• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.3
• /
• pp.60-68
• /
• 2018

The Housing Act amended allows vertical extension up to three floors and increases the units of housing (or total floor area) to site up to 15%. Currently, the feasibility of performing vertical extension is evaluated based on safety diagnosis provisions and manuals with preliminary investigations on slope, uneven settlement, load-bearing capacity, and durability. However, a need for more reasonable evaluation methodology for the preliminary investigation is still required because the current procedures are borrowed from safety diagnosis provisions and manuals for reconstruction without detailed examinations on evaluation criteria and sampling methods. Accordingly, this study is intended to suggest a method to obtain feasible sampling size for durability assessment by statistically analyzing the safety evaluation data sets on concrete carbonation and steel corrosion obtained from apartment complexes. The results of this study are expected to be beneficial for establishing more reasonable field sampling size, and in turn, more reliable durability assessment protocol for vertical extension.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.15 no.2
• /
• pp.19-30
• /
• 2019

In this study, to evaluate conservatism of various fatigue life evaluation procedures, fatigue tests were conducted using compact tension (CT) specimens with a round notch, made of A516 Gr.70 carbon steel and A240 TP304 stainless steel, under load-controlled cyclic condition. Experimental fatigue failure cycles were measured and compared with predicted fatigue lives using two different life evaluation methods; (1) Design-By-Analysis (DBA) procedure given in ASME B&PV Code, Sec. III, Div. 1, Subsec. NB-3200 and (2) structural stress-based approach provided in ASME B&PV Code, Sec. VIII, Div. 2, Part 5. To predict fatigue failure cycles, three-dimensional elastic finite element analysis was conducted. Fatigue lives were predicted by both design fatigue curve given in ASME B&PV Code, Sec. III, Div. 1, Appendices and best-fit fatigue curve suggested in NUREG/CR-6815 for the DBA procedure. Finally, fatigue lives evaluated by various methods were compared with test results, and then conservatism between each evaluation procedure was discussed.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.3
• /
• pp.106-115
• /
• 2011

This study proposed a new methodology for seismic capacity evaluation of low-rise reinforced concrete (RC) buildings based on non-linear required spectrum. In order to verify the reliability of the proposed method, relationships between results obtained using the proposed method and the non-linear dynamic analyses were investigated. Compared with the seismic protection index (Es=0.6) defined in the Japanese Standard, the applicability of the method was also estimated. Research results indicate that the method proposed in this study compares reasonably well with the detailed evaluation methods. Using the seismic evaluation method developed in this study, the seismic capacity category and earthquake damage degree of low-rise RC buildings corresponding to a specific earthquake level can be effectively estimated.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.5
• /
• pp.160-168
• /
• 2011

As importance of the field of maintenance and management come to the fore because of collapses of the Seongsu bridge and the Sampoong department store, "Special Act for the Safety Control of Public Structures" was established in 1995 and the major maintenance and management system began taking effect "Detailed inspection and Precision safety diagnosis". However, a technical standard of "Detailed inspection and Precision safety diagnosis" was low because its history was not long, and also the results of research were not enough so anxiety for "Insufficient Detailed inspection and Precision safety diagnosis" was continuously left. While its evaluation system introduced in 2002, the ratio of "Insufficient Detailed inspection and Precision safety diagnosis" has been getting lower. However, according to the evaluation result after carrying out "Detailed inspection and Precision safety diagnosis" recently, it seems difficult to become lower for the ratio of "Insufficient Detailed inspection and Precision safety diagnosis" in future. Therefore, it is considered of questionary survey of the concerned organization and the mechanism side in connection with "Insufficient Detailed inspection and Precision safety diagnosis". So it is arranged the fundamental problems caused by an "Insufficient Detailed inspection and Precision safety diagnosis" that is to show the improving direction of the existing evaluation system in a based on this.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.6
• /
• pp.114-122
• /
• 2014

Currently, global warming has become a serious problem arising from the usage of fossil fuels such as coal and petroleum. Moreover, due to the global warming, heat wave, heavy snow, heavy rain, super typhoon are frequently occurring all over the world. Due to these serious natural disasters, concrete structures and infrastructures are seriously damaged or collapsed. In order to handle these problems, climate change oriented construction technology and codes are necessary at this time. Therefore, in this study, the validity of the present concrete mixture proportions are evaluated considering temperature and humidity change. The specimens cured at various temperature and humidity conditions were tested to obtain their compressive and split tensile strengths at various curing ages. Moreover, performance based evaluation (PBE) method was used to analyze the satisfaction percentage of the concrete cured at various condition. From the probabilistic method of performance evaluation of concrete performance, feasibility and usability can be determined for future concrete mix design.

• KEPCO Journal on Electric Power and Energy
• /
• v.6 no.4
• /
• pp.439-445
• /
• 2020

In this paper, the seismic performance evaluation was performed on 100 existing open-cut power cable tunnels, including ones that did not consider seismic design, in order to verify that the government's demand level (seismic special grade, 0.22 g). The results of the seismic performance evaluation show that most of the tunnels have seismic performance of 0.3 to 1 g, satisfying the level of the seismic special grade and securing the seismic safety. Meanwhile, the earthquake response analysis and structural test were performed to verify the validity of the method and the results of the seismic performance evaluation of the tunnels by the response displacement method, and to verify their seismic safety. As a result, the relative displacement due to the response displacement method under the 0.22 g earthquake was conservative than the results of the earthquake response analysis, and the results of load-displacement curves and response modification coefficient calculation by real scale structural tests showed the safety of the tunnels.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.5
• /
• pp.259-266
• /
• 2022

In this study, we developed a deep learning and vision sensor-based assembly performance evaluation method isfor prefabricated steel structures. The assembly parts were segmented using a modified version of the receptive field block convolution module inspired by the eccentric function of the human visual system. The quality of the assembly was evaluated by detecting the bolt holes in the segmented assembly part and calculating the bolt hole positions. To validate the performance of the evaluation, models of standard and defective assembly parts were produced using a 3D printer. The assembly part segmentation network was trained based on the 3D model images captured from a vision sensor. The sbolt hole positions in the segmented assembly image were calculated using image processing techniques, and the assembly performance evaluation using the k-nearest neighbor algorithm was verified. The experimental results show that the assembly parts were segmented with high precision, and the assembly performance based on the positions of the bolt holes in the detected assembly part was evaluated with a classification error of less than 5%.

• The Journal of Sustainable Design and Educational Environment Research
• /
• v.21 no.4
• /
• pp.1-12
• /
• 2022

The main purpose of this study was to propose an objective basis model for determining business types through renovation and remodeling by quantifying and comprehensively reviewing functional, performance, structural safety, and economic indicators for rational renovation and remodeling of deteriorated school facilities. Delphi analysis and AHP analysis were applied as the main methodologies for setting evaluation indicators, and scores for each evaluation item was allocated based on 34 points in the function and performance fields, 51 points in the structural safety field, and 15 points in the economic field. In the future, judgment on the execution of objective and reasonable reconstruction can be expected, focusing on the evaluation indicator index model, and it is necessary to determine the business type for each target school teacher building through a multi-faceted review of the current status of the target school.

• Structural Monitoring and Maintenance
• /
• v.5 no.1
• /
• pp.79-92
• /
• 2018

The evaluation theory of reliability, availability, maintainability and safety (RAMS) as a mature theory of state evaluation in the railway engineering, can be well used to the evaluation, management, and maintenance of complicated structure like the long-span bridge structures on the high-speed railway. Taking a typical steel-truss arch bridge on the Beijing-Shanghai high-speed railway, the Nanjing Dashengguan Yangtze River Bridge, this paper developed a new method of state evaluation for the existing steel-truss arch high-speed railway bridge. The evaluation framework of serving state for the bridge structure is presented based on the RAMS theory. According to the failure-risk, safety/availability, maintenance of bridge members, the state evaluation method of each monitoring item is presented. The weights of the performance items and the monitoring items in all evaluation levels are obtained using the analytic hierarchy process. Finally, the comprehensive serving state of bridge structure is hierarchical evaluated.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.34 no.4
• /
• pp.175-182
• /
• 2021

There have been many instances of damage to buildings with soft stories, and it is important to consider vertically irregular buildings when evaluating the seismic performance of existing buildings. However, because conventional methods do not easily reflect vertical irregularities with sufficient accuracy, it is possible to underestimate or overestimate the seismic performance of buildings with vertical irregularities. This study aims to develop a seismic performance evaluation method for vertically irregular buildings using the stiffness-based soft story ratio (SSR), which is a parameter that represents the ratio of the demand and the capacity for displacement and refers to the ratio of displacement concentration in buildings. The seismic performance evaluation method developed in this study is compared with the conventional seismic performance evaluation method for four piloti buildings, using the first-floor column as a variable. Conventional seismic performance evaluation methods often overestimate the seismic performance for models in which vertical irregularities are maximized. However, results of the proposed seismic performance evaluation method are identical to those from a detailed evaluation for all models. Therefore, it is considered that the proposed seismic performance evaluation method can provide more precise seismic performance evaluation results than conventional methods in the case of piloti buildings, where vertical irregularities are maximized.