• Structural Engineering and Mechanics
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• 제54권4호
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• pp.793-807
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• 2015

Constructing the influence lines of forces of statically indeterminate structures is a traditional issue in structural engineering and mechanics. However, the existing kinematic method for establishing these force influence lines is an indirect or mixed approach by combining the force method with the theorem of reciprocal displacements, which is yet inconsistent with the kinematic method for statically determinate structure. This paper proposes the direct kinematic method in conjunction with the load-displacement differential relation for exactly constructing influence lines of reaction and internal forces of indeterminate structures. Firstly, through applying the principle of virtual displacement, the formula for influence lines of reaction and internal forces of indeterminate structure via direct kinematic method is derived based on the released structure. Then, a computational approach with a clear concept and unified procedure as well as wide applicability based on the load-displacement differential relation of beam is suggested to achieve conveniently the closed-form expression of force influence lines, and exactly draw them. Finally, three representative examples for constructing force influence lines of statically indeterminate beams and frame illustrate the superiority of the proposed method.

• Architectural research
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• 제3권1호
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• pp.71-80
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• 2001

It is quite difficult to calculate the collapse probability of a system such as statically indeterminate structure that has many possible modes or paths to complete failure and the problem has remained essentially unsolved. A structure is synthesized by several components or elements and its capacity to resist the given loads is a function of the capacity of the individual element. Thus it is reasonable to assess the probability of failure of the system based upon those of its elements. This paper proposes an efficient technique to directly assess the reliability of a complex structural system from the reliabilities of its components or elements. The theory for the calculation of the probability of a structural system is presented. The target requirements of the method and the fundamental assumptions governing the method are clearly stated. A portal frame and two trusses are selected to demonstrate the efficiency of the method by comparing the results obtained from the proposed method to those from the existing methods in the literature.

• 한국농공학회논문집
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• 제57권6호
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• pp.59-68
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• 2015

Traditional structure analysis method is based on numerical matrix analysis to use the geometries consisting of the structure. The characteristics require a lot of computer memories and computational time. To avoid these weaknesses, new approach to analyze truss structure was suggested by adopting topological load redistribution method. The axial forces to be not structurely analyzed yet against outside loads were redistributed by using nodal equation of equilibrium randomly at each node without constructing global matrix. However, this method could not calculate the axial forces if structure is statically indeterminate due to degree of many indeterminacies. Therefore, to apply the method suggested in this research, all redundancies of truss structure were replaced by unit loads. Each unit load could make the deformation of a whole structure, and a superposition method was finally adopted to solve the simultaneous equations. The axial forces and deflections agreed with the result of commercial software within the relative error of 1 %, whereas in the case that the axial forces are relatively very smaller than others, the relative errors were increased to 2 %. However, as the values were small enough not to be considered, it was practically useful as a structural analysis model. This model will be used for structural analysis of truss type of large structure such as agricultural farming facility.

• 한국산업융합학회 논문집
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• 제10권3호
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• pp.149-155
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• 2007

Damage assessment and Damage index for RC members failed in flexure was investigated by using the nonlinear finite element analysis, included with nonlocal constitutive law, which is analyzed for the localization of the failure on the post-peak region. In the nonlcal constitutive law, The local strains obtained at gauss points were averaged over a particular length, i.e. characteristic length and it was used to evaluate the damage of RC column member. As the analysis results, The value of nonlocal strain shows less mesh sensibility. In the damage assessment, It was confirmed that evaluations of damage of RC member were able to use nonlocal compressive strain on a cover concrete and a core concrete of the member. Moreover it was confirmed that damage process for the statically indeterminate structure was able to evaluate the damage context of the component members of the structure.

• 한국안전학회지
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• 제18권1호
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• pp.94-100
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• 2003

Generally, cable-stayed bridges are both statically indeterminate structure with a high degree of redundancy and flexible structure. So it is very important to ensure precision control during both fabrication and construction. In precision control of cable-stayed bridges, precision control under multi-objective programming method is needed, because precision control problem of cable-stayed bridges is a multi-objective programming problem in which many objective functions are regard as variables. In previous studies, it was regarded as a single-objective problem, so it had many problems in respect of usefulness and rationalness. In this study, precision control under multi-objective programming method is proposed considering economy, efficiency, and safety at best in precision control of cable-stayed bridges. Precision control problem of cable-stayed bridges is formulated with satisfying trade-off method which is a kind of multi-objective programming method, then it is optimized with min-max method. A computer program is presented including above process.

• Steel and Composite Structures
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• 제45권5호
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• pp.715-728
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• 2022

Closed steel supports of different shapes are used in mining and underground constructions. The supports are prefabricated from rolled, usually robust, steel profiles. The load carrying capacity of a support is considerably influenced by the active loading and passive forces. The passive forces are induced by interactions between the support and the surrounding rock mass. The analysis herein comprises three parts: The first part consists of structural geometry processing. The second part involves finding the numerical solution of a statically indeterminate structure for a specified load. The third part is calculation of the load carrying capacity and the components of internal forces and deformations. For this, the force method and numerical integration are used. The Winkler model is applied when the support interacts with the surrounding environment. The load carrying capacity is limited by the slip resistance of the connected parts and it is limited by reaching the ultimate state of the profile. This paper serves as a comprehensive reference for the determination of the load carrying capacity of closed steel supports and includes stepwise derivations of the governing formulas.

• Smart Structures and Systems
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• 제4권5호
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• pp.605-628
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• 2008

In bridge structures, damage may induce an additional deflection which may naturally contain essential information about the damage. However, inverse mapping from the damage-induced deflection to the actual damage location and severity is generally complex, particularly for statically indeterminate systems. In this paper, a new load concept, called the positive-bending-inspection-load (PBIL) is proposed to construct a simple inverse mapping from the damage-induced deflection to the actual damage location. A PBIL for an inspection region is defined as a load or a system of loads which guarantees the bending moment to be positive in the inspection region. From the theoretical investigations, it was proven that the damage-induced chord-wise deflection (DI-CD) has the maximum value with the abrupt change in its slope at the damage location under a PBIL. Hence, a novel damage localization method is proposed based on the DI-CD under a PBIL. The procedure may be summarized as: (1) identification of the modal flexibility matrices from acceleration measurements, (2) design for a PBIL for an inspection region of interest in a structure, (3) calculation of the chord-wise deflections for the PBIL using the modal flexibility matrices, and (4) damage localization by finding the location with the maximum DI-CD with the abrupt change in its slope within the inspection region. Procedures from (2)-(4) can be repeated for several inspection regions to cover the whole structure complementarily. Numerical verification studies were carried out on a simply supported beam and a three-span continuous beam model. Experimental verification study was also carried out on a two-span continuous beam structure with a steel box-girder. It was found that the proposed method can identify the damage existence and damage location for small damage cases with narrow cuts at the bottom flange.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.301-304
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• 2008

선시공 조립식 거푸집 공법을 사용한 계단의 접합부는 힌지로 처리하여 구조설계를 하는 것이 일반적인 방법이다. 계단참과 경사계단이 만나는 접합부를 힌지로 간주하게 되면 접합부의 모멘트 성능이 전혀 없으므로 계단부분의 휨모멘트가 증가하게 되어 철근 배근량이 늘어난다. 또한 진동 및 피로하중에 의한 접합부 손실이 증가하여 사용성이 저하된다. 그럼에도 불구하고 계단 접합부를 핀접합하는 이유는 현장에서의 시공성이 용이하기 때문이다. 최근들어 시공성을 고려하면서 접합부의 휨성능을 향상시킬 수 있는 반강접에 대한 상세가 제시되고 있으나, 이러한 상세를 구조설계에 전혀 반영하지는 못하고 있다. 따라서 본 연구에서는 계단의 반강접 접합부를 설계에 반영할 수 있는 방법을 제시하고자 하였다. 강접합, 반강접합, 핀접합으로 설계된 계단 접합부에 대해 모멘트 성능을 비교하고, 부정정 구조물인 계단 코아부분의 비선형 해석을 통해 항복 이후의 변화를 비교하였다. 연구결과 반강접합 성능을 반영하기 위한 휨강성계수를 도입하였고, 이를 적용한 비선형 해석결과 핀접합보다는 안정적인 결과를 보였고, 강접합에 비해 연성이 뛰어나 내진 및 진동에 대해 유리한 시스템으로 판단된다.