Accurate Design Approach Research Articles

Optimizing Gene Expression Programming to Predict Shear Capacity in Corrugated Web Steel Beams

Corrugated web steel systems, such as corrugated web girders (CWG) and beams (CWSB), have the potential to influence the modern construction industry due to their unique properties, including enhanced shear strength and reduced necessity for transverse stiffeners. Nevertheless, the lack of a rapid and accurate design approach still limits its wide applications. Recently, gene expression programming (GEP) has been employed to predict the shear capacity of cold-formed steel channels, demonstrating superior predictive accuracy and compliance with established standards. This study applies GEP to predict the shear capacity of sinusoidal CWSBs and optimizes its predictive performance by employing a systematic grid search to explore combinations of chromosomes, head sizes, gene counts, and linking functions. The process involved testing 19 different parameter combinations and more than 60 developed models. The findings include the sensitivity of the model's performance to gene count and the critical role of the linking function. The optimal model in the study, GEP13, achieved R² of 0.95, an RMSE of 100.5, and an MAE of 86.6 in the testing dataset with 150 chromosomes, a head size of 12, and four genes using a multiplication linking function. Doi: 10.28991/CEJ-2024-010-05-02 Full Text: PDF

Elastic local buckling coefficients of I-shaped beams considering flange–web interaction

Since using high–strength and high–performance steels has become a more common structural design practice in building and bridge construction, there is an increased potential for designing extremely thin-walled I-shaped beam members to enhance the efficiency of the steel beam design. For a more accurate design approach for these thin-walled I-beam members, particularly when they are near noncompact limits, it is necessary to explore more rational methods for determining the elastic local buckling strength of I-beams. This study aimed to investigate the local buckling behavior and strength of I-shape structural sections by considering flange-web interactions through three-dimensional finite element analysis. The goal was to provide a more reasonable estimation of local buckling strength under uniform bending. To evaluate the local buckling behavior of flange and web panels and explain it reasonably, this study adopted the ratio of flange-web slenderness (λf/λw) and height-to-width ratio (H/bf) of I-shaped beams which can affect buckling mode shapes and local buckling strength of I-shaped beams induced by flange local and web bend bucklings. Finally, this study presented design equations for both flange local and web-bend buckling coefficients considering λf/λw and H/bf. It was expected that the presented local buckling coefficients (kf) for flanges and webs could lead to a more reasonable design, as compared to the existing AISC design provisions.

Local–distortional buckling mode of steel cold-formed columns: Generalized direct strength design approach

Cold-Formed Steel (CFS) members are highly susceptible to several structural instability phenomena, involving either individual (Local — L, Distortional — D and Global — G) or interaction (LD, LG, DG, and LDG) buckling modes. The buckling mode interaction of CFS columns and beams may lead to strength erosion compared to isolated modes and must be considered in structural design. The North American, Australian/New Zealand and Brazilian standards incorporated the Direct Strength Method (DSM) that provides accurate design approach for columns and beams affected by L, D, G, and LG buckling modes. However, the coupled LD, DG, and LDG buckling modes are not currently considered in the DSM and many recent research projects have been focused on these topics. The procedure adopted by DSM estimates the CFS member strength through experimentally calibrated design strength equations and curves, based on the relationship between the member elastic stability and the steel yielding property, respectively the elastic critical buckling load and the plastic load, represented by the slenderness factor. The more accurate the buckling load, the more improved will be the result of the column strength by the DSM equations. In this context, the present paper presents the main results of the investigation, based on both experimental and finite element method numerical results, that conducted to calibrated strength curves for CFS unstiffened sections columns without holes covering LD interaction buckling mode. To take into account the effect of the LD buckling, the proposed procedure for design purposes incorporates the slenderness factor ratio RλDL=λD/λL as the main variable, and λL, λD, λG as the local, distortional and global slenderness factors, respectively.

CFS Columns Under Buckling Interaction: Direct Strength Method Generalised Approach

AbstractCold‐Formed Steel (CFS) members are highly susceptible to several structural instability phenomena, involving either individual (Local – L, Distortional – D and Global – G) or interaction (LD, LG, DG, and LDG) buckling modes. The buckling mode interaction of CFS columns and beams may lead to strength erosion compared to isolated modes and must be considered in structural design. The North American, Australian/New Zealand and Brazilian standards incorporated the Direct Strength Method (DSM) that provides accurate design approach for columns and beams affected by L, D, G, and LG buckling modes. Moreover, the coupled LD, DG, and LDG buckling modes are not currently considered in the DSM and many research projects have been focused on these topics. The procedure adopted by DSM estimates the CFS member strength through experimentally calibrated design strength curves, considering the relationship between the member elastic stability and the steel yielding property. In this context, the present paper presents the main results of the investigation, based on both experimental and finite element method numerical results, that conducted to calibrated Winter‐type strength curves for CFS columns covering LD, DG, and LDG buckling modes. To take into account the effect of the buckling modes interaction, the proposed procedure for design purposes incorporates the slenderness factors ratio RλDL = λD/λL and λG/ λmaxLD, with λmaxLD = max {λL, λD} and λL, λD, λG as the local, distortional and global slenderness factors, respectively.

Derivation of a normalised failure surface for square CECFST columns embedded with circular steel tube: A unified approach

Concrete-Encased Concrete-Filled Steel Tube (CECFST) columns are a new type of composite columns that possess great strength, stiffness, ductility, corrosion and fire resistance. To fully realise their benefits, an accurate design approach of calculating the strength of these members is necessary. In this paper, the plastic stress distribution (PSD) and load contour (LC) methods in the design code of predicting the cross-section strength of CECFST columns is first evaluated through numerical and published experimental data. Considering the shortcomings of conventional design methods, a unified design approach is then developed. Compared to the conventional PSD method, the developed method can yield conservative resistance predictions for uniaxial eccentric loaded (UEL) CECFST columns. In addition, instead of using linear moment interaction curves to predict the strength of biaxial eccentric loaded (BEL) CECFST columns, elliptical moment interaction curves are adopted in the proposed design approach. Most importantly, a normalised 3D axial-load–biaxial-moment (n–my–mz) interaction surface can be generated through the proposed method, which only requires determining 6 critical points on the interaction surface. Unlike the conventional design approach, in which the UEL and BEL composite columns need to be respectively designed through PSD and LC methods, a unified design procedure can be achieved through the proposed approach. Besides, the confinement effect from both the steel tube and the stirrups can also be considered in the proposed approach and much higher accuracy and consistency can be achieved in predicting the cross-section strength of CECFST columns.

Quality Driven Systematic Approximation for Binary-Weight Neural Network Deployment

Neural networks (NNs) with large scales of artificial neurons are increasingly used in recognition and classification tasks. In power-constrained scenarios, the tradeoff between performance and hardware consumptions must be carefully evaluated before silicon tape-out. In this paper, we proposed a systematic approach to design ultra-low power NN system. This work is motivated by the facts that NNs are resilient to approximation in many of the computations and NNs are outputting statistical tensors which are acceptable to less-than-perfect results. We resort to the front-back end approach with a twofold aim: (1) a fast and accurate design approach is proposed by estimating the computing quality of low-power approximate adder arrays, and it is adopted to evaluate the neural network system; (2) a quality configurable engine with different approximation degrees while processing NNs is implemented. The proposed work is demonstrated with a comprehensive keyword spotting (KWS) system as an ultra-low power NN engine. The experimental environment is setup with ten keywords from the google speech command dataset (GSCD) using an industrial 22-nm ultra-low-leakage (ULL) process. Comparing to the state-of-the-art KWS processors, the proposed approximate NN engine can demonstrate over 60% improvement in power efficiency and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.1\times $ </tex-math></inline-formula> area efficiency while achieving similar recognition accuracy.

Anti-frost heave design method for a parabolic canal based on the hydraulic optimal solution set in seasonally frozen regions

Parabolic canals are commonly used in seasonally frozen regions because of their excellent hydraulic characteristics and frost heave resistance. However, severe frost damage can still occur, mainly because the design of canals is based on experience, and the analytical mechnical models and design methods are limited. First, the frost heave characteristics of parabolic canals were analysed, and the canal lining was simplified as an arched thin shell structure under the normal frost heave force, tangential freezing force, and gravity. Second, an analytical mechanical model of frost damage to the lining was established, and the equations for the axial force, bending moment, tensile stress were derived; the accuracy of the model was verified by field measurements and numerical simulations of a canal case. Third, the effects of groundwater depth and canal size were analysed, and the frost damage mechanism was investigated. Fourth, the anti-frost heave design method of a canal based on the hydraulic optimal solution set was proposed, and the method was encapsulated into digital design software with Python language. This mechanical model can explain the frost damage of the canal, and the nonuniform frost heave of foundation soil caused by different groundwater depths in different parts of the canal is the cause of lining damage. The bi-objective optimization design method can consider the hydraulic performance and anti-frost heave performance of the canal, and the digital design software can assist engineers with developing a quick and accurate design approach. The research results can provide a theoretical basis and technical means for cold-region canal design.

Design of a Kitchen-Monitoring and Decision-Making System to Support AAL Applications.

Numerous researchers are working on Ambient Assisted Living systems to enable more comfortable and safer living for senior people in their homes. Due to modern lifestyles and an aging population, this has become a very important issue. According to the available literature, it is obvious that the kitchen is one of the most important and most dangerous rooms in the home. However, there is still evident lack of monitoring systems suitable for specific kitchen activities. In this paper, we propose a monitoring system capable of identifying activities related to the cooking process, and a decision-making system capable of identifying some unwanted and possibly critical conditions. The proposed systems are designed to satisfy the requirements of the modern Ambient Assisted Living systems dedicated to older adults. The proposed monitoring system consists of ultrasound, temperature, and humidity sensors. The acquired results from these sensors are the inputs for the decision-making system, which generate warnings or alarms intended for the senior users and/or formal or informal caregivers. This system is designed to improve home safety related to kitchen activities, as well as to provide information about the lifestyle and daily activities of senior users. Experimental validation of the proposed system confirms its functionality and accurate design approach.

Integrated photonic guided metalens based on a pseudo-graded index distribution

In this article, we report an integrated optical nanolens exhibiting a pseudo-graded index distribution in a guided configuration. This dielectric metalens relies on a permittivity distribution through dielectric strips of the core material, which is compatible with existing silicon photonic technology. We show in this paper that effective medium theory (EMT) inaccurately predicts the focal length of such devices, and we propose an efficient and accurate design approach based on 2D finite element method (FEM) mode calculations that are in good agreement with 3D FDTD simulations. The lens was fabricated on a 200 mm silicon on insulator pilot line, and fibre-to-fibre optical characterizations revealed an excellent transmission of 85% for TM polarization, in line with the simulated performance (90%). The proposed approach can be easily extended to width-variable strips, enabling the realization of all types of graded index devices, especially those derived from transformation optics.

An optimal mutually coupled concentric circular antenna array synthesis using ant lion optimization

This paper presents an accurate design approach for concentric circular antenna array (CCAA) synthesis to improve the far-field radiation characteristics using a meta-heuristic optimization technique called ant lion optimization (ALO). The far-field radiation pattern is improved with lower side lobe level (SLL) which is essential for the reduction of interference in the entire side lobe regions. The ALO algorithm is a recently proposed evolutionary technique which is applied to determine the optimal sets of current excitation weights and to find the optimal inter-element spacing between the array elements in the 3-ring structure of the CCAA design. In this context, the design examples of two 3-ring CCAAs, one having the set of (4, 6, 8) elements and the other having the set of (8, 10, 12) elements, with and without the centre element, are presented by optimizing the array parameters. The results obtained by using the ALO algorithm–based approach show considerable improvement of SLL with respect to that of the uniform array pattern and those of the methods reported in the recent literature.

Developing a Methodology for Integration of Whole Life Costs into BIM Processes to Assist Design Decision Making

A common barrier to achieving design intent is the absence of comprehensive information about operational performance during design development. This results in uninformed decision-making which impacts on actual building performance, in particular Whole Life Costs (WLC). It is proposed that Building Information Modelling (BIM) has the potential to facilitate a more comprehensive and accurate design approach from the initial stages if the model can utilize reliable and robust cost and performance data from buildings in use. This paper describes the initial findings of a research project that has investigated the integration of WLC estimation into BIM processes. The study focusses specifically on the rapidly emerging Private Rental Sector (PRS) as the build-to-rent market has repeatable tasks and similar workflow patterns, roles and responsibilities, but impacts of WLC can significantly influence the business model. The study adopted a mixed method approach for the development and validation of a structured standardized process for timely WLC estimation through BIM. The research identified a number of barriers. These included varying definitions of WLC calculation methodologies; the availability and standards of data sources, in particular, the misalignment of coding systems for identification and classification of components at various levels of development, proprietary ownership of data, lack of knowledge and skills in team members to produce and/or utilize data sources, and limitations of software. However, the research proposes that these may be addressed by a reverse-engineered systematic process that uses the Integrated DEFinition (IDEF) 3 structured diagramming modelling technique that can be incorporated into a software model and has developed a model for a systematic approach for BIM-enabled WLC assessment based on CE principles which would include access to live data streams from completed buildings. The paper describes this model development which has the potential to enhance BIM lifecycle management through an augmented decision-making approach that is integral to the natural design development process.

LOCAL BUCKLING BEHAVIOR OF DOUBLE-COPED STEEL BEAMS

Local web buckling is one of the most common failure modes for coped steel beams. While several studies have been undertaken focusing on the behavior of top-flange/single-coped beams, double-coped beams have received little attention. To fill this knowledge gap, this paper presents experimental and numerical studies on local web buckling behavior of double-coped steel beams. Five full-scale tests were conducted, and the main test parameters were cope length and cope depth. Local web buckling was observed as the main failure mode for all of the five specimens, and the buckling resistance was found to decrease with increasing cope length and cope depth. A FE study was subsequently conducted, where the response of the FE models agreed well with the test results, especially in terms of buckling mode and buckling resistance. The test and FE results were compared with those predicted by an existing design approach. The design results were found to be quite conservative, and hence further investigation may be required to achieve a more accurate design approach. procedure and faster computational efficiency than the Modal Pushover Analysis (MPA) procedure for irregular bridges.

MIMO Transmission Using a Single RF Source: Theory and Antenna Design

An approach for transmitting multiple signals using a single switched parasitic antenna (SPA) has been recently reported. The idea there is to map the signals to be transmitted onto a set of basis functions that serve as “virtual antennas” in the beamspace (i.e., wavevector) domain. In this paper, we generalize the derivation of the antenna pattern basis functions regarding a three-element SPA of arbitrary radiating elements, within a symmetric array topology, for multiplexing signals in the wavevector domain (using different beampatterns) rather than in the hardware antenna domain with multiple feeding ports. A fully operational antenna system example is modeled, optimized regarding its return loss and the power imbalance between the basis functions, and finally realized. The measurements of the SPA show good agreement with the simulated target values, revealing an accurate design approach to be adopted as a fast SPA prototyping methodology. The SPA has been successfully employed for multiplexing two binary phase-shift-keying (BPSK) datastreams over-the-air, thus paving the way for practically compact and highly efficient MIMO transceiver designs.

Performance Evaluation of HTS Synchronous Motor Using Finite Element Method

A 100 HP rated synchronous motor with superconducting rotating field winding has been designed based on the formulated equations established from 2 dimensional magnetic field distributions in a cylindrical coordinate. The cross-section was drawn based on calculated design results via Fortran program and then modeled with FEM (finite element method) to investigate the machine performances. First of all, the magnetic field distributions are analyzed in many ways according to the field directions and the armature currents. Especially after the rotating field winding is arranged with BSCCO-2223 high-temperature superconducting (HTS) pancake coils, the exerted magnetic field normally on the HTS tape is calculated through FEM. And the machine output power is calculated according to the torque angles that lie between the field and the armature main flux lines. Moreover, this paper includes the eddy-current loss variations of a copper damper located between the field and the armature coils. Finally, 3 dimensional magnetic field distribution is also calculated via FEM. The radial components of magnetic field are compared along the center line of an armature conductor section between 2 dimensional and 3 dimensional results. By the comparison we make sure that about 30% of machine output is added from the end effect of HTS field coil and more accurate design approach is possible.

An accurate design approach for TM mode dielectric resonator filters in circular waveguide below cutoff

A CAD procedure is described for designing bandpass filters realized with circular cylindrical dielectric resonators placed in circular waveguide below cutoff. The dielectric resonators operate on TM/sub 01/spl delta// mode, in order to allow both low loss achievement and reduced spurious passbands. The described CAD procedure employs a monomodal equivalent circuit of the filter structure in order to allow a synthesis approach for designing small or moderate percentage bandwidth filters; however the computation of equivalent circuit parameters is based on an accurate multimodal characterization of the discontinuity between the empty circular waveguide and the dielectric loaded waveguide, which makes use of mode matching. The CAD procedure requires a preliminary choice of some geometrical parameters of the structure. Guidelines for this choice are also given, in order to show how different design targets may be achieved, such as low losses, miniaturization of the structure, and a sufficiently large frequency range free from spurious passbands. To verify the procedure, some numerical simulations, performed employing the generalized scattering matrix techniques, are also presented and compared with measurements on a prototype filter designed through said procedure and actually fabricated. >