstructure type, PSC box girder bridge which was the most common among the concrete bridges in the inspection database was investigated.
Throughout this basic study of the design items for standardization in foundation structures are suggested. Reliablity-based methods of desin skills and data analysis are suggested in this paper for standardization. Limit state design method for retaining wall structures are standardized as the National Design Guide.
In this site, TBM tunnel section was composed of weak-to-moderate fine sedimentation layer, mixing claystone with gypsum. Maximum advance rate of shield TBM hits a record of digging during the tunnel work period. It is to be compared the site's cycle time data with planning stage.
By comparing the computed displacement with the stress and displacement determined by entering side numbers 3, 5, and 7 into the tunnel lining inverse analysis program, the optimal number of monitoring points is determined. From the results of the research, it can be inferred that the number of monitoring points needs to be at least 5 points, considering the efficiency of monitoring in practice and the loss-and-damage rate of tunnel monitoring.
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.
Mechanically fastening FRP (MF-FRP) strips using nails and anchors, has been shown to provide a more ductile behavior to the strengthened structural element than using bonded FRP. To further advance the state of the knowledge on this strengthening method, the current study examined environmental effects for six months on MF-FRP beams.
Reinforced concrete beams strengthened with mechanically fastened FRP strips and subjected to sustained loads for six months were exposed to outdoor weather and constant high temperatures (40°C). For comparison, the behavior of RC beam with and without sustained loads was evaluated. Results from flexural tests did not show any significant degradation or change of failure mode as a result of sustained load and of environmental effects such as high temperatures and outdoor weather over a period of six months.
An experimental study was performed to evaluate the ultimate strength of GFRP-strengthened RC beams compared to those obtained from main design guidelines. The results of this study indicated that ultimate strength method requires accounting for the stiffness of the applied FRP and the value of concrete compressive stain for its application to strengthened beams.
This paper deals with steel braced frame as increasing the lateral strength and ductility in order to seismic retrofit of existing buildings. However, There is a problem in utilizing this method. It is the approach to provide an adequate connection between the existing RC frame and the installed steel braced frame. So, the designer must be confirmed if it satisfies the required performance or not.
Among the costs composing the life-cycle cost of nuclear containment, the expected loss due to leakage of radioactive material is usually exorbitant, and it takes large amount in the evaluation of life-cycle cost. This study presents a process to determine optimal target reliability for nuclear containments, mainly focuses on its expected loss. It is estimated considering the surrounding environment of nuclear containment. Target reliability of containments having different lifespan can be determined by revising the expected loss estimated from the 20, 40 and 60 years of operation.
New materials having outstanding properties of matter than existing concretes and structure steels is in at an early stage of commercialization in construction filed.
By the side of America, Europe or Japan, domestic research is turned over, but a number of research agencies are carrying out research projects and parts of them are putted to practical use lately.
We studied on strength enhancement of concrete mixing carbone nanotube among new materials. As a result, compression strength was partially increased on concrete mixed with CNT(2.0wt%) than common concretes, but it was diluted when CNT blended with concrete more than 2.0wt%. It is estimated at effect that CNT is lumped.
This is an experimental study on manufacturing of non-cement matrix. Materials like cement and blowing agent in foamed concrete is replaced by by-products from blast furnace slag and paper ash. Further, the experiment was performed by replacing alkali with natural gypsum by (0, 5, 15, 20, 25, 35, 45) of weight of alkali (wt.%) in order to reduce the amount of expensive alkali activator. Sample NG-0.15 with density showed lowest. After this point, density increases as replacement ratio increases. The compressive strength test result, showed a similar trend with density. And it showed that compressive strength of the NG-0.45 was highest.