• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 추계 학술논문 발표대회
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• pp.26-27
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• 2014

Study on high temperature properties of concrete and internal force estimation of structural member subjected to high temperature mainly applied high temperature strength model based on experimental results with concrete under 40MPa. However, it is reported that degradation of internal force at high temperature and spalling of ultra high strength concrete are higher than that of normal strength concrete. Therefore, this study attempts to propose compressive strength degradation model which is suitable to ultra high strength concrete comparing to existing model by evaluating high temperature properties of ultra high strength concrete.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.1165-1170
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• 2005

In order to perform the spatial buckling analysis of the curved beam element with nonsymmetric thin-walled cross section, exact static stiffness matrices are evaluated using equilibrium equations and force-deformation relations. Contrary to evaluation procedures of dynamic stiffness matrices, 14 displacement parameters are introduced when transforming the four order simultaneous differential equations to the first order differential equations and 2 displacement parameters among these displacements are integrated in advance. Thus non-homogeneous simultaneous differential equations are obtained with respect to the remaining 8 displacement parameters. For general solution of these equations, the method of undetermined parameters is applied and a generalized linear eigenvalue problem and a system of linear algebraic equations with complex matrices are solved with respect to 12 displacement parameters. Resultantly displacement functions are exactly derived and exact static stiffness matrices are determined using member force-displacement relations. The buckling loads are evaluated and compared with analytic solutions or results by ABAQUS's shell element.

• 한국안전학회지
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• 제23권6호
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• pp.115-121
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• 2008

By bond mechanism between the prestressing strand and the concrete surrounding it, the effective force of prestressing must be transferred to the concrete entirely. The distance required to transfer the effective force of prestressing is called the transfer length, and the development length is the bond length required to anchor the strand as it resists external loads on the member. Transfer length was determined from the concrete strain profile at the level of the strands at transfer and development length was determined from various external loading lengths and compared with current code equation. Through the test results, bond failure is predicted based on the distress caused by cracks when they propagate within the transfer zone of prestressing strand. The current code equation was found to be conservative in comparison with the measured value.

• 한국소음진동공학회논문집
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• 제12권12호
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• pp.956-963
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• 2002

In a recent construction industry, cable supported structures such as a cable-stayed bridge or space stadium have been increasingly constructed according to rapidly upgrade their related technologies. Generally stay cables as a critical member need to be rearranged for being satisfied with design tension forces. In this purpose, a vibration method has been applied to estimate the tension forces exerted on existing stay cables. In this study, cable vibration tests were tarried out to evaluate the cable tension forces comparing with theoretical and practical formulas. Using the measured frequencies obtained from free vibration and Impulsive tests, an accuracy of the estimated tension forces is confirmed according to use the first single mode only or higher multiple modes.

• Steel and Composite Structures
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• 제17권1호
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• pp.47-67
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• 2014

Due to thermal expansion, the structural behaviour of beams in steel structures subjected to temperature increase will be affected. This may result in the failure of the structural members or connection due to extra internal force in the beam induced by the thermal increase. A method to release some of the thermally generated internal force in the members is to allow for some movements at the end supports of the member. This can be achieved by making the plane of the end-plate of the connection slanted instead of vertical as in conventional design. The present paper discusses the mechanical behaviour of beams with bolted slant end-plate connection under symmetrical gravity loads, subjected to temperature increase. Analyses have been carried out to investigate the reduction in internal force with various angles of slanting, friction factor at the surface of the connection, and allowable temperature increase in the beam. The main conclusion is that higher thermal increase is tolerable when slanting connection is used, which means the risk of failure of structures can be reduced.

• Steel and Composite Structures
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• 제16권2호
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• pp.117-133
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• 2014

Natural vibration of truss cable structures is analyzed based upon the general structural analysis software ANSYS, energy variational method and Rayleigh method, the calculated results of three methods are compared, from which the characteristics of free-vibration are obtained. Moreover, vertical seismic response analysis of truss cable structures is carried out via time-history method. Introducing three natural earthquake waves calculated the results including time-history curve of vertical maximal displacement, time-history curve of maximal internal force. Variation curve of maximal displacement of node along span, and variation curve of maximal internal force of member along span are presented. The results show the formulas of frequencies for truss cable structures obtained by energy variational method are of high accuracy. Furthermore, the maximal displacement and the maximal internal force occur near the 1/5 span point. These provide convenient and simple design method for practical engineering.

• Earthquakes and Structures
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• 제8권5호
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• pp.1147-1170
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• 2015

In this paper, the behavior of underground strutted retaining structure under seismic condition in non-liquefiable dry cohesionless soil is analyzed numerically. The numerical model is validated against the published results obtained from a study on embedded cantilever retaining wall under seismic condition. The validated model is used to investigate the difference between the static and seismic response of the structure in terms of four design parameters, e.g., support member or strut force, wall moment, lateral wall deflection and ground surface displacement. It is found that among the different design parameters, the one which is mostly affected by the earthquake force is wall deflection and the least affected is the strut force. To get the best possible results under seismic condition, the embedment depth of the wall and thickness of the wall can be chosen as around 100% and 6% of the depth of final excavation level, respectively. The stiffness of the strut may also be chosen as $5{\times}105kN/m/m$ to achieve best possible performance under seismic condition.

• 한국구조물진단유지관리공학회 논문집
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• 제7권2호
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• pp.247-261
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• 2003

The technique of posttensioning has been used successfully to improve the performance of existing concrete structures. However, very few applications of this technique can be found in steel structures. Posttensioning by means of high strength cable or bar can be used to effectively increase the working load capacity of Truss Bridges. The benefits of posttensioning trusses can be achieved in strengthening of existing structures as well as in the design of new structures. In this paper, the elastic behavior of posttensioned trusses with straight and draped tendon profiles is examined. For the analysis of posttensioned trusses in the elastic range of behavior, two methods are presented, namely, the flexibility method and the mixed-method, i.e., a combination of the stiffness and flexibility methods. Using the presented methods, the effects of design variables such as the tendon profile, truss type, prestress force, and tendon eccentricity on the working load and deflection of trusses are studied. The results show that the allowable load of truss increases proportionally with increase in prestress force and eccentricity. Posttesioning enlarges the elastic range, increases redundancy, and reduces deflection and member stresses. Thus, the remaining life of a truss bridge can be increased relatively inexpensively.

• 기술발표회
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• 통권2006호
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• pp.342-355
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• 2006

The Tunnel portal is designed on temporary support system which is composed by 28m height H-Pile method and Ground Anchor method. The tunnel has excavated about 30m from the portal, but some deformation is found on the surface ground just above the tunnel face. It was investigated very carefully to find out the causes of deformation. By the observation and study, two main causes of deformation are found out. The one is earth pressure increase compared with classical earth pressure theory. That was due to the direction of ground rock mass's discontinuities. It causes the increase of earth pressure that are activated by the direction of discontinuity. The other one is that present design method neglect the transferred force by removal of temporary support members and ground anchor within the tunnel contour line as the tunnel excavation proceeds As the result of removals of the member and anchor, some force transferred from removed systems to remaining supporting systems. In designing the portal support systems, lt must be considered the discontiunity of ground mass and the transfered force due to excation.

• 국제강구조저널
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• 제18권5호
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• pp.1654-1665
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• 2018

In an irregular prism tensegrity, the number of force equilibrium equations is less than the number of unknown parameters of nodal coordinates and member force ratios. As a result, the form-finding process normally becomes nonlinear with additional conditions or needs to be carried out with the use of iterative procedures. For cases of irregular prism tensegrity which involves large number of members, it was found that previously proposed methods of form-finding are not practical. Moreover, there is a need for a form-finding approach which is able to cater to different requirements on final configuration. In this paper, the length relation condition is introduced to be used in combination with the force equilibrium equation. With the combined use of length relation and equilibrium conditions, a linear form-finding approach for irregular prism tensegrity was successfully formulated and developed. An easy-to-use interactive form-finding tool has been developed which can be used for form-finding of irregular prism tensegrities with large number of elements as well as under diverse specific requirements on their configurations.