Construction Sites In Korea Research Articles

Deep neural network-based probabilistic classifier of occupational accident types on a construction site in Korea

ABSTRACT The number of accidents in the Korean construction industry has been increasing rapidly, reaching about 25,000 every year. Although strong and binding laws and systems have been implemented to reduce accidents in the construction industry, the frequency of accidents is still higher than that of other industries. While existing studies have provided models for predicting occupational accidents, there are limitations in predicting individual workers’ occupational accidents specific to site conditions and worker tasks. This study proposed a deep neural network model that can classify and predict core accident types for workers in construction sites, considering the characteristics of the site and workers based on 70,204 case data from the Korea Occupational Safety and Health Agency. The result of this study would contribute to improve safety in construction sites by being used for safety accident prevention training customized for workers at construction sites. Additionally, the model can be expanded to develop a real-time construction site occupational accident monitoring and early warning system by integrating ICT-based safety management technologies such as wearable devices and CCTV.

Accuracy Evaluation of Real-time Kinematic Positioning Service Based on Digital Multimedia Broadcast Network for Highway Construction Site in Korea

Accuracy Evaluation of Real-time Kinematic Positioning Service Based on Digital Multimedia Broadcast Network for Highway Construction Site in Korea

Identifying Critical Factors and Trends Leading to Fatal Accidents in Small-Scale Construction Sites in Korea

Small-scale construction sites in South Korea account for about 91.5% of all construction workplaces and contribute to 72.3% of the total accidents and fatalities. Safety measures at these sites are often underestimated, and proper safety education is lacking. In particular, the fatality rate is about 4.43 times higher compared to medium-/large-scale construction sites. In this study, a systematic analysis was conducted to examine the causes and trends of industrial accidents in small-scale construction sites to address these issues. This study analyzed industrial accidents in small-scale construction sites using statistical analysis, LDA topic modeling, and network analysis based on data from the Korea Occupational Safety and Health Agency (KOSHA) from 2018 to 2022. The analysis revealed that the most critical cause of accidents in small-scale construction sites is ‘Scaffolding and working platforms’, with accidents primarily involving ‘Fall’. Furthermore, various risk factors and accident trends were identified in apartment construction, new building projects, and mobile scaffolding usage. This study systematically analyzed the causes and trends of industrial accidents at small-scale construction sites, providing important evidence to enhance safety management and preventive measures. The results are expected to play a crucial role in establishing a safety culture at construction sites and ensuring the wellbeing of construction workers.

Probability-Based Crack Width Estimation Model for Flexural Members of Underground RC Box Culverts

Crack control for slabs and beams in current design practices in Korea are based on the Frosch’s model, which is adapted in ACI 318. It is more difficult to have consistent quality control in underground construction sites, such as the RC box culverts used for electric power distribution built below the ground level. There are more discrepancies between the as-built dimensions and the design dimensions provided in drawings in these structures. Due to this variability in construction error, the crack widths measured in such structures have higher potential to have more differences than the calculated values. Although crack control is a serviceability concern, if the owner chooses to have a target crack width that needs better control, crack width estimations can be improved by considering such construction variability. The probability-based crack width model suggested in this study will allow minimizing the discrepancies between the measured and calculated crack widths and provide reliable estimations of crack widths. Typical size of slabs and beams ranging between 300 mm (12 in.) to 500 mm (20 in.) used in underground RC box culverts in Korea were tested under the four-point bending test program. The thicker specimens had smaller bar spacings which created more cracks with smaller crack widths. However, with smaller crack widths generated in these specimens, there were more errors between the measurements and calculated values. From site investigations in Korea, the thickness of slabs in underground box culverts varied the most among all parameters. As a result, the bottom concrete covers had the highest variability. Bottom concrete covers and bar spacings are the two most important parameters in concrete crack control. A probability-based crack width estimation model for flexural members was developed in this study to consider this construction variability. Monte Carlo simulations were performed to evaluate the probabilistic characteristics of the design surface crack widths with a target width of either 0.3 mm (12 mils) or 0.5 mm (20 mils). The probabilistic models of design variables included in the crack width estimation model were generated based on field-collected information from construction sites in Korea. Because the surface crack widths in RC flexural members are sensitive to the construction errors of concrete cover depths, and since there are differences between the assumed and actual stress distribution closer to the reinforcing bars, the probability of having surface cracks of 0.3 mm width (12 mils) is found to be quite high, such as 89% at the positive moment region (mid-span, bottom surface) of the top slab in RC box culverts and 45% for the negative moment region (support area, top surface) of the top slab with current design practice. In order to ensure crack widths to be smaller than the design target width, probability-based crack width factors are recommended in this study to improve estimations depending on the selected target reliability levels.

Design charts for consolidation settlement of marine clays using finite strain consolidation theory

In this study, design charts for estimating consolidation settlement are proposed according to finite strain consolidation theory using a nonlinear constitutive relationship equation. Results of parametric sensitivity analysis shows that the final settlement, initial height, and initial void ratio exerted the greatest effect, and the coefficients of the void ratio–effective-stress. Proposed design charts were analyzed for three regions using a representative constitutive relationship equation that enables major dredged-reclaimed construction sites in Korea. The regional design charts can be calculated accurately for the final settlement because it is applied directly to the numerical analysis results, except for reading errors. A general design chart applicable to all marine clays is proposed through correlation analysis of the main parameters. A final self-weight consolidation settlement with various initial void ratios and initial height conditions should be estimated easily using the general design chart and constitutive relationship. The estimated final settlement using the general design chart is similar to the results of numerical analysis obtained using finite strain consolidation theory. Under an overburden pressure condition, design charts for estimating consolidation settlement are proposed for three regions in Korea.

Simulation of Debris-Flow Runout Near a Construction Site in Korea

This study analyzed landslide susceptibility and numerically simulated the runout distance of debris flows near a construction site in Korea. Landslide susceptibility was based on a landslide prediction map of the study area. In the prediction map, 3.5% of the area had a 70–90% landslide probability, while 0.79% had over 90% probability. Based on the landslide susceptibility analysis, debris flows in four watersheds were simulated to assess possible damage to the construction site. According to the simulations, debris flow in Watershed C approaches to within 9.6 m of the site. Therefore, the construction site could be impacted by debris flow in Watershed C. Although the simulated flows in Watersheds A and D do not directly influence the construction site, they could damage the nearby road and other facilities. The simulations also show that debris runout distance is strongly influenced by the volume of debris in the on-slope source area and by the slope angles along the debris-flow path.

BIM-based Hazard Recognition and Evaluation Methodology for Automating Construction Site Risk Assessment

Construction sites in Korea are the locus of many disasters and work-related illnesses, and construction workers are particularly likely to be exposed to serious disasters such as falls, collapses, and burial. At domestic construction sites, the concept of Design for Safety has been adopted from abroad, and current regulations are intended to secure the personnel safety at each site. However, current government guidelines and regulations are difficult to apply in the field, mainly because they do not clearly address work issues and safety management measures. The current safety review method depends too much on the subjective experience of site workers or managers. This study analyzes the step-by-step tasks required for more automated building information modeling (BIM)-based construction site safety management. An example BIM-based assessment of one specific construction site hazard, the risk of a worker fall, is carried out. In the risk analysis stage, all of the associated hazards are identified and the attendant risks are estimated and quantified. A broader risk rating methodology is derived based on the scenarios of each possible disaster at a construction site, and the hazards are extracted by defining the relationships between each building element based on the BIM information. The result is a risk rating methodology derived from a BIM-based risk assessment.

Risk Analysis on the Causes of Safety Accident at Construction Site in Korea using Eigenvector

Risk Analysis on the Causes of Safety Accident at Construction Site in Korea using Eigenvector

Evaluation of Static and Dynamic Residual Mechanical Properties of Heat-Damaged Concrete for Nuclear Reactor Auxiliary Buildings in Korea Using Elastic Wave Velocity Measurements.

The main objectives of this study are (1) to investigate the effects of heating and cooling on the static and dynamic residual properties of 35 MPa (5000 psi) concrete used in the design and construction of nuclear reactor auxiliary buildings in Korea; and (2) to establish the correlation between static and dynamic properties of heat-damaged concrete. For these purposes, concrete specimens (100 mm × 200 mm cylinder) were fabricated in a batch plant at a nuclear power plant (NPP) construction site in Korea. To induce thermal damages, the concrete specimens were heated to target temperatures from 100 °C to 1000 °C with intervals of 100 °C, at a heating rate of 5 °C/min and allowed to reach room temperature by natural cooling. The dynamic properties (dynamic elastic modulus and dynamic Poisson’s ratio) of concrete were evaluated using elastic wave measurements (P-wave velocity measurements according to ASTM C597/C597M-16 and fundamental longitudinal and transverse resonance tests according to ASTM C215-14) before and after the thermal damages. The static properties (compressive strength, static elastic modulus and static Poisson’s ratio) of heat-damaged concrete were measured by the uniaxial compressive testing in accordance with ASTM C39-14 and ASTM C469-14. It was demonstrated that the elastic wave velocities of heat-damaged concrete were proportional to the square root of the reduced dynamic elastic moduli. Furthermore, the relationship between static and dynamic elastic moduli of heat-damaged concrete was established in this study. The results of this study could improve the understanding of the static and dynamic residual mechanical properties of Korea NPP concrete under heating and cooling.

Predicting types of occupational accidents at construction sites in Korea using random forest model

Although industrial accident rates are gradually decreasing in Korea, the construction industry's accident rate is still higher compared with other industries. Human errors, mentally unstable workers, insufficient safety training, and safety policy affect the occurrence of construction accidents. Owing to the characteristics of this industry, occupational accident types, such as fall from height, collision with objects, rollover, and those due to falling objects, can be related to the weather data.Therefore, to reduce and prevent occupational injury, it is necessary to classify and predict occupational accident types in detail. In this study, we built a model to classify and predict occupational accident types using a random forest (RF). We extracted important factors that affect the occupational accident types at construction sites using feature importance, and we analyzed the relationship between these factors and occupational accident types. The accuracy score of the RF model was obtained as 71.3%, and we presented key construction safety factors considering the feature importance. For future research, we will collect data and develop models to predict occupational accident types in real-time. Real-time construction accident prediction research will reduce accident at construction sites.

Study of Performance Standard and Improvement of On-Site Construction of Through-Penetration Firestop System

According to the detailed guidelines for firestops, a through-penetration firestop system should be installed in a building to prevent the spread of fire when there is a gap in fire compartments due to the penetration of pipes, cable trays, etc. However, the inspection of 39 construction sites in Korea has revealed that the existing firestop system involves complex installation prcesses of 4~7 steps, resulting in wide variations in the quality of construction depending on situations at the construction site or the proficiency of workers. Furthermore, there are sites where firestop systems are not constructed due to the lack of knowledge of the builders. Thus, this study aims to set up a proper guide for firestop systems as per the rules, notices, and guidelines of Korea, and suggest a technical improvement plan for through-penetration firestop systems that can achieve the required fire resistive-performance while involving only 1~2 steps for the installation processes. Keywords: Fire Compartment, Through Penetration Firestop System, Fire Resistance Performance

ASSIGNMENT OF RESPONSIBILITY AND ROLE TO CONSTRUCTION CLIENT IN OCCUPATIONAL SAFETY AND HEALTH SYSTEM

This study investigated the client's duty and role to prevent construction accidents by participating construction client into the occupational safety and health management system. Since the fatal accidents of the construction sites in Korea are higher than other OECD countries and approximately 500 workers annually have died on construction sites, various efforts have been performed to prevent construction accidents. Recently, in Korea, the client’s participation in the safety and health management system has been focused as a fundamental method to prevent serious accidents. To examine the necessity of client’s participation, the survey was performed for construction participants. And, survey results and existing studies about client's role were analyzed to assign responsibility and role to the client. Results showed that safety managers and supervisors were strongly agreed for imposing client's duty (average scores of 4.373 and 4.107 in likert 5point scale) while clients showed the lowest agreement (average score of 3.153). In addition, the detailed role was proposed in the whole project stage, that is plan, design, and construction stage. Client can be a key player in reducing the fatal construction accidents by doing the accurate roles proposed in this study.

Identifying Effective Fugitive Dust Control Measures for Construction Projects in Korea

In recent years, the awareness of the seriousness of the damage caused by fugitive dust and the need to manage it have increased. In particular, construction sites comprise 84% of business places that have reported fugitive dust generation, and they are required to have inspection and management to prevent the occurrence of fugitive dust at construction sites. However, the number of complaints in the construction industry due to fugitive dust has increased. The reason for this increase is the fact that existing control measures are defined based on emission processes rather than construction work types, which makes it difficult to apply fugitive dust control measures to construction sites. Therefore, this research evaluated the effectiveness of fugitive dust control measures for construction sites in Korea through a Delphi study. This Delphi study was conducted in two rounds with 12 experts in an on-site panel, and the factors that were determined to be effective control measures were convergence, the content validity ratio (CVR), and stability. This study’s results will be utilized to direct the establishment of future guidelines for fugitive dust control measures based on types of construction work.

Measuring the Effectiveness of Safety Incentives in Construction Sites in Korea

The purpose of this study is to investigate the effect of motivation factors that actively induce construction workers participate in safety prevention activities and to investigate the effect of incentive program as motivation factor by conducting questionnaire survey. The survey was conducted for construction workers from September, 2017 to October, 2018, and the number of respondents was 256. The results of this study are that the factor of the greatest role in encouraging workers to voluntarily participate in accident prevention activities is management factors and that the introduction of new management methods such as safety incentives to reduce safety accidents is necessary. These results indicate that the accident prevention facilities and safety education and training have their limitations. Therefore, it is necessary to thoroughly reconsider what has already been done, and to find more innovative methods to reduce construction accidents.

Analyzing psychological conditions of field-workers in the construction industry

The Korean construction industry has experienced poor labor productivity and high accident rates. Previous studies have reported that workers' mental health can cause negative impacts on work performance; thus, enhancing workers' psychological conditions would help achieve more productive and safer workplaces. This research aimed to understand the level of psychological conditions of construction field-workers using four categories: (1) stress (occupational stress and stress-coping style), (2) personal temperament, (3) emotional disturbance (depression and trait anxiety), and (4) drinking habits. This research used validated questionnaires commonly used in the field of clinical psychology, surveyed 430 respondents from road, bridge, tunnel, subway, and apartment construction sites in Korea, and analyzed the overall psychological tendency of construction workers with the collaboration of professional clinical psychologists using the Z-test, analysis of variance (ANOVA), and cross-tabulation. The research also investigated how the mental conditions differed according to different working conditions, such as demographic information, employment status, work types, work experience, and wage conditions. The results indicated that construction workers suffer from a high level of stress and showed high inclination for problem-focused coping: impulsive, cautious, and dependent on other people. Two out of five construction workers suffer from depression and experience trait anxiety. More seriously, three out of five workers show alcohol-use problems that require clinical attention. This study also revealed the particular psychological problems that occur under different working conditions. The findings can be used to promote the awareness of the importance of construction workers' mental well-being and to help in setting targets for improvement.

A new approach for estimation of the rock mass deformation modulus: a rock engineering systems-based model

The deformation modulus of a rock mass is one of the crucial parameters used in the design of surface and underground rock engineering structures. Due to the problems in determining the deformability of jointed rock masses at the laboratory scale, various in-situ test methods have been developed. Although these methods are currently the best techniques, they are expensive and time-consuming, and present operational problems. To overcome this difficulty, in this paper, based on the basic concepts of a rock engineering systems (RES) approach, a new model for the prediction of the deformation modulus of a rock mass is presented. The newly proposed approach involves seven effective parameters (depth, rock quality designation, uniaxial compressive strength, the discontinuity density, the condition of discontinuities, the groundwater condition, and an adjustment for the orientation of discontinuities) pertinent to the deformation modulus of a rock mass, yet keeping simplicity as well. The performance of the RES model is compared with multiple regression models. The estimation abilities offered using RES and multiple regression models were presented by using field data obtained from road and railway construction sites in Korea. The results achieved indicate that the RES-based model predictor with the least mean square error and a higher coefficient of determination (R 2) performs better than the multiple regression models.

Characteristic Analysis of Concrete for Radiation Shielding Evaluation of Gamma Irradiation Facilities

Physical and chemical properties of concrete sample was obtained using various methods such as density analysis, elemental analysis and WD-XRF analysis to get accurate characteristics of concrete collected in our construction site in Korea. Using these results, in this study, we perform the simulation to compare the dose evaluation results between NBS concrete of ANSI/ANS 6.4.3 and characteristics of concrete samples using MCNPX. As a result, simulation results of collected concrete samples in our facility were underestimated up to 54.01%. Through these results, we verify the necessity of accurate properties of materials.

속채움 콘크리트와 철근으로 보강된 대구경 합성 PHC말뚝의 휨성능 평가

최근 구조물의 대형화에 따른 큰 지지력의 말뚝에 대한 수요가 증가하는 추세이다. 이에 따라 기성 PHC말뚝의 경우에도 700~1,200 mm 범위의 대구경 말뚝에 대한 활용이 증가하고 있고 최근 국내 현장에 적용되고 있다. 이 연구에서는 대구경 PHC말뚝의 휨성능을 향상시키기 위해 철근과 콘크리트로 보강하여 합성 PHC말뚝을 제작하였다. 휨강도 평가는 4등분점 제하실험을 통해 변위제어 방법으로 수행되었다. 휨실험을 통해 LICPT 실험체 횡방향 철근의 변형률 분포를 분석한 결과 횡방향 철근의 배근은 전단균열의 진전과 균열폭 제어에 효과적인 것으로 나타났고, 복부전단균열 발생을 억제할 수 있었다. LICPT 실험체는 LICP 실험체 보다 휨강도가 약 1.08배, 중앙부 변위가 약 1.19배 증가하였고, 횡방향 철근의 배근은 말뚝의 연성적인 휨거동 확보에 유리한 것으로 나타났다. 말뚝 제작시 사용되는 각각의 재료가 휨강도에 기여하는 수준을 층상화 단면 해석으로 계산된 축강도-휨모멘트 상관도를 통해 평가하였다. 기성 PHC말뚝과 LICP 실험체의 실제 휨강도를 1.13배, 1.16배의 안전율로 예측할 수 있었다. A demand of high bearing capacity of piles to resist heavy static loads has been increased. For this reason, the utilization of large diameter PHC piles including a range from 700 mm to 1,200 mm have been increased and applied to the construction sites in Korea recently. In this study, in order to increase the flexural strength capacity of the PHC pile, the large diameter composite PHC pile reinforced by in-filled concrete and reinforcement was developed and manufactured. All the specimens were tested under four-point bending setup and displacement control. From the strain behavior of transverse bar, it was found that the presence of transverse bar was effective against crack propagation and controlling crack width as well as prevented the web shear cracks. The flexural strength and mid-span deflection of LICPT specimens were increased by a maximum of 1.08 times and 1.19 times compared to the LICP specimens. This results indicated that the installed transverse bar is in an advantageous ductility performance of the PHC piles. A conventional layered sectional analysis for the pile specimens was performed to investigate the flexural strength according to the each used material. The calculated bending moment of conventional PHC pile and composite PHC pile, which was determined by P-M interaction curve, showed a safety factor 1.13 and 1.16 compared to the test results.

Indirect estimation of deformation modulus of an in situ rock mass: an ANFIS model based on grid partitioning, fuzzy c-means clustering and subtractive clustering

Deformability of rock masses influencing their behavior is an important geomechanical property for the rock structures design. Due to the problems in determining the deformability of jointed rock masses at the laboratory-scale, various in situ test methods such as plate loading tests, dilatometer etc. have been developed. Although these methods are currently the best techniques, they are expensive and time consuming, and present operational problems. Furthermore, the influence of the test volume on modulus of deformation depending on the technique used is also important. For these reasons, in this paper, the adaptive network-based fuzzy inference system (ANFIS) was used to build a prediction model for the indirect estimation of deformation modulus of a rock mass. Three ANFIS models were implemented by grid partitioning (GP), subtractive clustering method (SCM) and fuzzy c-means clustering method (FCM). The estimation abilities offered using three ANFIS models were presented by using field data of achieved from road and railway construction sites in Korea. In these models, rock mass rating (RMR), depth, uniaxial compressive strength of intact rock (UCS) and elastic modulus of intact rock (Ei) were utilized as the input parameters, while the deformation modulus of a rock mass was the output parameter. Various statistical performance indexes were utilized to compare the performance of those estimation models. The results achieved indicate that the ANFIS-SCM model has strong potential to indirect estimation of deformation modulus of a rock mass with high degree of accuracy and robustness.

An experimental study on structural performance evaluation of steel wire-integrated deck plate

Recently, due to the decreased work term and the convenience of construction work, the steel wire-integrated deck plate has been widely used in the construction sites in Korea. Most of all, owing to its good stiffness and economic consideration, the steel wire-integrated deck plate system has become very popular in recent years. This research suggested the new-type shear connector that can perform the roles of vertical bar and shear connector at the same time to obtain safety on construction load of the steel wire-integrated deck plate and improvement on constructability, and used many variables such as the location of lattice end and diameter of the lattice bar to evaluate the structural safety of the steel wire-integrated deck plate in construction step. The test results show that the new-type shear connectors sufficiently perform the roles of the vertical bars.