Cause Of Collapse Research Articles

Delineation of subsurface features by electrical resistivity tomography and induced polarization in upstream basin of Chaq-Chaq dam – northeastern Iraq

The construction of dam is important for many reasons. Prior to construction, it is essential to assess the dam's base reservoir to identify any subsurface cavities. This study was conducted along nine electrical resistivity (ERT) profiles and eight induced polarization (IP) profiles, which are traditional ERT profiles, trending SW to NE direction in the reservoir part of the failed Chaq-Chaq dam NW of Sulaimaniyah city. The aim of this study was to delineate subsurface layers, underground features, determine the depth to bedrock, and investigate indications of the causes of collapse of the constructed Chaq-Chaq dam. The Res2Dinvx64 program used in the inversion method to obtain true 2D resistivity sections using a Schlumberger-Wenner array, which is highly sensitive to changes in resistivity both vertically and laterally. Based on the resistivity values, it was found that the area consists of three geological layers; the first layer consists of soil, while the second layer consists of rock fragments, the interface between them has disappeared because the first layer is thin, and the third layer is specified as consolidated and cohesive limestone of the Kometan Formation. The surface of the Kometan limestones is irregular due to weathering and faulting resulting from tectonic movements leading to the collapse of the area and later filled with sediments of recent deposition. The IP method was only used to distinguish clay and water. According to IP values, water is present in the subsurface of the study area. According to the ERT sections, a sinkhole with a depth range of (15 – 39 m) was encountered at the beginning of most of the profiles.

State of the Art on Forensic Bridge Engineering in Chile. A Management and Technical Overview

Chile is a country highly affected by natural hazards, especially scour and seismic phenomena. Therefore, throughout the twentieth century and the beginning of the twenty-first, total or partial collapses of bridges have been evidenced, particularly those that occurred in the 1960 and 2010 earthquakes. From these experiences, the Chilean Highway Administration has promoted a series of management activities in order to reduce the number of collapsed structures. In this context, since 2019 the Ministry of Public Works of Chile (MOP) supported by the Chilean universities started a program to develop the subject of forensic engineering on bridges, in order to include the methodology in the technical codes and provide a standardization of protocols for the implementation of activities in the case of the collapse of structures. The aspects included in this methodology are: Determination of volatile and non-volatile information; Actions for intervention on the structure and protection of users; Gathering of technical information through the application of tests; Review of stress–strain states through Finite Element Method (FEM); Elaboration of hypotheses and review of them through a decision tree; and, finally, Conclusions and recommendations from a technical and contractual perspective. This paper presents a detailed description of the current forensic engineering methodology in Chile and its first application in the Cancura Bridge case study. In addition, a historical compilation of Chilean bridge collapses is presented, in each case identifying the typology of the structure, the causes of collapse and the main inspection techniques used. Finally, a statistical review is carried out analyzing aspects such as stages of the life cycle where collapse has occurred: design, construction or operation, and the incidence of natural hazards in these phenomena. From this analysis, the cases of Loncomilla, Cancura and Huasco bridges are highlighted. Since the collapse of these bridges occurred without the implementation of current methodology, the article concludes on the advantages and disadvantages of the methodology, providing a comparative analysis with the inspection activities in these structures.

A study of stone arch bridge’s flood reliability through a surrogate model approach

Europe’s historic masonry arch bridges are culturally and economically significant, but their long-term safety must be ensured. Scour effects are the most common cause of collapse, so it is necessary to carry out structural assessments to mitigate the risk and prevent potential failures. In this study, a metamodel-based method was used to determine the probability of failure of an existing stone arch bridge in Portugal due to local and contraction scour on the abutments. Non-linear finite element analysis supported the calculation of the reliability index, which took into account the soil-structure interaction and the failure mechanism. The variables with the greatest influence on the load-carrying capacity of the structure were identified and a surrogate model was implemented. Fragility curves were then derived based on the surrogate model, using scour depth as a measure of intensity and load factor as an engineering requirement parameter. The results of the study indicate that the load capacity of the numerical model is compromised when the scour depth of 1.5 m reaches the base of the foundation. As a result, stability problems and settlements are observed in the model. At a depth of 2.5 m, the soil reaches its ultimate bearing capacity.

Historical cisco Coregonus artedi population collapses in Green Bay, Lake Michigan, and Saginaw Bay, Lake Huron, during the 1950s

AbstractCoregonus populations across their Holarctic range have often undergone unexplained collapses. Here, we document causes of collapse for two of the largest Coregonus populations in the world, cisco (C. artedi) in Green Bay, Lake Michigan, and Saginaw Bay, Lake Huron, during the 1950s. We used simulation models, rank‐order correlations, and historical literature to evaluate effects of overfishing, interactions with introduced rainbow smelt (Osmerus mordax), and overwinter bottom hypoxia on both cisco populations. Fully selected exploitation rates for cisco were alarmingly high (0.82–0.84), correlations and anecdotal evidence suggested negative interactions with rainbow smelt, and extensive areas of hypoxia coincident with cisco declines suggested incubation of cisco embryos was impaired regionally. Our findings suggested that negative effects of rainbow smelt were mainly responsible for the cisco population collapse in Green Bay and that overfishing and hypoxia had suppressed the Saginaw Bay cisco population before rainbow smelt caused its final collapse.

Is Commodification of Education Doomed to Fail: An Empirical Case Study Investigation into Commodification as the Cause of Failure of UK HE Providers

This paper examines the commodification model as a cause of collapse by establishing if there is a link between commodification and the failure of HE institutions. The study aims to answer 3 questions: Is profit-driven commodification the main cause of the collapse of private HE providers? If not, what is the cause and to what extent is the model a contributor to its decline? What lessons can be learned from understanding failure to prevent it? Methodology – interpretive, phenomenological case study approach based on a single case of a small-sized alternative higher education provider in London. The mixed method using observation along with documentation and interviews provided an opportunity for triangulation to improve reliability. Primary data from focus group interviews with staff, students and senior management were analyzed using thematic analysis. Findings – the study found that the commodification trend in the form of corporatization and profiteering was the leading cause, of failure. The commodification model is incompatible with education outcomes. Findings also revealed that student welfare, progress and learning outcomes are better goal which would positively impact in success. Profiteering puts heavy pressure on outcomes, negatively impacting on motivation, low morale, staff demotivation, student dissatisfaction, financial and emotional pressure on students, create a culture of victimization, unethical predatory practice etc.

A Study on Causes and Stability of Masonry Retaining Walls by Case Analysis

Masonry retaining walls, which have been used since long time, have recently been widely used in the construction of small complexesas an easy-to-purchase material and eco-friendly structure. Disasters owing to the collapse of these masonry retaining walls have frequently occurred over time. The purpose of this study is to quantitatively evaluate the causes for the collapse of masonry retainingwalls by collecting and analyzing collapse data using collapse phenomenon field trips, literature review, and search tools, and to use this analysis data, to suggest measures to prevent the collapse of masonry retaining walls. As a result of collecting and analyzing collapse case data, this study found that the main causes of masonry retaining wall collapse were the loss of foundation ground (scour), ground displacement owing to the excavation of adjacent land, settlement owing to ground softening because of rainfallinfiltration, poor drainage, and inclination of stonework. The causes for collapse were of eight types, including slope sliding additionalloading, and vibration, and 16 types when literature data were included. An analysis of the collapse frequency based on the causes for collapse revealed that the two causes for collapse, foundation and drainage, accounted for approximately 60% of the total cause,and measures for stability and Governing law of critical factor were proposed using this result.

An analysis approach for building collapse accident using system thinking approach and SEA model

The frequent occurrence of building collapse accidents not only causes significant casualties, but also jeopardizes local economies. This paper adopts a combinatory assessment approach to showcase the lessons learned from a recent building collapse in Changsha, China. The proposed approach blends the system thinking approach and strategic environmental assessment (SEA) model. It delineates the causes of collapse and provide key leverage points for safety management. The results show that the primary causes for the collapse are the poor construction quality, illegal alterations, and lack of regulations enforcement. The management of rural housing construction in Hunan Province achieved a total score of 4 out of 30. It was also determined that the key prevention measures for abating these deleterious phenomena involve ensuring quality assurance/quality control, efficiently assessing safety risk, and timely performing structural health monitoring. This study is bound to enhance the understanding of collapse accidents and foster the achievement of sustainable cities and communities.

Assessment and initial management of the collapsed endurance athlete

Participation in endurance events such as marathons is increasingly popular. Those taking part in these events may collapse and require medical attention for a range of reasons, some of which are well known and recognised by prehospital providers. However, there are conditions that are specific to endurance exercise which may be less well known so potentially less likely to be recognised and managed appropriately. The most common cause of collapse in the endurance athlete is exercise-associated collapse. However, practitioners should be vigilant regarding life-threatening differentials such as exertional heatstroke and exercise-associated hyponatraemia, which are not uncommon. Identifying the cause of collapse in the endurance athlete is difficult as clinical presentations are often similar. The causes, symptoms and management of these conditions are discussed and a management algorithm proposed.

The historical bridge of Plaka: Interpretation of structural behavior and collapse

The arched stone bridge of Plaka, built in 1866, is situated in the mountainous region of Epirus, Greece, and it bridges the river Arachtos. A significant part of the bridge, namely the central part of the arch and the east pier, have collapsed on February 1st, 2015, after heavy rainfalls in the region. The National Technical University of Athens (NTUA) has mobilized its staff and offered the documentation of the bridge, as well as the preliminary design for its restoration.The bridge was accurately modelled, in terms of geometry and properties of materials. Numerical calculations have revealed the cause of pre-existing damage, as well as the cause of collapse of the bridge.The thorough documentation and the assessment have proven that the bridge, at its original state, was able to safely withstand the actions expected to be exerted on it. Thus, the restoration was performed without alteration of the original structural system, and completed five years after the collapse.

Damage and restoration of historical urban walls: literature review and case of studies

Within this work, the causes of collapses and damages occurred in masonry artefacts have been evaluated to properly identify suitable monitoring and restoration methods. In this regard, a comprehensive literature review has been performed. Based on the results, the moisture has found to be a critical parameter, which affects the structural health of masonry artefacts. Diverse non-destructive methods were employed to measure the moisture and monitor the materials involved: the Infrared Thermography, the Electrical Resistivity Tomography and the Ground Penetrating Radar, the Laser Scanning and Digital Terrestrial Photogrammetry, the Global Navigation Satellite Systems, the Unilateral Nuclear Magnetic Resonance, the Laser-Induced Fluorescence technique, the Acoustic Imaging and the Acoustic Tomography, the Geographic Information System and on-site survey process as well as computer modeling of the structure with specific FEM software. Finally, the implementation of tie-beams, Fiber Reinforced Polymers layers, ventilation, draining systems, and high-quality materials are proposed as solutions for controlling the moisture effect and retrofitting.

Genetic variation in drying collapse and heartwood properties at mid-rotation age of Eucalyptus globoidea

Main causes of drying degrade in most plantation-grown eucalypt timber are collapse and checking. Appropriate but costly sawing and drying techniques are employed to alleviate these problems. Eucalyptus globoidea is an emerging plantation species. This study investigated the genetic control of collapse and other tree features in an E. globoidea breeding population established at three different sites. Using a 14-mm diameter corer, thousands of E. globoidea trees representing 163 families were sampled, and genetic parameters for heartwood and sapwood collapse, extractive content, and heartwood diameter were estimated. Heartwood collapse was under genetic control with a narrow sense heritability ranging from 0.22 to 0.44. Considering the coefficient of genetic variability of ∼13–23%, heartwood collapse in E. globoidea can be reduced through selection. The significant genetic correlation between sites for heartwood collapse (rg = 0.73–0.83) suggested low genotype by environment (G × E) interaction. In line with the physical causes of collapse, heartwood collapse was positively correlated with extractive content. Extractive content and heartwood diameter are other traits of interest, as E. globoidea is grown for its ground-durable heartwood. The heritability of extractive content ranged from 0.40 to 0.71. Heartwood diameter was shown to be negatively correlated to extractive content. No significant genotype by environment (G × E) interaction was found for extractive content while genotype by environment (G × E) interactions for heartwood and sapwood diameter were small. Finally, 12 families had above-average heartwood diameter, extractive content, and below-average heartwood collapse. In summary, this study has shown that genetic selection for collapse and other wood properties of E. globoidea is feasible.

Fatigue life analysis of high-strength bolts based on machine learning method and SHapley Additive exPlanations (SHAP) approach

Fatigue failure of high-strength bolts is one of the causes of collapse of steel structures. In this paper, six different machine learning models were used to analyze and predict the fatigue life of high-strength bolts, and the relationship between fatigue life of the bolts and the influencing factors was analyzed by SHAP method. During this process, a data set of fatigue life of high-strength bolts was presented, and 30 percent of the data was randomly selected as the test set. Geometric dimensions and stress states of bolts were as input features, and fatigue life was output label. After training the model, the errors of bolt fatigue life prediction of six machine learning models were compared. Finally, the most adverse factors affecting the fatigue life of the bolts are analyzed. It was found that XGBoost has the best performance on prediction of fatigue life of high-strength bolts, R2 reaches 0.881 and 0.788 in training set and test set, respectively. At the same time, the prediction result of the model is also better than that of the traditional fracture mechanics method. In addition, according to the analysis of SHAP value, the stress amplitude (SA) applied on the bolt has the greatest impact on the fatigue life. Larger SA value will accelerate the expansion of fatigue crack, thus increasing the degree of fatigue damage of the bolt. At the same time, the combination of MAXS (maximum stress applied on high-strength bolts) and SA is the most unfavorable factor to affect the fatigue life of the bolt. Increasing both factors can greatly reduce the fatigue life of the bolt. Finally, the current mainstream steel structure design codes have sufficient safety reserves, and M39 bolt has the best fatigue performance.

Seismic vulnerability assessment through global-and local-scale analyses for a historic masonry building constructed in 1896

The causes of collapse in masonry buildings are different than those of reinforced concrete and steel-framed buildings. This is due to differences in structural behavior as a result of the materials and techniques used in the construction of such buildings. The most significant contribution to this behavioral difference is made by the out-of-plane behavior of masonry buildings. Therefore, in addition to overall collapse, out-of-plane behaviors of the facade walls must also be determined in such buildings. Accordingly, not only global behavior but also local behaviors should be considered while evaluating structural performance. This paper, therefore, presents a seismic performance assessment of a masonry building by global-and local-scale analyses. The examined 3-story building was constructed in 1896 and used for different purposes. Linear, nonlinear, and kinematic limit analysis approaches were used. Shear forces on the walls and inter-story drifts obtained by the linear and nonlinear analyses were analogized with the limit values envisaged in the local building codes, thus the seismic vulnerability of the building was determined. Overturning, vertical bending and lateral bending mechanisms were obtained by local analysis

Social sustainability under threat: a case of two collapsed buildings in Lagos, Nigeria

PurposeHousing provision and the neighbourhood's safety are significant social sustainability concerns. If structural issues are not well checked, housing provision and the neighbourhood's safety may become threatened, especially in Lagos State, Nigeria. Thus, this study aims to investigate the perceived root cause of collapsed buildings at the construction stage using two case studies, its effect on social sustainability aspects and suggested measures to mitigate future happening and enhance achieving social sustainability aspects goals.Design/methodology/approachThe researchers collected data from Nigeria's built environment experts and eyewitnesses/employees of selected cases of collapsed buildings. The study adopted a phenomenology type of qualitative research design and analysed collated data via thematic analysis and achieved saturation. The analysed data created three themes.FindingsResults reveal that inadequate heavy equipment and personnel incapacitated relevant government agencies are responsible for handling emergency and rescue during building projects collapse. Preliminary findings show developers' greed and systematic failures as the root cause of Nigeria's building project collapse (BPC). It categorised the root causes into three groups (developer's related-cause, design team related-cause and government entities related-cause). The study suggested measures to mitigate future happening. The emerged measures were grouped into a penalty, regulatory, byelaw act, technical and safety measures.Originality/valueThis study contributes to curbing the threat to social sustainability of housing provision in cities. It reveals the underlying perceived root cause of collapsed buildings in Nigeria's building industry. Also, it suggested feasible measures to mitigate BPC. These measures may be modified and adopted by other developing countries facing similar challenges.

Influence of Different Dapped-End Reinforcement Configurations on Structural Behavior of RC Dapped-End Beam

Severe damage or collapse of reinforced concrete dapped-end beams (RC-DEBs) may occur during the service life. The collapse of the Concorde overpass structure in Laval, Quebec, Canada, in 2006 revealed the causes of collapse, i.e., insufficient shear strength (no stirrups), misplacement of hanger reinforcement, etc. In addition, the inspection report of RC half-joint bridges in England until 2018 expressed that damages or failures of half-joint structures can be attributed to the poor condition of structures or non-compliant reinforcement detailing. These conditions exhibited how important it is to understand the proper detailing of dapped-end reinforcement. To date, some studies have performed investigations on the effect of inadequate dapped-end reinforcement on the structural behavior of DEBs. However, the results of the research to date were not yet complete enough to disclose the role of each group of dapped-end reinforcement in resisting the working load. Therefore, this study was carried out to investigate the main role of each group of dapped-end reinforcement separately on the structural performance of RC-DEBs. Eight large-scaled RC-DEBs (with sizes of 1800 mm length, 120 mm width and 250 mm height) were prepared, cast and cured. All DEB specimens were tested under the three-point loading up to failure. To localize the effect of shear failure, the shear span-depth ratio (av⁄d) of 1.43 was set. Test results exhibited that arrangement of a specific group of dapped-end reinforcement separately affects the structural performance of DEBs significantly. The diagonal reinforcement (DR) group was found to be more effective than the vertical hanger reinforcement (HR) group. The failure load capacity of the DR group (DEB-18) achieved 0.29 times that of the control beam (DEB-3). Meantime, the nib flexure reinforcement (NFR) group demonstrated the most important role in the structural performance of DEBs compared to other dapped-end reinforcement groups. The failure load capacity of the NFR group (DEB-39) reached 0.62 times that of the control beam, while rupture deflection of the NFR group also exhibited the highest value than other groups, i.e., 0.62 times that of the control beam. In addition, analysis results of rosette strain gages (RSGs) data indicated that regions near to re-entrant corner and its vicinity experienced the highest stress concentration factor (SCF) compared to other places of the beams. These regions were more susceptible to experiencing the first crack, progressive crack, damage or failure first than other regions of DEBs. The greater the value of SCF, the greater the probability of collapse occurring in the related structural elements, which is also followed by a lower failure load capacity. DEB-1 (without dapped-end reinforcement) has the highest SCF (205.68), and the lowest failure load capacity (12.58 kN), whilst DEB-3 (with the complete dapped-end reinforcement) has the lowest SCF (79.62), but the highest failure load capacity (105.26 kN). Obviously, DEB-3 can withstand the working load properly. Its adequate dapped-end reinforcement is able to accommodate and distribute the high stress flows in the dapped-end region properly, which causes the SCF value to decrease.

Effect of loss of bond on the behaviour of RC beams under service load conditions

Deviation of the flexural reinforcement spacing from code specifications appears to underly the cause of the loss of bond (LoB) between concrete and steel that preceded the unexpected collapse of the top-floor balcony of a building under service load conditions on 15 October 2021 in Athens. Although rare, LoB has also been identified as the cause of collapse of buildings under similar conditions in the UK and Canada. However, the codes of practice for reinforced concrete (RC) design neither make reference to the effect of LoB on structural behaviour, nor include LoB in the parameters that the formulae currently used for assessing load-carrying capacity are dependent on. In view of this, a description of the effect of LoB on the function of RC beams is provided in this paper and this description is used as the basis for the derivation of a formula linking LoB with load-carrying capacity. The validity of the proposed formula is verified using published experimental information on the subject. The proposed formula is used for the structural assessment of the collapsed balcony, taking into account the design details, physical state and loading conditions of structural members similar to the one that collapsed.

Failure analysis and countermeasures of highway tunnel crossing fault fracture zone in coal-bearing strata: A case study

Collapse occurs frequently during the construction of highway tunnel crossing fault fracture zone in coal-bearing strata. This paper presents a case study on the failure mechanism and treatment measures of the collapse of a tunnel. In-situ investigation indicates that the continuous looseness of surrounding rock caused by the crushing of coal seam is the main cause of collapse. The uniaxial compressive strengths of coal and rock was subsequently determined based on point load test. The in-situ stress measurement results show that the tunnel is in the extremely high stress zone. In addition, the collapse mechanisms were analyzed in aspects of in-situ stress, groundwater, surrounding rock mechanical properties and geology. The countermeasures of grouting and support strengthening were taken to improve the stability of surrounding rock. The effects of countermeasures were discussed by analyzing monitoring data. The lesson learned from the collapse case study can provide a reference for similar tunnels.

26 Case Report of a Pseudoaneurysm from Distal Anastomosis of Open AAA 32 Years Previously, Contained Within Original Aortic Sac

Abstract An 86-year-old gentleman attended hospital with confusion following collapse at home. On examination the abdomen was soft, non-tender and distended with an expansile mass. He underwent elective open repair of a 7cm AAA 32 years prior to current presentation. His past medical history included severe aortic stenosis and atrial fibrillation for which he was anticoagulated with warfarin. CT imaging of head for intracranial pathology. Triple phase contrast CT studies to assess possible aortic pathology. CT brain excluded intracranial pathology as cause of collapse. CT triple phase aortogram demonstrated an 8.4cm infrarenal abdominal aortic aneurysm. Arterial phased images show contrast in the previous aortic repair, however delayed images showed extravasation of contrast from a potential leak at the distal suture line, with blood filling the original aortic sac, outside the aortic surgical graft. No retroperitoneal leak was identified. This presentation was amenable to relining of the aorta with an EVAR however given the patient was asymptomatic and had significant comorbidities, no further intervention was undertaken. The patient and family agreed with this plan of action, and the patient died 3 weeks later. The duration of this contained leak was unknown.

Cause analysis of pit wall collapses in Kumtor Mine

In 2002 and 2006, pit walls collapsed in Kumtor Mine. The collapse of 2002 was accompanied by negative consequences. The volume of the collapsed rock mass was about 3 Mm3. The height of the collapse was 280 meters, and the width of the collapse at the base was about 270 meters. It took a significant amount of cost and time to resume the work of the open pit. In all cases of pit wall collapses, it is important to perform a cause analysis in order to reduce the risk of re-collapse in the course of further mining. The investigation analyzed data from monitoring of pit wall displacements, structural mapping, rock properties, meteorological and seismic data, groundwater level data, mining sequence prior to collapse, etc. Explanations of eyewitnesses of the collapse were heard. Invited experts from various consulting firms considered various versions of the possible causes and processes that led to the collapse, but so far the final opinion among experts about the reasons for the collapse in 2002 has not been formed. It is believed that the main reason for the collapse was the unfavorable three-dimensional orientation of the fault, which was not identified during the period of engineering and geological surveys. In support of this version, the results of numerical simulations in a 2D formulation were presented. Numerical modeling showed that a similar picture of pit wall collapse is possible in the presence of a gently dipping fault, which cuts the exposed steeply dipping fault. At the same time, the gently dipping fault did not have an outlet to the surface of the wall and extended below the bottom of the open pit. To improve the safety of mining operations, it was decided to clarify the structural-tectonic and geological model of the open pit and update the field observation program by use a laser monitoring system. Thanks to the updated monitoring system, it was possible to avoid the tragic consequences of the collapse of the pit wall in 2006. At the same time, the collapse occurred and it was necessary to analyze the causes of the collapse. The main direction of the analysis of the causes of collapse is the search for structural-tectonic faults, along which the collapse surface was formed. The search for the failure surface, taking into account the exposed surfaces of structural-tectonic faults, indicates that the failure surface is not always formed according to the classical schemes adopted for fractured rock masses. The pit wall collapses that occurred in Kumtor Mine in 2002 and 2006 indicate that the failure surface was formed by several intersecting structural-tectonic faults. The analysis of the causes of pit wall failure should be performed taking into account the three-dimensional orientation of structural faults on the basis of numerical modeling. 3D numerical modeling was carried out in FLAC 3D. The numerical simulation results for the collapse confirmed that the 2006 failure surface was formed from several structural faults. The obtained results allowed the development of recommendations for safe mining operations for 15 years.

건설공사 실무유형별 ｢불법 재하도급」의 해석문제 및 개선방안

Safety in construction industries has been emphasized since January 2022 due to enacting ‘Serious Accidents Punishment Act’, moreover illegal re-subcontract is pointed out as main cause of collapse during demolition in Gwangju on June 2021. In other words cost reduction by illegal re-subcontract caused poor construction. Therefore Government has prepared countermeasure for illegal re-subcontract on Aug. 2021, however illegal re-subcontract maybe not improved in construction field. Sub-contractors are able to reduce their risk on direct execution and to earn commission, and resubcontract can award their work without bidding, so illegal resubcontract is still beneficial for both parties. In addition, the indifference of the main contractor are also seen as the reason. This thesis examines basic judgment principal regarding illegal resubcontract under Framework Act on the Construction Industry, and we intend to suggest legislative and practical improvement plan for illegal re-subcontract.