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This study investigates a turbulent wind-induced dynamic behavior of a soundproof tunnel structure with un-symmetric shape. The combined computational fluid dynamics (CFD) and fluid-structure interaction (FSI) simulations proposed in this study may allow us not only to investigate realistic wind effects but also to provide various parameters for the structural design. The CFD and FSI simulation were verified in comparisons with a full-scale experiment of soundproof frames. Subsequent simulation results present that displacements, stresses, and shear forces induced from the FSI analysis are heavily dependent on curved shapes and the wind direction of the soundproof tunnel. From parametric results, the technique proposed in this study is computationally efficient in characterizing behaviors for complex structures such as soundproof tunnels with un-symmetric shapes.

In South Korea, sewage pipeline exploration devices have been developed using high resolution digital camera of 2 mega-pixels or above. However, most of the devices are less than 300 kilo-pixels due to poverty of the business. Moreover, since 100 kilo-pixels devices are widely used, environment for image processing is very poor. In this study, we adapted very low resolution (240 × 320 = 76,800 pixels) images by which it is difficult to detect cracks. Considering that images of sewers in South Korea have very low resolution, this study selected low resolution images to be investigated. An automatic crack detection technique has been studied using digital image processing technology for low resolution images of sewage pipeline. Authors have developed a program to automatically detect cracks as per eight steps based on MATLAB’s functions. In this study, the third step covers an algorithm developed to find optimal threshold value, and the sixth step deals with algorithm to determine cracks. When we select [1.11:1.29] of zero padding range, exact detection rate is 89.2% and error rate is 4.44%. As the result, in spite of very low-resolution images, the performance of crack detection turned out to be excellent.

Imaging devices of less than 300,000 pixels are mostly used for sewage conduit exploration due to the petty nature of the survey industry in Korea. Particularly, devices of less than 100,000 pixels are still widely used, and the environment for image processing is very dim. Since the sewage conduit images covered in this study have a very low resolution (240 × 320 = 76,800 pixels), it is very difficult to detect cracks. Because most of the resolutions of the sewer conduit images are very low in Korea, this problem of low resolution was selected as the subject of this study. Cracks were detected through a total of six steps of improving the crack in Step 2, finding the optimal threshold value in Step 3, and applying an algorithm to detect cracks in Step 5. Cracks were effectively detected by the optimal parameters in Steps 2 and 3 and the user algorithm in Step 5. Despite the very low resolution, the cracked images showed a 96.4% accuracy of detection, and the non-cracked images showed 94.5% accuracy. Moreover, the analysis was excellent in quality. It is believed that the findings of this study can be effectively used for crack detection with low-resolution images.

This study analyzes gestation stall structures with high strength concrete. The ANSYS program described in this paper is effective not only because it shows good accuracy but also it shows the goodness of parameter studies by using APDL(ANSYS Parametric Design Language). We have performed the various parameter studies by thickness change. The results is presented by using contours and tables. The analysis results showed that it was effective to increase the height thickness(tz) rather than longitudinal thickness(tx).

The finite element analysis of large sized rectangular water tank structures made of stainless steel materials is carried out for various combined load cases. The combined load cases for a large size of 5,000ton are further determined using the specification(KS B 6283) established from the Korean Standards Association. For the better numerical efficiency, the rectangular panels are modelled using the ANSYS program. The numerical results obtained for different load cases show as follows. In order to resist the snow load, it takes the influence of the gap than the size of the column. Also, in order to resist the water pressure, it shall increase the thickness of the wall. But, increasing the thickness of the wall is considerably less economical. Therefore, the angle with big thickness should be placed right next to the wall.

Night-time surveillance is important for safety and security purposes. For this reason, several studies have attempted to automatically detect people intruding into restricted areas by using infrared cameras. However, detecting people from infrared CCTV (closed-circuit television) is challenging because they are usually installed in overhead locations and people only occupy small regions in the resulting image. Therefore, this study proposes an accurate and efficient method for detecting people in infrared CCTV images during the night-time. For this purpose, three different infrared image datasets were constructed, two obtained from an infrared CCTV installed on a public beach and another obtained from a forward looking infrared (FLIR) camera installed on a pedestrian bridge. Moreover, a convolution neural network (CNN)-based pixel-wise classifier for fine-grained person detection was implemented. The detection performance of the proposed method was compared against five conventional detection methods. The results demonstrate that the proposed CNN-based human detection approach outperforms conventional detection approaches in all datasets. Especially, the proposed method maintained F1 scores of above 80% in object-level detection for all datasets. By improving the performance of human detection from infrared images, we expect that this research will contribute to the safety and security of public areas during night-time.

A disaster preventive structural health monitoring (SHM) system needs to be equipped with the following abilities: First, it should be able to simultaneously measure diverse types of data (e.g., displacement, velocity, acceleration, strain, load, temperature, humidity, etc.) for accurate diagnosis. Second, it also requires standalone power supply to guarantee its immediate response in crisis (e.g., sudden interruption of normal AC power in disaster situations). Furthermore, it should be capable of prompt processing and realtime wireless communication of a huge amount of data. Therefore, this study is aimed at developing a wireless unified-maintenance system (WUMS) that would satisfy all the requirements for a disaster preventive SHM system of civil structures. The WUMS is designed to measure diverse types of structural responses in realtime based on wireless communication, allowing users to selectively use WiFi RF band and finally working in standalone mode by means of the field-programmable gate array (FPGA) technology. To verify its performance, the following tests were performed: (i) A test to see how far communication is possible in open field, (ii) a test on a shaker to see how accurate responses are, (iii) a modal test on a bridge to see how exactly characteristic real-time dynamic responses are of structures. The test results proved that the WUMS was able to secure stable communication far up to nearly 800 m away by acquiring wireless responses in realtime accurately, when compared to the displacement and acceleration responses which were acquired through wired communication. The analysis of dynamic characteristics also showed that the wireless acceleration responses in real-time represented satisfactorily the dynamic properties of structures. Therefore, the WUMS is proved valid as a SHM, and its outstanding performance is also proven.

This paper introduces a digital image processing(DIP) method as a method for measuring the displacement of pylon. The comparison of DIP results and ANSYS analysis results verified the validity of the image processing technique. Normalized cross-correlation(NCC) coefficient was used and experiments were performed three times. It shows that the displacement difference was 22% and 5% compared to ANSYS results. Therefore, the image processing method is expected to be able to measure the displacement of pylon sufficiently.

In this paper, we study the calculation for the fracture area of the composite material specimens using digital image processing techniques. This study was able to calculate the area of the fracture region through the main operation step 7 on the basis of improved image. To extract the area in the original image, we have to use opening operation, close operation, the Hit-or-Miss operation and Bottom hat filter, Top hat filter, etc. In particular, to extract the area of the composite specimen discussed in this study, we have to use the combination of the operations and filters because it is non-isotropic material, or should develop a new algorithm based on it.

This study analyzes performance-cost ratio of various polycarbonate(PC) pigpen. The finite element models using the ANSYS program described in this paper is attractive not only because it shows excellent accuracy in analysis but also it shows the benefit of parameter study by using APDL. We have performed various parameter study of total 6 models. And we compared and analyzed the results of 6 models. From the numerical examples, we recommend model M2. Model M2 is PC pigpen with steel in PC.

In the Strut-Tie-Model(STM), the width of a node is important in both analysis and design. Its effects on the force distribution at truss analogy system. In addition, it effects the verification of all struts and nodes, which need to be checked to satisfy the code of design. Code here refers to the ACI-318 code. Four methods were used to define the width of node: 1) effective depth is assumed to equal to 0.9 of the overall depth of beam, 2) moment equilibrium 3) assumption of the width of node at the bottom equal to 380mm, and 4) the new proposed method by this study. 106 selected samples of a parametric study obtained from the four methods were analyzed. Because total steel requirement from these four methods are similar, the easiest would be a good choice for a time saving calculation.

Abstract : This study analyzes performance-weight ratio of polycarbonate(PC) pigpen and steel pigpen. The finite element models using the ANSYS program described in this paper is attractive not only because it shows excellent accuracy in analysis but also it shows the benefit of parameter study by using APDL. We have performed a parameter study by the width variation of PC pigpen. And we compared and analyzed the results of PC pigpen and steel pigpen. From the numerical examples, we confirmed the validity of PC pigpen. Key Words: pigpen, polycarbonate, ANSYS, finite element 주요어: 돈사, 폴리카보네이트, ANSYS, 유한요소 Corresponding author : Son, Byung Jik, Associate Professor, Department of Civil & Environmental Engineering, Konyang University Tel: +82-43-730-5634, E-mail: strustar@konyang.ac.kr투고일: 2014년 9월 1일 / 수정일: 2014년 9월 11일 / 게재확정일: 2014년 9월 15일 1. 서 론 현재 돈사(돼지우리) 구조물의 재료로 콘크리트와 강재가 쓰이고 있다. 기존 콘크리트 및 강재 돈사는 많은 장점이 있지만, 내구성 및 유지관리가 다소 어려운 단점이 있다. 이에 강도는 물론 내구성이 우수한 폴리카보네이트 재료를 돈사용으로 사용하기 위해 구조안정성 검토를 수행하고자 한다. 폴리카보네이트(PolyCarbonate, PC)는 열가소성 플라스틱의 일종으로 내충격성, 내열성, 내후성, 자기 소화성, 투명성 등의 특징이 있고, 강화 유리의 약 150배 이상의 충격도를 지니고 있어 유연성 및 가공성이 우수한 재료이다. 또한, 사출성형이 쉽고, 표면이 부드러워 강재나 콘크리트에 비해 돼지의 피부 보호에도 좋은 재료이다. 본 연구에서 사용된 PC는 강도 증진을 위해 카본이 10%정도 섞인 재료이다.본 연구는 반 영구성 재료인 PC를 사용한 돈사 구조물의 타당성 검토를 구조해석을 통해 하고자 한다. 기존 강재와 비교하여, 안전성 및 무게 대비 성능을 비교, 분석하였다.

Deep beam shall be designed either by taking into account nonlinear distribution of strain or by Appendix A of Strut-and-Tie Models (STM) according to ACI 318(M) from version of 2002. Although STM is accepted as tool in design Discontinuity region (D-region) which mostly exist in Deep beam, Corbels, Dapped ends etc., it has been modified by many researchers. In this study we design deep beam by STMs which use simple truss for load distribution and the model of complex truss for load distribution compare with the ACI traditional which is designed by flexure design method and shear provided by concrete() as provided in special provisions section of 11.8 in ACI 318-99 [1]. This study aims to find the different and efficiency of deep beam design based on variation of parameter compiled from many samples selected from ACI traditional and two model of STMs, simple and complex load distribution.

This paper describes a detailed assessment of the structural safety, serviceability, capacity rating and long-term durability of a fiber-reinforced polymer (FRP) vehicular slab bridge superstructure. This first all-FRP slab bridge was installed in Korea on May the 22nd, 2002. The FRP slab bridge superstructure is a simply supported, its length is 10.0 m, and is designed to carry two-lane traffic and has an overall width of 8.0 m. The FRP slab bridge is a sandwich structure with a corrugated core, fabricated by a hand lay-up process with E-glass fibers and vinyl ester resins. The assessment includes a visual inspection, field load test identical to that performed in 2002. The field load test under actual service conditions was conducted as specified by the Korean Highway Bridge Design Code. In this first part, the field load test results performed in 2002, 2004 and 2011 are presented and the capacity-ratings of FRP slab bridge was evaluated. The assessment indicates that the FRP slab bridge has no structural problems and is structurally performing well in-service as expected. The assessment may provide a baseline data for the FRP slab bridge capacity rating assessment and also serve as part of a long-term performance of all-FRP bridge superstructure.

In this study, composite laminate cantilever type cylindrical shells with edge-stiffeners are analyzed. A versatile 4-node flat shell element which is useful for the analysis of shell structures is used. An improved flat shell element is established by the combined use of the addition of non-conforming displacement modes and the substitute shear strain fields. Two models by load conditions are considered. Load type A and B are loaded by point load at the free edge and line load respectively. A various parameter examples are presented to obtain proper stiffened length and stiffened thickness of edge-stiffeners. It is shown that the thickness of shell can be reduced minimum 30% by appropriate edge-stiffeners.

Key Words: Wind Turbine Blade(풍력블레이드), Dual-Axis Loads(이축하중), Puck Failure Criterion(Puck파손지수), Composite Laminate(복합적층), Static Behaviors(정적거동), Inter-fiber FailureCriterion(모재파손지수), Fiber Failure Criterion(섬유파손지수)초록: 블레이드의성능평가를위하여실제사용환경과근접한하중모사에따른이축하중의필요성이제기되고있으며, 본본문에서는이러한이축하중에따른블레이드의거동을해석하였다. 100kW급풍력블레이드를대상으로하였으며, ANSYS를사용하여정적거동을분석하였다. 정적거동은파손해석과좌굴거동으로분석하였으며, 파손평가는Puck이제안한파손방정식을이용하여섬유파손과섬유간파손기준을검토하였다. 이축하중의하중비가증가함에따라루트부단면이변하는후연부와루트에서Z+ 3300~3600인지점에서응력이상대적으로크게나타났다. 또한이축하중비가증가함에따라블레이드좌굴지점이루트부쪽으로이동되고있음을확인하였다. 따라서블레이드의사용신뢰성을검증하기위해서는이축하중에의한시험이요구되고있음을본해석을통해서확인하였다.Abstract: For the assessment of the performance of a wind-turbine blade, a simulated loading test may be required. Inthis study, the blade behavior was investigated through numerical analysis using a dual-axis loading test, closelysimulating the real operation conditions. The blade structure for the 100-kW-class wind-turbine system was modeledusing the finite element (FE) program ANSYS. The failure criteria and buckling analysis under dual-axis loading wereexamined. The failure analysis, including fiber failure and inter-fiber failure, was performed with Puck's failure criterion.As the dual-axis load ratio increases, the relatively increased stress occurs at the trailing edge and skin surface 3300–3600 mm away from the root. Furthermore, it is revealed that increasing the dual-axis load ratio makes the locationthat is weakest against buckling move toward the root part. Thus, it is seen that the dual-axis load test may be anessential requirement for the verification of blade performance.

This paper presents the flexural behavior of a hybrid Glass Fiber-Reinforced Polymer(GFRP)-steel decks for use in deteriorated bridge decks replacement. Static load tests were conducted to investigate the structural characteristics of the hybrid FRP-steel deck. The tested deck panel satisfied the design criteria. The failure mode of the hybrid deck was demonstrated ductility with deformation beyond initial yielding. The responses were compared with the ANSYS finite element predictions. It was found that the presented hybrid deck was efficient for use in bridges. The thickness of the hybrid deck may be decreased when compared to that of the all FRP deck with similar flexural rigidity.

This paper presents the static and fatigue performance of composite sandwich bridge decks with hybrid GFRP–steel core. The composite sandwich bridge deck system is comprised of wrapped hybrid core of GFRP grid and multiple steel box cells with upper and lower GFRP facings. Its structural performance under static loading and fatigue loading with a nominal frequency of 5 Hz was evaluated. The responses from laboratory testing were compared with the ANSYS finite element predictions. The failure mode of the proposed composite sandwich bridge deck was more favourable because of the yielding of the steel tube when compared with that of all-GFRP decks. The ultimate failure of the composite sandwich deck panels occurs by shear of the bonded joints between GFRP facings and steel box cells. Results from fatigue load test indicated no loss in stiffness, no signs of de-bonding and no visible signs of deterioration up to 2 million load cycles. The thickness of the composite sandwich deck retaining the similar stiffness may be decreased to some extent when compared with the all-GFRP deck. This paper also presents design of a connection between composite sandwich deck and steel girder.

A hybrid concept of composite sandwich panel with hybrid fiber-reinforced polymer (FRP)—steel core was proposed for bridge decks in order to not only improve stiffness and buckling response but also be cost efficient compared to all glass fiber-reinforced polymer (GFRP) decks. The composite sandwich bridge deck system is comprised of wrapped hybrid core of GFRP grid and multiple steel box cells with upper and lower GFRP facings. Its structural performance under static loading was evaluated and compared with the ANSYS finite element predictions. It was found that the presented composite sandwich panel with hybrid FRP-steel core was very efficient for use in bridges. The thickness of the hybrid deck may be decreased by 19% when compared with the all GFRP deck. The failure mode of the proposed hybrid deck was more favorable because of the yielding of the steel tube when compared with that of all GFRP decks.

Recently, there have been many theoretical and experimental studies on advanced composite materials (ACM) bridges in various fields over the world. Compared with a reinforced concrete or steel bridge, an ACM bridge has more advantages in strength, stiffness, transportation, and installation. Many demonstration projects have been carried out in the US, and Europe. They are also being developed and tested in South Korea. In South Korea the first of all ACM short-span bridge superstructure was installed on a public highway system in May 2002. Since these composite materials are new to bridge applications, reliable data is not available for their in-service performance. This paper describes in-service performance assessments of all ACM bridge superstructures. To investigate its in-service performance, field load testing and visual inspections were conducted under an actual service environment. The paper includes the presentation and discussion for the ACM bridge capacity rating based on the stress modification coefficients obtained from the test results. The test result indicates that the ACM bridge superstructure has no structural problems and is structurally performing well in-service as expected. The results may provide a baseline data for future field ACM bridge capacity rating assessments and also serve as part of a long-term performance of ACM bridge superstructure.

A finite element simulation study was performed to gain an insight about the crash test details. Accuracy of the simulation was verified using qualitative and quantitative comparisons. Based on in-depth examination of crash simulation recordings, energy distributions occurred in the breakaway type posts against the car are determined. The numerical results for various parameters are verified by comparing different material models with internal energy distribution occurred in the breakaway type posts from the crash simulation.

Effects of crack on static behavior in steel box girder were investigated to identify the possibility of crack detection and location using conventionally measured static data including deflection and inclination. Finite element analysis with finely meshed 3-D models and experiments were performed for steel box girder with crack. To eliminate the variation according to load magnitude, compliance technique was applied to analysis of the result. Through this study, the quantitative relationship between crack size and structural responses of deflection and inclination were obtained as a form of relation-curve. This relation-curve can be utilized to evaluate crack size in the steel box girder bridge. The results also demonstrated that the location of crack can be estimated by static measurement.

Recently, there have been many theoretical and experimental studies on advanced composite materials (ACM) bridges in various fields over the world. Compared with a reinforced concrete or steel bridge, an ACM bridge has more advantages in strength, stiffness, transportation, and installation. Many demonstration projects have been carried out in the U.S, and Europe. They are also being developed and tested in South Korea. In South Korea the first of all ACM short-span bridge superstructures was installed on a public highway system in May 2002. Since these composite materials are new to bridge applications, reliable data is not available for their in-service performance. This paper describes in-service performance assessment of all ACM bridge superstructures. To investiga te its in-service performance, field load testing and visual inspections were conducted under an actual service environment. The p aper includes the presentation and discussion for ACM Bridge capacity rating based on the stress modification coefficients obtained from the test results. The test result indicates that the ACM bridge superstructure has no structural problems and is structurally performing well in-service as expected. The results may provide a baseline data for future field ACM bridge capacity rating assessments and also serve as part of a long-term performance of ACM bridge superstructure.

Background: A quantitative model was developed and applied for analyzing the correlation between hydrogen-induced corrosion cracking in both main cable wires and degraded stiffening of the girders of a cable suspension bridge, considering maintenance effects across time and space. Method: Bayesian inference is applied for predicting the correlations among the wires in the main cables owed to hydrogen-induced cracking (HIC) in the cable wires of a steel bridge, by using the improved hierarchical Bayesian models proposed here. Results: The simulated risk prediction under decreased strength of cable wires, due to the corrosion cracking, yields posterior distributions based on prior distributions and likelihoods. The Bayesian inference model can be applied to the design and maintenance of highly corroded and correlated components Data are updated through analyzed information from previous crack steps. A numerical example including not only reliability indices but also probabilities of failure for cable wires, damaged by HIC, is then presented. Compared with a conventional linear prediction model, the one herein developed provides highly improved convergence and closeness to the analyzed data. Conclusion: The proposed model can be used as a diagnostic or prognostic prediction tool for the performance of corroded bridge cable wires with crack propagation, allowing the development of maintenance plans for mechanical components and the overall structural system.

In this study, a cochlea-inspired artificial filter bank (CAFB) was developed to efficiently obtain dynamic response of a structure, and a dynamic response measurement of a cable-stayed bridge model was also carried out to evaluate the performance of the developed CAFB. The developed CAFB used a band-pass filter optimizing algorithm (BOA) and peakpicking algorithm (PPA) to select and compress dynamic response signal containing the modal information which was significant enough. The CAFB was then optimized about the El-Centro earthquake wave which was often used in the construction research, and the software implementation of CAFB was finally embedded in the unified structural management system (USMS). For the evaluation of the developed CAFB, a real time dynamic response experiment was performed on a cable-stayed bridge model, and the response of the cable-stayed bridge model was measured using both the traditional wired system and the developed CAFB-based USMS. The experiment results showed that the compressed dynamic response acquired by the CAFB-based USMS matched significantly with that of the traditional wired system while still carrying sufficient modal information of the cable-stayed bridge.

This paper presents a simplified analysis method using the elastic equivalent modelling not using the global finite element modelling of deck for the basic design GFRP composites deck with cellular tubes or sandwich structural type. In order to verify the validation of the simplified method ANSYS software package is used and compared the results analyzed on the global finite element modelling and the elastic equivalent modelling. And the laboratory testing by 4-point bending is conducted to compare the results based on the simplified analysis method proposed in this paper. The comparison of the results based on the analysis and the testing are discussed. It is found that the presented simplified analysis is applicable to the use in the basic design GFRP composite deck.