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19 pages, 12108 KiB

Open AccessArticle

Geometric Imperfection Simulations in Cee-Shape Cold-Formed Steel Members Based on Newly Developed Machine-Vision Inspection Techniques

by Hanbo Guan, Xi Zhao, Pengfei Du and Xiaoyan Sun

Buildings 2023, 13(11), 2786; https://doi.org/10.3390/buildings13112786 - 6 Nov 2023

Viewed by 1127

Abstract

This paper insightfully studies geometric imperfection simulations of cee-section CFS members from laser-based measurements. A machine-vision imperfection inspection technique is first developed where an algorithm is implemented to automate imperfection characterization from volumetric data. The measured imperfections are statistically analyzed and resemble past [...] Read more.

This paper insightfully studies geometric imperfection simulations of cee-section CFS members from laser-based measurements. A machine-vision imperfection inspection technique is first developed where an algorithm is implemented to automate imperfection characterization from volumetric data. The measured imperfections are statistically analyzed and resemble past measurements from other researchers. Two imperfection simulation approaches are studied, i.e., the modal imperfection simulation method and the 1D spectral simulation method, where strength performance and deformation are predicted from finite element analysis. The analysis results are compared with those of testing. The 1D spectral simulation method is superior where stochasticity and regularity of real im-perfection can be properly addressed. The study provides feasible access to imperfection simulations of cee-section CFS members that other researchers can directly apply. The prediction results can aid the future direct analysis and design of CFS members. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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25 pages, 18378 KiB

Open AccessArticle

Digital Twin-Based Numerical Simulation Method for Cee-Shape Cold-Formed Steel Members

by Pengfei Du, Xi Zhao, Zhidong Zhang, Xiaoyan Sun and Gang Du

Buildings 2023, 13(9), 2388; https://doi.org/10.3390/buildings13092388 - 20 Sep 2023

Cited by 1 | Viewed by 1158

Abstract

Cold-formed steel (CFS) structures are widely used in construction and infrastructure due to their lightweight and high-strength properties. However, their thin-walled nature makes them geometrically sensitive to compressive loading. The Digital Twin (DT)-based numerical simulation method is developed using the actual geometries of [...] Read more.

Cold-formed steel (CFS) structures are widely used in construction and infrastructure due to their lightweight and high-strength properties. However, their thin-walled nature makes them geometrically sensitive to compressive loading. The Digital Twin (DT)-based numerical simulation method is developed using the actual geometries of CFS shapes, which are acquired by a 3D laser scanner. The DT-based numerical simulation incorporates the reconstructed measurement point clouds into the finite element modeling, ensuring that actual geometric features are retained. A series of tests, including material and axial compression testing, are conducted to validate the modeling parameters, such as mesh sizes and boundary conditions. The advantages of the DT-based numerical simulation method are highlighted compared to the traditional CFS member numerical simulation, which incorporates only the first mode of geometric imperfection. Additionally, DT-based numerical simulations offer more accurate load capacities and deformation predictions. Moreover, the automated and validated DT-based numerical simulation demonstrates prevalence in modeling efficiency and computation effectiveness. The DT-based numerical simulation method holds potential for application in smart structural analysis, where accurate geometries derived from extensive measurement point clouds are integrated into numerical modeling. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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16 pages, 7213 KiB

Open AccessArticle

Experimental Study on the Seismic Performance of L-Shaped CFST Columns in Different Combinations

by Dongji Han, Zhong Tao, Wahab Abdul Ghafar, Md Mehedi Hasan, Weichao Xiao, Tao Wang, Kun Zhou and Hongye Dai

Buildings 2023, 13(9), 2320; https://doi.org/10.3390/buildings13092320 - 13 Sep 2023

Viewed by 1683

Abstract

L-shaped concrete-filled steel tubular (CFST) columns represent a valuable structural element with an L-shaped cross-section, primarily employed in the corner columns of framed structures. These columns offer several advantages, including space efficiency by avoiding column protrusion, robust mechanical properties, high load-bearing capacity, ductility, [...] Read more.

L-shaped concrete-filled steel tubular (CFST) columns represent a valuable structural element with an L-shaped cross-section, primarily employed in the corner columns of framed structures. These columns offer several advantages, including space efficiency by avoiding column protrusion, robust mechanical properties, high load-bearing capacity, ductility, and efficient utilization of internal building space. This article presents the outcomes of an experimental investigation into the seismic behavior of L-shaped CFST columns. The experimental study investigated the seismic performance of nine L-shaped CFST columns while considering different cross-sectional dimensions, their combinations, and varying levels of confinement. The results obtained from this study indicate that L-shaped CFST columns possess favorable seismic performance characteristics. However, there exists the potential for significant improvement by modifying certain parameters. Enhancements in seismic performance were observed when increasing the cross-sectional dimensions of the column and the length of its legs. The use of steel tubes and the provision of adequate confinement also demonstrated notable benefits. Moreover, the better arrangement of steel tubes within the column positively influenced seismic performance. These findings can potentially inform and enhance the design of L-shaped CFST columns, rendering them more resilient to seismic forces. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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14 pages, 4350 KiB

Open AccessArticle

Experimental Research on the Cold-Forming Effect of Cold-Formed Thick-Walled Steel

by Xiaochao Fu, Wenjing Xu, Shaole Yu and Xujiang Mei

Buildings 2023, 13(5), 1201; https://doi.org/10.3390/buildings13051201 - 30 Apr 2023

Cited by 2 | Viewed by 1847

Abstract

To study the cold-forming effect on the yield strength distribution of cold-formed thick-walled steel, material tensile tests and axial compression tests were conducted on steel-lipped channels. To undertake the material tensile tests, five types of cold-formed lipped channel sections with varied thicknesses and [...] Read more.

To study the cold-forming effect on the yield strength distribution of cold-formed thick-walled steel, material tensile tests and axial compression tests were conducted on steel-lipped channels. To undertake the material tensile tests, five types of cold-formed lipped channel sections with varied thicknesses and nominal yield strengths were selected. The material test samples were taken from the web, flange, curled edge, and corner of the lipped channel sections, respectively. Next, a corresponding distribution model for the yield strength of cold-formed thick-walled lipped channel sections was developed. Following this, axial compression tests of five short columns with the same section as the coupon tests were conducted to further investigate the cold-forming effect. Finally, the results from the short column tests, the results based on the proposed yield strength distribution model, and the results calculated for related codes in various countries were compared. These revealed that the yield strength distribution, bearing capacity, and ductility were considerably influenced by the cold-forming effect and mainly depended on the width-to-thickness ratio (h/t) of the plate involved. When h/t was less than 34, the curve slowly decreased after reaching the peak load and had good ductility. Conversely, when h/t was greater than 71, local buckling had an obvious influence on the bearing capacity of the specimen, and the column ductility was poor. Overall, the results based on the Chinese code GB 50018-2002 were closest to the experimental values with the smallest variation coefficient, and therefore this code has the best applicability. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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18 pages, 4295 KiB

Open AccessArticle

Theoretical Study and Nonlinear Finite Analysis of Four-Line Restoring Force Model for Double-Superimposed Slab Shear Walls

by Dawei Zhang, Binhui Huang, Yujian Zhang, Shaole Yu and Junhao Bie

Buildings 2023, 13(3), 749; https://doi.org/10.3390/buildings13030749 - 13 Mar 2023

Cited by 5 | Viewed by 1419

Abstract

This paper is concerned with the seismic behavior of a superimposed slab shear wall. Based on the test results of the specimens under low cyclic reversal loading, the formulas with respect to the top displacement and capacity of a shear wall in the [...] Read more.

This paper is concerned with the seismic behavior of a superimposed slab shear wall. Based on the test results of the specimens under low cyclic reversal loading, the formulas with respect to the top displacement and capacity of a shear wall in the consecutive loading process are derived. The concrete grade differentiation between the prefabricated layer and the cast-in-site layer of the shear wall is considered to improve the calculating precision. With the help of these equations, the extent of participation of the prefabricated concrete layers in the different loading stages is revealed, demonstrating a great confirmation of the test results. Two ideal conditions, utterly with and without connective effect between a combined interface, are considered to investigate the action of the bond–slip effect. On this basis, the finite element analysis is completed in the framework of OpenSees. Its quadrilinear restoring force model, with the consideration of the stiffness degradation and pinching effect, is established in this paper by various feature points from the theoretical derivation of capacities in different loading stages. The rationality of the restoring force model of the shear wall is testified by the satisfactory agreement of the test results and simulation results. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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19 pages, 8540 KiB

Open AccessArticle

Out-of-Plane Dynamic Response of Elliptic Curved Steel Beams Based on the Precise Integration Method

by Xiaofei Li, Haosen Zhai and Dongyan Zhao

Buildings 2023, 13(2), 368; https://doi.org/10.3390/buildings13020368 - 28 Jan 2023

Cited by 1 | Viewed by 1575

Abstract

The dynamic response of curved steel beams has long been a research focus in curved bridges. The formula for the dynamic response under a moving load was derived according to the basic principles of the precise integration method. Combined with the necessary conditions [...] Read more.

The dynamic response of curved steel beams has long been a research focus in curved bridges. The formula for the dynamic response under a moving load was derived according to the basic principles of the precise integration method. Combined with the necessary conditions of this method, the stiffness matrix of a variable-curvature beam was obtained using matrix inversion, and the mass matrix of the structure was obtained using the concentrated mass method. The dynamic response of the structure was obtained by applying moving loads and masses at different speeds to the curved beam. Finite element simulation and laboratory curved-beam models of the variable-curvature steel beam were established. By comparing the laboratory measurement results against the theoretical data obtained in this study, we propose that our theory has practical engineering significance. It can be used as a theoretical basis for the study of variable curvature steel beam structures and for guiding the construction of curved beams. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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25 pages, 26553 KiB

Open AccessArticle

Study on Restoring Force Model of Cold-Formed Thin-Walled Steel Lipped Channel Beam-Columns under Cyclic Load

by Xingyou Yao, Jiabao Yang and Yanli Guo

Buildings 2023, 13(1), 114; https://doi.org/10.3390/buildings13010114 - 1 Jan 2023

Cited by 6 | Viewed by 1654

Abstract

In order to study the hysteretic behavior and restoring force model of cold-formed thin-walled steel (CFTWS) lipped channel beam-column, a finite element analysis (FEA) model considering the material and geometric nonlinearity and the influence of the initial geometric imperfection under cyclic loading was [...] Read more.

In order to study the hysteretic behavior and restoring force model of cold-formed thin-walled steel (CFTWS) lipped channel beam-column, a finite element analysis (FEA) model considering the material and geometric nonlinearity and the influence of the initial geometric imperfection under cyclic loading was established by ABAQUS software. Based on the verified FEA model, the hysteretic behavior of CFTWS lipped channel beam-column members with different influencing factors was analyzed by parameterization. The effects of width-to-thickness ratio, axial compression ratio and slenderness ratio on ductility, energy dissipation capacity and stiffness degradation were studied. Based on the results of parameter analysis and the theoretical and regression analysis, the calculation formula of each characteristic point of the trilinear skeleton curve of beam-column member was proposed. Based on the hysteresis curve analysis of beam-column member, the simplified restoring force model (SRFM) of CFTWS lipped channel beam-column was established according to different hysteresis rules for the different buckling modes. The results showed that the SRFM under different buckling modes was in good agreement with the hysteretic curve of FEA, which can better indicate the hysteretic behavior of the member. The proposed SRFM was accurate and applicable, and can provide a fundament for the seismic analysis of the CFTWS lipped channel beam-column. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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23 pages, 9577 KiB

Open AccessArticle

Performance of Grouting Sleeve-Connected Prefabricated Beams Subjected to Impact Loading

by Longyun Zhou, Xiaojun Li and Qiushi Yan

Buildings 2022, 12(12), 2146; https://doi.org/10.3390/buildings12122146 - 6 Dec 2022

Cited by 7 | Viewed by 2058

Abstract

The potential of accidental loads such as explosions and impacts cannot be overlooked given the widespread use of precast concrete (PC) buildings. However, research on the impact resistance of reinforced concrete precast beams is limited. In order to explore the dynamic behavior of [...] Read more.

The potential of accidental loads such as explosions and impacts cannot be overlooked given the widespread use of precast concrete (PC) buildings. However, research on the impact resistance of reinforced concrete precast beams is limited. In order to explore the dynamic behavior of PC beams connected by grouted sleeves under impact loads, this work developed a numerical model based on the finite element program LS-DYNA. First, the experimental process was described in detail, and the numerical model was evaluated and calibrated according to the experimental data. Then, parameters such as impact location, concrete strength of precast section and stirrup rate of cast-in-place area were studied. Finally, a simpler model based on equal high-frequency impulse impact force was suggested, and the viability of a single-degree-of-freedom model theory was proved for the dynamic analysis of PC simply supported beams subjected to impact loading. According to the findings, the interface of precast concrete and cast-in-place concrete is the weak point of the PC beam, which is prone to shear damage under impact loads. Second, when the middle of the cast-in-place part of the PC beam is impacted, wide cracks from the bottom to the top are quite likely to form. As a result, the most disadvantageous impact position for PC beams is in the middle of the cast-in-place portion. Although increasing the concrete strength of the precast section can reduce crack formation, it has minimal influence on the interface’s shear resistance. Furthermore, increasing the stirrup rate in the post-cast portion can increase the overall shear resistance of the PC beams. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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Graphical abstract

21 pages, 23558 KiB

Open AccessArticle

Free-Form Shape Optimization of Advanced High-Strength Steel Members

by Lingfeng Yin, Tianyang Deng, Yu Niu and Zhanjie Li

Buildings 2022, 12(12), 2101; https://doi.org/10.3390/buildings12122101 - 1 Dec 2022

Cited by 1 | Viewed by 2142

Abstract

The high yielding strength of advanced high-strength steel (AHSS) provides great opportunities for cold-formed steel (CFS) members with much higher load-carrying capability. However, if manufactured into the traditional cross-section shapes, such as C and Z, the material advantage cannot be fully exploited due [...] Read more.

The high yielding strength of advanced high-strength steel (AHSS) provides great opportunities for cold-formed steel (CFS) members with much higher load-carrying capability. However, if manufactured into the traditional cross-section shapes, such as C and Z, the material advantage cannot be fully exploited due to the cross-section instabilities. The purpose of this study was to establish a shape optimization method for cold-formed sections with AHSS and explore the potentially material efficiency that AHSS could provide to these sections in terms of their axial strength. In this study, the insights provided from the elastic buckling analysis and nonlinear finite element (FE) simulations of a set of traditional CFS sections were employed to determine the appropriate section size and length for optimization. Then, the optimization method was established using the particle swarm optimization (PSO) algorithm with the integration of computational analysis through CUFSM and the design approach (i.e., the direct strength method, DSM). The objective function is the maximum axial strength of the CFS sections manufactured with AHSS using the same amount of material (i.e., the same cross-section area). Finally, the optimal sections were simulated and verified by FE analysis, and the characteristics of the optimal cross-sections were analyzed. Overall, the optimization method in this paper achieved good optimization results with greatly improved axial strength capacity from the optimal sections. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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Graphical abstract

16 pages, 18742 KiB

Open AccessArticle

Experimental Study of the Seismic Behavior of a Prefabricated Low-Rise Steel Frame Structure with Hinged Joints

by Bin Jia, Wenying Zhang, Ti Wu, Yuanqing Wang and Shaole Yu

Buildings 2022, 12(12), 2088; https://doi.org/10.3390/buildings12122088 - 29 Nov 2022

Cited by 1 | Viewed by 2355

Abstract

This paper investigated the seismic behavior of a prefabricated steel braced frame structure with hinged joints. Six steel frame specimens with different enclosure walls were tested under pseudo-static loading. The results indicated that the vertical load of the hinged braced frame system was [...] Read more.

This paper investigated the seismic behavior of a prefabricated steel braced frame structure with hinged joints. Six steel frame specimens with different enclosure walls were tested under pseudo-static loading. The results indicated that the vertical load of the hinged braced frame system was mainly resisted by the beam and column members, and the lateral stiffness was completely provided by the bracing members. The final failure mode of all specimens was the failure of the bracings, while the beam-column members and the joints remained largely intact. The rigidly braced specimen was mainly damaged by buckling, yielding, and tearing, and the flexibly braced specimen was mostly damaged by buckling, yielding, and node failure. The energy dissipation of the specimens primarily depended on lateral force-resistant components such as braces and enclosure walls. Different building envelopes exert significant effects on the lateral stiffness and energy dissipation capacity of the structure. The ductility coefficient of all specimens ranged between 1.4 and 1.9, which indicates that the structural system mainly relies on lateral stiffness and elastic deformation to resist earthquakes, rather than structural ductility. The proposed prefabricated steel frame system with hinged connections has wide prospects of application in economically underdeveloped areas because of its convenience in transportation and installation. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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20 pages, 12295 KiB

Open AccessArticle

Research on the Simplified Method of Nonlinear Finite Element Analysis for CFS-SPR Connections

by Ailin Zhang, Zhiqiang Xie, Leilei Shi, Yanxia Zhang, Daxing Zhou and Xiangdong Zhang

Buildings 2022, 12(11), 1925; https://doi.org/10.3390/buildings12111925 - 8 Nov 2022

Cited by 1 | Viewed by 2036

Abstract

This study reviewed some simplified methods of finite element analysis (FEA) for connections in cold-formed steel (CFS) structure, and summarized eight simplified methods divided into three categories. Shear performance tests were performed for six groups of self-piercing riveted (SPR) connection in CFS. A [...] Read more.

This study reviewed some simplified methods of finite element analysis (FEA) for connections in cold-formed steel (CFS) structure, and summarized eight simplified methods divided into three categories. Shear performance tests were performed for six groups of self-piercing riveted (SPR) connection in CFS. A constitutive model of shear behavior for SPR connections was proposed, which was simplified from the load–displacement curve of shear performance test results. The models of SPR connection were established in ABAQUS by the eight simplified methods, and then the FEA results and the test results were compared. The applicable scope of each simplified model was explored, and a simplified method of FEA that was most suitable for the shear behavior of the CFS-SPR connection was proposed. Moreover, the shear performance test of the CFS shear wall with SPR was conducted by considering the rivet spacing, and failure modes and load–deformation curves were obtained. On this basis, numerical models of the CFS-SPR connection shear wall were established. By comparing the test results and the FEA results for the CFS-SPR connection shear wall, the feasibility of a simplified method of FEA applied to the CFS-SPR connection was verified. The main failure modes of the CFS-SPR connection were that the rivet tail pulled out from the bottom sheet and the rivet head pulled over from the top sheet. The SPR connection of the CFS frame could be simplified with a pin or a fastener element, and the SPR connection between the steel frame and the sheathing could be simulated by a Cartesian connector or a Spring2 element. The FEA results were highly similar to the test results for the CFS-SPR shear wall. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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21 pages, 6402 KiB

Open AccessArticle

Load Distribution Optimization of Steel Storage Rack Based on Genetic Algorithm

by Tianyang Deng, Yu Niu, Lingfeng Yin, Zhiqiang Lin and Zhanjie Li

Buildings 2022, 12(11), 1782; https://doi.org/10.3390/buildings12111782 - 24 Oct 2022

Cited by 1 | Viewed by 2167

Abstract

The distribution of load has high uncertainty, which is the main cause of a rack structure’s instabilities. The objective of this study was to identify the most unfavorable and favorable load distributions on steel storage racks with and without bracings under seismic loading [...] Read more.

The distribution of load has high uncertainty, which is the main cause of a rack structure’s instabilities. The objective of this study was to identify the most unfavorable and favorable load distributions on steel storage racks with and without bracings under seismic loading through a stochastic optimization—a genetic algorithm (GA). This paper begins with optimizing the most unfavorable and favorable load distributions on the steel storage racks with and without bracings using GA. Based on the optimization results, the failure position and seismic performance influencing factors, such as the load distributions on the racks and at hazardous positions, are then identified. In addition, it is demonstrated that the maximum stress ratio of the uprights under the most unfavorable load distribution is higher than that under the full-load normal design, and it is not the case that the higher the center of gravity the more dangerous the steel storage rack is, demonstrating that the load distribution pattern has a significant impact on the structural safety of steel storage racks. The statistics of the distributions of the load generated during the optimization of the GA and the contours of the probability distributions of the load are generated. Combining the probability distribution contours and the GA’s optimization findings, the “convex” distribution hazard model and the “concave” distribution safety model for a steel storage rack with bracings are identified. In addition, the features of the distribution hazard model and the load distribution safety model are also identified for steel storage racks without bracings. Full article

(This article belongs to the Special Issue Steel Structures and Sustainable Building Structure System)

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