Structural Performance Research Articles

Impact of Eccentric Loading on the Structural Performance of Reinforced Concrete Pad Footings: An Experimental Study

Setting out of building footings are usually carried out using profile board. This method is usually not accurate in locating the position of columns. Hence, columns that are designed as a concentric columns to their respective footings ends up being columns having eccentricities to the pad footings that supports them. Since the stress distribution under pad footing with concentric column is different from that of pad footing with eccentric column, there is need to study the effect of these eccentricity on the load carrying capacity of the pad footing. In carrying out this work, four pad footings and a typical foundation were used. The pad footings were of sizes 230 mm x 230 mm x 150 mm, with columns of 150 mm x 150 mm cross-section. The first pad footing P1SH was pad footing with short column and zero eccentricity, the second pad footing P2SL was pad footing with slender column and zero eccentricity, the third pad footing P3SL was footing with slender column with 40 mm eccentricity, while the forth pad footing P4SL was footing with slender column with 80 mm eccentricity. The foundation comprises of sand which was contained in a sandbox. The sandbox was made of steel plate of dimensions 0.3 m × 0.3 m × 0.2 m of 4 mm thickness, was used to provide support for the foundation. The foundation was produced by compacting loose sand in three layers with 20 blows per layer in the steel box and with density of about 735 kg/m3. The pad footings were placed on top of the foundation contained in the sandbox, and together were placed on the loading plate of Universal Testing Machine (UTM). Compressive load was applied on each of the pad footings through the columns till failure occurred, using UTM. It was found out that pad footing P1SH have the highest load capacity of 261.25 kN, P2SL pad footing with load capacity of 124.24 kN, P3SL pad footing with load capacity of 39.34 kN, while P4SL pad footing with load capacity of 23.30 kN.

Surface modification of Cu-coated carbon fiber for improved mechanical performance of Acrylonitrile Butadiene Styrene composites using 3-Aminopropyl triethoxy silane

This study investigates the use of 3-Aminopropyl triethoxy silane as a surface modifier for Cu-coated Carbon Fibers. The modified fibers were subsequently incorporated into Acrylonitrile Butadiene Styrene matrix composites through melt blending and high-temperature compression molding. The research evaluates the effect of 3-Aminopropyl triethoxy silane on the interfacial structure and mechanical performance of these composites. Results demonstrate a substantial enhancement in the wettability and surface energy of Cu-coated Carbon Fibers, with the static contact angle reduced from 111.2° to 84.5° and surface energy increased from 44.67 mN·m−1 to 56.66 mN·m−1. These surface modifications contributed to an 82.7 % increase in tensile strength and a 76.4 % improvement in tensile modulus of the resultant composites.

A Simple Method to Evaluate the Bearing Capacity of Concrete-Filled Steel Tubes with Rectangular and Circular Sections: Beams, Columns, and Beam–Columns

This study investigates the behavior and capacity of concrete-filled steel tubes (CFTs) with rectangular and circular sections under various loading conditions: axial loads, pure-bending, and combined axial load-bending moments. A finite element-based numerical model is developed and validated against existing experimental data. Using an extensive databank generated from finite element analysis, this research proposes analytical empirical relations for determining the bearing capacity of rectangular and circular composite beams, columns, and beam–columns. These relations provide a direct, concise, and efficient method for calculating the ultimate strength of CFT members, making them valuable for engineering design. Comparisons between the proposed analytical results and previous experimental studies demonstrate the high accuracy of this method in analyzing rectangular and circular CFT member behavior. The findings contribute to a better understanding of CFT structural performance and offer practical tools for designers working with these composite elements.

Optimal design of vibration resistance of fiber-reinforced composite sandwich plates embedded in a viscoelastic square honeycomb core

This work focuses on investigating the optimal design of composite sandwich plates (FCSPs) with a viscoelastic square honeycomb core (VSHC). Firstly, using the cross-fill theory, the complex modulus technique, the first-order shear deformation theory, the minimum strain energy principle, and the Newmark-β method, a theoretical model of the VSHC-FCSPs under half-sine pulse excitation is formulated to calculate the inherent frequencies, the peak and vibration decay time of the transient response in time domain. The peak and vibration decay time are taken as the indexes of the anti-vibration performance. Considering an index of structural stiffness performance, the average value of the inherent frequencies is adopted to calculate the overall stiffness. After a set of literature validations and optimization validations, the multi-objective genetic algorithm is employed to study the optimization issue of VSHC-FCSPs. The optimization objectives are to minimize the three design variables of the transient response peak, vibration decay time, and reciprocal of overall stiffness. Then, the fiber laying angle of each layer, the core thickness ratio and the modulus ratio are assumed as optimization variables. Finally, the results with good vibration resistance and structural stiffness in the Pareto front are chosen as references, and these corresponding variations of the design variables and optimization objectives are obtained. The optimization results have revealed that the optimization variables corresponding to the intermediate points should be selected as references to improve the anti-vibration capacity and ensure the structural stiffness performance.

Effects of Anisotropic Mechanical Behavior on Nominal Moment Capability of 3D Printed Concrete Beam with Reinforcement

In this study, 3D-printed reinforced concrete beams were tested for flexural performance and compared with the analytical model based on the material test results. Two cementitious mixes (PSU and GCT) were designed for concrete printing and were mechanically tested and compared. Anisotropies in the compressive strength and modulus of elasticity of printed concrete were observed, applied to the analytical prediction of flexural bending behavior, and validated by actual test results. Significant differences between analytical predictions and experimental tests of the bending behaviors of the printed concrete beams were observed. Furthermore, higher compressive strengths and moduli of elasticity were observed when the loading direction was perpendicular to the printed layers or with the PSU mix. The effect of anisotropic mechanical properties on a reinforced beam was compared to the flexural bending tests for both mixes. The analytical model based on the material test results was compared to the flexural bending test results. The significant errors in the prediction of printed concrete’s structural performance, from 10% to 50%, suggest that factors other than reduced compressive strengths may influence the structural behaviors of printed concrete beams.

Superhydrophobic foamed concrete based on response surface method: Mix design and its potential application in roofing systems

This study employs the response surface method to optimize the mixture design of superhydrophobic foamed concrete. The study investigates the influence of calcium stearate (CS, dosage 1 %∼5 %), polydimethylsiloxane (PDMS, dosage 2 %∼8 %), and hydroxypropyl methylcellulose (HPMC, dosage 0.05 %∼0.2 %) on various properties of foamed concrete, including density, compressive strength, contact angle, and water absorption. Additionally, the research explores the application of superhydrophobic foamed concrete in integrated roofing systems and assesses its thermal and structural performance through finite element analysis. Results reveal that foamed concrete achieves a contact angle greater than 150° when formulated with a mix ratio of CS (3 %), PDMS (8 %), and HPMC (0.05 %), or CS (3 %), PDMS (5 %), and HPMC (0.125 %). A negative linear correlation between the heat transfer coefficient and the thickness of foamed concrete is found. Furthermore, the heat transfer coefficient is inversely related to the spacing between the concave and convex drainage boards. Specifically, for a toe spacing of 50 mm and foamed concrete thickness exceeding 70 mm, the heat transfer coefficient of the roof measures 0.788 W/(m²·K). When the roof thickness increases from 70 mm to 100 mm, the roof heat transfer coefficient drops to 0.69 W/(m2∙K). When the toe spacing is increased from 50 mm to 60 mm, the heat transfer coefficient of the roof drops sharply to about 0.66 W/(m2∙K) at the thickness of 50 mm. The insulation requirements for the roof are satisfactorily met to 0.8 W/(m²·K). Under applied roof loads, the maximum von Mises stress experienced by the integrated roof is 0.6 MPa at a toe spacing of 50 mm. With the increase of the roof thickness, the maximum value of the DAMAGEC damage coefficient gradually decreases from 0.3 to 0.17. The maximum damage position has always been at the weak position of the four corners, which is consistent with the actual use status. The research findings on superhydrophobic foamed concrete have significant theoretical and engineering application value. Moreover, the construction of an "insulation/hydrophobic integrated" roof system demonstrates the feasibility of an integrated roof system and the potential for insulation/hydrophobic integration in roof system construction.

A Mesoscale Comparative Analysis of the Elastic Modulus in Rock-Filled Concrete for Structural Applications

Rock-filled concrete (RFC) is an advanced construction material that integrates high-performance self-compacting concrete (HSCC) with large rocks exceeding 300 mm, providing advantages such as reduced hydration heat and increased construction processes. The elastic modulus of RFC is a critical parameter that directly influences its structural performance, making it vital for modern construction applications that require strength and stiffness. However, there is a scientific gap in understanding the effects of rock size, shape, arrangement, and volumetric ratio on this parameter. This study investigates these factors using mesoscale finite element models (FEMs) with spherical and polyhedral rocks. The results reveal that polyhedral rocks increase the elastic modulus compared to spherical rocks, enhancing RFC’s load-bearing capacity. Additionally, a 5% increase in the elastic modulus was observed when the rockfill ratio was increased from 50% to 60%, demonstrating a direct correlation between rock volume and mechanical performance. Furthermore, the elastic modulus rises significantly in the early stages of placement, followed by a gradual increase over time. Optimal rock sizes and a balanced mix of rock shapes allow for improved concrete flow and mechanical properties, making RFC a highly efficient material for construction. These findings offer valuable insights for designers and engineers looking to optimize RFC for structural applications.

Development of Scaffolds with Chitosan Magnetically Activated with Cobalt Nanoferrite: A Study on Physical-Chemical, Mechanical, Cytotoxic and Antimicrobial Behavior.

Background/Objectives: This study investigates the development of 3D chitosan-x-cobalt ferrite scaffolds (x = 5, 7.5, and 10 wt%) with interconnected porosity for potential biomedical applications. The objective was to evaluate the effects of magnetic particle incorporation on the scaffolds' structural, mechanical, magnetic, and biological properties, specifically focusing on their biocompatibility and antimicrobial performance. Methods: Scaffolds were synthesized using freeze-drying, while cobalt ferrite nanoparticles were produced via a pilot-scale combustion reaction. The scaffolds were characterized for their physical and chemical properties, including porosity, swelling, and mechanical strength. Hydrophilicity was assessed through contact angle measurements. Antimicrobial efficacy was evaluated using time kill kinetics and agar diffusion assays, and biocompatibility was confirmed through cytotoxicity tests. Results: The incorporation of cobalt ferrite increased magnetic responsiveness, altered porosity profiles, and influenced swelling, biodegradation, and compressive strength, with a maximum value of 87 kPa at 7.5 wt% ferrite content. The scaffolds maintained non-toxicity and demonstrated bactericidal activity. The optimal concentration for achieving a balance between structural integrity and biological performance was found at 7.5 wt% cobalt ferrite. Conclusions: These findings suggest that magnetic chitosan-cobalt ferrite scaffolds possess significant potential for use in biomedical applications, including tissue regeneration and advanced healing therapies. The incorporation of magnetic properties enhances both the structural and biological functionalities, presenting promising opportunities for innovative therapeutic approaches in reconstructive procedures.

Compositing of rGO to TiO2 by Low-Temperature Treatment and Their Photocatalytic Properties

Reduced graphene oxide (rGO)/TiO2 nanocomposites were prepared by low-temperature and low-pressure heat treatment. The structure and photocatalysis performance of the composites were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and UV-visible diffuse reflectance spectrum (UV-Vis DRS). The photocatalytic degradation performance of methyl orange (MO) by composites with different raw material ratios was studied under simulated solar-irradiation conditions. Results indicated that graphene oxide (GO) was reduced to graphene during heat treatment and bonded well with TiO2. Compared with TiO2, GO addition greatly improved its photocatalytic efficiency. Under simulated sunlight irradiation, the samples exhibited good photocatalysis performance. Within 50[Formula: see text]min, MO can be rapidly degraded by TiO2/40% rGO composite.

Comprehensive Review on Valuation Method for Bill of Quantities in Prefabricated Shear Wall Structures Using BIM

Prefabricated shear wall structure is widely used, it can not only meet the structural performance needs of buildings, but also greatly improve the construction efficiency of buildings. The bill of quantities valuation model has important theoretical and practical significance for optimizing the cost control of prefabricated shear wall structure and improving the efficiency of project management. From the perspective of combining theory and practice, this paper explores the bill of quantity valuation method of assembled shear wall structure under BIM environment, integrates BIM technology and SQL Sever database technology, and extracts the attribute information of model components through the secondary development of Revit with the data platform provided by BIM. The construction of bill of quantities is realized according to the specification of bill of quantities, and the association between bill of quantities and model components is established to realize the visual traceability query of bill of quantities, which provides a BIM technology-based construction engineering measurement and valuation technology and method, hoping to provide a new perspective and theoretical basis for related fields.

Effect of a gunite lining on the stability of salt caverns in bedded formations for hydrogen storage

In this paper, a novel methodology to improve the structural behaviour and durability of bedded salt caverns for hydrogen storage is proposed. The suggested technology consists in applying a gunite lining over the whole cavern surface by means of a pneumatic air blowing. This continuous flow projected at high speed onto the cavern surface produces a self-compacted gunite facing. The effect of adding a gunite lining on the structural performance of a bedded salt cavern is analysed. The nonlinear finite element method is then applied to solve the inherent nonlinear solid mechanics problem. It is shown that reinforcing salt caverns with a gunite lining improves the cavern behaviour, specially in the case of caverns located within a horizontal salt stratum confined between other strata. When dealing with these salt formations, the stratum geometry limits the cavern height. In general, wider caverns that exhibit larger displacements are required to achieve a huge storage capacity. Moreover, these caverns can be located at a considerable depth, where the temperature has an important role on the creep deformation process. Therefore, the proposition of stabilization techniques is required to ensure both their structural integrity and the ground subsidence. This technology allows the safe exploitation of salt caverns located at bedded-type stratified horizontal salt formations.

Analysis of Factors Affecting the Seismic Performance of Widened Flange Connections in Mid-Flange H-Beams and Box Columns

Following the Northridge and Kobe earthquakes, research has increasingly focused on achieving high ductility in beam-to-column connections. This study investigates the seismic performance of connections featuring widened beam-end flanges in mid-flange H-beams and box columns, an area with limited prior research compared to I-section columns and narrow-flange H-beams. Detailed finite element modeling using ABAQUS 6.1.4 demonstrates that widened beam-end flanges significantly improve bending capacity and ductility by relocating the plastic hinge away from the connection, thereby enhancing seismic resilience. Key findings include the identification of optimal design parameters: flange length ranging from 0.55 to 0.75 times the beam flange width, beam flange cutting length between 0.36 and 0.39 times the beam depth, and flange cutting depth from 0.19 to 0.23 times the beam flange width. These parameters ensure effective plastic hinge development and improved structural performance. This study introduces a novel approach that emphasizes geometric optimization over material-based enhancements, offering a cost-effective and practical solution for improving seismic performance and extending previous research insights.

Experimental study on the seismic performance of two-storey UHPC modular building structure

Ultra-high performance concrete modular building is a new structural system in which the module units made by the factory with UHPC materials are transported to the site for assembly. To study the seismic performance of UHPC module building structures, a two-story full-scale module building structure made by UHPC is designed in this study. Lateral cyclic loading tests are performed to investigate the seismic performance of the module building structures. The bearing capacity, failure mode, stiffness degradation, hysteretic performance, residual deformation, and strain skeleton curve are analyzed. Results indicate that the specimen undergoes three stress stages: elasticity, yield, and ultimate under lateral cyclic loading. At ultimate load capacity, the maximum inter-story drift ratio reached 1/57, and the load-bearing capacity was approximately 1.20 times the yield strength. The average ductility factor of the specimens was 3.42. The cracks mainly appear at the bottom and top of the walls of the module unit, and initial cracks occur at the top of the wall of the upper module unit. The specimen exhibits excellent seismic performance, full hysteretic curves, good dissipation capacity and ductility. The four corners between module units are connected by grouting sleeves in a reliable way to transfer force, which can ensure the overall deformation requirements of the structure.

Static and stability analyses of multi-strut type aluminium alloy suspen-dome structure with large opening

By combining the advantages of the multi-strut concept in cable dome structures with aluminum alloy material, a new type of prestressed spatial structure—the multi-strut aluminum alloy suspen-dome with a large opening—has been developed by integrating a lower prestressed support system into an aluminum alloy reticulated shell. The optimal structural configuration was determined by comparing the static, stability, and economic performance of three types of upper chord mesh topologies for this structure. Subsequently, an analysis of the static performance and large-scale parameters affecting the structural stability of the optimal grid topology was conducted. The study explored the influence of structural prestressing, overall shape, and support stiffness—encompassing three categories and seven parameters—on structural stability and material consumption. Additionally, the effects of initial imperfections and load distribution forms on structural stiffness and stability were further examined. Finally, the static properties, stability, and economic indicators of the structure were compared with two other structural systems: the steel suspen-dome and the cable dome. The results indicate that the pentagonal grid topology provides the best structural performance and that the structure is sensitive to cooling effects. Optimal values for key design parameters, such as the rise-span ratio and thickness-span ratio, were identified. Moreover, the economic advantages of the aluminum alloy suspen-dome compensate for its mechanical performance shortcomings compared to the steel suspen-dome. These findings offer innovative solutions and a scientific basis for the selection and stability design of aluminum alloy suspen-dome structures.

Structural topology optimization for plastic-limit behavior of I-beams, considering various beam-column connections

This work proposes topology optimization for steel I-beams, including consideration of bolted beam-column connections with geometric and material nonlinear analysis. The aim is to assess and compare the topological configurations influenced by different connections, examining their stress distribution and rotational stiffness to illustrate the potential of structural optimization. The bi-directional evolutionary structural optimization (BESO) approach is implemented. Furthermore, several bolted steel beam-column configurations were validated based on experimental tests. Subsequently, a series of finite element models were developed, contributing to a comprehensive understanding of the plastic-limit behavior of I-beams under different loading conditions. The proposed method could potentially use a lesser quantity of material while maintaining the same level of structural performance. The results indicate that the implementation of structural topology optimization on I-beams while considering various beam-column connections, yields structural performance similar to that of solid web configurations, achieved through material reduction.

Bamboo fiber-enhanced UHPC: Early hydration and microstructural/mesoscale analysis

This study investigates the impact of incorporating bamboo fibers, a natural and renewable material, into ultra-high performance concrete (UHPC) on its early hydration, mechanical properties, internal relative humidity, autogenous shrinkage, and microstructure. The results show that adding bamboo fibers significantly improves various UHPC properties. Bamboo fibers regulate hydration and prolong the hydration process through their water absorption and retention abilities. With a fiber content of 1.0 vol percent (vol%), the compressive strength increases by 10.2 %, reaching 97.1 MPa, and at 2.0 vol%, flexural strength and toughness increase by 37.9 % and 739.5 %, respectively. Additionally, bamboo fibers help maintain internal relative humidity above 98 % during the first 7 days of curing and reduce autogenous shrinkage by up to 55.9 %. The fibers also optimize the microstructure by minimizing voids, with a 1.0 % fiber content reducing the void ratio to 1.64 %. This reduces large voids and improves the material's density. Overall, bamboo fibers show great promise in enhancing UHPC's structural performance and environmental adaptability while being a sustainable and cost-effective material.

Numerical study of the vibration control performance of Kelvin foam

Vibration control in microsystems is an important challenge. Because of the space limitation, structures that consume minimal space but provide effective performance need to be identified. In this research, we evaluate the vibration damping performance of various Kelvin-cell structures in microsystems using the Finite Element Method. Nine types of unit cells are designed based on the tetrakaidecahedron with different geometric parameters. The lattices are composed of the aforementioned unit cells, and two types of boundary condition are set according to the actual application scenarios. The results of the simulation include dissipated energy , isolation efficiency, etc. The results are compared with each other and two types of non-Kelvin-cell structures. This comparative analysis aims to inform the development of space-efficient vibration absorbers for microsystems.

Experimental and numerical investigation of a novel passive energy dissipation system with viscoelastic damper and angle-reaction controller

Sharp and significant changes in the relative angle between beam and column during earthquakes often lead to failure of structural joints. This study proposed a novel passive Energy Dissipation system (PEDs) consisting of a viscoelastic damper (VED) and an angle-reaction controller (ARC). The ARC provides mutual support to the joint by establishing temporary supports in reinforced concrete or steel frames to allow for free-angle multilevel control in the case of excessive relative angle. This feature distinguishes the novel PEDs from previous systems as it allows the reaction force of the temporary support to compensate for the loss of joint rotational stiffness. The cyclic loading tests were conducted by constructing fundamental components, and then a mechanical model for the novel PEDs was established. Numerical simulations were performed to analyze parameter variations and to provide a comprehensive methodology for evaluating the seismic performance of the novel PEDs. The results demonstrated that two mechanisms were effectively incorporated into the novel PEDs: vibration energy dissipation and protection against excessive angles. The multistage flag hysteresis curve confirmed the reliability of our theoretical model in representing this novel PEDs. Therefore, supplementing rotational stiffness while achieving energy dissipation can be considered a new approach for enhancing seismic performance in frame structures.

Machine learning analysis/optimization of auxetic performance of a polymeric meta-hybrid structure of re-entrant and meta-trichiral

In the ever-evolving field of materials science, the quest for innovative design solutions continues. One such area of research is the optimization of auxetic performance in meta-hybrid structures. This study delves into the application of machine learning analysis to enhance the properties of a specific meta-hybrid structure combining re-entrant and meta-trichiral designs. The polymeric meta-hybrid structure is subjected to finite element (FE) analysis to determine its Poisson's ratio. Various machine learning methods, such as linear, quadratic, and non-linear approaches, are employed to accurate forecast the Poisson's ratio of the polymeric meta-hybrid structure. Although both linear and quadratic machine learning algorithms have shown some success in predicting Poisson's ratios, they cannot be considered outstanding. As a result, a non-linear machine learning algorithm has been developed to enhance the accuracy of Poisson's ratio prediction. The results indicate that non-linear machine learning techniques out performs both linear and quadratic methods when it came to predicting Poisson's ratio. Specifically, the non-linear model achieved an impressive R-sq value of 93.68%, demonstrating its exceptional accuracy and overall excellence in fitting the data. The optimum conditions for the meta-hybrid structure are determined to be a thickness of 4.35 mm, a temperature of 15 °C, and a strain rate of 1%. Under these specific parameters, the Poisson's ratio of the meta-hybrid structure is measured to be −3.899, well outside isotropic stability limit but acceptable for auxetic structures.

Analysis and experimental study of mixing performance of screw structure for two-component composite coating based on EDEM-CFD

Analysis and experimental study of mixing performance of screw structure for two-component composite coating based on EDEM-CFD