• Structural Engineering and Mechanics
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• v.32 no.2
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• pp.321-335
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• 2009

When a roof frame is subjected to the airblast loading, the conventional way to analyze the damage of the frame or design the frame is to use single degree of freedom (SDOF) model. Although a roof frame consists of beams and girders, a typical SDOF analysis can be conducted only separately for each component. Thus, the rigid body motion of beams by deflections of supporting girders can not be easily considered. Neglecting the beam-girder interaction in the SDOF analysis may cause serious inaccuracies in the response values in both Pressure-Impulse curve (P-I) and Charge Weight-Standoff Diagrams (CWSD). In this paper, an inelastic two degrees of freedom (TDOF) model is developed, based on force equilibrium equations, to consider beam-girder interaction, and to assess if the modified SDOF analysis can be a reasonable design approach.

• Computers and Concrete
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• v.22 no.4
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• pp.365-372
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• 2018

The current design codes present an equivalent frame method (EFM) for the analysis and design of two-way slab structures. However, since the EFM was developed to be suitable for two-way slab structures subjected to gravity loads only, it brings many problems in its application to the analysis of two-way slabs to which gravity and lateral loads are applied simultaneously. Therefore, authors proposed the unified equivalent frame method (UEFM) that can analyze the structural behavior of flat-plate slab systems subjected to gravity and lateral loads in their previous studies. In this study, the UEFM was modified to be applicable to the two-way slab system with beams. In addition, the accuracy of the proposed UEFM was then examined by comparing it to the lateral behaviors of the two-way slab specimens.

• Steel and Composite Structures
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• v.41 no.5
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• pp.663-679
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• 2021

To elucidate the differences in the collapse behavior between a single-story beam-column assembly and multi-story frame, two 1/3-scale two-bay composite frames, including a single-story composite beam-column assembly and a three-story composite sub-frame, were designed and quasi-statically tested. The load-displacement responses, failure modes, and internal force development of the two frames were analyzed and compared in detail. Furthermore, the resistance mechanisms of the two specimens were explored, and the respective contributions of different load-resisting mechanisms to the total resistances were quantitatively separated to gain deeper insights. The experimental tests indicated that Vierendeel action was present in the two-dimensional multi-story frames, which led to an uneven internal force distribution among the three stories. The collapse resistance of TSDWA-3S in the flexural stage was not significantly increased by the structural redundancy provided by the additional story, as compared to that of TSDWA-1S. Although the development of the load response was similar in the two specimens at flexural stage, the collapse mechanisms of the multi-story composite frame were much more complicated than those of the single-story beam-column assembly, and the combined action between stories was critical in determining the internal force redistribution and rebalancing of the remaining structure.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1043-1046
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• 2008

In this paper, we propose a Motion Estimation (ME) using new blocks based on the Frame Difference (FD) between two adjacent frames for Frame Rate-up Conversion (FRC). The proposed algorithm decides the shape of blocks by the FD. The experimental results show that the proposed method has better performance than conventional methods.

• Steel and Composite Structures
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• v.22 no.5
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• pp.1055-1071
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• 2016

The paper presents an innovative steel moment frame with the replaceable reinforced concrete wall panel (SRW) structural system, in which the replaceable concrete wall can play a role to increase the overall lateral stiffness of the frame system. Two full scale specimens composed of the steel frames and the replaceable reinforced concrete wall panels were tested under the cyclic horizontal load. The failure mode, load-displacement response, deformability, and the energy dissipation capacity of SRW specimens were investigated. Test results show that the two-stage failure mode is characterized by the sequential failure process of the replaceable RC wall panel and the steel moment frame. It can be found that the replaceable RC wall panels damage at the lateral drift ratio greater than 0.5%. After the replacement of a new RC wall panel, the new specimen maintained the similar capacity of resisting lateral load as the previous one. The decrease of the bearing capacity was presented between the two stages because of the connection failure on the top of the replaceable RC wall panel. With the increase of the lateral drift, the percentage of the lateral force and the overturning moment resisted by the wall panel decreased for the reason of the reduction of its lateral stiffness. After the failure of the wall panel, the steel moment frame shared almost all the lateral force and the overturning moment.

• Coupled systems mechanics
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• v.3 no.4
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• pp.367-384
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• 2014

The study deals with the physical modeling of a typical single storeyed building frame resting on pile foundation and embedded in cohesive soil mass using the finite element based software SAP-IV. Two groups of piles comprising two and three piles, with series and parallel arrangement thereof, are considered. The slab provided at top and bottom of the frame along with the pile cap is idealized as four noded and two dimensional thin shell elements. The beams and columns of the frame, and piles are modeled using two noded one dimensional beam-column element. The soil is modeled using closely spaced discrete linear springs. A parametric study is carried out to investigate the effect of various parameters of the pile foundation, such as spacing in a group and number of piles in a group, on the response of superstructure. The response considered includes the displacement at the top of the frame and bending moment in columns. The soil-structure interaction effect is found to increase the displacement in the range of 38 -133% and to increase the absolute maximum positive and negative moments in the column in the range of 2-12% and 2-11%. The effect of the soil- structure interaction is observed to be significant for the type of foundation and soil considered in this study. The results obtained are compared further with those of Chore et al. (2010), wherein different idealizations were used for modeling the superstructure frame and sub-structure elements (foundation). While fair agreement is observed in the results in either study, the trend of the results obtained in both studies is also same.

• Steel and Composite Structures
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• v.48 no.3
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• pp.321-333
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• 2023

This paper proposes a comprehensive investigation on lateral stiffness of corner-supported steel modular frame using splice connection. A full-scale modular frame with two stacked steel modules under lateral load is tested. Ductile pattern in the transfer of lateral load is found in the final failure mode. Two types of lateral stiffness, including tangent stiffness and secant stiffness, are defined from the load-displacement due to the observed nonlinearity. The difference between these two types of stiffness is found around 20%. The comparisons between the experimental lateral stiffness and the predictions of classical methods are also conducted. The D-value method using hypothesis of independent case is a conservative option for predicting lateral stiffness, which is more recommended than method of contraflexural bending moment. Analyses on two classical short-rod models, including fix-rod model and pin-rod model, are further conducted. Results indicate that fix-rod model is more recommended than pin-rod model to simplify splice connection for simulation on lateral stiffness of modular frame in elastic design stage.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.391-398
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• 2000

To evaluate the seismic performance of a base isolated building accurate analytical model should be selected. The analytical results such as reduced accelerations member forces and relative displacements of the superstructure of the base isolated building are only meaningful when the analytical model is close enough to the real structure. Real size one bay-two story steel frame and two kinds of seismic isolators(laminated elastomeric bearing and lead-rubber bearing) are designed. manufactured and constructed in the laboratory. Free vibration tests using fuse bars were conducted to evaluate the change of dynamic characteristics(period and damping) before and after base isolation of the steel frame. The experimental results of free vibration tests were also used as a bench mark for adjusting the selected analytical modeling to real base isolated steel frame.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.4
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• pp.11-18
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• 2007

A moving object detection algorithm for surveillance video is here proposed which employs background initialization based on two-stage median filtering and a background updating method based on state transition diagram. In the background initialization, the spatiotemporal similarity is measured in the subinterval. From the accumulated difference between the base frame and the other frames in a subinterval, the regions affected by moving objects are located. The median is applied over the subsequence in the subinterval in which regions share similarity. The outputs from each subinterval are filtered by a two-stage median filter. The background of every frame is updated by the suggested state transition diagram The object is detected by the difference between the current frame and the updated background. The proposed method showed good results even for busy, crowded sequences which included moving objects from the first frame.

• ETRI Journal
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• v.37 no.4
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• pp.657-666
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• 2015

We propose a two-stage resource allocation algorithm for the high link utilization of an orthogonal frequency-division multiplexing passive optical network (OFDM-PON). An OFDM-PON is assumed to use a synchronous frame structure in supporting service differentiation. In distributing resources, the proposed algorithm first allocates a time window for each optical network unit (ONU), and then it arranges a subchannel, which is a group of subcarriers. This algorithm needs to satisfy two constraints. First, computations for the resource allocation should be done using a frame unit. Second, an ONU has to use a single subchannel to send upstream data for multiple services within a frame duration. We show through a computer simulation that the proposed algorithm improves the link utilization.