Research

23 pages, 7749 KiB

Open AccessArticle

Design and Performance Study of a Six-Leg Lattice Tower for Wind Turbines

by Miao Li, Hao Li and Yang Wen

Buildings 2024, 14(4), 965; https://doi.org/10.3390/buildings14040965 - 01 Apr 2024

Viewed by 508

A new type of spherical node was used to design a laboratory-scale prototype of a six-leg lattice of steel tubes and concrete for application as a wind turbine tower. Repeated load tests were performed on the prototype tower for several weeks to evaluate [...] Read more.

A new type of spherical node was used to design a laboratory-scale prototype of a six-leg lattice of steel tubes and concrete for application as a wind turbine tower. Repeated load tests were performed on the prototype tower for several weeks to evaluate its load-carrying capacity, deformation, energy consumption, stress distribution based on damage patterns, hysteresis curves, skeleton curves, strength, and stiffness degradation curves. The findings indicated that the prototype tower underwent thread damage to the high-strength bolts of the inclined web and weld damage between the inclined web and sealing plate. Although the stress differences between different measurement points were significant, the stress values were small at most of the measurement points. The maximum equivalent stress value was 294 MPa, which appeared in the middle layer of the BC surface. The P-Δ hysteresis curve had an inverse “S”-shape, and the bearing capacity was high. The maximum energy dissipation appeared in the 1.75 Δ_y loading stage. The peak load of the specimen can reach 376.2 kN, and the corresponding peak displacement is 37 mm. However, the average ductility coefficient was only 2.33, indicating little plastic deformation. The maximum strain of the tower column foot is 1800 με, and the force of the inclined web member in the middle layer is the largest. The strain of the transverse web bar increased significantly after the tower yielded, which contributed to maintaining the integrity of the structure. Full article

(This article belongs to the Special Issue Novel Steel and Steel-Concrete Composite Structures)

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20 pages, 7994 KiB

Open AccessArticle

Evaluation of Hysteretic Performance of Horizontally Placed Corrugated Steel Plate Shear Walls with Vertical Stiffeners

by Ruomin Wu, Zhengping Hu and Jingzhong Tong

Buildings 2024, 14(3), 779; https://doi.org/10.3390/buildings14030779 - 13 Mar 2024

Viewed by 497

Abstract

Corrugated steel plate shear walls (CSPSWs) have been widely utilized as lateral-resistant and energy-dissipating components in multistory and high-rise buildings. To improve their buckling stability, shear resistance, and energy-dissipating capacity, stiffeners were added to the CSPSW, forming stiffened CSPSWs (SCSPSWs). Evaluating the hysteretic [...] Read more.

Corrugated steel plate shear walls (CSPSWs) have been widely utilized as lateral-resistant and energy-dissipating components in multistory and high-rise buildings. To improve their buckling stability, shear resistance, and energy-dissipating capacity, stiffeners were added to the CSPSW, forming stiffened CSPSWs (SCSPSWs). Evaluating the hysteretic performances of SCSPSWs is crucial for guiding seismic design in engineering practice. In this paper, the dissipated energy values of the SCSPSWs with different parameters were calculated. Based on the obtained dissipated energy values, the elastoplastic design theory of stiffeners was established, and the evaluation of the hysteretic performance of the SCSPSWs was provided. Firstly, a finite element (FE) model for analyzing the hysteretic performance of the SCSPSWs was developed and validated against hysteretic tests of the CSPSW conducted by the authors previously. Subsequently, using the validated FE model, approximately 81 examples of SCSPSWs subjected to cyclic loads were analyzed. Hysteretic curves, skeleton curves, secant stiffness, stress distribution, and out-of-plane displacement were obtained and examined. Results indicate that increasing the bending rigidity of the vertical stiffeners and the thickness of the corrugated steel plates, as well as reducing the aspect ratio of the corrugated steel plates, is beneficial for enhancing the load-carrying capacity, stiffness, and energy dissipation capacity of the SCSPSWs. Finally, the transition rigidity ratio μ_0,h was proposed to describe the hysteretic performances. When the rigidity ratio is μ = 50, dissipated energy values of the SCSPSW could achieve 95% of the corresponding maximum dissipated energy. In engineering practice, hence, it is recommended to use stiffeners with a rigidity ratio of μ ≥ μ_0,h = 50 to ensure desirable energy-dissipating capacity in the SCSPSW. Full article

(This article belongs to the Special Issue Novel Steel and Steel-Concrete Composite Structures)

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20 pages, 10088 KiB

Open AccessArticle

Elastic Local Buckling and Width-to-Thickness Limits of I-Beams Incorporating Flange–Web Interactions

by Lei Zhang, Qianjing Zhang, Genshu Tong and Qunhong Zhu

Buildings 2024, 14(2), 347; https://doi.org/10.3390/buildings14020347 - 26 Jan 2024

Viewed by 493

Abstract

The local buckling of I-section beams is investigated with the flange–web interactions taken into account. Using numerical results employing the finite element method and a semi-analytical method, the flange–web interactions of I-sections and their effects on the buckling stresses are explored and discussed. [...] Read more.

The local buckling of I-section beams is investigated with the flange–web interactions taken into account. Using numerical results employing the finite element method and a semi-analytical method, the flange–web interactions of I-sections and their effects on the buckling stresses are explored and discussed. Simple approximate solutions for the buckling coefficients of the web and compressive flange are developed using the energy method, and they are refined using the numerical results. Using the simple solutions for buckling coefficients, the limits for the width-to-thickness ratio of the compressive flange and web of I-section beams are then proposed. Comparisons with the results of existing solutions and provisions in design codes imply that the proposed solutions are superior in predicting the limits for width-to-thickness ratios, and they are capable of accounting for the flange–web interactions at the local buckling of I-section beams. Full article

(This article belongs to the Special Issue Novel Steel and Steel-Concrete Composite Structures)

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17 pages, 3068 KiB

Open AccessArticle

Optimal Design of a Novel Large-Span Cable-Supported Steel–Concrete Composite Floor System

by Meiwen Tan, Yifan Wu, Wenhao Pan, Guoming Liu and Wei Chen

Buildings 2024, 14(1), 113; https://doi.org/10.3390/buildings14010113 - 31 Dec 2023

Viewed by 925

Abstract

This paper optimizes the design of a novel large-span cable-supported steel–concrete composite floor system in a simply supported single-span, single-strut configuration, aiming for cost-effective solutions and minimal steel consumption. The optimization considers various cross-sectional dimensions, adhering to building standards and engineering practices, and [...] Read more.

This paper optimizes the design of a novel large-span cable-supported steel–concrete composite floor system in a simply supported single-span, single-strut configuration, aiming for cost-effective solutions and minimal steel consumption. The optimization considers various cross-sectional dimensions, adhering to building standards and engineering practices, and is based on a non-linear programming (NLP) algorithm. Parameters of live loads ranging from 2 to 10 kN/m² and spans from 20 to 100 m are considered. The optimization results show that cable-supported composite floors with a single strut exhibit robust economic feasibility for spans of less than 80 m and live loads under 8 kN/m². Compared to conventional composite floors with welded I-beams, the cable-supported system offers more cost-effective cross-sections and reduces steel consumption. The savings in economically equivalent steel consumption range from 20% to 60%. Discussion on the area ratio of cables to steel beam in the optimal cross-section reveals that the secondary load-bearing system (i.e., bending of the main beam with an effective span length of L/2) may require more steel in cases of ultra-large spans. Therefore, the economical efficiency of cable-supported composite beams with multiple struts and smaller effective span lengths warrants further exploration in future studies. Full article

(This article belongs to the Special Issue Novel Steel and Steel-Concrete Composite Structures)

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12 pages, 1577 KiB

Open AccessArticle

Optimal Design of Crossbeam Stiffness Factor in Bridge Towers Using a Reliability-Based Approach

by Wenhao Pan, Yi Zhu, Chuanhao Zhao and Jingzhong Tong

Buildings 2023, 13(8), 2095; https://doi.org/10.3390/buildings13082095 - 17 Aug 2023

Viewed by 791

Abstract

Optimal design of the crossbeam is essential for the economical design of bridge towers as the crossbeam could considerably enhance the lateral stiffnesses of these towers by providing a special bracing for the tower columns. By using a reliability-based approach, this paper studies [...] Read more.

Optimal design of the crossbeam is essential for the economical design of bridge towers as the crossbeam could considerably enhance the lateral stiffnesses of these towers by providing a special bracing for the tower columns. By using a reliability-based approach, this paper studies the optimal design of the crossbeam stiffness factor in bridge towers; this is defined as a dimensionless crossbeam stiffness relative to the tower column stiffness. A novel second-order matrix stiffness method (MSM) is applied to obtain a closed-form solution of the lateral stiffness of the bridge tower. The structural second-order stiffness matrix consists of combinations of the second-order element stiffness matrices and coordinate transformations. Subsequently, a reliability analysis to study the optimal design of the bridge tower is performed by considering the uncertainties arising from the design and construction of the bridge tower. The lateral stiffness of the bridge tower is set as an objective function while the total usage of materials is set as a constraint condition. Then, the influence of the crossbeam stiffness factor on the lateral stiffness of the bridge tower, including the fragility curve and the probabilistic behavior, is examined. Based on the reliability analysis, optimal design recommendations on the crossbeam stiffness of the bridge tower are presented. Full article

(This article belongs to the Special Issue Novel Steel and Steel-Concrete Composite Structures)

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17 pages, 6191 KiB

Open AccessArticle

Flexural Experiment and Design Method of Steel-Wire-Enhanced Insulation Panels

by Jinliang Jiang, Linyi Xu, Enyuan Zhang, Jian Hou and Jingzhong Tong

Buildings 2023, 13(8), 1978; https://doi.org/10.3390/buildings13081978 - 02 Aug 2023

Viewed by 754

Abstract

A new type of non-dismantling composite insulation panel, namely a steel-wire-enhanced insulation panel, was proposed. Compared to traditional organic insulation panels, the construction procedure is reduced, and the fire resistance is improved. The flexural performance was explored experimentally and numerically to evaluate its [...] Read more.

A new type of non-dismantling composite insulation panel, namely a steel-wire-enhanced insulation panel, was proposed. Compared to traditional organic insulation panels, the construction procedure is reduced, and the fire resistance is improved. The flexural performance was explored experimentally and numerically to evaluate its ability to withstand lateral pressure when it was used as the formwork of a cast-in-place concrete wall. First, 6 groups of 12 specimens of steel-wire-enhanced insulation panels were conducted under 2 loading modes: 3-point bending loading and 4-point bending loading. The failure modes of these specimens included a straight crack at the bottom of the panel and the yielding of steel wire. The test results showed that the maximum bending moment of the specimens with an 80 mm thickness could reach 2.415 kN·m. Second, finite element (FE) models were developed for the steel-wire-enhanced insulation panels by ABAQUS, which were validated by the experimental results. Third, a parametric study with parameters, including the thermal insulation cover, the square gird spacing of the steel wire mesh, and the diameter of the steel wire, was performed. It was observed that the insulation cover had a significant effect on the flexural capacity in the simulated range. Finally, theoretical formulas for panel stiffness and flexural capacity were presented, which can predict the bending performance more conservatively compared to the experimental results. The research and analysis of this study could offer a valuable reference for designing this panel in practical applications. Full article

(This article belongs to the Special Issue Novel Steel and Steel-Concrete Composite Structures)

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22 pages, 11883 KiB

Open AccessArticle

Elastic Local Buckling of I-Sections under Axial Compression Incorporating Web–Flange Interaction

by Qianjing Zhang, Lei Zhang, Yujia Zhang, Yufei Liu and Jia Zhou

Buildings 2023, 13(8), 1912; https://doi.org/10.3390/buildings13081912 - 27 Jul 2023

Cited by 1 | Viewed by 604

Abstract

The local buckling of I-section columns is investigated in this paper, where the interaction between the web and flanges is taken into account. An analytical method is first developed based on the classical theory of the elastic buckling of thin plates, with which [...] Read more.

The local buckling of I-section columns is investigated in this paper, where the interaction between the web and flanges is taken into account. An analytical method is first developed based on the classical theory of the elastic buckling of thin plates, with which the main parameters affecting the interaction between the web and flanges are analyzed. The interactive behaviors of the buckling deformations of the I-section with different parameters are then revealed by employing finite element analyses. Simple approximate solutions for the buckling coefficients of the web and flanges are proposed using the energy method, which is capable of providing very accurate predictions compared to the analytical results. Using the simple solutions for buckling coefficients, the limits for the width-to-thickness ratio of I-section columns are proposed. Comparisons between the existing solutions and provisions in design codes indicate that the proposed limits for width-to-thickness ratio are capable of precisely considering the web–flange interaction at the local buckling of I-section columns. Full article

(This article belongs to the Special Issue Novel Steel and Steel-Concrete Composite Structures)

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26 pages, 9868 KiB

Open AccessArticle

Model Analysis of Steel Frame Structures Considering Interactions between Racks and the Frame

by Weiguang Zhang, Chaoqun Yu and Genshu Tong

Buildings 2023, 13(7), 1732; https://doi.org/10.3390/buildings13071732 - 07 Jul 2023

Viewed by 1155

Abstract

The steel racks on the floor are seen as live loads in the current design process, ignoring the interaction with the supporting frames. In this paper, multiple steel racks with different masses and stiffnesses are placed on the first floor of a two-story [...] Read more.

The steel racks on the floor are seen as live loads in the current design process, ignoring the interaction with the supporting frames. In this paper, multiple steel racks with different masses and stiffnesses are placed on the first floor of a two-story main structure to form different real structures (RS). The corresponding simplified structures (SS) are frames with the mass of steel racks concentrated on the first floor of the main structure. Modal analysis is performed to analyze the relationship between the periods of RS and SS in the cross-aisle direction. Firstly, the beams on the first floor are assumed to be infinitely rigid. The relationship between the periods of the rack T_Rk, the simplified structure T_SS, and the real structure T_RS under different mass ratios α is established, and an accurate equation relating T_RS with T_Rk and T_SS is proposed. Moreover, by considering the influence of finite beam stiffness, the interaction between racks and the main structure is studied by constructing different analysis models. The effect of the main structure on the racks is reflected by a combined system consisting of beams and racks. A modified model, distinguished from SS by considering the effect of no-mass racks, is constructed to study the strengthening effect of the racks on the first-floor beams. The effect of the top connecting bars is also analyzed. Full article

(This article belongs to the Special Issue Novel Steel and Steel-Concrete Composite Structures)

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18 pages, 5893 KiB

Open AccessArticle

Development of Hybrid Machine Learning Models for Predicting Permanent Transverse Displacement of Circular Hollow Section Steel Members under Impact Loads

by Sy Hung Mai, Duc Hanh Nguyen, Viet-Linh Tran and Duc-Kien Thai

Buildings 2023, 13(6), 1384; https://doi.org/10.3390/buildings13061384 - 26 May 2023

Cited by 6 | Viewed by 1309

Abstract

The impact effect is a crucial issue in civil engineering and has received considerable attention for decades. For the first time, this study develops hybrid machine learning models that integrate the novel Extreme Gradient Boosting (XGB) model with Particle Swam Optimization (PSO), Grey [...] Read more.

The impact effect is a crucial issue in civil engineering and has received considerable attention for decades. For the first time, this study develops hybrid machine learning models that integrate the novel Extreme Gradient Boosting (XGB) model with Particle Swam Optimization (PSO), Grey Wolf Optimizer (GWO), Moth Flame Optimizer (MFO), Jaya (JA), and Multi-Verse Optimizer (MVO) algorithms for predicting the permanent transverse displacement of circular hollow section (CHS) steel members under impact loads. The hybrid machine learning models are developed using data collected from 357 impact tests of CHS steel members. The efficacy of hybrid machine learning models is evaluated using three performance metrics. The results show that the GWO-XGB model achieves high accuracy and outperforms the other models. The values of R², RMSE, and MAE obtained from the GWO-XGB model for the test set are 0.981, 2.835 mm, and 1.906 mm, respectively. The SHAP-based model explanation shows that the initial impact velocity of the indenter, the impact mass, and the ratio of impact position to the member length are the most sensitive parameters, followed by the yield strength of the steel member and the member length; meanwhile, member diameter and member thickness are the parameters least sensitive to the permanent transverse displacement of CHS steel members. Finally, this study develops a web application tool to help rapidly estimate the permanent transverse displacement of CHS steel members under impact loads. Full article

(This article belongs to the Special Issue Novel Steel and Steel-Concrete Composite Structures)

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