• Steel and Composite Structures
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• v.39 no.4
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• pp.435-451
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• 2021

Shear lag effect was a significant mechanical behavior of steel-concrete composite beams, and the effective flange width was needed to consider this effect. However, the effective flange width is mostly determined by static load test. The cyclic vehicle loading cases, which is more practical, was not well considered. This paper focuses on the study of shear lag effect of the concrete slab in the negative moment region under fatigue cyclic load. Two specimens of two-span steel-concrete composite beams were tested under fatigue load and static load respectively to compare the differences in the negative moment region. The reinforcement strain in the negative moment region was measured and the stress was also analyzed under different loads. Based on the OpenSees framework, finite element analysis model of steel-concrete composite beam is established, which is used to simulate transverse reinforcement stress distribution as well as the variation trends under fatigue cycles. With the established model, effects of fatigue stress amplitude, flange width to span ratio, concrete slab thickness and shear connector stiffness on the shear lag effect of concrete slab in negative moment area are analyzed, and the effective flange width ratio of concrete slab under different working conditions is calculated. The simulated results of effective flange width are compared with calculated results of the commonly used specifications, and it is found that the methods in the specifications can better estimate the shear lag effect in concrete slab under static load, but the effective flange width in the negative moment zone under fatigue load has a large deviation.

• Journal of Korean Association for Spatial Structures
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• v.3 no.2 s.8
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• pp.69-75
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• 2003

In case of rectangular lattice dome which shearing rigidity is very small, it has a concern to drop Buckling strength considerably by external force. So, by means of system to increase buckling-strength, there is a method of construction that lattice of dome is one with roof material. In a case like this, shearing rigidity of roof material increases buckling-strength of the whole of structure and can be designed economically from the viewpoint of practice. In case of analysis is achieved considering roof material that adheres to lattice of dame, there is method that considers the rigidity that use effective width frame as method to evaluate rigidity of roof material. therefore, this study is aimed at deciding effective width of roof material united with rectangular lattice dome to evaluate rigidity of roof material by effective width of frame and investigating how much does rigidity of roof material united with lattice of dome increase buckling-strength of the whole of structure according to rise-ratio. Conditions of loading are vertical-type-uniform loading. Analysis method is based on FEM dealing with the geometrically nonlinear deflection problems.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.405-410
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• 2001

To investigate factors influencing the effective width of. SRC column-steel beam joint resisting the moment as strut, six specimens are designed and tested. Parameters in the test are column width, beam height and horizontal tie within beam depth. From the test, using either wide column width or ties, strength and stiffness of joint were developed. The lower beam height the specimens showed the lower moment.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.165-168
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• 2003

The objective of this paper is to investigate the effective width of wide beam. Three specimens were designed to have different depths of wide beam and to simulate exterior beam-column joint including spandrel beam. Load reversals were applied to the end of wide beam to model behaviors under seismic situation. From the test, it was shown that the strength and effective width of specimens were improved when the depth of specimens increased. The effective width of wide beam depended on the depth of it. Formulas in ACI 318-02 underestimated the effective width of wide beam even though these reflected the contribution of the depth of beam.

• Structural Engineering and Mechanics
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• v.21 no.3
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• pp.295-313
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• 2005

This paper evaluates the effective width of composite steel beams with precast hollowcore slabs numerically using the finite element method. A parametric study, carried out on 27 beams with different steel cross sections, hollowcore unit depths and spans, is presented. The effective width of the slab is predicted for both the elastic and plastic ranges. 8-node three-dimensional solid elements are used to model the composite beam components. The material non-linearity of all the components is taken into consideration. The non-linear load-slip characteristics of the headed shear stud connectors are included in the analysis. The moment-deflection behaviour of the composite beams, the ultimate moment capacity and the modes of failure are also presented. Finally, the ultimate moment capacity of the beams evaluated using the present FE analysis was compared with the results calculated using the rigid - plastic method.

• Structural Engineering and Mechanics
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• v.21 no.4
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• pp.407-422
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• 2005

Plate elements in fully profiled sandwich panels are generally subjected to local buckling failure modes and this behaviour is treated in design by using the conventional effective width method for plates with a width to thickness (b/t) ratio less than 100. If the plate elements are very slender (b/t > 1000), the panel failure is governed by wrinkling instead of local buckling and the strength is determined by the flexural wrinkling formula. The plate elements in fully profiled sandwich panels do not fail by wrinkling as their b/t ratio is generally in the range of 100 to 600. For this plate slenderness region, it was found that the current effective width formula overestimates the strength of the fully profiled sandwich panels whereas the wrinkling formula underestimates it. Hence a new effective width design equation has been developed for practical plate slenderness values. However, no guidelines exist to identify the plate slenderness (b/t) limits defining the local buckling, wrinkling and the intermediate regions so that appropriate design rules can be used based on plate slenderness ratios. A research study was therefore conducted using experimental and numerical studies to investigate the effect of plate slenderness ratio on the ultimate strength behaviour of foam supported steel plate elements. This paper presents the details of the study and the results.

• Journal of the Optical Society of Korea
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• v.20 no.5
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• pp.628-632
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• 2016

We studied experimentally and theoretically the vertical range of the confined electric field in the gap area of metamaterials, which was analyzed for various gap widths using terahertz time-domain spectroscopy. We measured the resonant frequency as a function of the thickness of poly(methyl methacrylate) in the range 0 to 3.2 μm to quantify the effective detection volumes. We found that the effective vertical range of the metamaterial is determined by the size of the gap width. The vertical range was found to decrease as the gap width of the metamaterial decreases, whereas the sensitivity is enhanced as the gap width decreases due to the highly concentrated electric field. Our experimental findings are in good agreement with the finite-difference time-domain simulation results. Finally, a numerical expression was obtained for the vertical range as a function of the gap width. This expression is expected to be very useful for optimizing the sensing efficiency.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.73-79
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• 2022

Purpose: The purpose of this study was to investigate the relationship between the minimum effective width (90cm) of the exit of the evacuation stairway installed in accordance with the Building Act and the evacuation time of all occupants using the corresponding floor from an evacuation point of view. Method: The evacuation simulation (Pathfinder) was used to investigate how the change in doorway width affects the evacuation time of occupants. Result: It was found that as the effective width of the doorway became larger than the minimum standard of 90cm, the evacuation time to the evacuation stairs was shortened. This is also proof that the effective width of the evacuation stair entrance can be appropriately applied differently depending on the number of occupants on the floor. Conclusion: In the future, in order to secure evacuation safety of occupants, it is judged that the effective width standard for the exit of the evacuation stairway considering the total number of occupants by use is necessary. In addition, it is expected that the evacuation efficiency of occupants can be greatly increased if various effective width standards for entrances are made according to the number of occupants by use through research and experiments.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.83-84
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• 2014

The whole wall system behaves as one section because single walls composing irregular wall are connected to each other. Although stress of a single wall is affected to the connected wall under lateral load, the stress is not transferred to whole sections and is concentrated on particular part of the wall as well. Therefore these walls can be divided into the effective and ineffective section. The purpose of this study is to compare design result of irregular wall using codes and previous studies on an effective width of the wall and to analyze reduction of the longitudinal bar of irregular wall.

• Progress in Medical Physics
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• v.32 no.4
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• pp.165-171
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• 2021

Purpose: This study aimed to evaluate the effect of collimator width on effective atomic number (EAN), relative electron density (RED), and stopping power ratio (SPR) measured by dual-layer dual-energy computed tomography (DL-DECT). Methods: CIRS electron density calibration phantoms with two different arrangements of material plugs were scanned by DL-DECT with two different collimator widths. The first phantom included two dense bone plugs, while the second excluded dense bone plugs. The collimator widths selected were 64 mm×0.625 mm for wider collimators and 16 mm×0.625 mm for narrow collimators. The scanning parameters were 120 kVp, 0.33 second gantry rotation, 3 mm slice thickness, B reconstruction filter, and spectral level 4. An image analysis portal system provided by a computed tomography (CT) manufacturer was used to derive the EAN and RED of the phantoms from the combination of low energy and high energy CT images. The EAN and RED were compared between the images scanned using the two different collimation widths. Results: The CT images with the wider collimation width generated more severe artifacts, particularly with high-density material (i.e., dense bone). RED and EAN for tissues (excluding lung and bones) with the wider collimation width showed significant relative differences compared to the theoretical value (4.5% for RED and 20.6% for EAN), while those with the narrow collimation width were closer to the theoretical value of each material (2.2% for EAN and 2.3% for RED). Scanning with narrow collimation width increased the accuracy of SPR estimation even with high-density bone plugs in the phantom. Conclusions: The effect of CT collimation width on EAN, RED, and SPR measured by DL-DECT was evaluated. In order to improve the accuracy of the measured EAN, RED, and SPR by DL-DECT, CT scanning should be performed using narrow collimation widths.