Most reinforced concrete (RC) school buildings constructed in the 1980s have seismic vulnerabilities due to low transverse reinforcement ratios in columns and beam-column joints. In addition, the building structures designed for only gravity loads have the weak-columnstrong- beam (WCSB) system, resulting in low lateral resistance capacity. This study aims to investigate the lateral resistance capacities of a two-story, full-scale school building specimen through cyclic loading tests. Based on the experimental responses, load-displacement hysteresis behavior and story drift-strain relationship were mainly investigated by comparing the responses to code-defined story drift limits. The test specimen experienced stress concentration at the bottom of the first story columns and shear failure at the beam-column joints with strength degradation and bond failure observed at the life safety level specified in the code-defined drift limits for RC moment frames with seismic details. This indicates that the seismically vulnerable school building test specimen does not meet the minimum performance requirements under a 1,400-year return period earthquake, suggesting that seismic retrofitting is necessary.

In this study, static and dynamic analyses were conducted on three atypical building models to evaluate the displacement response reduction performance based on the outrigger system installation location in a atypical building that incorporated both tapered and twisted shapes. Three 60-story models were developed with a fixed 3-degree taper and twist angles of 1, 2, and 3 degrees per story. Outrigger systems were installed at 10-story intervals and additionally between the 20th and 40th floor at 1-story intervals. The results indicated that, although there were variations depending on the seismic loads, the displacement response reduction performance was generally most effective when the outriggers were installed in the upper stories (41st to 60th floors) of the analytical models.

This paper aims to quantify the retrofit effect of the Bolt Prefabricated Concrete-Filled Tube reinforcement method on non-seismic school reinforced concrete building through static cyclic loading experiments. To achieve the objective, two-story specimens including a non-retrofitted frame(NRF) and a Bolt Prefabricated Concrete-Filled Tube Reinforcement Frame(BCRF) were tested under static cyclic loading, and the lateral resistant capacities were compared in terms of maximum strength, initial stiffness, effective stiffness, and total energy dissipation. In addition, the load-displacement curves were compared to the story drift limit specified in Seismic Performance Evaluation and Retrofit Manual for School Facilities to investigate if the retrofitted frame was satisfied in target performance(life safety). Experimental results showed that BCRF successfully met the target performance, with a 200% increase in maximum strength and a 300% increase in energy dissipation capacity. Additionally, both initial stiffness and effective stiffness improved by more than 30% compared to NRF. Furthermore, BCRF exhibited an effect that delayed the occurrence of bond failure.

This study was conducted through experiments by producing an image output evacuation guide light linked with a smoke detector. To summarize the results, first, the biggest recognition distance of the door at 30% smoke concentration was found to be the image output evacuation guide light. This is because of visual impairment and fear caused by indoor smoke, and in the process of finding the light of the emergency exit, accurate recognition of the evacuation behavior was searched even at the farthest distance, and it is judged that the time required for evacuation was short. Second, the biggest recognition distance of the door at 70% smoke concentration was the image output evacuation guide light, which showed the longest recognition distance. It is judged that even in smoke with many evacuees, the door is accurately recognized while seeing the light of the image output evacuation guide light and exits safely. Third, when the smoke concentration was 100%, the smoke rose and the evacuation guide light at the top of the door was not identified as thick smoke, and the image output evacuation guide light was displayed on the bottom of the passage, indicating that the evacuee accurately recognized the door and escaped safely to the outside even from a long distance.

This study aims to model an accident that occurred at building demolition work sites in Gwangju in 2021 by using functional resonance analysis method(FRAM) and to understand a range of factors contributing to the accident based on the concepts and principles of FRAM and Safety-II. The nature of building demolition works needs to be understood from the viewpoint of socio-technical systems. Not only technical factors but also non-technical factors, including human, organizational, and political factors, and their complicated interrelationships should be considered in the modeling and analysis of accidents happening in the works. Because of the inherent complexity of a demolition works, it is unlikely to specify all of the necessary activities to be conducted in the works and their accountable actors. Additionally, unexpected situations are likely to happen and therefore some activity procedures cannot be followed in a prescribed way, which means that workers sometimes should conduct their activities in an improvisional way. Those characteristics of building demolition works indicate that a traditional accident analysis method based on a linear cause-effect relationship would be inadequate, and that more systemic approaches that can deal with the socio-technical complexities and characteristics of demolition works should be used. With this in mind, we applied FRAM to the accident happening in Gwangju in 2021 and attempted to understand the accident based on the concepts and principles of FRAM and Safety-II (e.g. a functional variablity and its propagation to another function). Lastly, we also suggested ways to enhance the safety of building demolition working sites.

Piloti-type buildings are widely constructed in urban areas of South Korea. Due to stiffness irregularities, piloti-type buildings are vulnerable to lateral loads such as earthquakes. Although seismic retrofitting is necessary for piloti-type buildings, many of these structures are privately owned, and the extensive number of buildings creates significant challenges in terms of cost and time for regional seismic performance evaluation. This study proposes a methodology for determining the seismic performance of multiple piloti-type buildings within a region by utilizing structural parameters. Information on piloti-type buildings is classified into public building data and exterior building data, which are integrated to define structural parameters for estimating the first natural period of the buildings. Linear regression analysis was performed to develop a regression equation correlating structural parameters with the natural period. Additionally, the natural period and structural parameters are used to perform another linear regression analysis to estimate the yield and ultimate points of the capacity curve. The capacity curves derived from the regression equations facilitate seismic performance evaluation based on structural parameters.

Structures compromised by a seismic event may be susceptible to aftershocks or subsequent occurrences within a particular duration. Considering that the shape ratios of sections, such as column shape ratio (CSR) and wall shape ratio (WSR), significantly influence the behavior of reinforced concrete (RC) piloti structures, it is essential to determine the best appropriate methodology for these structures. The seismic evaluation of piloti structures was conducted to measure seismic performance based on section shape ratios and inter-story drift ratio (IDR) standards. The diverse machine-learning models were trained and evaluated using the dataset, and the optimal model was chosen based on the performance of each model. The optimal model was employed to predict seismic performance by adjusting section shape ratios and output parameters, and a recommended approach for section shape ratios was presented. The optimal section shape ratios for the CSR range from 1.0 to 1.5, while the WSR spans from 1.5 to 3.33, regardless of the inter-story drift ratios.

The primary purpose of this study is to develop system modules of school buildings and the seismic loss function of the system modules for regional loss assessment of school buildings. System modules of school buildings were developed through statistical analysis of school facilities in Korea. The structural system of school buildings with non-seismic details is defined as reinforced concrete with partially masonry walls (RCPM), and 27 system modules of RCPM were developed considering the number of stories, spans, and the age of the building. System modules were designed to assess the structural behavior by applying the shear spring model and the shear failure of the columns of the school building. Probabilistic seismic demand models for each component of system modules were derived through nonlinear dynamic analysis to determine the relationship between seismic intensity, drift ratio, and peak floor acceleration of system modules. The seismic loss function was defined as the total damage ratio, which is the ratio of replacement cost to repair cost to evaluate the seismic loss quantitatively. The system module-based seismic loss well predicted the observed data. It will be possible to help many stakeholders make risk-informed decisions for a region through the regional loss assessment of school buildings in Korea.

In densely populated urban areas, reinforced concrete residential buildings with an open first floor and closed upper floors are preferred to meet user demands, resulting in significant vertical stiffness irregularities. These vertical stiffness irregularities promote the development of a soft-story mechanism, leading to concentrated damage on the first floor during seismic events. To mitigate seismic damage caused by the soft-story mechanism, stiffness-based retrofit strategies are favored, and it is crucial to determine an economically optimal level of retrofitting. This study aims to establish optimal seismic retrofit strategies by evaluating the seismic losses of buildings before and after stiffness-based retrofitting. An equivalent single-degree-of-freedom model is established to describe the seismic response of a multi-degree-of-freedom model, allowing for seismic demand analysis. By convolving the seismic loss function with the hazard curve, the annual expected loss (EAL) of the building is calculated to assess the economic losses. The results show that stiffness-based retrofitting increases first-story lateral stiffness by 20-40%, enhancing structural seismic performance, but also results in a rise in EAL compared to the as-built state, indicating lower cost-effectiveness from an economic perspective. The research concludes that retrofit options that increase first-story lateral stiffness by at least 60% are more appropriate for reducing financial losses.

The diagrid structural system has a braced frame that simultaneously resists lateral and vertical loads, and is being applied to many atypical high-rise buildings for aesthetic effects. In this study, a 60-story structure with twisted degrees of 0° to 180° was selected to determine seismic response control performance of twisted high-rise structures whether the diagrid system was applied and according to the reduction of braced frame material quantity. For this purpose, ‘Nor’ model without the diagrid system and the ‘DS’ model with the diagrid system, which was modeled by reducing braced frame member section to 700~400, were modeled. As a result, the 'DS' model showed an seismic response control effect in all Twisted models even when the quantity was reduced, and especially, the Twisted shape model was found to have an superior response control effect compared to the regular structure. In addition, the ‘600DS’ analysis model, which matched the ‘Nor’ model by 99.0% in quantity, showed an increase in seismic response control performance as the rotation angle increased.

지진발생 시, 건물은 작게는 손상에서 크게는 붕괴까지 이어지므로 인명과 재산상의 피해가 생길 수 있다. 이러한 지진의 위험성에 대비하여 건물의 내진성능평가가 필요하다. 현재 내진성능평가 기법의 경우 개별 건물을 대상으로 하기에 많은 시간이 투자되어야 한다. 따라서, 지역규모의 건물들을 대상으로 하는 내진성능평가 기법의 개발이 필요한 실정이다. 본 연구는 RC 주거형 건물의 내진 성능을 평가하고 보강계획을 수립하기 위해 비선형 Shear Spring을 가진 단자유도모델을 구축하였다. 구조물의 비선형 응답을 모사 하기 위한 비선형 Shear Spring은 T-SR-μ를 매개변수로 정의된다. 해당모델에 100개의 PEER 지진을 적용하여, 최대층간변위비 응답 으로 건물의 내진성능을 평가하였다. 제안기법의 적용성을 확인하기 위하여 상세모델과 비교하였을 때, 두 모델 모두 건물의 내진성 능을 같은 수준으로 판단하였음을 확인하였다. 본 연구는 제안된 방식이 실제 건물의 내진성능을 예측할 수 있음을 보여주었다.

Due to seismically deficient details, existing reinforced concrete structures have low lateral resistance capacities. Since these building structures suffer an increase in axial loads to the main structural element due to the green retrofit (e.g., energy equipment/device, roof garden) for CO2 reduction and vertical extension, building capacities are reduced. This paper proposes a machine-learning-based methodology for allowable ranges of axial loading ratio to reinforced concrete columns using simple structural details. The methodology consists of a two-step procedure: (1) a machine-learning-based failure detection model and (2) column damage limits proposed by previous researchers. To demonstrate this proposed method, the existing building structure built in the 1990s was selected, and the allowable range for the target structure was computed for exterior and interior columns.

In modern society, buildings are becoming more complex, and the population is becoming more densely populated. Such large buildings require a variety of evacuation measures, as there is a high possibility of large-scale human casualties due to increased evacuation distance and evacuation time in the event of a fire. Strobe light and exit sign light are used as important evacuation equipment to provide early warning and evacuation directions. In this thesis, we conducted a fire simulation assuming that a fire occurrence point notification function and a strobe light function were added to equipment such as visual alarms and evacuation guidance, and compared and analyzed the difference in evacuation completion time with existing equipment. The scenarios for the simulation were divided into “general fire situations” and “fire location and evacuation exit guidance situation” and the differences in evacuation completion time in the event of a fire were compared and analyzed for each floor from the 1st floor to the 3rd floor. The maximum travel distance to complete evacuation in the case of a fire on the first floor decreased by 80.6 m and the evacuation completion time decreased by 329.4 seconds, and the maximum travel distance to complete evacuation in the case of a second-floor fire decreased by 28.5 m and the evacuation completion time by 438.8 seconds. During the fire on the third floor, the maximum distance decreased until evacuation was completed to 3.4 m, and the evacuation completion time was reduced by 355.6 seconds. It is expected that if the congestion level of evacuation routes is reduced by utilizing the congestion level of evacuation exits when fire alarm systems and evacuation equipment are activated, the evacuation completion time will be further shortened and evacuations will be carried out quickly and safely.

The purpose of this study is to present a plan for reducing noise between floors of apartment houses in Korea and to examine the method for evaluating noise blocking performance rating between floors. The definition of floor noise and classification method of floor noise can be described, and floor noise can be distinguished into lightweight impact sound and heavy impact sound. The wall-type structure, which is mainly adopted in domestic apartments, relatively transmits vibration caused by impact sources rather than using columns and beams, so noise problems between floors are relatively higher than systems using columns and beams. Three representative methods for reducing and blocking floor noise are described, and criteria for evaluating the effectiveness of floor noise reduction by each method are described. In addition, the method for noise reduction and blocking grades for each construction method currently applied in Korea was described, and as a result, it was judged that the domestic rating evaluation method was not suitable for the current domestic situation, and a new evaluation method and standard were needed.

High-rise buildings are equipped with TMD (Tuned Mass Damper), a vibration control device that ensure the stability and usability of the building. In this study, the seismic response control performance was evaluated by selecting the design variables of the TMD based on the installation location of the twisted irregular building. To this end, we selected analysis models of 60, 80, and 100 floors with a twist angle of 1 degree per floor, and performed time history analysis by applying historical seismic loads and resonant harmonic loads. The total mass ratio of TMDs was set to 1.0%, and the distributed installation locations of TMDs were selected through mode analysis. The analysis results showed that the top-floor displacement responses of all analysis models increased, but the maximum story drift ratio decreased. In order to secure the seismic response control performance by distributed installation of TMDs in twisted irregular buildings, it is judged that the mass ratio distribution of TMDs will act as a key variable.

Piloti-type structures with vertical irregularity are vulnerable to earthquakes due to the soft structure of the first story. Structural characteristics of buildings can significantly affect the seismic loss function, calculated based on seismic fragility, and therefore need to be considered. This study investigated the effects of the number of stories and core locations on the seismic loss function of piloti-type buildings in Korea. Twelve analytical models were developed considering two variations: three stories (4-story, 5-story, and 6-story) and four core locations (center core, x-eccentric core, y-eccentric core, and xy-eccentric core). The interstory drift ratio and peak floor acceleration were assessed through incremental dynamic analysis using 44 earthquake records, and seismic fragility was derived. Seismic loss functions were calculated and compared using the derived seismic fragility and repair cost ratio of each component. The results indicate that the seismic loss function increases with more stories and when the core is eccentrically located in the piloti-type structure model. Therefore, the uncertainty due to the number of stories and core location should be considered when deriving the seismic loss function of piloti-type structures.