• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.212-220
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• 2011

These days, many cable-stayed bridges were constructed in accordance with the trend in Korea. At the moment, construction technology of cable-stayed bridges has been remarkably developed but design technology still relies upon foreign technology very much. The cable anchor system that is one of key technologies of cable-stayed bridge brings powerful cable tension to produce local stress concentration and to disturb stress seriously, so for safety must be designed by a local detailed analysis is required. But without a clear design standard or design theory relying on F.E.M, and engineers don't understand theoretical basic mechanism of cable anchor system. As a result, engineers can be lose their judgement. Accordingly, this study examined theoretical design flow of fixing pipe in guide pipe-anchor system and additional considerations, in accordance with design standards at home and abroad to keep them in order and to suggest supplementary design flow.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.130-138
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• 2023

In this study, experimental and analytical studies were conducted on the structural performance of permanent steel formed wide beams in construction stage. Four specimens were fabricated with different rib spacings of the side steel formwork and fixing plate depths, and experimental tests were performed to investigate the effects of variables on the structural performance. Also, an finite element analysis model of the steel permanent formwork wide beam was proposed based on the test results. Using the proposed model, parametric studies were performed with variables including rib spacing of the bottom and side steel formwork, spacing, depth, and thickness of the fixing plate to derive optimized details. Furthermore, an artificial neural network model was developed to easily estimate the deformation of the steel permanent formwork wide beam with various details.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.107-115
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• 2011

In this study, the vibration analysis of the underground box structures induced train movement is studied. In order to perform these analysis, dynamic data, which was measured when subway is in service, are gained by attaching accelerometers on the structure such as lower beam, lateral wall and upper slab. Also, accelerometers are attached on the lower beams and side walls of the gravel ballast and concrete ballast sections in order to compare vibration due to ballast materials. The vibration results of upper slabs and lower beams reveal that the vibration on the upper slabs is greater than the lower beams. Also, the results of the crack gauge on the upper slab show that crack width dose not change due to vibration, These means that the effect of the vibration on the structure is very limited. In order to evaluate the vibration of the structure, acceleration unit is converted to velocity unit comparing with the existing velocity data gained from the platforms.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.51-60
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• 2011

In this study, structural safety capacity analysis of the overpass railway bridge between Konkuk Univ. and Guui station railroad has been performed. The overpass is expected to have suffered durability reduction by deterioration. The weight reduction of the overpass has been implemented to prevent further durability reduction and to improve performance capacity. To reduce the weight, 3 procedures of replacing concrete soundproofing wall to light-weight soundproofing wall, replacing gravel ballast to concrete ballast, and reducing the weight of trough have been performed. The analysis of static/dynamic behaviors and improved capacity of the light-weighted overpass bridge has been performed. The structural safety verification of the improved structure has been implemented by using rating factors of load carrying capacity of PSC I girder. The results have shown that the deflection has been reduced by 2.6mm and tensile strength has been improved by 1.07MPa, which indicate that the structural capacity has effectively been improved. Also, the natural frequency has improved by approximately 30% where vibration reduction and dynamic behavior improvement have been achieved. Moreover, in the rating factor evaluation based on analysis and test results, an improvement from 1.82 to 1.93 has been observed. Therefore, weight reduction method for the overpass is effective considering overall results.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.569-572
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• 2008

A series of the field inspection and the test have been performed on 297 existing bridges, in order to evaluate the bridges since 1995. In this study, based on the test results of the in-depth inspection, the identification of the extent of the chloride content and the incidence of the carbonation depth was conducted, and construction age and member type, environment condition were considered in this analysis. According to simple regression of the tested carbonation depth, the carbonation rate coefficient of the bridges in metropolises was estimated 5.41 and greater than 3.89 and 1.91 in case of marine condition and etc respectively. After measuring chloride content in concrete member, it was concluded that the chloride content of the bridges in marine condition was 4.7 times greater than the others. Especially, slabs had the most highly chloride content and it was estimated 0.709 $kg/m^3$

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.138-149
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• 2014

This study proposes an estimation method of strain distribution for multi-span steel beam structure under unspecific loading conditions. The estimation method in this paper employs the curve fitting using the least square method from measured strain data, not analytical method. To verify the proposed estimation method, a static loading test for multi-span steel beam on which distributed and concentrated loads act was conducted. The strain data for verification was measured by FBG sensors that have multiplexing technology. The analysis of the accuracy of strain estimation for distributed and concentrated loads and the errors by considering the number of measured points used in the estimation were conducted. In the maximum strain points, the strains could be estimated with the errors of 5.89% (loading step 1) and 6.26% (loading step 2). In case of decreasing the number of sensors, it was also confirmed that the errors increased (0.26~0.37%). Through the curve fitting method, it is possible to estimate the strain distribution (maximum strains and their locations) of multi-span beam for unspecific loads and go over the limit of the analytical estimation method which is suitable for specific distributed loads.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.132-139
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• 2017

A huge amount of de-icing agent is sprayed during winter to promote traffic safety in cold regions, and the quantity of de-icing agent sprayed has increased each year. The main ingredients in commonly used de-icing agents are chlorides, such as calcium chloride($CaCl_2$) and sodium chloride(NaCl). While calcium chloride is mostly used in Korea and sodium chloride is usually used in the U.S. and Japan, all de-icing agents include chloride ions. The chlorides included in sprayed calcium chloride-based de-icing agents have severe adverse effects, including the corrosion of reinforcing steels through salt damage by infiltrating into road structures, reduced structural performance of pavement or damage to bridge structures, and surface scaling, in combination with freezing damage in winter, as well as water pollution. In addition, the deterioration of paved concrete road surface that occurs after the use of calcium chloride-based de-icing agent accelerates the development of visual problems with traffic structures. Therefore, the present study was performed to prepare an environment-friendly liquid de-icing agent through a reaction between waste organic acids and calcium-based by-products, which are industrial by-products, and to analyze the properties of the de-icing agent in order to evaluate its applicability to road facilities.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.43-52
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• 2024

In this study, we evaluated the seismic performance of a masonry building that was not designed to be earthquake-resistant and attempted to improve the seismic performance by adopting a seismic reinforcement method on the exterior of the building. In addition, the building seismic design standards and commentary(KDS 41 17 00:2019) and existing facility(building) seismic performance evaluation methods were applied to evaluate seismic performance, and a pushover analysis was performed using non-linear static analysis. As the result of this study, it was determined that seismic reinforcement was urgent because the distribution rate of earthquake-resistant design of houses in Korea was low and masonry structures accounted for a large proportion of houses. When reinforcing the steel beam-column+brace frame in a masonry building, the story drift angle was 0.043% in the X direction and 0.047% in the Y direction, indicating that it satisfied the regulations. The gravity load resistance capacity by performance level was judged to be a safe building because it was habitable in both X and Y directions. In conclusion, it is believed that the livability and convenience of the house can be secured by reinforcing the exterior of the building and the seismic performance and behavior of the structure can be clearly predicted.

• Korean Journal of Construction Engineering and Management
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• v.15 no.2
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• pp.62-70
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• 2014

An apartment house, a private facility, is a house built for many persons to live independently in a building. An apartment house is a building where life damage can happen most in case of a safety accident due to insufficient inspections. However, formal inspections are being realized due to awareness shortage of managing bodies about safety inspection and low-price order-receiving of diagnosing enterprises via the lowest bidding method. This is because it is judged that remarkable costs are inputted in repairs and reinforcement such as maintenance of a structure and that there is a large possibility of human damage in case of a safety accident in a structure. So, this paper aims to derive the points to improve in the current criterion to execute an efficient detailed inspection. As its method, the design price and execution price situation of 66 buildings inspected in detail for recent 3 years for the class 2 facilities in Gwangju Metropolitan City and Jeonranam-do are examined and analyzed. The state2 object buildings to inspect are selected through this. And this paper aims to present the points to improve through the analysis of current problems by evaluating the detailed inspection report and the detailed inspection execution price calculation criterion for the selected 10 apartment houses.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.63-70
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• 2019

The number of vehicle-to-barrier collisions has increased due to improved driving environments. In addition, it is reported that the number of accidents led to impact severity larger than current capacity of a median barrier has increased. It is required to develop a high performance median barrier in order to secure expressway safety. This paper aims at proposing impact loading model and locations for a high performance median barrier based on analysis of median-barrier-related accident history. The SB6 test level (Impact severity: 420 kJ, Mass: 25 ton, Impact speed: 80 km/h, Impact angle: $15^{\circ}$) was suggested for target impact severity based on statistical data analysis. The suitable locations also were proposed from investigation of driver behaviors for installation and rehabilitation of high performance median barrier.