• Computers and Concrete
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• v.16 no.5
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• pp.703-722
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• 2015

This study investigates the performance of advanced hollow reinforced concrete (RC) bridge column sections with triangular reinforcement details. Hollow column sections are based on economic considerations of cost savings associated with reduced material and design moments, as against increased construction complexity, and hence increased labor costs. The proposed innovative reinforcement details are economically feasible and rational, and facilitate shorter construction periods. We tested a model of advanced hollow column sections under quasi-static monotonic loading. The results showed that the proposed triangular reinforcement details were equal to the existing reinforcement details, in terms of the required performance. We used a computer program, Reinforced Concrete Analysis in Higher Evaluation System Technology (RCAHEST), for analysis of the RC structures; and adopted a modified lateral confining effect model for the advanced hollow bridge column sections. Our study documents the testing of hollow RC bridge column sections with innovative reinforcement details, and presents conclusions based on the experimental and analytical findings. Additional full-scale experimental research is needed to refine and confirm the design details, especially for the actual detailing employed in the field.

• International journal of steel structures
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• v.18 no.5
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• pp.1723-1740
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• 2018

This paper presents a Finite Element (FE) study on Lean Duplex Stainless Steel stub column with built-up sections subjected to pure axial compression with column web spacing varied at different position across the column flanges. The thicknesses of the steel sections were from 2 to 7 mm to encompass a range of section slenderness. The aim is to study and compare the strength and deformation capacities as well as the failure modes of the built-up stub columns. The FE results have been compared with the un-factored design strengths predicted through EN1993-1-4 (2006) + A1 (2015) and ASCE8-02 standards, Continuous Strength Method (CSM) and Direct Strength Method (DSM). The results showed that the design rules generally under predict the bearing capacities of the specimens. It's been observed that the CSM method offers improved mean resistance and reduced scatter for both classes of cross-sections (i.e. slender and stocky sections) compared to the EN1993-1-4 (2006) + A1 (2015) and ASCE 8-02 design rules which are known to be conservative for stocky cross-sections.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.466-470
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• 1988

A tunable reduced-order distillation model is proposed for real-time applications. To develop the model, a binary distillation column with MaCabe-Thiele assumptions was considered first and then the governing equations for the column were reduced to a simplified vector differential equations using the collocation method combined with cubic spline interpolation function. The final reduced-order model has four tuning parameters, relative volatilities and liquid holdups for rectifying and stripping sections, respectively. To assess the applicability of the developed model,the real-time adjustment of the model was tried by recursively updating the tuning parameters using the BKF algorithm. As a result, it was found that the reduced-model follows the simulated distillation process very closely as the parameters are improved.

• Earthquakes and Structures
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• v.23 no.2
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• pp.183-196
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• 2022

Reduced beam section (RBS) moment connections used in special moment resisting frames are currently limited to beam sections that are not larger than nominal depths of 920 mm, weight of 447 kg/m and flange thickness of 44 mm. Due to the higher demand for structural components with jumbo sections, which can potentially be applied in the transfer girders in long-span building structures, the newly available steel heavy members are promising. To address this issue, advanced numerical models are developed to fully evaluate the distribution of stresses and concentrations of plastic strains for such jumbo RBS connections. This paper first presents a brief overview of an experimental study on four specimens with large beam and column sections. Then, a numerical model that includes initial imperfections, residual stresses, geometric nonlinearity, and explicitly modeled welds is presented. The model is used to further explore the behavior of the test specimens, including distribution of stresses, distribution of plastic strains, stress triaxiality and potential for fracture. The results reveal that the stresses are highly non-uniform across the beam flange and, similarly, the plastic strains concentrate at the extreme fiber of the bottom flange. However, neither of these phenomena, which are primarily a function of beam flange thickness, is reflected in current design procedures.

• Structural Engineering and Mechanics
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• v.41 no.1
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• pp.43-65
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• 2012

The primary objective of this study was to identify concrete contribution to the initial shear strength of reinforced concrete (RC) hollow columns under lateral loading. Seven large-scale RC rectangular hollow column specimens were tested under monotonic or cyclic lateral loads. The most important design parameter was column length-to-depth aspect ratio ranging between 1.5 and 3.0, and the other test variables included web area ratio, hollow section ratio, and loading history. The tests showed that the initial shear strength reduced in a linear pattern as the column aspect ratio increased, and one specimen tested under cyclic loading achieved approximately 83% of the shear strength of the companion specimen under monotonic loading. Also, several pioneering shear models proposed around the world, all of which were mainly based on tests for columns with solid sections, were reviewed and compared with the test results of this study, for their possible applications to columns with hollow sections. After all, an empirical equation was proposed for concrete contribution to the initial shear strength of RC hollow columns based on fundamental mechanics and the test results.

• Journal of Korean Association for Spatial Structures
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• v.14 no.2
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• pp.69-78
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• 2014

The purpose of this study is to increase applicability of high strength steel, HSA800 to the structure. Selected study of structure is to consider high strength steel, and following parts, 1) Tensile member with no consider of buckling, 2) Truss existing both tension and compression members with small slenderness ratio. This studied structure is included tension column hang on to the upper bridge truss. The structure element quantity with apply HSA800 instead of SM570 is reduced about 38.9% of tension column and 29.7% of bridge truss. In addition, the number of element's division is reduced about two sections due to reduction of self weight that the crane is able to lift up. This improves to reduce erection sequence and construction period which can save about a month. All connections are reviewed as welding and bolt. Also, the cost of welding is reduced about 41.3% due to apply HSA800. In conclusion, applying HSA800 to the hanging structure aggressively can secure economic and constructability.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.3
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• pp.265-274
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• 2017

This study presents a sustainable design method to optimize the embodied energy and $CO_2$ emission complying with the design code for reinforced concrete column. The sustainable design method effectively achieves the minimization of the environmental load and energy consumption whereas the conventional design method has been mostly focused on the cost saving. Failure of reinforced concrete column exhibits compressive or tensile failure mode against an external force such as flexure and compression; thus, optimization analyses are conducted for both failure modes. For the given sections and reinforcement ratios, the optimized sections are determined by optimizing cost, embodied energy, and $CO_2$ emission and various aspects of the sections are thoroughly investigated. The optimization analysis results show that 25% embodied energy and 55% $CO_2$ emission can be approximately reduced by 10% increase in cost. In particular, the embodied energy and $CO_2$ emission were more effectively reduced in the tensile failure mode rather than in the compressive failure mode. Consequently, it was proved that the sustainable design method effectively implements the concept of sustainable development in the design of reinforced concrete structure by optimizing embodied energy consumption and $CO_2$ emission.

• Structural Engineering and Mechanics
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• v.88 no.1
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• pp.25-42
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• 2023

This paper presents a finite element (FE) simulation of eccentrically loaded lightweight aggregate concrete-encased steel (LACES) columns with H-shaped steel sections, analytical equations are also established to estimate the columns' axial and bending moment interaction capacities. The validity of the proposed models is checked by comparing the results with experimental data. Good agreements between the test and proposed models' results are found with acceptable agreements. Moreover, design parameters, including the lightweight aggregate concrete (LWAC) strength, eccentricity, column slenderness ratio, and confinement, are studied using the FE analysis, and their efficiency factors are discussed. The results show that the ultimate axial capacity of the LACES composite columns subjected to eccentric loading is negatively affected by the increase in the columns' height, but it is positively affected by the increase of the confinement. Increasing the eccentricity and columns' height reduced the columns'stiffness. In addition, the ultimate capacity of the LACES column is significantly influenced by the LWAC strength and eccentricity, where the ultimate capacity of the LACES column is significantly increased by increasing LWAC strength, and it is remarkably decreased by increasing the eccentricity. When the eccentricity changed from zero to 70 mm, the ultimate axial capacity and stiffness decreased by 67.97% and 63.56%, respectively.

• Steel and Composite Structures
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• v.34 no.3
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• pp.347-359
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• 2020

The objective of this study is to experimentally scrutinize the axial performance of built-up concrete filled steel tube (CFT) columns composed of steel plates. In this case, the main parameters cross section types, compressive strength of filled concrete, and the effect of welding lines. Welded built-up steel box columns are fabricated by connecting two pieces of cold-formed U-shaped or four pieces of L-shaped thin steel plates with continuous penetration groove welding line located at mid-depth of stub column section. Furthermore, traditional square steel box sections with no welding lines are investigated for the comparison of axial behavior between the generic and build-up cross sections. Accordingly, 20 stub columns with thickness and height of 2 and 300 mm have been manufactured. As a result, welding lines in built-up specimens act as stiffeners because have higher strength and thickness in comparison to the plates. Subsequently, by increasing the welding lines, the load bearing capacity of stub columns has been increased in comparison to the traditional series. Furthermore, for specimens with the same confinement steel tubes and concrete core, increment of B/t ratio has reduced the ductility and axial strength.

• Journal of Korean Society of Steel Construction
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• v.13 no.4
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• pp.395-405
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• 2001

A test program was conducted on seismic-resistant steel moment connections constructed using Reduced Beam Sections with beam web openings. In the connection, in order to enhance ductility capacity under severe cyclic loads, a portion of the beam web near the beam-to-column connection is cut out instead of the beam flange as in dogbone connections. A total of 4 large scale specimens were tested in this program. The specimens were all made using $H-458{\times}417{\times}30{\times}50$ sections for the columns and $H-792{\times}300{\times}14{\times}22$ sections for the beams. Test specimens showed excellent performance similar to that of dogbone connections.