• Journal of Korean Society of Steel Construction
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• v.21 no.2
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• pp.155-164
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• 2009

In this study, a computationally efficient parallel axial-flexural plastic hinge model is proposed for nonlinear dynamic progressive collapse analysis of welded steel moment frames. To this end, post-yield flexural behavior and the interaction of bending moment and axial force of the double-span beams in the column's missing event was first investigated by using material and geometric nonlinear parametric finite element analysis. A piece-wise linear parallel point hinge model that captures the moment-axial tension interaction was then proposed and applied to nonlinear dynamic progressive collapse analysis of welded steel moment frames with the use of the OpenSees Program. The accuracy as well as the efficiency of the proposed model was verified based on the inelastic dynamic finite element analysis results. The importance of including the catenary action effects for proper progressive collapse resistant analysis and design was also emphasized.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.1
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• pp.27-35
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• 2014

In this study, an improved energy-based nonlinear static analysis method are proposed to be used for more accurate evaluation of progressive collapse potential of steel moment frames by reflecting the contribution of a double-span floor slab. To this end, the behavior of the double-span floor slab was first investigated by performing material and geometric nonlinear finite element analysis. A simplified energy-absorbed analytical model by idealizing the deformed shape of the double-span floor slab was developed. It is shown that the proposed model can easily be utilized for modeling the axial tensile force and strain energy response of the double-span floor slab under the column-removal scenario.

• Magazine of the Korea Concrete Institute
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• v.2 no.3
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• pp.73-80
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• 1990

This research program is directed at studying the behavior and the strength of reinforced concrete slabs sub¬jected to certain combination of punching shear and in-plane tension. Major variables to be investigated are the shear span to depth ratio of reinforced concrete slabs and the degree of the in-plane tensile force which is act¬ing tangent to the slabs. The experimental results are used for understanding of the degree of tbe interaction between the two loadings, and for developing a new practical design equation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.450-453
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• 2009

본 논문에서는 지진하중을 고려하여 충분한 연성거동이 가능하도록 배근한 철근콘크리트 횡하중 저항 골조(내진상세)와 고정하중과 적재하중만을 고려하여 설계한 중력하중 저항 골조(일반상세)를 대상으로 외부기둥과 내부기둥에 연결된 보의 연쇄붕괴 거동을 평가하기 위한 실험을 수행하였다. 일방향 가력실험 결과에 따르면 내진상세의 경우 대변형 상태에서 보의 하단철근의 파단이후 상단 압축철근이 인장력을 부담하면서 전체 보 부재는 축인장력이 작용을 하면서 힘-변위 곡선은 상승하는 현수작용이 발현되었다. 그러나 일반상세의 경우 충분한 현수작용이 발현되기 전에 보의 주근이 정착된 외부기둥 접합부의 파괴로 인하여 저항내력이 감소하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.159-166
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• 2000

A new method of estimating axial nail force is proposed. An instrumented soil nail wall is selected to investigate the effectiveness of the new proposed method. The new method includes effect of creep and age of cement grout surrounding the steel bar, The new method also considers cracks in the grout generated during and after the end of the wall construction. It is found from this study that a reduced grout stiffness due to creep with age and crack of the grout must be considered for estimating correct axial nail forces. The reduced grout stiffness is considered also providing significant part of axial nail load compared to that of steel bar.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.6
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• pp.15-20
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• 2001

This paper presents the experimental study of the static stiffness for the BT shank(7/24 long taper) and the HSK tool shank(1/10 short taper) in the main spindle taper of machine tool. The static stif71ess test was performed under different experimental conditions. It is turned out that the effective axial drawing force is larger than 6kN in the 7/24 test tool shank and BkN in the 1/10 test tool shank. As a test result, considering that the actual drawing force of the machining center is about 1300k2f and axal drawing force 12kN is equivalent amount as a 1220kgf, it is turned out that 1/10 test tool shank superior to 7/24 test tool shank in the static stiffness.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.49-60
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• 2014

For simple and accurate analysis for behaviors of multi-span suspension bridges which are expected to be frequently constructed as strait-crossing bridges, the deflection theory as the peculiar theory of a suspension bridge can be applied. This paper performs a structural analysis for four-span suspension bridges using the deflection theory. Simply-supported beams with tension are used for girders and the deflections of the beams due to the vertical loads and moments at supports are calculated. The calculation is performed iteratively until the deflections satisfy the compatibility equations of cables. The results of the deflection theory analysis considering tower rigidity are compared with those of the finite element analysis for verification. Importance of the tower rigidity for four-span suspension bridges is confirmed using various compatibility equations of the cable due to variation of the constraint conditions between main cable and top of towers. In addition, the simple parametric analysis for variation of the center tower rigidity is performed.

• Journal of Korean Society of Steel Construction
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• v.19 no.4
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• pp.383-393
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• 2007

A simplified model which incorporates the moment-axial tension interaction of the double-span beams in a column-removed steel frame is presented in this paper. To this end, material and geometric nonlinear parametric finite element analyses were conducted for the double-span beams by changing the beam span to depth ratio and the beam size within some practical ranges. The beam span to depth ratio was shown to be the most influential factor governing the catenary action of the double-span beams. Based on the parametric analysis results, a simplified piece-wise linear model which can reasonably describe the vertical resisting force versus the beam chord rotation relationship was proposed. It was also shown that the proposed method can readily be used for the energy-based progressive collapse analysis of steel moment frames.