Stainless Steel Frame Research Articles

A new plastic global analysis approach for the fire design of steel and stainless steel structures

The new generation of structural codes for stainless steel allow carrying out global plastic analyses on certain types of stainless steel structures with plastic cross-sections at room temperature if the joints conforming the structure are classified as full-strength joints, a capability that has been long recognised for carbon steel structures. However, the requirements for the fire design of carbon and stainless steel structures in current and upcoming European design standards are still primarily based on the resistance of individual members, disregarding the redistribution of internal forces and strain hardening effects. Recent studies have proven that carbon and stainless steel frames with plastic cross-sections and full-strength joints are capable of redistributing internal forces at elevated temperatures, and failed describing global plastic collapse mechanisms under fire situation, suggesting that system effects are also relevant at elevated temperatures and could be taken into account for more efficient designs. On this basis, this paper develops an extensive numerical study focused on carbon and stainless steel frames under fire situation, and proposes a new methodology based on plastic global analysis to estimate the resistance of such structures under fire situation accounting for their redistribution capacity, improving the accuracy of the predicted fire time resistances significantly for the two materials.

Experimental study on seismic performance of stainless steel full-scale frames: Global response

This paper presents an experimental study of the seismic performance of austenitic stainless steel full-scale frames using the pseudo-static test method. The bottom single-span, two-storey substructure of the designed prototype frame was chosen as the test frame. Two full-scale frames were tested, one with a bolt-welded joint and the other with an extended end-plate joint. This paper is the first of two accompanying papers to this experimental study and focuses on the specimen design, testing details and global response of the stainless steel frame under cyclic loading. The test results were utilized to analyse the global response of the frames, encompassing failure mode, bearing capacity, deformation capacity, energy dissipation capacity, the overstrength factor, ductility factor and seismic response modification factor. The experimental findings suggest that the stainless steel frames with two joint types demonstrate consistent ability to dissipate energy during cyclic loading. The structure also performs well in terms of deformation, with uniform inter-storey deformation and no soft-storey detected. The maximum storey drift ratio of the frame is 7%. Prior to reaching a storey drift ratio of 2%, the frames with both joint types exhibit similar cumulative plastic deformation, stiffness degradation, and cumulative energy dissipation.

Deep Learning-based marine species detection and classification framework for biomonitoring in the Arctic fjords, Svalbard

The effects of ongoing climate change have caused a poleward shift in the distribution of species due to the rapidly rising water temperatures. This calls for an immediate need to assess and document the extent of climate change-driven animal migrations occurring in the Arctic waters. However, the extreme climatic conditions and the remoteness of the region makes biomonitoring tedious in the Arctic ecosystem. The present study puts forward a deep learning-based analysis of a large underwater video dataset that was captured from the Arctic region. The dataset was acquired using underwater cameras mounted on custom-made stainless-steel frames. The video footages were collected over a period of 26 days from the Kongsfjorden- Krossfjorden twin Arctic fjords in Svalbard, Norway. The collected data sets were used to train YOLO-based object detection framework (You Only Look Once) for an automated detection of the organisms. The YOLO model employed for the study was found to be very efficient in classifying the underwater images captured from the region. The object detection framework could detect images of Comb jelly, Echinoderm, Sea Anemone and Ulke (Shorthorn sculpin) from the underwater images. The model attained a superior value of Mean Average Precision (mAP), precision, and recall of 99.5%, 99.2%, and 97.4%, respectively.

A comparative analysis of damage identification methods based on multi-channel data fusion and convolutional neural network for frame structures

Vibration-based damage identification methods are crucial for structural health monitoring. In recent years, deep learning methods, such as convolutional neural networks (CNNs), have been widely used for damage identification due to their superior performance. To enhance the accuracy of damage identification for complex frame structures and effectively utilize data measured from multiple sensors, this study proposes and compares four different damage identification methods based on CNN and four different kinds of multi-channel data fusion approaches, i.e., data splicing, matrix reconstruction, data dimension elevation, and sub-model integration. Firstly, the original one-dimensional vibration signals of the frame structures are measured. Then, multi-channel data fusion is performed on the signals to construct datasets used as input to train the CNN model. Finally, the sensitive damage features are automatically extracted using the trained CNN models after parameter tuning, and the structural damage patterns are identified. The effectiveness of these damage identification methods is evaluated using the numerical model of IASC-ASCE Benchmark structure, the Qatar University Grandstand Simulator test, and a three-layer stainless steel frame structure test. The efficiency of damage identification methods using multi-channel data is compared to those using only single-channel data. Additionally, the impact of noise on damage identification accuracy is also analyzed. The results demonstrate that the proposed four different damage identification methods based on CNN and multi-channel data fusion, outperform the methods that solely rely on single-channel data. Furthermore, these methods significantly enhance the accuracy of damage identification.

I-section stainless steel portal frames: Loading tests and numerical modelling

Austenitic stainless steel is an attractive structural material due to its high ductility, appropriate toughness, significant strain hardening and good fire resistance. Also the laser welding technology for fabrication of structural stainless steel profiles has recently become increasingly popular. However, there is still only a limited amount of experimental data on laser-welded stainless steel members. And loading tests of whole structures made of these sections have still not been published. Therefore, loading tests were performed on two austenitic stainless steel frames made of laser-welded I-sections. The frames had pinned columns and were loaded both vertically and horizontally. The objective of the loading tests was to capture the effects of material nonlinearity on the global sway behaviour of the stainless steel frames. In fact, material nonlinearity leads to a gradual loss of stiffness, which results in higher deformations and thus a higher second-order effect. The resulting load-displacement diagrams of the experiment are tabulated, allowing their further use. A numerical model of the studied frames was developed and validated on the basis of the performed experiments. Based on the elastic buckling load factor and the modified elastic buckling load factor, a large influence of material nonlinearity on second-order effect has been demonstrated.

Experimental investigation on the square and rectangular hollow section stainless steel portal frames

Cold-rolled hollow sections are the most commonly used stainless steel sections in the construction industry, because the production of this type of profile is the most cost-effective in smaller volumes. However, very little experimental research has been carried out so far on whole structures made of these sections. Therefore, experiments on stainless steel frames were carried out. In total, 5 portal frames made of austenitic stainless steel SHS/RHS were tested. These tests are described in detail, including the layout of auxiliary elements and measuring devices. The aim of the experiments was to capture the effects of material nonlinearity on the global behaviour of the stainless steel frames. The load–displacement diagrams are presented in tables, enabling their use for the validation of numerical models. Tensile coupon tests were carried out and parameters for common material models were determined. Numerical models of the studied frames were developed and validated using the experiments performed. These numerical simulations have been shown to be able to capture the general load–displacement response in a global, in-plane mode. Linear buckling analysis was carried out. Resulting elastic critical load factors indicated a high susceptibility of the frames to second order effects. In addition, modified elastic critical load factors were determined, showing the large influence of material nonlinearity on second order effects.

Micromechanical Loading Studies in Ex Vivo Cultured Embryonic Rat Bones Enabled by a Newly Developed Portable Loading Device.

Mechanical loading has been described as having the potential to affect bone growth. In order to experimentally study the potential clinical applications of mechanical loading as a novel treatment to locally modulate bone growth, there is a need to develop a portable mechanical loading device enabling studies in small bones. Existing devices are bulky and challenging to transfer within and between laboratories and animal facilities, and they do not offer user-friendly mechanical testing across both ex vivo cultured small bones and in vivo animal models. To address this, we developed a portable loading device comprised of a linear actuator fixed within a stainless-steel frame equipped with suitable structures and interfaces. The actuator, along with the supplied control system, can achieve high-precision force control within the desired force and frequency range, allowing various load application scenarios. To validate the functionality of this new device, proof-of-concept studies were performed in ex vivo cultured rat bones of varying sizes. First, very small fetal metatarsal bones were microdissected and exposed to 0.4 N loading applied at 0.77Hz for 30s. When bone lengths were measured after 5days in culture, loaded bones had grown less than unloaded controls (p < 0.05). Next, fetal rat femur bones were periodically exposed to 0.4 N loading at 0.77Hz while being cultured ex vivo for 12days. Interestingly, this loading regimen had the opposite effect on bone growth, i.e., loaded femur bones grew significantly more than unloaded controls (p < 0.001). These findings suggest that complex relationships between longitudinal bone growth and mechanical loading can be determined using this device. We conclude that our new portable mechanical loading device allows experimental studies in small bones of varying sizes, which may facilitate further preclinical studies exploring the potential clinical applications of mechanical loading.

Plastic redistribution capacity of stainless steel frames in fire

Stainless steel frames with compact cross-sections are capable of redistributing internal forces at room temperature and forming plastic failure mechanisms, which is reflected in the new generation of structural codes for stainless steel by allowing to carry out global plastic analyses on certain types of stainless steel if the joints conforming the structure are classified as full-strength joints. Nevertheless, the requirements for the fire design of stainless steel structures in current standards is still primarily based on the resistance of individual members, disregarding strain hardening effects and the redistribution of internal forces, mainly because the influence of the performance of stainless steel joints on the response of the frames under fire situation is yet unknown. On this basis, this paper presents a numerical study focused on stainless steel frames with compact rectangular hollow sections, both at room temperature and at elevated temperatures, to analyse the influence of full-strength joints on the frame's response by means of two joint modelling techniques, and to assess the plastic redistribution capacity of stainless steel frames, especially under fire situation. In addition, an exhaustive revision of the failure criteria for stainless steel frames under fire situation is carried out and a new failure criterion is proposed based on the results derived from the parametric study. The results demonstrate that stainless steel frames are also capable of redistributing internal forces and forming plastic collapse mechanisms under fire situations, suggesting a new procedure to predict the response of these structures under fire situation more accurately.

Optimization design of remotely operated vehicle (ROV) for Madura Strait Area

Nowadays, the development of unmanned vehicles is significantly increased. Since the remotely operated vehicle (ROV) has more advantages than Diver. Then, ROV has an important role in underwater inspection and research in various sectors, such as offshore infrastructure development. ROV will give some critical information to the operator about an underwater inspection like bathymetry, pipeline inspection, and the other crucial subsea structure that the divers can’t reach. The optimization design has been carried out to determine ROV operational requirements in Madura Strait by Total-Based Method. ROV will be divided into 3 leading function groups, they are Features, Survive and Operate. Every group will be divided into Function Breakdown Structure (FBS). FBS will be divided again into Work Breakdown Structure (WBS). The optimum design will be determined by linking every breakdown function. The results are the ROV has 2MP 1080P resolution for camera, 2000 lumens for lighting, 50 m detection area for sonar and echosounder, 100 N grip force for Gripper, equipped with stainless steel frame, 2 hours long for operational duration, 5kg.f for thruster, operated with cable 300 m long and equipped with 6-unit thruster.

Pseudo-static test on stainless steel frame with high-strength bolted extended endplate joint

Many studies have been conducted on stainless steel materials, components and joints; however, experimental research on the seismic response of stainless steel structures is rare. This study reports pseudo-static loading tests on S2205 duplex stainless steel and Q355B carbon steel frames with high-strength bolted extended endplate beam-to-column joints. The two frames have the same geometric configuration and equivalent elastic limits (approximately 350 MPa). The detailed test processes and failure modes are presented. The Q355B carbon steel frame failed with extensive plastic deformation at the end of the beam, whereas the S2205 duplex stainless steel failed from fracture of the weld between the beam flange and endplate. The test results were analyzed at the global level (lateral load capacity, energy dissipation, etc.), beam-column joints (hysteresis curves), and yielding sequence. Owing to the considerable strain-hardening of stainless steel, the S2205 stainless steel frame had a higher loading capacity, whereas the Q355B carbon steel frame had a higher ductility and energy dissipation capacity.

Pengembangan Mina Bisnis Blue Crab (Callinectes sapidus) dengan TTG Blue Crab Boiler Pada UD. Selat Madura 33 untuk Meningkatkan Daya Saing

Blue Crab (Callinectes sapidus) is one of the most popular export commodities. One of the activities carried out by crab fishermen is traditional steaming so the steaming time is relatively long and the quality of the crab meat obtained is not good because it contains a lot of water. Therefore, the purpose of this activity is to improve the quality of the crab by using a mechanical boiler. The target partners are Mr. Abd. Malik, the owner of UD. SM 33 (Madura Strait 33). The mechanical steamer machine is a stainless steel frame cabinet model with dimensions of 50 cm x 50 cm x 120 cm which has 5 shelves inside. This service method provides socialization and training on the use of this machine. The results of this activity can improve the skills of partners so that the quality of crab meat is better maintained because it reduces water content by 70% and production cost efficiency by 60%.

Optimization of X-Ray Spectra in Medical Sterilization Accelerator through MCNP

A Bremsstrahlung converter for medical apparatuses sterilization has been designed using tantalum and stainless-steel frame for a high energy electron accelerator operating at an incident electron energy of 7.5 MeV. Optimization of the x-ray spectra of the converter is investigated in this paper by adding a beam hardening filter from copper, aluminum, and stainless steel. The MCNP code is used to simulate the particle transport through the converter design. To survey the effect of each filtered spectra, angular dose distribution in the air is measured at radial distances of 50, 75, and 100 cm from the tantalum for the angle of 0° to 90°. A comparison between the unfiltered and the filtered spectra shows a marked decrease in low energy photon intensity up to the energy of 100 keV by all three filter materials with a greater reduction and hardening when combining the filter materials. These findings result in the angular dose distribution of the produced x-ray having a lower intensity at closer radial distances to the target due to the decreased intensity of x-rays with low energy, denoting a better dose homogeneity over the irradiated material.

Numerical study of thermal diffusion in a passive autocatalytic recombiner: Possible effects on catalyst temperature and hydrogen distribution

This paper describes a numerical study of the influence of thermal diffusion (the Soret effect) on the operational behaviour of a passive autocatalytic recombiner (PAR). The study proposes a detailed three-dimensional computational fluid dynamics (CFD) model of hydrogen oxidation along a cylindrical-type PAR catalyst section (RVK-500, RET, Russia) inside a small-scale vertical channel. The CFD model was developed in STAR-CCM+ and uses multi-step chemical kinetics with a conjugated approach (surface and gas-phase included). The catalyst temperature and hydrogen conversion with and without the Soret effect in the model were determined numerically and compared against experimental measurements. The experiments reported here have previously been conducted on the cylindrical-type catalyst section, for 5–7 vol % inlet H2 concentration. Numerical simulations demonstrate that local hydrogen concentration can be increased due to thermal diffusion at the lower side of the stainless-steel frame. Results identified that the catalyst temperature can be underpredicted by 10–20 °C without thermal diffusion included in the model.

Experimental study on stainless steel tubular members under cyclic loading

Stainless steel is an excellent construction material due to its high ductility, strain hardening, durability and aesthetic characteristics. To date, most studies on stainless steel have been devoted to understanding its mechanical properties and the behaviour of individual structural members and simple structures under monotonic loading. As a result, next versions of stainless steel codes, traditionally based on carbon steel codes, will enable efficient structural designs under static forces. However, advances related to the performance of stainless steel structural members under cyclic forces are still scarce, and there are no specific rules for the seismic design of stainless steel structures in Eurocode 8 in spite of the notable differences between this material and other steels. On this basis, an experimental programme on austenitic stainless steel hollow section elements subjected to cyclic loading has been recently conducted. A total of nine specimens with different local and member slenderness values were tested under cyclic bending around their major axis following a cantilever loading scheme. This paper describes the experimental set-up adopted for the tests, including the loading scheme and instrumentation, and discusses the load–displacement, moment–rotation, degradation of stiffness and energy dissipation values obtained in detail. In addition to providing fundamental information on the response of stainless steel members under cyclic loading, the description of the set-up reported in this paper will assist researchers in planning similar experimental programmes, while the results will serve as a reference to validate numerical analyses of stainless steel members and frames subjected to cyclic loading.

Stainless Steel Portal Frame Tests

AbstractExperiments on stainless steel frames were carried out within this research. In total, 5 portal frames made of austenitic stainless steel SHS/RHS were tested. The paper thoroughly describes the performance of the loading tests including the layout of auxiliary elements and measuring devices. The technical drawing of the experiment layout with a description is presented as well as several photos. The load‐bearing capacities of the frames are summarised in a table. The research aims for a global structure behaviour examination with a particular focus on stainless steel structures. Their behaviour is highly influenced by nonlinear material stress‐strain response. Material nonlinearity leads to loss of stiffness, which results in greater deflections. And greater deflections generate greater second‐order effects. Worldwide research show this particularity needs to be taken into consideration when conducting a global analysis of the structure.

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.

Reliability of stainless steel frames designed using the Direct Design Method in serviceability limit states

Steel structures can be consistently and efficiently designed using system-based design-by-analysis approaches such as the Direct Design Method. However, since direct design approaches lead to potentially lighter structural configurations, they can also result in larger deformations under service loads. Thus, greater attention may be required to serviceability limit states in structures designed using design-by-analysis approaches than for structures designed elastically at their ultimate limit state following current two-stage approaches, especially for materials showing highly nonlinear stress vs strain responses such as stainless steel alloys. With the aim of investigating the influence of allowing larger deformations in the ultimate limit state design of stainless steel structures, this paper presents an explicit analysis framework for assessing serviceability reliability at system level. Using this framework, the paper investigates the serviceability reliability of cold-formed stainless steel portal frames designed using the Direct Design Method for different load cases, including the gravity load and the combined gravity plus wind load combinations. The study considers six baseline frames covering the most common stainless steel families and international design frameworks (i.e., Eurocode, US and Australian frameworks), for which the reliability of vertical deflection and lateral drift serviceability limit states is investigated using advanced numerical simulations and First-Order Reliability Methods. From the comparison of the calculated average annual reliability indices and the relevant target reliabilities for the different design frameworks, it was found that the reliability of stainless steel frames appears to be adequate for the serviceability limit states investigated for the Eurocode, US and Australian frameworks.

System-based reliability analysis of stainless steel frames subjected to gravity and wind loads

In the process of developing the next generation of design standards for steel structures, most relevant international structural codes including AISC360, AISC370, AS/NZS4100 and Eurocode3 already incorporate preliminary versions of system-based design-by-analysis approaches that allow a direct evaluation of the strength of steel and stainless steel structures from advanced numerical simulations. As a result, recent research works have focused on building rigorous structural reliability frameworks to investigate acceptable target reliability indices for structural systems and to develop new design methods in conjunction with adequate system safety factors and system resistance factors. Although design recommendations exist for the direct design of hot-rolled and cold-formed steel structures based on advanced finite element analysis, the extension of the method to other materials such as stainless steel is under development. This paper is part of a research effort to build a reliability framework for stainless steel structures subject to different load combinations and presents the results of system reliability calibrations carried out on six stainless steel portal frames subjected to combined gravity and wind loads. The study covers the most common stainless steel families and three international design frameworks (i.e., Eurocode, US and Australian frameworks). From the reliability calibrations derived, suitable system safety factors γM,s and system resistance factors ϕs are proposed for the direct design of stainless steel frames under combined gravity and wind loads using advanced numerical simulations.

Simplified expressions for reliability assessments in code calibration

First Order Reliability Methods (FORM) have been used by specification committees in the reliability analyses required for the calibration of resistance and safety factors for the past 40 years. However, these methods are iterative, require input information that may not be readily available, and make comparisons between different approaches or design frameworks difficult. This paper presents a set of simplified equations to estimate reliability indices β, resistance factors ϕ and partial safety factors γM based on simpler First Order Second Moment (FOSM) considerations for the US and Eurocode frameworks, which are particularized for different load cases, and on the semi-probabilistic approach prescribed in the Eurocode 0. The equations provide direct relationships between the reliability calibration results corresponding to different design frameworks, and can be used to estimate resistance factors as simple cross-checks for the US framework based on the partial safety factors derived for the Eurocode (or vice versa) from basic statistical input information and given target reliability, including when the data available in the literature is insufficient to perform FORM analyses. The accuracy of the proposed equations is assessed against reliability results derived using FORM techniques for an extensive database of steel and stainless steel frames subjected to gravity and combined gravity plus wind load cases collected from the literature, and limitations for their applicability are recommended. The results demonstrate that the set of equations proposed in this paper provides accurate estimations of the reliability index β, resistance factors ϕ and partial safety factors γM and can assist specification committees in the process of calibrating suitable ϕ and γM-factors.

A New Type of Quartz Smog Chamber: Design and Characterization.

Since the 1960s, many indoor and outdoor smog chambers have been developed worldwide. However, most of them are made of Teflon films, which have relatively high background contaminations due to the wall effect. We developed the world's first medium-size quartz chamber (10 m3), which is jointed with 32 pieces of 5 mm thick polished quartz glasses and a stainless-steel frame. Characterizations show that this chamber exhibits excellent performance in terms of relative humidity (RH) (2-80%) and temperature (15-30 ± 1 °C) control, mixing efficiency of the reactants (6-8 min), light transmittance (>90% above 290 nm), and wall loss of pollutants. The wall loss rates of the gas-phase pollutants are on the order of 10-4 min-1 at 298 K under dry conditions. It is 0.08 h-1 for 100-500 nm particles, significantly lower than those of Teflon chambers. The photolysis rate of NO2 (JNO2) is automatically adjustable to simulate the diurnal variation of solar irradiation from 0 to 0.40 min-1. The inner surface of the chamber can be repeatedly washed with deionized water, resulting in low background contaminations. Both experiments (toluene-NOx and α-pinene-ozone systems) and box model demonstrate that this new quartz chamber can provide high-quality data for investigating SOA and O3 formation in the atmosphere.