International Design Standards Research Articles

Comparative Analysis between SA-516 Gr 70 Material with SA-537 Class 2 Material in Shell Pressure Vessel Fabrication Process

A pressure vessel is a container designed to hold fluids under pressure, including liquids and gases with varying pressures and temperatures. The pressure exerted on the vessel's walls and body is a critical factor that must be carefully considered to ensure compliance with applicable international design standards and prioritize worker safety and security. This research focused on a pressure vessel to investigate the impact of temperature on shell thickness to meet ASME standards. The study utilized shell components made from SA-516 Gr 70 and SA-537 materials. Experiments were conducted with each material at temperatures of 250°C, 235°C, and 343°C, revealing that thickness varies based on material and temperature. The research findings demonstrate compliance with ASME standards, as the shell thickness in all trials exceeded the minimum specified in the drawings.

Experimental and numerical analysis of L-shaped concrete-filled steel tube stub columns

This paper reports experimental and numerical studies on the cross-sectional compression resistance and behaviour of a novel L-shaped concrete-filled steel tube system. The novel composite system is proposed to eliminate concave corners and enhance the confinement of the outer steel tube to the concrete infill. A testing programme was firstly conducted, including nine tensile steel coupon tests, six compressive concrete cube tests and ten stub column tests. Upon testing, all the ten L-shaped concrete-filled steel tube stub column specimens were found to fail by local buckling. Finite-element models were then developed in the finite-element analysis software ABAQUS and validated against test results. The validated models were then employed to perform parametric studies to obtain an additional set of 48 numerical data. Test and numerical results were used to perform a design analysis, in which the suitability of the design rules in the European code EN 1994–1-1, the American specification ANSI/AISC 360 and the Chinese code GB 50936 for the developed L-shaped concrete-filled steel tube stub column system was assessed. The analysis results reveal that both EN 1994–1-1 and GB 50936 yield unsafe compression resistance predictions for the studied L-shaped concrete-filled steel tube stub columns, owing to the improper consideration of the contributions of the outer steel tube and the concrete infill to the overall capacity, while ANSI/AISC 360 offers safe design with high accuracy. The research findings are expected to contribute to the safe and wide use of the proposed novel L-shaped concrete-filled steel tube system in structural engineering and also to the further development of the current international design standards.

Using Machine Learning Algorithms to Develop a Predictive Model for Computing the Maximum Deflection of Horizontally Curved Steel I-Beams

Horizontally curved steel I-beams exhibit a complicated mechanical response as they experience a combination of bending, shear, and torsion, which varies based on the geometry of the beam at hand. The behaviour of these beams is therefore quite difficult to predict, as they can fail due to either flexure, shear, torsion, lateral torsional buckling, or a combination of these types of failure. This therefore necessitates the usage of complicated nonlinear analyses in order to accurately model their behaviour. Currently, little guidance is provided by international design standards in consideration of the serviceability limit states of horizontally curved steel I-beams. In this research, an experimentally validated dataset was created and was used to train numerous machine learning (ML) algorithms for predicting the midspan deflection at failure as well as the failure load of numerous horizontally curved steel I-beams. According to the experimental and numerical investigation, the deep artificial neural network model was found to be the most accurate when used to predict the validation dataset, where a mean absolute error of 6.4 mm (16.20%) was observed. This accuracy far surpassed that of Castigliano’s second theorem, where the mean absolute error was found to be equal to 49.84 mm (126%). The deep artificial neural network was also capable of estimating the failure load with a mean absolute error of 30.43 kN (22.42%). This predictive model, which is the first of its kind in the international literature, can be used by professional engineers for the design of curved steel I-beams since it is currently the most accurate model ever developed.

Assessment of design models for aluminium alloy CHS beam-columns with stocky cross-sections

There is little information on the prediction accuracy of the international design standards for aluminium alloy circular hollow section (CHS) beam-columns. To bridge this gap, this paper presents a comprehensive numerical investigation on the performance of aluminium alloy CHS beam-columns with stocky cross-sections. A non-linear finite element (FE) model was developed and validated against experimental results. The validated FE model was employed to conduct an extensive parametric study of aluminium CHS members subjected to combined axial compression and bending over a range of lengths, cross-sections and applied eccentricities. The effect of these parameters was investigated for two material grades, 6061-T6 and 6082-T6, resulting in a total of 168 FE models. The numerically obtained capacities were used to assess the accuracy of the strength predictions of Eurocode 9 (EC9), the Aluminium Design Manual (AA) and the Direct Strength Method (DSM). On the basis of the results, EC9, with the exponent of the interaction formula, ψc, calculated as a function of the buckling reduction factor χ, was found to provide the most accurate strength predictions with a mean value equal to 1.01 for both examined material grades. The most conservative predictions were given by the DSM, whilst the most scattered predictions by the AA, with a Coefficient of Variation (COV) equal to 0.17. Finally, based on the DSM buckling strength and the plastic cross-sectional moment resistance, a new interaction curve is proposed for CHS beam-columns with stocky cross-sections.

Prediction of the shear strength of lightweight concrete beams without web reinforcement based on a machine learning model optimized by a genetic algorithm

The shear performance of concrete beams is affected by several factors, and some of effective variables and control mechanisms should be considered in predicting shear strength. Compared with ordinary concrete, lightweight concrete (LWC) is more unique, which greatly increases the difficulty of prediction. This is also why it is necessary to introduce machine learning (ML) technology with stronger data processing capabilities to predict the shear performance of LWC. Therefore, the aim of this study is to employ four well-known machine learning methods to predict the shear performance of LWC beams, namely, support vector machine (SVM), artificial neural network (ANN), radial basis function (RBF) neural network and random forest (RF). First, the shear test results of 220 LWC beams were collected, and the corresponding datasets were established based on possible influencing factors. Then, the optimal dataset partitioning methods for four different ML models were explored and determined. The parameter search process of the four models under the optimal dataset partitioning ratio was optimized using a genetic algorithm (GA), and four GA-ML prediction models were developed. The results show that the developed GA-RF model achieves a train set accuracy of 95.3 % and a test set accuracy of 93.3 %. The GA-ML technology significantly improves the accuracy of the prediction of shear strength compared to the formulaic model based on current international design standards. The prediction mechanism of the model is further analyzed to ensure that the model is reliable. The results indicate that it can be applied to predict the shear strength of LWC. In summary, the GA-RF model and importance analysis proposed in this article are practical methods for predicting and explaining the shear strength of LWC.

Reluctance of Students to Utilize Virtual Educational Environments in Public Schools: Real World Experiences

This study aimed to explore the perspectives of public-school students who were hesitant to use the Darsak Educational Platform (DEP) during the COVID-19 pandemic in order to understand their real-life experiences. To achieve the aim of the study, the researchers employed a qualitative approach in its phenomenological form. The study sample consisted of 12 male and female students from various public schools in Jordan. The participants were chosen using an intentional method. Semi-structured interviews were used to collect the data. The study’s findings revealed a variety of causes that contributed to students’ resistance to using DEP. These causes include the students’ lack of readiness to learn through DEP, the DEP’s failure to comply with international design standards, the inadequate physical and technical teaching environment, and the limited digital competencies of teachers needed in the virtual learning environment. Given the findings of this research, the researchers advise that additional consideration should be given to the design of DEP. They also advise providing students with appropriate guidance in the usage of educational platforms.

Algorithm for Evaluating the Effectiveness of Compositional Equilibrium of Graphical User Interfaces

Formulation of the problem: with the rapid development of information technology, numerous analogues of multidisciplinary programs are increasingly appearing on the software market. Despite the similarity of functions and identical sets of tools, these programs have different graphical user interfaces - program shells that provide the user with the opportunity to interact with the program using logic. In most cases, the overall assessment of users regarding the quality of programs depends on the effectiveness of interfaces. Having a scientific and methodological tool for assessing the effectiveness of interfaces, we can analyze them for the presence of various defects. Currently, there is no comprehensive tool for assessing the effectiveness of interfaces in the scientific literature. The purpose of the work is to develop evaluation tools that allow assessing the effectiveness of software product interfaces in numerical form. Methods: to achieve the stated goal, a comparative analysis of existing quantitative methods, metrics and laws from the scientific literature and international standards for software design and their software interfaces was carried out. Novelty: in comparison with existing methods, the developed approach is presented in the form of an algorithm capable of calculating indicators in the direction of the effectiveness of the compositional equilibrium of graphical user interfaces, which has not previously been evaluated by other researchers. Result: an algorithm has been developed for assessing the effectiveness of the compositional balance of graphical user interfaces, which allows for the evaluation and comparison of software products in this area.

Topology optimisation of offshore wind turbine jacket foundation for fatigue life and mass reduction

Offshore wind turbines are frequently regarded as a pricey source of electricity, and efforts are being made to lower both capital and operational costs by developing lighter and more robust structures. This paper presents a topology optimisation method to obtain a novel jacket foundation design by finding the optimum load path on the structure. The OC4 jacket model was computationally simulated considering the Aero-Hydro-Servo-Elastic loads, and the topology optimisation method was used to obtain a series of new designs. The structural optimisation is performed based on the dynamic response of the jacket, whilst restrained by relevant international design standards. In particular, time-domain fatigue simulations were performed to assess the structural integrity of the topology-optimised jacket for the first time. As a result, a range of optimised models with various thickness and diameter options are presented, which are shown to be rational and verify the optimisation procedure. The structural performance of the optimised geometry demonstrates the original jacket foundation is conservative, and the selection of optimised geometry achieved a mass reduction of 35.2% and simultaneously realised a 37.2% better fatigue life. The overall optimisation procedure and results provide useful practicalities for the design of offshore wind turbine foundations and potentially facilitate the structural integrity and cost reduction of the relevant industry.

Analytical and experimental shear evaluation of GFRP-reinforced concrete beams

Reinforced Concrete (RC) technology is advancing towards new frontiers enhancing its sustainability and durability through innovative materials. In particular, the application of Glass Fiber Reinforced Polymer (GFRP) bars, in lieu of steel reinforcement, shows excellent performance, especially in aggressive environments. Nevertheless, current international design guidelines and standards tend to be rather conservative, especially concerning shear reinforcement. This element hinders the technology’s competitiveness, not only in terms of material consumption but also in construction efficiency. This research aims to conduct an analytical comparison and experimental validation of the formulations found in some international standards pertaining to shear capacity in a specific case. The focus is on scenarios involving reduced shear reinforcement and cases where the number of stirrups falls below the minimum recommended by these standards. In the sample beam tests, two distinct flexural GFRP reinforcement ratios were employed to evaluate their influence on shear capacity, leading to diverse failure mechanisms: rupture of longitudinal GFRP bars and concrete crushing. The experimental results were used to compare the North American ACI, French AFGC, and Italian CNR shear capacity design approaches in the case of reduced transversal reinforced ratio. Analytical capacity expressions of the standards above are discussed with some remarks aiming at structural optimization.

Stakeholders’ Perspective on the Quality of Virtual Learning Material in Google Classroom

The COVID-19 pandemic stimulated education system worldwide to employ online learning to support learning despite difficult times. To respond to this challenge and to promote Sustainable Development Goal (SDG) 4, advocating quality education, a virtual learning material (VLM) for Biology was articulated in Google Classroom. Accordingly, this study aimed to evaluate its acceptability and conformity to the international standards for online courses using the Open SUNY Course Quality Review (OSCQR) rubric as the questionnaire. Respondents (N=40) involved four stakeholders: Senior High School Students, Pre-service Science Teachers, High School Teachers, and Science Instructors/Professors, with n=10 representatives each group. Their perspectives of the VLM acceptability in terms of Overview and Information, Technology and Tool, Design and Layout, Content and Activities, Interaction, and Assessment and Feedback were obtained through a Google Form by rating the 50-item questionnaire on a 4-point Likert scale together with two open-ended questions. With a grand mean of 3.81(SD=0.40), the findings revealed highly acceptable results. The qualitative responses also substantiated this result. Significant differences in the responses are also discussed, while the Cronbach alpha reliability test is high (α=0.923). Significantly, the VLM conforms with the international standards for online course design, suggesting it can be implemented among target students.

ANALYSIS OF DOMESTIC AND WORLD STANDARDS REGARDING THE CRITERIA OF THE BOUNDARY STATES FOR THE STEEL SILOS FOUNDATIONS

In the process of operation the structures of steel silos undergo various failures associated with natural and climatic loads and influences, the insufficient study of engineering and geological conditions, as well as some errors during operation. Damage to the above-ground structures of steel silos is mainly caused by roof structures and silo shells failures. Whilst operating silos, various types of raw material flow are distinguished during unloading. Possible scenarios of the operating technology violations can lead to deviations from the approved flow regime during unloading and they quite often become factors of an emergency situation. The conditions of loading and operation of silos have been compared pursuant to their presentation in the domestic and the foreign regulatory documents. A significant number of industrial accidents are associated with operation failures of reinforced concrete foundations, their insufficient load-bearing capacity and their deformability. It should be noted that the construction of the foundation affects its "flexibility", which may cause uneven settlement of the foundations and their base. Sometimes this leads to extra-design loads on the upper structure of the silo. In the domestic practice of increased diameters silos construction, the foundations with an underground gallery are the most common. For the construction areas having a high level of groundwater, the foundations with an above-ground under-silo storey are used. For the silos with an above-ground discharge funnel, the type of outflow influences the load pattern of the foundation. Whilst operating normally, the loads are uniform, and when the storage material hangs on the walls, the loads are uneven, which can lead to the destruction of the above-ground structure or a foundation tilting. The type of funnel significantly determines the shape of the outflow, which affects the distribution of internal forces in the silo and the load on the foundation. In this work, a brief analysis of the failure factors of steel silos has been carried out, and a comparative analysis of modern domestic and international design standards has been suggested concerning the criteria for the occurrence of boundary states of steel silos foundations during designing. There has also been analyzed the special operational features taking into account specific technological loads on silo shells and foundations, the certain features of engineering and geological conditions of construction sites. Conclusions have been made that the main criteria for foundations designing and calculating are the deformation criteria for limiting settlement and tilting. It should be noted that the foreign regulations place the issue of limiting maximum settlements within the scope of a designer's competence. Keywords: reinforced concrete foundation, steel silo, failure, boundary state, design norms.

Dynamic response analysis of a monopile-supported offshore wind turbine under the combined effect of sea ice impact and wind load

The existence of drifting ice is a key challenge for structural design of offshore wind turbines (OWTs) in cold regions. To better understand the structural behavior of OWT under combined sea ice impact and wind load effects, this paper investigates the dynamic response of a monopile-supported OWT using the nonlinear finite element method. The interaction between the OWT and ice impact, wind loads and soil contact are addressed in the developed numerical models in LS-DYNA. The coupling between the main program and the aerodynamic damping model is achieved by a user-defined load subroutine. To calibrate and verify the ice material model and the simulation technique, model test data are used of ice impacts with a nearly vertical monopile foundation. In the case study, numerical simulations of the interaction between a typical 5-MW monopile-supported OWT and an ice sheet are performed under various combined load scenarios. The dynamic response characteristics are presented and the effects of ice drifting speed and mean wind speed are elucidated by statistical methods. Finally, insights into the ice loads are obtained by comparing the simulation results against two international design standards. The present study contributes to an improved understanding of load effects of monopile OWTs in cold regions.

Overcoming tunnelling challenges on the Mumbai Coastal Road project in India

Completed in January 2022, the 2.1 km long 12.2 m dia. twin-bore Mumbai Coastal Road tunnel is the country’s largest ever constructed using a tunnel boring machine. It is also India’s first undersea tunnel embracing all current international design and operational standards. This paper describes Mumbai’s unique hydrogeological conditions and its impact on the choice of tunnelling machine. It then discusses the logistics of transporting the huge machine through one of the world’s most congested cities; the decisions made in its assembly, lowering and relaunch; and how overall tunnelling challenges were overcome.

Bond prediction of stainless-steel reinforcement using artificial neural networks

Stainless-steel reinforcement has become increasingly popular in the construction industry in recent years, mainly due to its distinctive characteristics and excellent mechanical properties. There is a real need to develop a fundamental understanding of the bond behaviour of stainless-steel-reinforced concrete (RC). This paper investigates the bond behaviour of stainless-steel-RC using the advancement of artificial neural networks (ANNs) and compares the performance with experimental data available in the literature with reference to existing bond design rules according to international design standards. Accordingly, a new bond design formula is proposed to predict the bond strength capacity of stainless-steel reinforcement. The results show an excellent agreement between the experimental results and the predictions of the ANN model. Both Eurocode 2 and model code 2010 are shown to be extremely conservative compared with ANN predictions. The proposed ANN-based formula provides an excellent basis for engineers to specify bond strength of stainless-steel reinforcement in RC members in an efficient and sustainable manner, with minimal wastage of materials.

Microzonation of Sejong City Area Based on Site Amplification Generated by Pohang-Type Seismic Waves

When an earthquake occurs, the behavior of the ground is significantly influenced by the seismic wave characteristics (waveform) and soil layer conditions. In local and international seismic design standards, it is recommended that the input seismic wave should correspond to the design response spectrum and reflect the fault characteristics. In this study, ground response analysis was performed to satisfy the seismic design standards using modified design seismic waves generated by the Pohang seismic waves measured at the bedrock location. The peak ground acceleration, ground amplification ratio, and natural period of Sejong-si for Pohang-type seismic waves were determined using the Sejong-si 120 site exploration results. From a plotted risk map, a map of floors that could experience relatively large seismic loads during an earthquake was determined. Based on the risk map plotted in this study, it is possible to prepare for earthquake damage in advance by identifying the degree of seismic damage to a structure when an earthquake occurs and selecting the building inspection or seismic reinforcement priority.

Direct Design of Stainless Steel Frames: Recommendations and Case Studies

AbstractAcknowledging the potential of system‐based design approaches, most international design standards for steel structures include preliminary versions of such alternative design methods. The Direct Design Method (DDM) is one of these approaches, which allows designing steel structures directly using advanced numerical analyses without requiring further member checks. This paper presents the DDM design (and verification) procedure and summarizes the key aspects of the advanced finite element model necessary for the determination of the system strength, with an emphasis on cold‐formed stainless steel portal frames. Through the design of two frames, the DDM design procedure is illustrated and the resulting cross‐sections are compared with those derived using the traditional two‐step design approach in the Eurocode and ASCE design frameworks. The results demonstrate that the DDM verification process is simpler and more direct, and that lighter structures are obtained when designing using the DDM for strength considerations. Finally, this paper also highlights that allowing larger deformations in the ultimate limit state design for the DDM does not have additional negative effects on the serviceability requirements if compared to the traditional two‐step design approach.

Mechanical properties of macro synthetic fiber reinforced concrete at elevated temperatures: A systematic review and meta‐analysis

AbstractThe current infrastructure boom combined with the latest outcomes from 26th UN Climate Change Conference of the Parties (COP 26) seeking a carbon neutral society by 2050 have driven the increasing need for sustainable alternatives to be considered in construction. One such alternative is macro synthetic fibers, which have been gaining acceptance on major infrastructure projects. However, only limited uptake has occurred in permanent structures, due to a lack of knowledge around the behavior of macro synthetic fiber reinforced concrete (MSFRC) when exposed to elevated temperatures. Existing Australian and international design standards do not take into account the loss of strength for MSFRC after exposure to elevated temperatures. Hence, this systematic review sets out to combine all the existing knowledge on the mechanical properties of MSFRC and lay the groundwork for determining acceptable relationships between relative strengths and elevated temperatures. This study proposes relationships between temperature and compressive strength, splitting tensile strength, elastic modulus, flexural strength and residual flexural, and tensile strengths of MSFRC. These are compared to existing relationships determined for plain concrete and steel fiber reinforced concrete to position MSFRC within the context of existing and accepted knowledge.

Modified Meyerhof approach for forecasting reliable ultimate capacity of the large diameter bored piles

The static loading test is undoubtedly the most reliable method for forecasting the ultimate capacity of the large diameter bored piles (LDBP). However, in-situ loading of this class of piles until reaching failure is practically seldom due to the large amount of settlement required for shaft and base mobilization. Therefore, many international design standards recommend either capacity-based or settlement-based methods to estimate the LDBP ultimate capacity in case of the impossibility of performing loading tests during the design phase. However, those methods are invariably associated with various degrees of uncertainty resulting from several factors, as evidenced in several comparative analyses available in the literature. For instance, the settlement-based method of the Egyptian code of practice (ECP 202/4) usually underestimates the ultimate capacity of LDBP. In contrast, Meyerhof's capacity-based method often overestimates the LDBP’s ultimate capacity. In this paper, a modified approach has been proposed to forecast the ultimate capacity of the LDBP. This approach was modified from Meyerhof’s classical formula (1976) through three fundamental stages. First, an assessment study was performed to evaluate the reliability of the estimated LDBP ultimate capacity using Meyerhof’s classical method. For this purpose, results of full scale loaded to failure loading LDBP test and related twenty-eight parametric numerical models with various pile geometrical and soil geotechnical parameters have been used. Based on the assessment study findings, the essential modifications were suggested in the second stage to adapt Meyerhof’s classic method. In the third stage, the results of several numerical models and in-situ loading tests were employed to assess the accuracy of the developed modified method. This study showed that Meyerhof's classical method overestimated the ultimate capacity of LDBP with an error percentage ranging from 14 to 46%. On the other side, the proposed modified approach has succeeded in estimating the ultimate capacity of loaded to failure in-situ LDBP test and twenty numerical LDBP models with error percentages ranging from 0.267 to 7.75%.

Composite overwrap repair of pipelines-reliability based design framework

Considering the ages and need for repairment of the gas and oil transmission pipes in the world, in the past years, lab and field experiments were performed on fiber reinforced polymer (FRP) wrapping to steel pipes. Although this technology has widely been employed for decades, further improvement on the design guidelines is still needed. In this context, this study proposes a reliability structural design framework for the repairment of corroded pipelines using FRP composite wrapping. To be consistent with international structural design standards, reliability-based design framework is to be proposed within a semi-probabilistic approach by calibrating safety factors to account for the associated uncertainties in capacity and load effects to best meet the cost-safety balance in design. Currently, the repair design practice for corroded pipelines is based on a deterministic approach, and it cannot ensure the proper consideration of uncertainties and meeting a consistent level of target reliability in design. This study involves comprehensive experiments of FRP materials under two different environmental conditions for onshore and offshore pipes, which were used to propose the best-fit statistical models to the design parameters to realistically represent the random variables in the proposed safety factor based structural design framework. Through extensive reliability analyses, the values for the safety factors for composite and steel have been proposed according to the target reliability indices and the corrosion rate. The proposed design framework for corroded steel pipes with FRP overwrap repairment is expected to improve the current design practice and optimize the cost and safety by meeting the target reliability level.

Experimental investigation on the flexural behaviour of stainless steel reinforced concrete beams

The durability of reinforced concrete (RC) structures and infrastructure has been the subject of significant attention from the engineering research community in recent years, mainly owing to the deterioration of RC elements due to corrosion of the embedded steel reinforcement. In this context, stainless steel reinforcement can provide an efficient solution to enhance the expected lifetime of concrete structures, reducing the damage due to corrosion of the reinforcement and carbonation and deterioration of the concrete. However, current international design standards for reinforced concrete structures do not include appropriate guidance for stainless steel reinforced concrete (SSRC). In order to investigate the behaviour of stainless steel RC beams, a series of six beam tests was conducted and is discussed herein. The key performance measures for RC beams such as load-deflection response, cracking behaviour and deflections at service load are assessed. The validity and applicability of existing design rules, which were developed for carbon steel RC, are also examined for stainless steel reinforced concrete members. Other recently developed design procedures, based on the Continuous Strength Method and including an accurate material model for the stainless steel bars, are also examined.