開口形 隔壁을 갖는 상자형에 대한 實驗的 硏究

鄭熺孝,蔡奉佑 경상대학교 생산기술연구소 2000 生産技術硏究所論文集 Vol.16 No.-

Box Girder is the popular bridge type for long span or curved bridges because of its structural advantage on torsional stiffness. It has been the practice of designers to provide diaphragms in these boxes but often the position and strength of the diaphragms has been determined arbitrarily rather than on any well founded basis. The presence of diaphragms in the box introduces some additional dead load, but this effect is not likely to be a serious factor in the design. The analysis on this thesis expanded that analogy for BEF and was able to calculate warping stresses, distortion stressesand displacement of each point according to the position of diaphragms. And this method was verified accuracy of result as compared with the experimental result. The experimental results of the model box girder proved the effective value of the analysis on this thesis, and behavior of box girders that was measured by eccentric load showed up aspects of displacements, strains of each point according to the load size.

影響線으로 考廬한 偏心荷重을 받는 箱子형의 隔璧間隔에 관한 硏究

鄭熺孝 慶尙大學校生産技術硏究所 1992 生産技術硏究所論文集 Vol.8 No.-

The box girder is suitable for torsional members because of its high torsional stiffness. The diaphragms are largely used for stiffners of box girder under torsional load, and the distance of diaphragms influences much to magnitude of the warping stress and distortional moment. In this study the influence lines were showed for the warping stresses and distortional moments of box girder under eccentric load. In the influence lines it was considered that diaphragms reduce much of distortional moment but small quantity of warping stress for box girder. Therefore, the diaphragm is a suitable stiffner for distortional deformation.

鋼箱子桁 壓縮플랜지의 補强재에 대한 硏究

鄭熺孝,金洪俊 경상대학교 생산기술연구소 2002 工學硏究院論文集 Vol.2 No.-

The sufficient safe factor for buckling must be obtained by pertinent stiffness in steel box girder. In this paper, the critical stress of stiffened plate with longitudinal ribs is estimated by the classic approximate method of analysis, integration of the two Karman's differential equtions and the energy method which put strain energy of bending equals the work done during buckling by the compressive force. Especially, according to change of thickness of compressional flange and area of stiffening ribs, the critical load of stiffened plate was analytically investigated and these results of theory and experiment were compared with analysis program, SAP2000

상자형의 전단지연 현상과 유효폭에 관한 연구

鄭熺孝,金洪俊,李承烈,朴峻熙 경상대학교 생산기술연구소 2002 工學硏究院論文集 Vol.2 No.-

In a box girder, it is an accepted practice in structural engineering to represent the effect of 'shear lag' by adopting an 'effective width' concept. The actual width of flange plate (b) is replaced by a reduced width (b_e) over which the longitudinal stresses may be considered uniformly distributed and the application of the elementary theory of bending to the transformed girder cross section gives the correct value of maximum longitudinal stress (σ_max). This paper provides how to determine the magnitude of 'shear lag' and 'effective width ratio' in case of orthotropic box girder which is simply supported, symmetrically loaded only.

경사격벽을 가진 상자형의 해석

鄭熺孝,安光列,李承烈,朴泳珏 경상대학교 생산기술연구소 2001 工學硏究院論文集 Vol.1 No.-

It is necessary at present to adapt the design of bridge structures to transport requirement and the restrictive conditions of environment. City bridges, bridges spanning railway lines and stations, skew crossing of streets and highways, etc., require an irregular arrangement of internal supports. If diaphragms are applied, they are usually skew. It is advantageous to use a box girder as the basic component for a bridge of this kind because the box girder provides a high torsional stiffness, a favorable stresses, and due to the small shear stresses arising due to torsion. This paper deal with the analysis of the function of irregularly situated support and skew diaphragms and with their influence on the resulting state of stress of the box girder. The solution is shown for a box girder under eccentric load and according to the length of skew diaphragms.

矩形 鋼版의 後挫屈 擧動에 對한 硏究

鄭熺孝,金洪俊,禹宗昊 경상대학교 생산기술연구소 2003 工學硏究院論文集 Vol.19 No.-

A uniformly compressed plate start to deflect at the critical load estimated by linear buckling theory and by means of it's rigidity increase resist axial load over critical load when the plate go into finite transverse deflection. As this characteristic of plate is pronounced of postbuckling and having very significant meanings in thin walled structures, so the postbuckling strength of inelastic, nonlinear behavior of plate must to be considered in the design and strength evaluation of steel structures constituted by thin plates. In this paper, to investigate change aspect and increase of longitudinal stress after buckling of rectangular plates, aspect ratio (a/b) and deflection of steel plates are selected to variables.

3次元 解析에 의한 R.C 라멘교의 龜裂檢討에 대한 硏究

鄭熺孝,金羽中,李承烈,李景和,金庚映 경상대학교 생산기술연구소 2003 工學硏究院論文集 Vol.19 No.-

In this study, longitudinal crack at reinforced concrete rahmen bridges occurred when reinforced concrete rahmen bridges wall back filling beginning and working vehicles passed over reinforced concrete rahmen bridges slab. Therefore, crack reason is estimated the early-aged concrete hydration heat and service load. Occumng longitudinal crack pattern in lower slab hunch is same as crack by concrete hydration heat. Theoretically, longitudinal crack don t occur using the established(1996, Korea Highway Corporation) load factor and load combination but longitudinal crack occur using new-proposing(2002, K.H.C) load factor and load combination. Reinforced concrete rahmen bridges by 3-dimension analysis is shown that longitudinal crack reason under service load for three reinforced concrete rahmen bridges. It is found that transverse bending moment under service loads become reason of longitudinal crack and the distribution bars under the service loads become the main reinforcing bar in 3-dimension analysis. If hunch s distribution bar spacing is same as slab center's distribution bar spacing, longitudinal crack is control for three reinforced concrete rahmen bridges.

죽재를 이용한 콘크리트의 사용성에 관한 실험적 연구

鄭熺孝,金洪俊,李承列,黃俊碩 경상대학교 생산기술연구소 2002 工學硏究院論文集 Vol.2 No.-

The purpose of this study is about the possibility of using bamboo to reinforce concrete in comparison with the reinforced concrete in the same experimental condition by conducting concrete using bamboo material and mechanical test of a bamboo. As a substitute material for the reinforced concrete, to check the possibility of using concrete with bamboo material either saving iron resources or developing lighter material was tried. Conclusions of this study can be summarized as follows; In contrast to reinforced concrete, bamboo concrete was failed brittly about cracked state, the failure was occurred by slip between concrete and bamboo before it reached yielding stress of bamboo. In the pullout test, bamboo pullout specimens were crushed by brittle crack and steel bar pullout specimens by pullout failure.

중간스프링을 가진 개선된 탄성지반상(彈性地盤上) 보의 휨해석

鄭熺孝,李承烈,安光列 慶尙大學校 經營行政大學院 2004 工學硏究院論文集 Vol.20 No.-

While the BEF(Beam on Elastic Foundation, Wright et al, 1968) analogy has been widely used in straight and simple supported box girder analysis, the EBEF(Equivalent Beam on Elastic Foundation, Yao. T. Hsu et al, 1995) analogy has been made possible in curved and continuous box girder. Instead of using the traditional trigonometric foundation to solve a BEF problem, EBEF analogy used stiffness matrix considering bending, shear, elastic foundation and defined middle diaphragms in box girder as middle supports of continuous beam. In this study, for the comparison with BEF analogy, the element length of beam is determined first and infinity support stiffness corresponding to dimensionless middle diaphragm stiffness is determined in EBEF analogy. Two approaches, BEF and EBEF analogy are compared in the beam on elastic foundation.

스트레인 게이지 브리지 종류에 따른 탄성계수의 실험적 연구

鄭熺孝,李承烈,朴泳珏,朴峻熙 경상대학교 생산기술연구소 2001 工學硏究院論文集 Vol.1 No.-

Strain gauges are widely used for physical force measurements in mechanical, marine, aircraft and civil engineering as well as the fields of architecture, automobiles, and medical science. Strain is measured to determine the degree and behavior of forces such as stress or load. Strain gauges are easy to use and offer a high degree of accuracy and stability. This paper is shown the accuracy of experimental elastic modulus in the tension test according to the strain gauges connections and bridge circuits which are Quarter Bridge(single active uni-axial gauge), Half Bridge(two active on possion gauge), Full Bridge(four active two possion gauge).