• Structural Engineering and Mechanics
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• v.81 no.6
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• pp.751-767
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• 2022

In the hogging bending moment area, continuous composite beams are subjected to the ultimate limit state of lateral-torsional buckling (LTB), which depends on web stiffness as well as concrete slab and shear connection stiffnesses. The design of the LTB and the determination of the elastic critical moment are produced approximately, using the European Standard EN 1994-1-1:2004, for continuous composite steel beams, but is applicable only for those with a plane web steel profile. Also, and from the previous researches, the elastic critical moment of the continuous composite beams with corrugated sinusoidal web steel profiles was determined. In this paper, a finite element analysis (FEA) model was developed using the ANSYS 16 software, to determine the elastic critical moments of continuous composite steel beams with various corrugated web profiles, such as trapezoidal, zigzag, and rectangular profiles, which were evaluated against numerical data of the sinusoidal one from the literature. Ultimately, the failure load of a composite steel beam with various web profiles was predicted by studying 46 models, based on FEA modeling, and a procedure for predicting the elastic critical moment of composite beams with various web steel profiles was proposed. When compared to sinusoidal web profiles, the trapezoidal, zigzag, and rectangular web profiles required an average increase in load capacity and stiffness of 7%, 17.5%, and 28%, respectively, according to the finite element analysis. Also, the rectangular web steel profile has a greater stiffness and load capacity. In contrast, the sinusoidal web has lower values for these characteristics.

• Steel and Composite Structures
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• v.46 no.6
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• pp.857-865
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• 2023

This study aimed to develop a seismic retrofit technique using a steel frame which can be easily transported and assembled on site. This enables the retrofit steel frame to be easily attached to an existing structure minimizing the unwanted gap between the structure and the steel frame assembly. A one-story one-bay RC frame was tested with and without seismic retrofit using the proposed steel frame to verify the seismic retrofit effect of the proposed system, and an analysis model was developed in Opensees for seismic performance evaluation of a case study soft first-story model structure retrofitted with the developed steel frame assembly. Seismic performance of the model structure was also evaluated considering soil structure interaction effect. The experimental study confirmed that the proposed seismic retrofit system can be applied effectively to improve the seismic performance of framed structures. Time history analysis results of the model structure showed that the proposed steel frame assembly was effective in increasing the seismic load resisting capacity of the soft first-story structure. However more steel frame assemblies were required to satisfy the given performance limit state of the model structure located on weak soil due to the negative soil-structure interaction effect.

• Steel and Composite Structures
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• v.51 no.1
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• pp.93-101
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• 2024

This paper presents an experimental and analytical study on a steel slit damper designed as an energy dissipative device for earthquake protection of structures considering soil-structure interaction. The steel slit damper is made of a steel plate with a number of slits cut out of it. The slit damper has an advantage as a seismic energy dissipation device in that the stiffness and the yield force of the damper can be easily controlled by changing the number and size of the vertical strips. Cyclic loading tests of the slit damper are carried out to verify its energy dissipation capability, and an analytical model is developed validated based on the test results. The seismic performance of a case study building is then assessed using nonlinear dynamic analysis with and without soil-structure interaction. The soil-structure system turns out to show larger seismic responses and thus seismic retrofit is required to satisfy a predefined performance limit state. The developed slit dampers are employed as a seismic energy dissipation device for retrofitting the case study structure taking into account the soil-structure interaction. The seismic performance evaluation of the model structure shows that the device works stably and dissipates significant amount of seismic energy during earthquake excitations, and is effective in lowering the seismic response of structures standing on soft soil.

• Steel and Composite Structures
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• v.50 no.5
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• pp.549-562
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• 2024

In this study a steel moment frame system to be installed on the exterior surface of an existing structure is proposed as a seismic retrofit device. The seismic performance of the retrofit system was investigated by installing it on the exterior of a single story single bay reinforced concrete frame and testing it under cyclic loading. The cyclic loading test results indicated that the steel frame significantly enhanced the strength and ductility of the bare structure. Finite element analysis was carried out to validate the test results, and it was observed that there was good agreement between the two results. An analytical model was developed in order to apply the retrofit system to an example structure subjected to seven mainshock-aftershock sequential earthquake records. It was observed that the model structure was severely damaged due to the mainshock earthquakes, and the seismic response of the model structure increased significantly due to the subsequent aftershock earthquakes. The seismic retrofit of the model structure using the proposed steel frame turned out to be effective in decreasing the seismic response below the given limit state.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.92-101
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• 2020

It is necessary to develop a rational method for evaluating the safety of bridges for the passage of inseparable crane vehicles exceeding the limit weight. In this study, the same method applied to the development of the recently introduced reliability-based highway bridge design code - limit state design method is applied to the calibration of the live load factor for the crane vehicle. Structural analysis was performed on the concrete bridge and the required strengths of the previous design code, the current design code and AASHTO LRFD were compared. When comparing the unfactored live load effect, the live load of the crane was greater than that of the current and previous design code. When comparing the required strength by applying the calibrated live load factor, the previous design code demands the largest strength and the current design code and the crane live load effect yields similar value. The results of safety evaluation of the actual bridges on the candidate route for the crane passage secured the same reliability as the target reliability index required by the design code and the strength of the cross section of the actual bridge is calculated greater than the required strength for the passage of the crane, which confirms the safety for the passage of the crane.

• Journal of the Korean Geotechnical Society
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• v.35 no.12
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• pp.45-58
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• 2019

In this study, a stochastic analysis procedure based on numerical analysis was proposed to evaluate a kind of intensity-duration rainfall threshold for the initiation of slope failure due to rainfall infiltration. Fragility curves were generated as a function of rainfall intensity-duration from the results of probabilistic slope stability analysis by MCS considering the uncertainty of the soil shear strength, reflecting the results of infiltration analysis of rainfall over time. In the probabilistic analysis, slope stability analyses combined with the infiltration analysis of rainfall were performed to calculate the limit state function. Using the derived fragility curves, a chart showing the relationship between rainfall intensity and slope failure-time was developed. It is based on a probabilistic analysis considering the uncertainty of the soil properties. The proposed probabilistic failure distribution analysis could be beneficial for analyzing the time-dependent failure process of soil slopes due to rainfall infiltration, and for predicting when the slope failure should occur.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.161-175
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• 1996

There were many reports that elevations in the levels of active and latent collagenase in gingival crevicular fluid(GCF) have been correlated positively with periodontal disease activity. To provide a simple diagnostic approach for testing GCF collagenolytic activity, the detection limit of enzyme activity was compared using radiofibril assay(Sodek et.al.1981) and spectrophotometric collagenolytic assay(Nethery et al. 1986). The detection limits of both assay for standard bacterial enzyme were similar and the radiofibril assay showed a little (1/2) lower detection limit for tad pole collagenase. To evaluate the relationship between periodontal tissue destruction and the collagenolytic activity, GCF was collected, and latent and active enzyme activities were measured by a spectrophotometric collagenolytic assay. Twelve subjects showing progressive lesions were selected according to the presence of immediate tissue destruction, frequent abscess formation, and increasing need for tooth extraction, and the absence of underlying systemic disease and previous antibiotic medication history within 6 months. Comparisons were made between sites with either: 1) inflammation with a previous history of progressive loss of periodontal tissue and bone support(2l progressive sites): 2) previous history of bone loss and periodontal destruction but now clinically stable(12 comparably stable sites); or 3) no loss of periodontal tissue and bone support(11 control sites including 5 gingivitis sites and 6 healthy sites). Active collagenase activity was the highest in the progressive sites and decreased in the order of the gingivitis sites, the stable sites, and the healthy sites. The total enzyme activity was $2{\sim}3$ fold higher in the progressive sites and the gingivitis sites, compared to the stable and the healthy sites. The ratio of active to total collagenolytic activity was twice in the progressive sites. Analysis of active collagenase level(5mU) and the ratio of active to total collagenolytic activity(0.8) as a diagnositic test indicates that these measurements have the sensitivity of 0.81 and 0.86, the specificity of 0.70 and 0.65, and the overall agreement of 0.75 and 0.73, respectively. Thus, this method has significant merits as a diagnostic tool to determine wherher the site is in a state of remission or progression.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.5
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• pp.129-138
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• 2006

Composite deck plate using a pre-assembled re-bar truss for slab with corrugated zinc galvanized sheet iron at manufactory, is given the improvement on design, manufacture, and performance for construction work of cast-in-place reinforced concrete slab by enabling to cast concrete directly without the form work. There are two methods in analyzing composite deck : Simplified 2D analysis and 3D analysis. Although simplified 2D analysis is being used up to date, the use of 3D analysis, allowing for the vierendeel behavior of composite deck by real configuration correlating to bar reducing, is demanded. To compare the simplified 2D analysis applied to allowable stress design with 3D analysis applied to limit state design, 8 specimen are manufactured. Main variables include the depth of slab, the length of span, the diameter of bottom bar and lattice bar, and the presence of corrugated zinc galvanized sheet iron. The comparison from the experimental result and analytical result indicates that applying of simplified 2D analysis is possible for the use of D10 with bottom bar. However, it is more reasonable to apply 3D analysis which allows to indicate vierendeel behavior considered the real configuration.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.133-140
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• 2008

The design method of the reinforced concrete structures is converting from the current limit state design method to the reliability based design method and active studies have been done in the US, Europe, and Japan etc. Performance based design method is considering lots of uncertainty of current design provision rationally and make sure that structure have a reliable reliability and safety. The main area of these studies is to secure the non-linear analysis technology with high reliability. The data for reinforced concrete columns tested by many researchers are used to verify the applicability of the nonlinear finite element analysis program (RCAHEST, Reinforced Concrete Analysis in Higher Evaluation System Technology). A comparison is made between analysis and test, calculated safety factor based on reliability theories to applies to analysis result.

• Journal of architectural history
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• v.21 no.3
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• pp.29-44
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• 2012

If cultural Heritageis located in the downtown, conservation areas was developed or is being developed In most cases Therefore, in this case, the relative height of the building during construction than the regulatory limit is reasonable, is emerging need to be objectified. This study was utilizes GIS analysis techniques for 'View Corridor' and building height standards were determined. First, 'View Corridor' set and building height restrictions for the analysis of urban environmental factors were analyzed in. In particular, the topography and urban planning, and existing buildings, including the distribution of the physical urban environment, with detailed analysis on the major historical and cultural assets with a combination of a review of the impact factor for the formation of the urban landscape recognize the scope has been expanded. Second, the key selection criteria for View point largely focused on cultural Heritageand the surrounding communicative point of view and, consequently, connectivity, and symbolism, accessibility, analysis, factors such as Prospect, setting the standards by applying a detailed assessment of each item the main view point were derived. Third, the derived key View point on the terrain and landscape characteristics simulation analysis carried out by considering together the main axis, and this suggests a reasonable height for the proposed standards.