Critical Geometric Parameters Research Articles

Multifunctional metamaterials for simultaneous sound absorption and flexural vibration isolation

Controlling the noise and vibration simultaneously in some engineering scenes is extremely essential to eliminate harmful effects on the humans and equipments. To overcome this challenge, a multifunctional metamaterial plate with both airborne sound absorbtion and flexural vibration isolation simultaneously is investigated theoretically, numerically, and experimentally. The plate consists of a host plate and a Helmholtz resonator, where Helmholtz resonance is used to absorb sound waves and its external solid domain plays as role of a local resonator to isolate the flexural vibrations. The theoretical models were established to characterize the mechanism of the sound absorption and vibration isolation. The experimental results demonstrated that the proposed metamaterial plate can achieve perfect sound absorption at 649 Hz and a flexural wave band gap at 289–470 Hz. Besides, although the sound absorption and vibration isolation functions are integrated in the same component, our theory identifies several critical geometrical parameters which can manipulate the absorption peak and the flexural wave bandgap, allowing us to design its frequency of multiple functions as desired. This work provides a promising solution for noise and vibration reduction in engineering.

CFD (Computational Fluid Dynamics) Simulation of Hydrodynamic Vortex Turbine Performance: Influence of Notch Angle Variation on Flow Patterns and Efficiency

Hydrodynamic vortex turbines (HVTs) offer a promising solution for harnessing renewable energy from low-head water sources. The inlet notch angle, a critical geometric parameter, significantly influences the flow patterns within the turbine basin and, consequently, its overall performance. This study investigates the impact of notch angle variation on HVT efficiency and flow characteristics using computational fluid dynamics (CFD) simulations. A 3D model of an HVT was developed and simulated using ANSYS Fluent. The notch angle was varied between 7° and 15° in 2° increments. The k-ω SST turbulence model was employed to capture the complex flow behavior. Velocity and pressure contours were analyzed to understand the flow patterns, while turbine performance metrics, including torque, power output, and efficiency, were computed. The results revealed a strong correlation between notch angle and turbine performance. Increasing the notch angle led to higher flow velocities in the turbine basin, resulting in enhanced vortex formation and increased energy extraction. Consequently, both power output and efficiency improved with larger notch angles. The optimal notch angle, balancing efficiency and practical considerations, was identified. This study demonstrates the critical role of notch angle in HVT design. CFD simulations provide valuable insights into the flow dynamics and performance optimization of these turbines. The findings contribute to the advancement of HVT technology for sustainable micro-hydro power generation.

Optimising miniaturised hydrocyclones for enhanced separation of microplastics

Microplastics, particularly those in the 5–20µm range, pose substantial risks in aquatic environments, yet effective removal techniques are limited. This study assesses two critical geometric parameters of a 10 mm mini-hydrocyclone: inlet radius and insertion angle. Along with the inlet velocity, they are optimised collectively to enhance the MPs’ removal. Computational Fluid Dynamics (CFD) simulations using the Mixture model and Reynolds stress model were employed to track the particle–water–air interactions, revealing the flow dynamics and absence of an air core. The Response Surface Methodology (RSM) using a Box-Behnken design of experiments was adopted to assess the impact of the geometric and operational parameters and determine the optimal design. Recovery efficiency, concentration efficiency, and split rate were recorded during experiments and compared with CFD results, showing a good agreement between experiments and CFD simulations. The resulting novel design achieved an 88.53% MPs recovery and a concentration efficiency of 1.83, which represents an obvious improvement over the commercial design’s MPs recovery efficiency of 79.97% and concentration efficiency of 1.68. Simulations reveal that the novel design shortens the path for MPs through the forced turbulence region and modifies the velocity and turbulence fields, enhancing the concentration gradient of MPs within the mini-hydrocyclone’s chamber. Moreover, the novel design exhibits a more robust response to inlet velocity variations, a crucial advantage for its application in arrays. Experiments further confirm that a matrix composed of 10 novel mini-hydrocyclones achieves 10 percentage points higher recovery efficiency than the matrix with 10 commercial mini-hydrocyclones. These findings mark a significant step towards effective MP removal, addressing a critical environmental issue.

Effects of geometrical parameters on the performance of hydrogen regenerative pumps in proton exchange membrane fuel cell systems

Regenerative pumps are considered a promising option for hydrogen recirculation in proton exchange membrane fuel cell (PEMFC) systems. The geometry of the impeller exerts a direct influence on the pressurization process within the regenerative pumps. However, the influence has not been explored systematically in any available publications. This study investigates the effects of geometric parameters on pump performance and provides design guidelines for hydrogen regenerative pumps. A three-dimensional (3D) numerical model is developed and validated. The effects of critical geometric parameters, including the number of blades, impeller radius, and impeller radius ratio, on the performance of the regenerative pumps are then analyzed. Based on the analysis, this work recommends 35 blades and an impeller radius ratio of 0.65. To establish a correlation between operational performance and micro-flow mechanisms, the fluid velocity distribution at the interface of the rotating and stationary domains is quantitatively analyzed. Results indicate that a reduction in the flow rate results in increased axial velocity and decreased tangential velocity. The increased axial velocity enhances mass transfer, thus increasing the pressure and diminishing the efficiency, whereas the decreased tangential velocity intensifies the impact of the fluid on the blades, leading to increased shock losses and reduced efficiency.

Deep Learning‐Assisted Design of Bilayer Nanowire Gratings for High‐Performance MWIR Polarizers

AbstractOptical metamaterials have revolutionized imaging capabilities by manipulating light‐matter interactions at the nanoscale beyond the diffraction limit. Bilayer nanowire grating configurations exhibit significant potential as exceptional elements for high‐performance polarimetric imaging systems. However, conventional computational approaches for predicting electromagnetic responses are time‐consuming and labor‐intensive, and thereby, the practical implementation remains challenging through an iterative design, analysis, and fabrication process. Here, a deep learning‐based design process is presented utilizing an artificial neural network (ANN) trained on finite element method (FEM) simulations that enables the prediction of bilayer nanowire gratings‐based electromagnetic responses. The study validates predictions through nanoimprinted bilayer nanowire gratings, demonstrating the reliability of the ANN's predictions. Furthermore, the research identifies critical geometric parameters significantly influencing transverse magnetic (TM) and transverse electric (TE) transmission. The ANN model effectively tailors design for specific mid‐wavelength infrared (MWIR) wavelengths, which may provide a practical tool for rapidly designing and optimizing metamaterial for high‐performance polarizers.

A Novel Asymmetric Interior Permanent Magnet Machine with Auxiliary Flux Barriers

AbstractA novel asymmetric interior permanent magnet (AIPM) machine is proposed in this paper. The machine's rotor consists of asymmetric poles and auxiliary flux barriers. The torque ripple of the machine is weakened by the asymmetric design of the left and right sides of the magnetic poles. The magnetic‐field‐shifting (MFS) effect improves the electromagnetic torque after adding the auxiliary flux barrier to shift the magnetic axis. The influence of critical geometrical parameters on the electromagnetic performance of the machine is investigated under the condition that the stator and permanent magnet volume remain unchanged. The relevant geometrical parameters of the machine are optimized and designed through the improved Taguchi method. The performance of the AIPM machine and the conventional machine under no‐load and load conditions are further compared by simulation analysis with finite elements, verifying the increase in electromagnetic torque and the reduction in torque ripple. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Fluidized bed hydrodynamics under variable air inlet configurations to enhance gasification reactor efficiency: Computational study

This study employs diverse strategies to enhance motion dynamics within the reactor, with a specific focus on the critical geometric parameter of air nozzle configuration. Methodical analysis of various air nozzle angles, 0°, 45o, and 90° relative to the horizontal bottom line is undertaken to discern their influence on these key parameters throughout multiple stages during the recorded flow duration. A CFD model of the physical model is constructed and solved using ANSYS software. Parameters scrutinized include the longitudinal and lateral distribution of particle volume fraction, alongside radial and axial velocities of particles. The results emphasize the significant impact of air-feeding orientation on both radial and axial particle velocities. Notably, 45° air nozzle angle is the best orientation for the fluidized bed reactor displaying maximal values in particle volume fraction fluctuations and bed height. Furthermore, peak values for radial and axial velocity persist consistently throughout the entire flow duration.

Integrated coplanar waveguide coil on diamond for enhanced homogeneous broadband NV magnetometry.

Nitrogen-vacancy (NV) centers in diamond have emerged as promising quantum sensors due to their highly coherent and optically addressable spin states with potential applications in high-sensitivity magnetometry. Homogeneously addressing large ensembles of NV centers offers clear benefit in terms of sensing precision as well as in fundamental studies of collective effects. Such experiments require a spatially uniform, intense, and broadband microwave field that can be difficult to generate. Previous approaches, such as copper wires, loop coils, and planar structures, have shown limitations in field homogeneity, bandwidth, and integration in compact devices. In this paper, we present a coplanar waveguide (CPW) gold coil patterned on a 3 × 3 mm 2 diamond substrate, offering full integration, enhanced stability, and broad bandwidth suitable for various NV sensing applications. Coil fabricated on diamond offers several advantages for magnetometry with NV centers ensemble, including enhanced heat dissipation, seamless integration, scalability, and miniaturization potential. We optimize critical geometrical parameters to achieve a homogeneous magnetic field with a coefficient of variation of less than 6% over an area of 0.5 mm 2 and present experimental results confirming the performance of the proposed CPW coil.

Multiple equilibria of pinned FGP-GPLRC circular arches under a half-span distributed radial load

This article presents a theoretical analysis on the multiple equilibria of pinned functionally graded porous graphene platelet reinforced composite (FGP-GPLRC) circular arches subjected to a half-span distributed radial load. The effective material properties of the arch with different porosity distribution modes are approximated via a modified Halpin–Tsai micromechanical model. The decoupled neutral-plane-based governing equations are then built in the framework of the principle of minimum potential energy, from which analytical solutions for the radial displacement at an arbitrary point on the arch axis are derived. Utilizing a perturbation method, the possible buckling modes are discussed. The complete buckling evolution process of bending moment and vertical displacement are followed, meanwhile the critical geometrical parameters that control buckling behaviors switching are identified. To validate the presented analytical solutions, Finite element (FE) analysis is carried out. An in-depth parameter analysis is performed subsequently to evaluate the fluences of porosity distributions, GPL weight fraction, and porosity coefficient on the multiple equilibria path of arches. It was found that the pinned FGP-GPLRC arches could buckle only in a limit point mode under a half-span distributed radial load. When λ ≥ 8.36 , the multiple equilibria phenomenon occurs and the external force corresponding to inflexion point vanishes.

Performance investigation on the bypass ejector for a proton exchange membrane fuel cell system

The poor entrainment performance of the conventional ejector is a significant problem that makes it hard to use in proton exchange membrane fuel cell (PEMFC) systems. This study aims to evaluate the entrainment performance of a bypass ejector for a 100 kW PEMFC system. The effects of three critical geometric parameters, namely the axial position, width, and angle of the bypass inlet, on the entrainment performance are thoroughly investigated. The results demonstrate that the bypass flow exhibits a significant performance improvement in the critical mode. In contrast, the performance improvement is negligible and even negative in the subcritical mode. After careful evaluation of the entrainment performance across various stack powers, the optimal axial position, width, and angle of the bypass inlet are found to be 1.1, 2 mm, and 10°, respectively. A comparative analysis between the bypass ejector and the conventional ejector underscores a significant advantage for the former, exhibiting a remarkable 22.1 % increase in the hydrogen entrainment ratio at the stack power of 101 kW. Nevertheless, the entrainment performance of the bypass ejector diminishes when operating at low stack powers below 24 kW.

Phase change plasmonic metasurface for dynamic thermal emission modulation

Plasmonic metasurfaces with adjustable optical responses can be achieved through phase change materials (PCMs) with high optical contrast. However, the on–off behavior of the phase change process results in the binary response of photonic devices, limiting the applications to the two-stage modulation. In this work, we propose a reconfigurable metasurface emitter based on a gold nanorod array on a VO2 thin film for achieving continuously tunable narrowband thermal emission. The electrode line connecting the center of each nanorod not only enables emission excitation electrically but also activates the phase transition of VO2 beneath the array layer due to Joule heating. The change in the dielectric environment due to the VO2 phase transition results in the modulation of emissivity from the plasmonic metasurfaces. The device performances regarding critical geometrical parameters are analyzed based on a fully coupled electro-thermo-optical finite element model. This new metasurface structure extends the binary nature of PCM based modulations to continuous reconfigurability and provides new possibilities toward smart metasurface emitters, reflectors, and other nanophotonic devices.

Deep learning-driven forward and inverse design of nanophotonic nanohole arrays: streamlining design for tailored optical functionalities and enhancing accessibility.

In nanophotonics, nanohole arrays (NHAs) are periodic arrangements of nanoscale apertures in thin films that provide diverse optical functionalities essential for various applications. Fully studying NHAs' optical properties and optimizing performance demands understanding both materials and geometric parameters, which presents a computational challenge due to numerous potential combinations. Efficient computational modeling is critical for overcoming this challenge and optimizing NHA-based device performance. Traditional approaches rely on time-consuming numerical simulation processes for device design and optimization. However, using a deep learning approach offers an efficient solution for NHAs design. In this work, a deep neural network within the forward modeling framework accurately predicts the optical properties of NHAs by using device structure data such as periodicity and hole radius as model inputs. We also compare three deep learning-based inverse modeling approaches-fully connected neural network, convolutional neural network, and tandem neural network-to provide approximate solutions for NHA structures based on their optical responses. Once trained, the DNN accurately predicts the desired result in milliseconds, enabling repeated use without wasting computational resources. The models are trained using over 6000 samples from a dataset obtained by finite-difference time-domain (FDTD) simulations. The forward model accurately predicts transmission spectra, while the inverse model reliably infers material attributes, lattice geometries, and structural parameters from the spectra. The forward model accurately predicts transmission spectra, with an average Mean Squared Error (MSE) of 2.44 × 10-4. In most cases, the inverse design demonstrates high accuracy with deviations of less than 1.5 nm for critical geometrical parameters. For experimental verification, gold nanohole arrays are fabricated using deep UV lithography. Validation against experimental data demonstrates the models' robustness and precision. These findings show that the trained DNN models offer accurate predictions about the optical behavior of NHAs.

Bloch oscillations probed quantum phases in HgTe quantum wells

The semiconductor quantum well based on mercury telluride is characterized by two distinct phases: conventional insulating phase and topological insulating phase with helical edge states. The system undergoes a topological quantum phase transition from one phase to the other, tuned by the critical geometric parameters of the quantum well. It is shown that the quantum states in each phase exhibit distinct flavors of Bloch oscillations, depending strongly on the geometric parameters and crystal momentum of the system. In particular, the group and Berry velocities and the real-space trajectories exhibit pronounced Bloch oscillations. Interestingly, the x- and y-components of the group velocity are interchanged by interchanging their corresponding components of the crystal momentum. In addition, a Gaussian wave packet undergoes distinct time evolution in each quantum phase of the HgTe quantum well. Moreover, the effects of applied in-plane electric and transverse magnetic fields are determined within the framework of Newtonian mechanics, leading to the geometric visualization of such an oscillatory motion. We find that in the presence of both applied in-plane electric and transverse magnetic fields simultaneously, the system undergoes a dynamic phase transition between confined and de-confined states, tuned by the relative strength of the fields. It is argued that the distinct Bloch oscillations originate from the peculiar band structure of HgTe quantum wells in each quantum phase. Furthermore, we find that the direct-current drift velocity in each quantum phase exhibits negative differential conductivity, a hallmark of the Bloch oscillation regime.

The efficiency of using simple heat pipes with a relatively low thermal conductivity for cooling transmit/receive modules

In this paper, we solved the problem of increasing the cooling efficiency of the basic version of the transmit/receive (T/R) module with a heat sink tilted in its working position while increasing its thermal power by a factor of 2 (from 112 W to 224 W). The purpose of the work is to confirm the correctness of the proposed strategy of cheap modernization of the T/R module through the use of inexpensive flat gravity heat pipes (HP) with a threaded evaporator and a relatively low effective thermal conductivity (3000 W/(m•°C)). The novelty of the work is the substantiation by the results of comparative numerical simulation of the possibility and efficiency of using such HPs in the basic version of the cooling system for T/R module and the determination of the critical geometric parameters and relationships necessary for this. It is shown that the integration of 16 flat HPs of a simplified design into the base of the radiator made it possible to reduce the maximum temperature non-uniformity of the mounting surface at an air speed of 1 m/s by more than two times and reduce the maximum temperature of the hottest transistor at 20.5 °C. The temperature non-uniformity of 8 transistors decreased from 10.5 °C to 1.6 °C. The minimum thermal impedance of the HP cooling system (0.06 °C/W) is half that of the base case. The correctness of the proposed strategy of cheap modernization of T/R modules is confirmed and the prospects of using HPs of a simplified design with working fluids with a freezing temperature below 0 °C are shown, which allows expanding the temperature range of operating conditions. The originality of the modernized cooling system and its world novelty are confirmed by the patent for the invention.

Modeling local interfacial area concentration for adiabatic and boiling bubbly flows

Bubbly flows appear in various heat and mass transfer systems, and interfacial area concentration (IAC) is a critical geometrical parameter for the flows. The fidelity of accurately computed IACs is essential for reliable three-dimensional computational fluid dynamics analyses of bubbly flows because the IACs directly affect the interfacial force and interfacial heat and mass transfer rates. This study targeted development of a simple and robust model for predicting the local IAC under steady-state bubbly flows with and without phase change. The dependent two-phase flow parameters of the IAC were derived by considering bubble coalescence and breakup rates. The IAC transport equation simplified under steady-state conditions was used for this purpose. A simplified turbulence model was introduced to formulate the energy dissipation rate per unit mass necessary for computing the bubble coalescence and breakup rates. The prediction accuracy of the local IAC model for bubbly flow conditions with area-average void fraction values less than 10 % was estimated to be 20 % based on 803 local data collected for adiabatic air–water bubbly flows in round tubes with diameters ranging from 9.0 to 200 mm. The model was also applied to predict the local IAC data of subcooled boiling flows in heated channels with hydraulic diameters ranging from 18.5 to 22.2 mm. The test conditions covered pressures from 0.1 to 1.46 MPa. The model prediction accuracy for bubbly flow conditions with area-average void fraction values less than 10 % was estimated to be 40 % based on 155 subcooled boiling flow data.

Research on the effect of rail cant on the dynamic performance and wear characteristics of subway vehicles

The rail cant is a critical geometric parameter of the track, which plays a significant role in the vehicle dynamics performance and wheel wear characteristics. Regarding the abnormal rail cants on the test route, this study employs a combined approach of field measurements and numerical simulations to investigate the influence of deviations from the standard values of rail cants on the vehicle’s straight-line operating performance and wheel wear. Additionally, it analyzes the difference in the effects of asymmetric rail cant on the inner and outer wheel's curve negotiation performance and wear characteristics. The research demonstrates that for straight track sections, rail cants ranging from 1/30 to 1/10 significantly reduce the critical speed of the wheel-rail wear profile, thereby affecting the operational stability of the vehicles. Moreover, the wheel-rail wear profile more prone to significant wear depths when the rail cants are within the range of 1/30 to 1/10. For curved track sections, when the outer rail cant is stable at 1/40, the amplitude fluctuation of the inner rail cant has a more significant impact on the curve negotiation performance of the outer wheel. Specifically, when the inner rail cant is within the range of 1/60 to 1/50, the derailment coefficient and wheel-rail lateral forces of the outer wheel increase significantly, and they are directly proportional to the degree of wheel-rail wear. When the inner rail cant is 1/30, the wheel-rail profiles at different wear stages often exhibit optimal curve negotiation performance. Moreover, an inner rail cant of 1/30 tends to achieve smaller wear depths at various wear stages.

Mechanics of re-entrant anti-trichiral honeycombs with nature-inspired gradient distributions

This study focuses on the nature-inspired gradient-based approach to re-designing re-entrant anti-trichiral (REAT) honeycombs through extensive experimental quasi-static compression. Novel perspectives on REAT honeycomb are offered through the introduction of gradient distributions on two critical geometrical parameters, the cylindrical diameter (chiral) and height of the unit cell, rather than the traditional thickness-based gradient approach. Chiral-based gradient approach demonstrated clear advantages in elastic stiffness, specific energy absorption (SEA) and densification strain over uniform REAT structures of constant geometrical parameters. These advantages are exhibited in their extended and constantly increasing quasi-plateau stage, consistent specific energy absorption (SEA) especially during early stages of compression, and most importantly, the ability to maintain a relatively constant energy absorption efficiency that is 25% more than that of the Base uniform REAT structure. Height gradient-based REAT structures, on the other hand, were able to leverage on associations between the negative Poisson's ratio (NPR) effect and height of unit cell to demonstrate notable deformation patterns across various portions of the structure. The present work reveals the performance enhancements through alternative gradient-based approaches over thickness-based gradient approaches and highlighted the differences in NPR between layers as the main driver of compressive collapse apart from the commonly concluded difference in relative density.

Cold-formed high strength steel CHS-to-RHS T- and X-joints: Performance and design after fire exposures

The post-fire structural performance of cold-formed high strength steel (CFHSS) T- and X-joints with circular hollow section (CHS) braces and square and rectangular hollow section (SHS and RHS) chords is numerically investigated in this study. The tubular members had the nominal 0.2% proof stress of 900 MPa. The CHS-to-RHS T- and X-joints were subjected to compression loads through brace members. The nominal values of peak fire temperatures (ψ) were 300°C, 550°C, 750°C and 900°C. Tests carried out by the authors investigating the post-fire static response of cold-formed S900 steel grade CHS-to-RHS T- and X-joints were formed the basis of the numerical investigation carried out in this study. The test results reported by the authors were used to develop accurate finite element (FE) models. The validated FE models were used to perform extensive numerical parametric studies comprising 768 FE specimens. The validity ranges of critical geometric parameters were extended beyond current limits mentioned in international codes and guides. The residual strengths of test and FE specimens were compared with the nominal resistances predicted from design equations given in Eurocode 3 and Comité International pour le Développement et l’ Etude de la Construction Tubulaire (CIDECT) Design Guide 3 using the measured post-fire residual material properties. Generally, design rules given in Eurocode 3 and CIDECT are shown to be quite conservative with very dispersed and unreliable predictions. As a result, accurate and reliable design rules are proposed in this study.

Design of cold-formed high strength steel rectangular hollow section T-joints under post-fire conditions

A comprehensive numerical investigation looking into the static post-fire structural performance of cold-formed high strength steel (CFHSS) T-joints is presented in this paper. The braces and chords of T-joints were made of square and rectangular hollow section (SHS and RHS) members. The steel grade of SHS and RHS members was S960 with nominal 0.2% proof stress of 960 MPa. The static strengths of SHS and RHS T-joints were investigated corresponding to four post-fire temperatures, including 300°C, 550°C, 750°C and 900°C. Pandey and Young [1] carried out tests to investigate the post-fire residual strengths of cold-formed S960 steel grade SHS and RHS T-joints. The test results were used to develop an accurate finite element (FE) model. Using the validated FE model, a comprehensive FE parametric study was performed in this investigation. The validity ranges of critical geometric parameters were extended beyond the current limits mentioned in international codes and guides. The nominal resistances predicted from design equations given in EC3 [2] and CIDECT [3], using post-fire material properties, were compared with a total of 765 test and FE joint resistances, including 756 numerical data obtained in this study. Overall, SHS and RHS T-joint specimens were failed by chord face failure, chord side wall failure and a combination of these two failure modes. Generally, the current design rules in EC3 [2] and CIDECT [3] are quite conservative and largely dispersed. As a result, accurate, less dispersed and reliable design equations are proposed in this study.

RHS-to-RHS cold-formed S960 steel fire exposed X-joints: Structural behaviour and design

This paper presents a detailed finite element (FE) analysis and design of cold-formed high strength steel (CFHSS) fire exposed X-joints with square and rectangular hollow section (SHS and RHS) brace and chord members. The nominal 0.2% proof stress of SHS and RHS members was 960 MPa. The static behaviour of SHS and RHS X-joints was numerically investigated corresponding to four post-fire temperatures, including 300°C, 550°C, 750°C and 900°C. The RHS X-joints were subjected to axial compression loads through brace members. The post-fire residual strengths of cold-formed S960 steel grade SHS and RHS X-joints were experimentally investigated by the authors. The test results were used to develop an accurate FE model. Through the validated FE model, a comprehensive FE parametric study comprising of 756 FE specimens was performed in this investigation. Overall, SHS and RHS X-joint specimens were failed by chord face failure, chord side wall failure and a combination of these two failure modes. The validity ranges of critical geometric parameters were extended beyond current limits mentioned in international codes and guides. Using the measured post-fire residual static material properties, nominal resistances were predicted from design rules given in Eurocode 3, CIDECT and literature. The residual joint strengths of test and FE specimens were compared with predicted nominal resistances. Generally, it has been shown that the existing design rules are quite conservative but unreliable. As a result, accurate and reliable design rules are proposed in this study.