• Smart Structures and Systems
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• v.17 no.6
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• pp.935-956
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• 2016

With the help of advanced image acquisition and processing technology, the vision-based measurement methods have been broadly applied to implement the structural monitoring and condition identification of civil engineering structures. Many noncontact approaches enabled by different digital image processing algorithms are developed to overcome the problems in conventional structural dynamic displacement measurement. This paper presents three kinds of image processing algorithms for structural dynamic displacement measurement, i.e., the grayscale pattern matching (GPM) algorithm, the color pattern matching (CPM) algorithm, and the mean shift tracking (MST) algorithm. A vision-based system programmed with the three image processing algorithms is developed for multi-point structural dynamic displacement measurement. The dynamic displacement time histories of multiple vision points are simultaneously measured by the vision-based system and the magnetostrictive displacement sensor (MDS) during the laboratory shaking table tests of a three-story steel frame model. The comparative analysis results indicate that the developed vision-based system exhibits excellent performance in structural dynamic displacement measurement by use of the three different image processing algorithms. The field application experiments are also carried out on an arch bridge for the measurement of displacement influence lines during the loading tests to validate the effectiveness of the vision-based system.

• Wind and Structures
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• v.36 no.6
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• pp.379-392
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• 2023

Structural health monitoring is used to ensure the well-being of civil structures by detecting damage and estimating deterioration. Wind flow applies external loads to high-rise buildings, with the horizontal force component of the wind causing structural displacements in high-rise buildings. This study proposes a deep learning-based predictive model for measuring lateral displacement response in high-rise buildings. The proposed long short-term memory model functions as a sequence generator to generate displacements on building floors depending on the displacement statistics collected on the top floor. The model was trained with wind-induced displacement data for the top floor of a high-rise building as input. The outcomes demonstrate that the model can forecast wind-induced displacement on the remaining floors of a building. Further, displacement was predicted for each floor of the high-rise buildings at wind flow angles of 0° and 45°. The proposed model accurately predicted a high-rise building model's story drift and lateral displacement. The outcomes of this proposed work are anticipated to serve as a guide for assessing the overall lateral displacement of high-rise buildings.

• Steel and Composite Structures
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• v.21 no.4
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• pp.863-882
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• 2016

This study aims to introduce a new bracing system by which even super-wide frames with large openings can be braced. The proposed system, hereafter called Cable-Pulley Brace (CPB), is a tension-only bracing system with a rectilinear configuration. In CPB, a wire rope passes through a rectilinear path around the opening(s) and connects the lower corner of the frame to its opposite upper one. CPB is a secondary load resisting system with a nonlinear-elastic hysteretic behavior due to its initial pre-tension load. As a result, the required energy dissipation would be provided by the MRF itself, and the main intention of using CPB is to contribute to the initial and post-yield stiffness of the whole system. Using a stiffness calibration technique, optimum placement of the CPBs is discussed to yield a uniform displacement demand along the height of the structure. A displacement-based design procedure is proposed by which the MRF with CPB can be designed to achieve a uniform distribution of inter-story drifts with predefined values. Obtained results indicated that CPB leads to significant reductions in maximum and residual deformations of the MRF at the expense of minor increase in the maximum base shear and developed axial force demands in the columns. In the case of a typical 5-story residential building, compared to SMRF system, CPB system reduces maximum amounts of inter-story and residual drifts by 35% and 70%, respectively. Moreover, openings of the frame are not interrupted by the CPB. This is the most appealing feature of the proposed bracing system from architectural point of view.

• Earthquakes and Structures
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• v.7 no.4
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• pp.587-607
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• 2014

Progressive collapse, which is referred to as the collapse of the entire building under local damages, is a common failure mode happened by earthquakes. The collapse process highly depends on the whole structural system. Since, asymmetry of the building plan leads to the local damage concentration; it may intensify the progressive collapse mechanism of asymmetric buildings. In this research the progressive collapse of regular and irregular 6-story RC ordinary moment resisting frame buildings are studied in the presence of the earthquake loads. Collapse process and collapse propagation are investigated using nonlinear time history analyses (NLTHA) in buildings with 5%, 15% and 25% mass asymmetry with respect to the number of collapsed hinges and story drifts criteria. Results show that increasing the value of mass eccentricity makes the asymmetric buildings become unstable earlier and in the early stages with lower number of the collapsed hinges. So, with increasing the mass eccentricity in building, instability and collapse of the entire building occurs earlier, with lower potential of the progressive collapse. It is also demonstrated that with increasing the mass asymmetry the decreasing trend of the number of collapsed beam and column hinges is approximately similar to the decreasing trend in the average story drifts of the mass centers and stiff edges. So, as an alternative to a much difficult-to-calculate local response parameter of the number of collapsed hinges, the story drift, as a global response parameter, measures the potential of progressive collapse more easily.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.3
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• pp.47-55
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• 2003

This study proposed a convenient seismic design procedure for buckling-restrained braced frames based on the equivalent energy concept. The design process begins with the computation of input energy from response spectrum. Then the elastic energy and plastic energy are computed based on the equal energy concept. The computed plastic energy is distributed to each story along energy distribution ratio and the cross-sectional area of each brace is computed so that all the plastic energy is dissipated by the brace. The proposed procedure was applied to the design of three-, six-, and twenty-story steel frames with buckling-restrained braces, and artificial earthquake records were used for verification of the proposed method. According to analysis results, top story displacements of the low-rise structure satisfies the given target displacement however that of the twenty-story structure was much smaller than the given target displacement.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.4
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• pp.63-69
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• 2003

In this study seismic design procedure for buckling-restrained braced frame systems was proposed using hysteretic energy spectrum and accumulated ductility spectrum constructed from single degree of freedom systems. The hysteretic energy spectra and accumulated ductility spectra corresponding to target ductility ratio were constructed first. The cross-sectional area of braces required to meet a given target displacement was obtained by equating the hysteretic energy demand to the accumulated plastic energy dissipated by braces. Twenty earthquake records were utilized to construct the spectra and to verify the validity of the design procedure. According to analysis results of three- and eight-story buckling-restrained braced frame structures designed using the proposed method, the mean values for the top story displacement correspond well with the given performance target displacements. Also, the inter-story drifts turned out to be relatively uniform over the structure height, which is desirable because uniform inter-story drifts indicate uniform damage distribution. Therefore if was concluded that the proposed energy-based method could be a reliable alternative to conventional strength-based design procedure for structures with buckling-restrained braces.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2917-2923
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• 2015

The three dimensional inelastic response characteristics of the standard school buildings depending on hysteresis models are reviewed. Three artificial earthquake records in accordance with KBC(Korea Building Code) are used and the inelastic response characteristics such as story shear force, story drift ratio, story displacement, hinge distribution state are reviewed with four hysteresis models. As results, story shear force is increased by maximum 27% and story drift ratio is increased by maximum 30% according to hysteresis models. Modified Takeda Model shows maximum story shear and story drift raio in longitudinal and short direction, expecting higher safety. Story shear shows minimum value with Clough Model in both directions and story drift ratio shows minimum with Takeda model in longitudinal and with Clough model in short direction, so these models are expected to decrease the safety ratio.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.123-129
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• 2003

Drift design using resizing techniques can be a very practical method in drift design of high-rise buildings since it cannot require sensitivity analysis and structural re-analysis. Resizing techniques has used the cross sectional areas as design variable and supposed that displacement participation factors are inversely proportional to structural weights. Efficiency of resizing techniques based on displacement participation factors may depend on proper selection of sectional properties as design variables. In this study, two different drift design methods with the different sectional properties as design variables are presented and applied to a 20-story structure.

• Computers and Concrete
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• v.16 no.1
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• pp.141-161
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• 2015

A significant portion of residential areas of Turkey is located in active earthquake zones. In Turkey occurred major earthquakes in last twenty years, such as Erzincan (1992), Kocaeli and $D{\ddot{u}}zce$ (1999), $Bing{\ddot{o}}l$ (2003), Van (2011). These earthquakes have demonstrated that reinforced concrete (RC) buildings having horizontal and vertical irregularities are significantly damaged, which in turn most of them are collapsed. Architectural design and arrangement of load-bearing system have important effect on RC building since architectural design criteria in design process provide opportunity to make this type of buildings safer and economical under earthquake loads. This study aims to investigate comparatively the effects of weak story irregularity on earthquake behavior and rough construction costs of RC buildings by considering different soil-conditions given in the Turkish Earthquake Code. With this aim, Sta4-CAD program based on matrix displacement method is utilized. Considering that different story height and compressive strength of concrete, and infill walls or their locations are the variables, a set of structural models are developed to determine the effect of them on earthquake behavior and rough construction costs of RC buildings. In conclusion, some recommendations and results related to making RC buildings safer and more economical are presented by comparing results obtained from structural analyses.

• Steel and Composite Structures
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• v.24 no.4
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• pp.441-453
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• 2017

In Y-shaped eccentrically braced frame fabricated with high strength steel (Y-HSS-EBF), link uses conventional steel while other structural members use high strength steel. Cyclic test for a 1:2 length scaled one-bay and one-story Y-HSS-EBF specimen and shake table test for a 1:2 length scaled three-story Y-HSS-EBF specimen were carried out to research the seismic performance of Y-HSS-EBF. These include the failure mode, load-bearing capacity, ductility, energy dissipation capacity, dynamic properties, acceleration responses, displacement responses, and dynamic strain responses. The test results indicated that the one-bay and one-story Y-HSS-EBF specimen had good load-bearing capacity and ductility capacity. The three-story specimen cumulative structural damage and deformation increased, while its stiffness decreased. There was no plastic deformation observed in the braces, beams, or columns in the three-story Y-HSS-EBF specimen, and there was no danger of collapse during the seismic loads. The designed shear link dissipated the energy via shear deformation during the seismic loads. When the specimen was fractured, the maximum link plastic rotation angle was higher than 0.08 rad for the shear link in AISC341-10. The Y-HSS-EBF is a safe dual system with reliable hysteretic behaviors and seismic performance.