• Steel and Composite Structures
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• v.52 no.2
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• pp.183-197
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• 2024

Not all structural columns maintain a vertical orientation. Several contemporary building structures have inclined columns, introducing distinct challenges, particularly in buckling behavior. This study examines the buckling behavior of inclined, thin-walled steel bundled columns, differing from typical vertical columns. Using specimens with three tubes welded to plates linearly aligned at the top and triangularly at the bottom, tests indicated that buckling capacity increases with tube wall thickness and diameter but decreases with column height. Inclined tubes in bundled columns showed improved buckling resistance over vertical ones. Results were verified against standard steel design guidelines to assess their predictive accuracy.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.273-276
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• 2006

In this paper the recent research and application activities on smart structure technologies for civil infra structures in Korea are briefly introduced. The developments of structural health monitoring systems and effective retrofit/maintenance methodologies for infra structures have become active in Korea since the middle of 1990's, as the number of the deteriorated infra structures, mostly built on the rapidly industrialized period of 1970's, has increased very rapidly. Discussions are made on smart sensors, non destructive technologies, monitoring and assessment methods and systems for civil infra structures.

• Steel and Composite Structures
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• v.35 no.3
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• pp.405-413
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• 2020

Current study on the buckling analysis of steel plate in composite structures normally focuses on applying finite element method to derive the buckling stress. However, it is time consuming, computationally complicated and tedious for general use in design by civil engineers. Therefore, in this study an analytical study is conducted to predict the buckling behavior of steel plates in composite structures. Hand calculation method was proposed based on energy principle. Novel buckling shapes with biquadratic functions along both loaded and unloaded direction were proposed to satisfy the boundary condition. Explicit solutions for predicting the critical local buckling stress of steel plate is obtained based on the Rayleigh-Ritz approach. The obtained results are compared with both experimental and numerical data. Good agreement has been achieved. Furthermore, the influences of key factors such as aspect ratio, width to thickness ratio, and elastic restraint stiffness on the local buckling performance are comprehensively discussed.

• Earthquakes and Structures
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• v.25 no.2
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• pp.135-148
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• 2023

The structure-soil-structure interaction (SSSI) effect in adjacent structures may affect the liquefaction-induced damage of shallow foundation structures. The existing studies only analysed the independent effects on the structural dynamic response but ignored the coupling effect of height difference and distance of adjacent structures (F) on liquefied foundations on the dynamic response. Therefore, this paper adopts finite element and finite difference coupled dynamic analysis method to discuss the effect of the F on the seismic response of shallow foundation structures. The results show that the effect of the short structure on the acceleration response of the tall structure can be neglected as F increases when the height difference reaches 2 times the height of the short structure. The beneficial effect of SSSI on short structures is weakened under strong seismic excitations, and the effect of the increase of F on the settlement ratio gradually decreases, which causes a larger rotation hazard. When the distance is smaller than the foundation width, the short structure will exceed the rotation critical value and cause structural damage. When the distance is larger than the foundation width, the rotation angle is within the safe range (0.02 rad).

• Steel and Composite Structures
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• v.19 no.4
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• pp.953-966
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• 2015

Carbonation depth was verified in 40 points of two 57 years old concrete viaducts. Field testing (phenolphthalein spraying) was performed on the structures. Data obtained were statistically analyzed by the Kolmogrov-Smirnov's test, one-way analysis of variance (ANOVA's test), and Fisher's method. The results revealed significant differences between maximum carbonation depths of different elements of the same concrete structure. Significant differences were also found in the carbonation of different concrete structures inserted in the same macroclimate. Microclimatic factors such as temperature and local humidity, sunshine, wind, wetting and drying cycles, among others, may have been responsible by the behavior of carbonation in concrete.

• Computers and Concrete
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• v.31 no.4
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• pp.315-325
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• 2023

Calcium leaching is one of the main deterioration factors in concrete structures contact with water, such as dams, water treatment structures, and radioactive waste structures. It causes a porous microstructure and may be coupled with various harmful factors resulting in mechanical degradation of concrete. Several numerical modeling studies focused on the calcium leaching depth prediction. However, these required a lot of cost and time for many experiments and analyses. This study presents an artificial neural network (ANN) approach to predict the leaching depth quickly and accurately. Totally 132 experimental data are collected for model training and validation. An optimal ANN model was proposed by ANN topology. Results indicate that the model can be applied to estimate the calcium leaching depth, showing the determination coefficient of 0.91. It might be used as a simulation tool for engineering problems focused on durability.

• Steel and Composite Structures
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• v.29 no.1
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• pp.139-149
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• 2018

In this paper a new multi-step damage detection approach is provided. In the first step, condensed modal residual vector based indicator (CMRVBI) has been proposed to locate the suspected damaged elements of structures that have rotational degrees of freedom (DOFs). The CMRVBI is a new indicator that uses only translational DOFs of the structures to localize damaged elements. In the next step, salp swarm algorithm is applied to quantify damage severity of the suspected damaged elements. In order to assess the performance of the proposed approach, a numerical example including a three-layer square laminated composite plate is studied. The numerical results demonstrated that the proposed CMRVBI is effective for locating damage, regardless of the effect of noise. The efficiency of proposed approach is also compared during both steps. The results demonstrate that in noisy condition, the damage identification approach is capable for the studied structure.

• Steel and Composite Structures
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• v.30 no.4
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• pp.315-325
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• 2019

Double skin composite walls offer structural and economic merits over conventional reinforced concrete counterparts in terms of higher capacity, greater stiffness, and better ductility. This paper investigated the axial behavior of double skin composite walls with steel truss connectors. Full-scaled tests were conducted on three specimens with different height-to-thickness ratios. Test results were evaluated in terms of failure mode, load-axial displacement response, buckling loading, axial stiffness, ductility, strength index, load-lateral deflection, and strain distribution. The test data were compared with AISC 360 and Eurocode 4 and it was found that both codes provided conservative predictions on the safe side.

• Wind and Structures
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• v.39 no.3
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• pp.191-205
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• 2024

To investigate the wind load characteristics of a large-span spherical shell structure, a rigid model pressure test was conducted in a wind tunnel laboratory. The study aimed to examine the impact of various external structures and internal stacking forms on the wind loads of a spherical shell structure in a practical engineering project. This project features two adjacent spherical structures, each spanning 130 m and standing 67 m tall. These two structures are connected by trestles and a transfer station. Variations in the shape factor and the integral force coefficient of the structure were compared and analyzed under different test cases. The results indicate that when two structures are arranged in series, with the adjacent structure positioned upstream, the shape factor of the structure is most affected, resulting in a significant reduction effect at the bottom of the windward surface. Compared to the external structure, the impact of various internal stacking forms on the shape factor of the structure is relatively weak. The adjacent structure significantly improves the wind resistance of the main structure. The integral force coefficient of the structure reaches its peak when internal stacking is full and is at its lowest when there is no internal stacking.

• Earthquakes and Structures
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• v.13 no.2
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• pp.193-200
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• 2017

To overcome the difficulty of performing multi-point response spectrum analysis for engineering structures under spatially varying ground motions (SVGM) using the general finite element code such as ANSYS, an approach has been developed by improving the modelling of the input ground motions in the spectral analysis. Based on the stochastic vibration analyses, the cross-power spectral density (c-PSD) matrix is adopted to model the stationary SVGM. The design response spectra are converted into the corresponding PSD model with appropriate coherency functions and apparent wave velocities. Then elements of c-PSD matrix are summarized in the row and the PSD matrix is transformed into the response spectra for a general spectral analysis. A long-span high-pier bridge under multiple support excitations is analyzed using the proposed approach considering the incoherence, wave-passage and site-response effects. The proposed approach is deemed to be an efficient numerical method that can be used for seismic analysis of large engineering structures under SVGM.