비선형 폭발해석에 의한 콘크리트 구조물의 손상도 평가

허택녕,김성윤 대한토목학회 2017 대한토목학회논문집 Vol.37 No.1

In general, the large loads which are applied from explosion, impact, earthquake and wind at a short time caused the materials ofstructures to large deformations, rotations and strains locally. If such phenomena will be analyzed, hydrocodes which can be consideredfluid-structure interaction under computational continuum mechanics are inevitably needed. Also, the explosion mechanism is so complicated, it is reasonable that the behaviors of structure are predicted through explosion analyses and experiment at the same time. But, unfortunately, it is true that explosion experiments are limited to huge cost, large experiment facilities and safety problems. Therefore, in this study, it is shown that the results of explosion analyses using the AUTODYN are agreed with those of existing explosion experiments for reinforced concrete slabs within reasonable error limits. And the explosion damage of the same reinforced concrete slab are assessed for quite different reinforcement arrangement spacings, concrete cover depths, and vertical reinforcements. From the explosion analyses, it is known that the more the ratio of slab thickness to reinforcement arrangement spacing is increased, and small-diameter reinforcements are used than large-diameter reinforcements on the same reinforcement ratio, and vertical reinforcements are used, the more the anti-knock capacities are improved. 일반적으로 구조물에 폭발, 충돌, 지진과 바람 등과 같이 짧은 시간에 큰 하중이 작용하게 되면 구조물은 국부적으로 재료의 대변형(large deformation), 대회전(large rotation), 대변형률(large strain)등이 발생하게 된다. 이와 같은 현상을 해석하려면 전산연속체 역학에 기초하여 유체-구조물 상호작용 등을 고려할 수 있는 하이드로코드(Hydrocode)의 도움이 필요하다. 또한, 폭발로 인해 발생되는 순간 동역학적인 폭발 메커니즘은 매우 복잡하기 때문에 폭발실험을 병행하여 거동을 예측하는 것이 합리적인 방법이지만 막대한 비용과 시설이 요구되므로 한계가 있는 것도 사실이다. 따라서 본 논문에서는 하이드로코드인 AUTODYN을 사용하여 폭발해석한 결과를 기수행된 철근콘크리트 슬래브의 폭발실험 결과와 비교하여 폭발해석 방법의 타당성을 검토하였고, 동일한 폭발해석 모형에 대하여 철근 배근간격, 피복두께의 변화 및 수직철근 유무에 따른 폭발 손상도를 비교검토하였다. 검토한 결과, 철근의 배근간격에 대한 철근콘크리트 슬래브 두께의 비가 커질수록, 지름이 큰 철근보다 지름이 작은 철근을 많이 사용할수록, 마지막으로 수직철근을 배근할수록 콘크리트 구조물의 내폭성능이 향상됨을 알 수 있었다.

평면 원호아치의 좌굴해석을 위한 동적 비선형해석 프로그램의 개발

허택녕,오순택 한국전산구조공학회 1994 전산구조공학 Vol.7 No.1

본 논문은 형상의 비선형성을 고려한 큰 동하중을 받는 낮은 원호아치의 동적해석에 관한 연구이다. 따라서 낮은 원호아치를 대상으로 동적 비선형 해석을 수행하고 임계좌굴하중을 구할 수 있는 컴퓨터 프로그램을 개발하는데 주안점을 둔다. 형상의 비선형성은 Lagrangian 운동좌표를 고려하여 해석하였으며 비선형 동적 운동방정식을 풀기 위하여 유한요소법을 사용하였다. 개발된 프로그램을 사용하여 만재 방사형 등분포하중을 받는 원호아치를 해석하고, 그 결과를 다른 연구결과와 비교하여 검증하였다. 또한 여러가지의 형상의 아치에 대한 좌굴 해석을 실시하여 임계좌굴하중을 구하였으며 기존의 연구와 비교하여 정확성을 확인하였다. 모형해석을 통해서 큰 동하중을 받는 원호아치는 기하학적 비선형 거동을 고려하여 해석되어야 하며 아치가 낮아질수록 좌굴발생 가능성이 높아짐을 알 수 있다. This paper summarizes a dynamic analysis of the shallow circular arches under dynamic loading, considering the geometric nonlinearity. The major emphasis is placed on the development of computer program, which is utilized for the analysis of the nonlinear dynamic behavior and for the evaluation of the critical buckling loads of the shallow circular arches. Geometric nonlinearity is modeled using Lagrangian description of the motion and a finite element analysis procedure is used to solve the dynamic equation of motion. A circular arch subject to normal step load is analyzed and the results are compared with those from other researches to verify the developed program. The critical buckling loads of arches are estimated using the non-dimensional time, load and shape parameters and the results are also compared with those from the linear analysis. It is found that geometric nonlinearity plays and important role in the analysis of shallow arches and the probability of buckling failure is getting higher as arches become shallower.

도로교의 충격계수산정을 위한 이동 군하중 모형의 개발

허택녕,권순동,윤태호 국립7개대학공동논문집간행위원회 2003 공업기술연구 Vol.3 No.-

Recently there has been significant damage in the road bridges due to large and overloaded trucks. Especially because moving truck loads have dynamic characteristics, the dynamic stresses that are larger than static stresses are occurred in road bridges. Therefore it is necessary to develop dynamic truck model to evaluate the dynamic response of road bridges The objectives of this study are to develop truck model which can provide a better estimation of the dynamic responses of road bridges during the passage of design truck. The bridge type is simply supported bridge and the spans of bridges are 10m, 20m, 30m, 40m, and 50m. The impact factors of bridges with different speed under various conditions such as truck speed, span length, running types are evaluated by the developed procedure. Also, impact factors of road bridge computed from the developed procedure are compared with the existing Based on the results of this study, it is found that the developed dynamic model of design truck is appropriate to obtain the dynamic response of rad bridges. It is concluded that the dynamic effects such as truck speed, road roughness, starting and braking conditions of truck are reasonably considered in the dynamic analysis of bridges.

기계기초 매스콘크리트의 온도제어를 위한 시공사례

허택녕,이제방,손영현 한국콘크리트학회 1996 콘크리트학회지 Vol.8 No.2

사장교의 내풍해석을 통한 인명보호 구조물의 내하능력평가

허택녕 한국산업융합학회 2022 한국산업융합학회 논문집 Vol.25 No.4

In the 2000s, a lot of cable-type grand bridges are being built in consideration of economic aspects such as the reduction of logistics costs and the distribution of traffic volume due to rapid economic development. In addition, because the recently installed grand bridges are designed in an aesthetic form that matches the surrounding environment as well as the original function of the road bridge, and serves as a milestone in an area and is used as an excellent tourism resource, attracting many vehicles and people, there is an urgent need for a safety structure that can ensure the safety of not only vehicles but also people. In order to make cable-stayed bridge safe on wind for additional five safety structures, main girder models with and without safety structures for wind-tunnel experiments was made, and wind tunnel experiments was carried out to measure aerodynamic force coefficients. Also, wind-resistant analyses of 3D cable-stayed bridge were performed on the basis of wind-tunnel experiment results. From the wind tunnel experiments for the aerodynamic force coefficients of main girder with five safety structures and the wind resistant analyses of cable-stayed bridge without safety structure and with safety structure, it was concluded that the best form of wind-resistant safety was shown in the order of mesh, standard, bracing, hollow, and closed type. And wind-resistant safety of cable-stayed bridge with hollow and closed type on design wind speed 68.0m/sec was not secured. Finally, as five safety structures are installed, maximum rate of stress increments was shown in the order of steel main beam, steel floor beam, concrete floor beam and cables.

기계기초 매스콘크리트의 균열제어를 위한 온도관리기법의 개발

허택녕,손영현,이석홍 한국구조물진단유지관리공학회 2001 한국구조물진단유지관리공학회 논문집 Vol.5 No.4

무한 및 반무한 경계를 가진 평면문제의 개별요소-경계요소 조합해석

허택녕,김문겸,황학주 대한토목학회 1992 대한토목학회 학술발표회 논문집 Vol.1992 No.1

개별요소와 경계요소 조합에 의한 무한 및 반무한 영역문제의 해석

허택녕,김문겸,황학주,Huh, Taik Nyung,Kim, Moon Kyum,Hwang, Hak Joo 대한토목학회 1992 대한토목학회논문집 Vol.12 No.4

무한 및 반무한 경계조건을 가진 지하구조체에 대하여 개별요소법과 경계요소법을 조합하여 해석하는 방법을 제안하였다. 일반적으로 무한 또는 반무한 경계를 가지는 지하구조체의 문제에 있어서 응력집중부, 굴착면 혹은 불연속면이 발달되어 있는 영역을 개별요소로 모형화하고 무한 영역은 선형경계요소를 사용하여 모형화 하였다. 여기서, 선형경계요소에 의한 무한 및 반무한 영역의 고려는 Kelvin의 무한 영역, Melan의 반무한 영역에서의 해로 구성하였다. 효율적인 해석을 위하여 선형 경계요소법, 개별요소법, 개별요소와 경계요소 조합방법 등이 독립적으로 연구되었다. 연구된 각 방법에 근거하여 조합된 해석방법을 무한 및 반무한 문제에 적용하여 기존의 이론해석치와 비교하여 검증을 실시하고, 지하구조체에 적용하여 조합해석방법의 실용성을 보였다. 따라서, 지하구조체에 조합방법을 사용하면 지반의 불연속 조건과 경계조건에 따르는 구조물의 거동을 합리적으로 예측할 수 있으며, 개별요소와 경계요소의 장점을 살려 보다 합리적인 해석의 수행이 가능할 것으로 판단된다. Numerical modeling of problems having infinite and semi-infinite boundaries is studied using a coupled method of distinct elements and boundary elements. The regions which are restricted on stress concentration area of loading points, excavation surface, and geometric discontinuity in the underground structures, are modeled using distinct elements, while the infinite and semi-infinite regions are modeled using linear boundary elements. Linear boundary elements for infinite and semi-infinite region are respectively composed using the Kelvin's and the Melan's solution, respectively. For the completeness, the boundary element method, the distinct element, and the coupled method of distinct elements and boundary elements are studied independently. The coupled method is verified and is applied to underground structures of infinite and semi-infinite regions. Through the comparison of the results, it is concluded that the coupled analysis may be used for discontinuous underground structures in the effective manner.

효율적인 관리체계개선을 위한 교량관리 시스템의 개발(Ⅱ) : 교량의 신설 및 보수 우선순위 결정

허택녕,성재진 국립7개대학공동논문집간행위원회 2004 공업기술연구 Vol.4 No.-

The majority of brides in our infrastructure were constructed in the years of the 1960's to 1970's when the growth of our transportation networks was less of an expansion and more of an explosion. These structures have performed so well, they have been so durable, that most of us, engineers or not, tent to take the bridge for granted. But the life of these structures will reach the stage when they will no longer be so durable, and we will no longer be able to take the bridge for granted. It is though that the rehabilitation and maintenance of them are needed. But the priority determination of rehabilitation and replacement of old bridge and the allocation of the limited funds are no small task. In this study, the bridge maintenance system(BMS) which can allocate the fund for bridge's rehabilitation and replacement are developed with of Visual C++6. Criteria for priority determination of rehabilitation and replacement of old bridges are implemented in the BMS based on literatures and reports. Also, in the BMS, the database which can maintains a record of the elements comprising a bridge and its relative condition and a description of the work that has been done to date on a structures as well as the work that is presently scheduled to be done is built. By the BMS, it is showed that the priority determination of old local bridge in Kyung-Nam area for their rehabilitation and replacement are maded, and the developed BMS is useful in the management of local bridges in Kyung-Nam area.

평면 원호아치의 좌굴해석을 위한 동적 비선형해석 프로그램의 개발

허택녕,오순택 한국전산구조공학회 1994 한국전산구조공학회논문집 Vol.7 No.1

본 논문은 형상의 비선형성을 고려한 큰 동하중을 받는 낮은 원호아치의 동적해석에 관한 연구이다. 따라서 낮은 원호아치를 대상으로 동적 비선형 해석을 수행하고 임계좌굴하중을 구할 수 있는 컴퓨터 프로그램을 개발하는데 주안점을 둔다. 형상의 비선형성은 Lagrangian 운동좌표를 고려하여 해석하였으며 비선형 동적 운동방정식을 풀기 위하여 유한요소법을 사용하였다. 개발된 프로그램을 사용하여 만재 방사형 등분포하중을 받는 원호아치를 해석하고, 그 결과를 다른 연구결과와 비교하여 검증하였다. 또한 여러가지의 형상의 아치에 대한 좌굴 해석을 실시하여 임계좌굴하중을 구하였으며 기존의 연구와 비교하여 정확성을 확인하였다. 모형해석을 통해서 큰 동하중을 받는 원호아치는 기하학적 비선형 거동을 고려하여 해석되어야 하며 아치가 낮아질수록 좌굴발생 가능성이 높아짐을 알 수 있다. This paper summarizes a dynamic analysis of the shallow circular arches under dynamic loading, considering the geometric nonlinearity. The major emphasis is placed on the development of computer program, which is utilized for the analysis of the nonlinear dynamic behavior and for the evaluation of the critical buckling loads of the shallow circular arches. Geometric nonlinearity is modeled using Lagrangian description of the motion and a finite element analysis procedure is used to solve the dynamic equation of motion. A circular arch subject to normal step load is analyzed and the results are compared with those from other researches to verify the developed program. The critical buckling loads of arches are estimated using the non-dimensional time, load and shape parameters and the results are also compared with those from the linear analysis. It is found that geometric nonlinearity plays and important role in the analysis of shallow arches and the probability of buckling failure is getting higher as arches become shallower.