• 대한토목학회논문집
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• 제41권4호
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• pp.331-340
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• 2021

본 논문은 비예측 극한하중인 폭발하중에 노출된 RC building 구조물의 폭발손상평가를 위한 수치해석적 연구이다. 수치해석의 효율성 및 정확성을 높이기 위해, 폭발하중에 대한 정의, 유체-구조 연성을 위한 Euler-Lagrange 커플링 기법 적용, 그리고 고변형률 속도가 고려된 콘크리트 및 강재 재료구성모델이 제안된다. 특히 효율적인 폭발하중 정의를 위해, Euler-FCT 기법을 통하여 TNT 질량에 따른 시간별 압력하중 데이터가 확보되고, 이는 RC building 구조물 총 7 지점의 폭발위치에 적용되며, ANSYS-AUTODYN 솔버에 연결되어 수치 시뮬레이션이 수행된다. 해석결과, TNT 질량 및 폭발 위치에 따라 손상 차이가 발생하였으며, 먼저 TNT 질량 20 kg 일 경우 3 곳의 폭발손상 지점에서 주부재 중 슬래브에서만 중간 및 가벼운 손상이 발생되었고, TNT 질량 100 kg 일 경우 5 곳의 폭발손상 지점 중 3 곳은 슬래브 및 보 부재에서 중간 손상이 발생되었으며, 2 곳은 슬래브에서 심각한 손상이 발생되었다.

• Steel and Composite Structures
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• 제49권1호
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• pp.65-79
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• 2023

This paper presents a development of empirical evaluations, which can be used to evaluate the damage of fiber-reinforced concrete composites (FRC) wall subjected to close-in blast loads. For this development, a combined application of numerical simulation and machine learning approaches are employed. First, finite element modeling of FRC wall under blast loading is developed and verified using experimental data. Numerical analyses are then carried out to investigate the dynamic behavior of the FRC wall under blast loading. In addition, a data set of 384 samples on the damage of FRC wall due to blast loads is then produced in order to develop machine learning models. Second, three robust machine learning models of Random Forest (RF), Support Vector Machine (SVM), and Extreme Gradient Boosting (XGBoost) are employed to propose empirical evaluations for predicting the damage of FRC wall. The proposed empirical evaluations are very useful for practical evaluation and design of FRC wall subjected to blast loads.

• Steel and Composite Structures
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• 제45권3호
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• pp.389-408
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• 2022

Residual capacity is defined as the load carrying capacity of an RC column after undergoing severe damage. Evaluation of residual capacity of RC columns is necessary to avoid damage initiation in RC structures. The central aspect of the current research is to propose an empirical formula to estimate the residual capacity of RC columns after undergoing severe damage. This formula facilitates decision making of whether a replacement or a repair of the damaged column is adequate for further use. Available literature mainly focused on the simulation of explosion loads by using simplified pressure time histories to develop residual capacity of RC columns and rarely simulated the actual explosive. Therefore, there is a gap in the literature concerning general relation between blast damage of columns with different explosive loading conditions for a reliable and quick evaluation of column behavior subjected to blast loading. In this paper, the Arbitrary Lagrangian Eulerian (ALE) technique is implemented to simulate high fidelity blast pressure propagations. LS-DYNA software is utilized to solve the finite element (FE) model. The FE model is validated against the practical blast tests, and outcomes are in good agreement with test results. Multivariate linear regression (MLR) method is utilized to derive an analytical formula. The analytical formula predicts the residual capacity of RC columns as functions of structural element parameters. Based on intensive numerical simulation data, it is found that column depth, longitudinal reinforcement ratio, concrete strength and column width have significant effects on the residual axial load carrying capacity of reinforced concrete column under blast loads. Increasing column depth and longitudinal reinforcement ratio that provides better confinement to concrete are very effective in the residual capacity of RC column subjected to blast loads. Data obtained with this study can broaden the knowledge of structural response to blast and improve FE models to simulate the blast performance of concrete structures.

• 한국산학기술학회논문지
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• 제15권8호
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• pp.4790-4795
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• 2014

공작기계는 기계산업의 생산 및 시제품가공 등에 널리 적용되고 있다. 폭발시 발생하는 지반진동은 인근 구조물의 손상이나 시설에 많은 영향을 미친다. 본 논문은 발파진동이 공작기계의 가공정밀도에 미치는 영향을 고찰하였다. 발파진동과 발파시 공작기계의 진동을 측정하였고, 진동허용치를 기준으로 평가하였다. 공작기계의 진동허용치를 기준으로 할 경우 본 연구에 사용된 공작기계의 발파시 진동허용치는 SLIGHTLY ROUGH~ROUGH에 해당된다. 발파진동이 반복될 경우 정밀도가 저하될 가능성이 많다.

• Corrosion Science and Technology
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• 제6권4호
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• pp.177-185
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• 2007

The purpose of this study is to evaluate freezing-thawing and surface scaling resistance in order to examine the frost durability of concrete in a chloride-inherent environment. The mixing design for this study is as follows: 3 water binder ratios of 0.37, 0.42, and 0.47; 2-ingredient type concrete (50% OPC concrete and 50% ground granulated blast-furnace slag), and 3-ingredient type concrete (50% OPC concrete, 15% fly ash, and 35% ground granulated blast-furnace slag). As found in this study, the decrease of durability was much more noticeable in combined deterioration through both salt damage and frost damage than in a single deterioration through either ofthese; when using blast-furnace slag in freezing-thawing seawater, the frost durability and surface deterioration resistance was evaluated as higher than when using OPC concrete. BF 50% concrete, especially, rather than BFS35%+FA15%, had a notable effect on resistance to chloride penetration and freezing/expansion. It has been confirmed that surface deterioration can be evaluated through a quantitative analysis of scaling, calculated from concrete's underwater weight and surface-dry weight as affected by the freezing-thawing of seawater.

• Structural Engineering and Mechanics
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• 제54권3호
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• pp.545-560
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• 2015

In this paper, blast-induced vibration effects on buildings located in rural areas were investigated. Damages to reinforced concrete, adobe and masonry buildings were evaluated in Çatakk$\ddot{o}pr\ddot{u}$ and Susuz villages in Silvan district of Diyarbakir, Turkey. Blasting of stiff rocks to construct highway at vicinity of the villages damaged the buildings seriously. The most important reason of the damages is lack of engineering services and improper constructed buildings according to the current building design codes. Also, it is determined that, inappropriate blast method and soft soil class increased the damages to the buildings. The study focuses on four points: Blast effect on buildings, soil conditions in villages, building damages and evaluation of damage reasons according to the current Turkish Earthquake Code (TEC).

• International Journal of Concrete Structures and Materials
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• 제1권1호
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• pp.29-36
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• 2007

The purpose of this paper is the assessment of the capacity of the reinforced concrete (RC) elements of an arch bridge when they are subjected to contact and near-contact explosive charges of various amounts, and the estimation of the critical charges for these components. The bridge considered is the Tenza Viaduct, a decommissioned structure south of Naples, Italy. Its primary elements, deck, piers and arches were analyzed. The evaluation was accomplished via numerical analyses that made possible to obtain the elements dynamic response when they are exposed to blast loading conditions. To evaluate the member's capacities, failure criteria for deck, piers and arches were proposed based on concrete damage parameters. Additionally, curves relating the explosive charge to the residual capacity and to damage level of the elements were also developed. The results of this work were taken into account to investigate the progressive collapse of the global structure.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1993년도 봄 학술회 논문집
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• pp.59-62
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• 1993

In this study, various problems of ground vibration from rock blasting have been discussed, and field tests of rock blasting-ground vibration were carried out to find out the system of evaluation and control method for selecting blast design values and the rationale for the selection. Criterla of estimating structural response and damage caused by ground vibration from rock blasting are also discussed for the safety design of blast.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2001년도 학술논문발표회
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• pp.157-162
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• 2001

Recently, lots of studies for high flowing concrete have been suggested under practical use that it is only a way to solve the confronted problem. However, most studies have been concentrated on the manufacture method and properties of fresh concrete, but there is few studies for the durability of hardened concrete, specially for the freezing and thawing. Therefore this study is to investigate for the resistance of high-flowing concrete using finely ground granulated furnace blast slag to frost with experimental parameters, such as binder, ratio of replacement of granulated furnace blast slag, superplasticizer, curing method and blain surface area of granulated furnace blast slag.

• Computers and Concrete
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• 제17권2호
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• pp.201-214
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• 2016

The outer tank of a liquefied natural gas (LNG) storage tank is a longitudinally and meridianally pre-stressed concrete (PSC) wall structure. Because of the current trend of constructing larger LNG storage tanks, the pre-stressing forces required to increase wall strength must be significantly increased. Because of the increase in tank sizes and pre-stressing forces, an extreme loading scenario such as a bomb blast or an airplane crash needs to be investigated. Therefore, in this study, the blast resistance performance of LNG storage tanks was analyzed by conducting a blast simulation to investigate the safety of larger LNG storage tanks. Test data validation for a blast simulation of reinforced concrete panels was performed using a specific FEM code, LS-DYNA, prior to a full-scale blast simulation of the outer tank of a 270,000-kL LNG storage tank. Another objective of this study was to evaluate the safety and serviceability of an LNG storage tank with respect to varying amounts of explosive charge. The results of this study can be used as basic data for the design and safety evaluation of PSC LNG storage tanks.