• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.435-442
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• 2007

Since the Ronan Point apartment collapsed in 1968, researches on the progressive collapse have been intermittently conducted, and the collapse of the World Trade Center twin towers made the researches active again. In the United States guidelines such as GSA (2003) and DoD (2005) were provided for design and analysis of building structures against the progressive collapse. In this study the progressive collapse-resisting capacity of steel moment resisting frames designed by KBC-2005 was investigated using linear elastic static analysis and linear dynamic analysis procedures suggested in the guidelines. The results showed that in accordance with the GSA guideline the moment frame designed only for gravity load turned out to be vulnerable to the progressive collapse, whereas the lateral load resisting frame designed for earthquake load satisfied the criteria for progressive collapse. However both systems sailed to satisfy the criteria of the DoD-2005 guideline.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1164-1169
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• 2014

Overturning of concrete poles are occurred annually due to natural disaster such as a typhoon. The present code for the resisting moment and the safety on overturning of concrete poles in inclined ground is inadequate. In this study, the concept of the code for those in flat ground is applied to calculate the resisting moment in inclined ground using general analysis program L-Pile Plus13.8. According to the analytical results, the resisting moment in inclined ground is rapidly decrease as increasing the slope angle although the embedded depth are added by the additional embedded depth on the code. It is revealed that the capacity in inclined ground is equivalent to that in flat ground if additional embedded depth is increased from 1.5 to 3 times.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.620-627
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• 2006

강재기둥으로부터 전달되어 내려오는 모멘트 하중에 의한 베이스판의 변형을 고려한 앵커볼트의 설계방법에 대해 소개하였다. 기둥-베이스판 접합부의 설계를 위해 간략해석 모델 (Simple Beam Model) 이 개발되었으며 인장력과 모멘트 하중에 동시에 저항하는 앵커볼트의 설계를 위해 국부 메카니즘 개념이 도입되었다. 제안된 새로운 설계법을 적용하여 앵커볼트와 베이스판 사이의 최대지압력을 계산할 수 있었으며 이를 바탕으로 앵커볼트의 사이즈를 결정할 수 있었다. 본 논문에서는 상기 간략히 소개된 앵커볼트 설계법을 보다 상세히 기술하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.259-262
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• 2010

최근 건물형상의 다양화로 인하여 수직부재의 불규칙성이 빈번하게 발생하면서 전통적인 보-기둥 형식의 골조에서 변형된 보와 기둥의 특징을 공유하고 있는 경사기둥의 사용빈도가 높아지고 있다. 현재 국내에서 사용하고 있는 내진설계방법은 강도에 근거를 둔 설계법으로서 구조물이 탄성상태에서 저항해야 하는 부재력에 근거하고 있다. 그러나 기준에서 규정하고 있는 또는 그 이상의 지진하중이 구조물에 가해지는 경우에 구조물은 비선형 거동을 하게 되는데 구조물이 비선형 거동을 할 때에는 탄성상태와는 다른 힘의 흐름을 나타내게 된다. 본 논문에서는 12층 철골 모멘트 골조 구조물에 대하여 횡력에 저항하는 정형화된 골조와 경사기둥을 이용한 골조의 내진성능 및 비선형 거동을 조사하였다. 그 결과 강기둥-약보로 설계된 정형화된 구조물에서는 보의 소성힌지가 계속적으로 발달하면서 구조물이 저항하는데 반하여 경사기둥을 가진 구조물은 비탄성 상태에서 경사기둥에 인접한 기둥부재로 하중이 집중되면서 정형골조에 비하여 붕괴 메카니즘이 훨씬 작은 변위에서 발생하는 것을 볼 수 있었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.539-546
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• 2006

The reliability analysis of simply-supported composite plate girder and box girder bridges under positive flexure is performed. The bridges are designed based on the AASHTO-LRFD specification. A performance function for flexural failure is expressed as a function of such random variables as flexural resistance of composite section and design moments due to permanent load and live load. For the flexural resistance, the statistical parameters obtained by analyzing over 16,000 samples of domestic structural steel products are used. Several different values of statistical parameters with the bias factor in the range of 0.95-1.05 and the coefficient of variation in the range of 0.15-0.25 are used for the live-load moment. Due to the lack of available domestic measured data on the dead load moment, the same values of statistical properties used in the calibration of AASHTO-LRFD are applied. The reliability indices for the composite plate girder and box girder bridges with various span lengths are calculated by applying the Rackwitz-Fiessler technique.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.4
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• pp.61-70
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• 1999

Cracking was observed in beam-to-column connections of many steel building frames during the 1994 Northridge and 1995 Kobe earthquakes. Thus extensive experimental researches are currently being conducted to improve the seismic performance of steel frames. A value of 0.015 radian was considered as a reasonable estimate of beam plastic rotation demand in steel moment-resisting frames subjected to severe earthquakes. The objective of this research is to develop a type of connection detail which moves the plastic hinge region in the beam away from the face of the column and can prevent cracking at the welded flange of the beam-to-column connection under seismic loading. An experimental investigation was undertaken on five beam-to-column connection specimens to study the performance of the connections with proposed details. The experiemental results showed that the flexural strength and rotational ductility of the beam connections were adequate for the seismic resistance steel frames to prevent possible cracks at the connections.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.241-244
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• 2008

In general, RC flat plate frames have been used as a gravity load resisting system(GLRS) in building. This system should be constructed with lateral force resisting system(LFRS) such as shear walls and brace frames. When lateral loads such as earthquakes occur, LFRS undergo displacement by which connected gravity systems experience lateral displacement. Thus, flat plate system designed as GLRS should be predict unbalanced moments and punching failure due to lateral deformation. This study developed an analytical mode for predicting nonlinear behavior of RC slab column connection for the seismic performance evaluation of RC flat plate frames. For verifying the analytical model, the test results of two flat plate specimens having two continous spans with the difference gravity shear ratio($V_g/{\phi}V_c$) were compared with the results of analysis. The developed model can predict the failure modes and punching failures.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.183-193
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• 2008

The reliability analysis of simply-supported and continuous composite plate girder and box girder bridges under flexure was performed to provide a basic data for the development of LRFD c ode. The bridges were designed based on LRFD specification with newly proposed design live load which was developed by analyzing traffic statistics from highways and local roads. A performance function for flexural failure was expressed as a function of the flexural resistance of composite section and the design moments due to permanent load and live load. For the flexural resistance, the statistical parameters obtained by analyzing over 16,000 domestic structural steel samples were used. Several different values of bias factors for the live load moment from 1.0 to 1.2 were used. Due to the lack of available domestic measured data on the moment by permanent loads, the same statistical properties used in the calibration of ASHTO-LRFD were ap plied. The reliability indices for the composite girder bridges with various span lengths, different live load factors, and bias fact or for the live load were obtained by applying the Rackwitz-Fiessler technique.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.6
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• pp.393-401
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• 2021

In this paper, we proposed a numerical model based on moment-curvature, to evaluate the resistance of reinforced concrete (RC) members subjected to blast loading. To consider the direct shear failure mode, we introduced a dimensionless spring element based on the empirical direct shear stress-slip relation. Based on the dynamic increase factor equations for materials, new dynamic increase factor equations were constructed in terms of the curvature rate for the section which could be directly applied to the moment-curvature relation. Additionally, equivalent bending stiffness was introduced in the plastic hinge region to consider the effect of bond-slip. To verify the validity of the proposed model, a comparative study was conducted against the experimental results, and the superiority of this numerical model was confirmed through comparison with the analytical results of the single-degree of freedom model. Pressure-impulse (P-I) diagrams were produced to evaluate the resistance of members against bending failure and direct shear failure, and additional parametric studies were conducted.

• Journal of the Korea Concrete Institute
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• v.20 no.4
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• pp.523-530
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• 2008

In structural design provision, maximum punching shear stress of slabs is prescribed as combined stress in direct shear occurred by gravity load and eccentric shear occurred by unbalanced moment. This means that the effect of unbalanced moment is considered to decide the punching shear stress. However, from the resistance capacity standpoint, the effect of unbalanced moment strength is not considered for deciding punching shear strength. In this paper, a model considering interrelation between unbalanced moment and punching shear was proposed. In the model, the relation between load effect and resistance capacity in unbalanced moment and punching shear was two-dimensionally expressed. Using the interrelation model, a method how unbalanced moment strength should be considered to decide the punching shear strength was proposed. Additionally, effective width enlargement factors for deciding the unbalanced moment strength of flat plates with shear reinforcements were proposed. The interrelation model proposed in this paper is very effective for the prediction of the behavior of slab-column connection because not only punching shear and unbalanced moment strengths but also failure modes of flat plates can be accurately predicted.