Simple Calculation Method Research Articles

Seismic behavior and mechanism of rectangular steel-concrete composite column with three cavities

This paper proposes a rectangular steel-concrete composite column (RSCC) with three cavities, which has a good architectural function. The composite column consists of steel tubes at both ends, steel plates in the middle, and concrete in the cavity. Five RSCC with three cavities were tested to investigate the seismic performance of the column width and headed studs. It was found that the specimens all exhibited flexural damage in the form of flexural tearing of the steel tube/plate and crushing of the concrete in the steel tube cavity. As the column width increases, the load bearing ratio and the percentage of shear displacement in the middle cavity of the specimen increase. The use of headed studs in RSCC with three cavities delay the stiffness degradation of the specimens, and the ductility of the specimens with column width of 400 mm and 500 mm set with headed studs increased by 10.1% and 4.6%, respectively, compared to that of the specimens without headed studs. In addition, a finite element model of the RSCC with three cavities was established, and the finite element analysis results matched well with the experimental hysteresis curves and damage characteristics. A simplified lateral force calculation method was established, and the average error between the predicted values and the corresponding test results for each specimen was 6.1%, which verified the applicability of the calculation model and provided a reference for the engineering application of the RSCC which has good function and performance.

Influence of method for determining thermal conductivity of coal combustion products on calculation accuracy

The determination of thermal conductivity of the combustion products of coal of various compositions by a simplified method and in accordance with the molecular-kinetic theory according to the Masson – Saxena equation is considered. Calculations were made for hard coal of the Volodarsky mine of grade A, Donetsk basin of grade OS, Kuznetsk basin of grade K, Tallinn section of grade G, Kizelovsky basin of grade G, and Tulganskoye deposit of grade 1B with the content of the combustible part by weight from 70.8% to 25.1%. The temperature of the combustion products varied from 200°C to 400°C in increments of 50°C, and the excess air coefficient varied from α = 1.15 to α = 1.5 in increments of 0.05. The discrepancy between the results of the simplified calculation and the results obtained by the Masson – Saxena equation was estimated using the relative error. Analysis of the calculation results showed that the thermal conductivity coefficient calculated according to the additivity rule using volume and mass fractions of the components of the combustion products is higher than that calculated using the Masson – Saxena equation at any excess air coefficients and temperature of the combustion products. With an increase in the temperature of the combustion products, in both cases, the error in determining the thermal conductivity decreases due to an increase in the value of the thermal conductivity. The use of simplified calculation methods leads to an increase in the thermal conductivity of combustion products by an average of 7.5% – 2% for coal of various compositions, depending on the temperature of the combustion products, compared with the values calculated using the Masson – Saxena equation.

Logistics-based design of collection system for asbeston-containing roof structures

Asbestos-containing roofing materials are an increasing hazard, which justifies their replacement by environmentally friendly roofing materials. Replacements can be carried out on an individual initiative basis, but a coordinated, systemic replacement will have a more significant impact. In order for such systemic asbestos removal to be successful from economics and logistics point of view, it is necessary to plan the associated logistics processes, as asbestos removal generates a significant transportation demand due to the large amount of waste generated. In the framework of this paper, the author presents an algorithm to plan the logistic process of centralized asbestos removal. A simple calculation method is presented to determine the cost of collection.

Post-fire performance of circular steel tube confined steel-reinforced concrete slender columns: Testing, simulation and design

Steel tube confined steel-reinforced concrete (STCSRC) stub columns offer good residual bearing capacity, great ductility, and large stiffness after fire exposure because inner steel profiles are unaffected by exterior temperature. Nonetheless, instability issues exist in STCSRC slender columns, and study into the mechanical characteristics of post-fire slender specimens is critical. At present, no relevant study on the axial performance of STCSRC slender columns after fire exposure has been reported. In this paper, nine circular STCSRC slender columns that had been exposed to fire were tested under axial load. The failure modes, axial load–displacement relationship, and lateral deflections of STCSRC columns were discussed. Furthermore, heat transfer analysis models and mechanical analysis models were established, and the effects of crucial variables on the buckling responses of STCSRC slender columns were explored. Among the parameters studied, sectional diameters and steel profile to concrete area ratio have a significant impact on buckling capacity. To calculate the buckling capacity of the post-fire STCSRC slender column, a simplified calculation method according to JGJ/T 471–2019 was proposed.

Review of Rydberg Spectral Line Formation in Plasmas

The present review is dedicated to the problem of an array of transitions between highly-excited atomic levels. Hydrogen atoms and hydrogen-like ions in plasmas are considered here. The presented methods focus on calculation of spectral line shapes. Fast and simple methods of universal ionic profile calculation for the Hnα (Δn=1) and Hnβ (Δn=2) spectral lines are demonstrated. The universal dipole matrix elements formulas for the Hnα and Hnβ transitions are presented. A fast method for spectral line shape calculations in the presence of an external magnetic field using the formulas for universal dipole matrix elements is proposed. This approach accounts for the Doppler and Stark–Zeeman broadening mechanisms. Ion dynamics effects are treated via the frequency fluctuation model. The accuracy of the presented model is discussed. A comparison of this approach with experimental data and the results of molecular dynamics simulation is demonstrated. The kinetics equation for the populations of highly-excited ionic states is solved in the parabolic representation. The population source associated with dielectronic recombination is considered.

Bulk and Surface Electrical Properties of BiSb on Flat and Ion‐Beam Nano‐Patterned InP Substrates

One route to the improvement of thermoelectric material performance is nanostructuring. Herein, BiSb thin films are grown by molecular‐beam epitaxy on two types of InP(001) substrate: flat epiready wafer, and nano‐patterned by ion bombardment and annealing (IBA). The effects of IBA on InP substrate are presented, and the structural and electrical properties of the BiSb films are measured. BiSb films on flat substrates are highly textured with (003) orientation, while films on IBA‐patterned substrates are less well ordered with mainly (012) orientation. A simple calculation method for nonplanar Hall measurements is proposed to explain the electrical conduction in rough films. The effects of BiSb film texture, roughness, and thickness on carrier density and mobility are provided. Sheet carrier density is independent of thickness at 77 K, which suggests conduction via surface states. Topological protection of such states may support nano‐patterning as a route to reducing thermal conductivity while maintaining electrical conductivity.

Study on seismic performance test and calculation method of recycled steel fiber reinforced concrete shear wall

SummaryRecycled steel wire is taken from used tires, and by procedures like mechanical cutting and friction treatment, it can be converted into industrial recycled steel fiber that meets precise criteria. Such green fiber may effectively limit the growth of fractures in concrete and diffuse the fracture energy of concrete when incorporated into concrete. An investigation of the effects of materials and horizontal reinforcement spacing on the seismic performance of shear wall specimens is presented in this research. The test and numerical simulation findings indicate that the RSFRC (recycled steel fiber reinforced concrete) shear wall's fracture is substantially narrower than that of a conventional shear wall and that the shear carrying capacity and deformation ductility of the shear wall have been greatly enhanced. The energy dissipation capacity of the RSFRC shear wall specimen with varying horizontal reinforcement spacing is significantly enhanced when compared to the conventional shear wall, and the ultimate displacements are reduced. RSFRC shear wall specimen has higher stiffness in the early stage, and the overall stiffness decreases slowly. With the decrease of fiber volume fraction of RSFRC shear wall in a certain range, the shear bearing capacity and stiffness of the model will decrease slightly, but the ductility will increase significantly. Compared with the RSFRC shear wall with fiber aspect ratio of 40 and 25, the bearing capacity and ductility of the two are close, but the RSFRC shear wall with low aspect ratio is slightly insufficient. When the axial compression ratio is in the range of 0.2–0.4, the horizontal shear capacity of RSFRC shear wall increases with the increase of vertical load, but the maximum horizontal displacement becomes smaller, and the model is damaged by compression. Using theoretical calculation, this work also creates the simplified calculation method and restoring force model for the bearing capacity of the diagonal section of RSFRC shear wall. The observed findings correspond well with the test hysteresis curve and may serve as a benchmark for future study. This study provides a new research direction for the seismic performance of RSFRC structures, as well as a solid theoretical foundation and promotion for future research.

Priority of Wind Energy in West Coast of Southern Thailand for Installing the Water Pumping Windmill System with Combining of Entropy Weight Method and TOPSIS

Wind energy potential or quality serve as the primary determinants influencing the decisions of Thai farmers regarding the installation of water-pumping windmills with heights ranging from 9 to 15 m and a cut-in wind speed requirement of 4 m/s, aimed at reducing their fuel costs. To introduce a simplified calculation method as one of their decision-making tools, the combined approach of the entropy weight method with TOPSIS has been introduced to assist them in prioritizing and assessing the wind quality in their respective areas. This study focuses on the western region of Southern Thailand, known for its high agricultural productivity. Initially, only 18 out of the 227 sub-districts with a minimum monthly wind speed exceeding 4 m/s were selected for thorough investigation. Subsequently, the entropy weight method was applied to the monthly wind speed data of these 18 chosen sub-districts to calculate their monthly weight values. These monthly weight values provide a quantifiable characterization of the wind quality in these specific sub-districts, revealing variations in wind quality between seasons, with superior quality during the summer season compared to the rainy season. Following the calculation of monthly weight values, the TOPSIS technique was applied to the wind data in conjunction with these monthly weight values, resulting in the determination of performance scores (Pi) for each of the 18 sub-districts. Pi values were found to vary from 0.0641 to 0.9006. In the final step of the analysis, these 18 sub-districts were ranked based on their respective Pi values, with the implication that sub-districts exhibiting higher Pi values are more suitable for the installation of water-pumping windmills with heights ranging from 9 to 15 m compared to those with lower Pi values.

Seismic behavior of steel frame infilled with wall-panels connected by sliding joint

This paper presents the experimental study on the seismic performance of steel frame structures equipped with novel sliding connection joints and wall panels reinforced by the fiber-reinforced polymer (FRP) sheet. Based on the proposed sliding connection joints and reinforced wall panels, five specimens were tested under cyclic loading. The bearing capacity, ductility performance, and energy dissipation capacity of the specimens were analyzed. Experimental results proved that the failure modes of all specimens were the crack of the panels and the column end buckling. And the infill wall panels had a significant supporting effect on the frame. The sliding joint and FRP sheet can enhance the collaborative ability, strength, and cumulative energy dissipation of the infill steel frame. Finally, a simplified calculation method is developed to evaluate the load-bearing capacity of the infill steel frame, considering the effect of the panels. The results proved the method owned acceptable accuracy, which could direct the practical design of the high-rise structure buildings.

Experimental and numerical study of zonal heat and moisture migration inside artificial ice rinks

Ice rinks feature typical non-uniform indoor environment with evident vertical and horizontal parameter differences. A validated CFD model established based on the on-site measurement is utilized to investigate the indoor environment along with the zonal heat and moisture transfer characteristics in a recreational ice rink. It is demonstrated that there are both cooling and heating demands inside the ice hall due to different control standards for various functional regions. Zonal mixing induces a large amount of additional load with 53.5% of the heat brought by the dehumidifiers eventually flowing into the ice sheet and carried away by the refrigeration system. The ice sheet cooperates with the dehumidifiers to dislodge the indoor moisture gain. The importance of proper design of ventilation systems and adequate physical separation is emphasized. Zonal migration coefficients are proposed, and the variation range influenced by different factors are investigated. The migration coefficients between the near-ice zone and the occupied ice field are around 4 W/(m2·K) and 5 g/(s·m2), and those between the occupied and unoccupied ice field are around 14 W/(m2·K) and 18 g/(s·m2). The findings provide a simplified calculation method for regional heat and moisture flow, and are beneficial for the optimization of system design and energy conservation in ice rinks.

The apparent effusivity method for normalized thermal contrast evaluation in infrared thermographic testing

Thermographic nondestructive testing is used for the detection of near-surface discontinuities in materials, where indications of potential defects or discontinuities are detected and evaluated by their thermal contrast. The key requirements for successful thermographic data processing include managing non-uniform heating and identifying nominal areas. Advanced methods often rely on numerical simulation, which can be challenging and time-consuming. This study suggests a new simple method of thermal contrast calculation for flash-pulse thermography. It is based on the analysis of the inverse apparent effusivity. It includes an automated indication of the sound (defect-free) area and the creation of an artificial reference sequence, which is based on a temperature profile of the sound area and the non-uniform heating map. Derivative analysis of the smoothed contrast data is applied to improve detectability and Contrast/Noise Ratio (CNR). An experimental comparison of the proposed method with other known methods is presented. In the presented example, it allowed detection of 23 defects with an average CNR of 6.13 dB, against the traditional differential absolute contrast method, which detected only 13 defects with an average CNR of 0.53 dB. Thus, high detectability and high CNR values provided by the proposed method are demonstrated.

Dynamic Response Analysis of Segmental Lining under Ground Shock: A Simplified Calculation Method

The tunnel lining segments are assumed to be rigid, and the tensile, compression, shear, and bending properties of the joints are considered. A simplified calculation method for the dynamic response of the structure under the ground shock is proposed, and its correctness is verified by comparing it with results from the finite element method. Using this method, the dynamic response of a subway tunnel lining is calculated, the change in joint force is studied, and the influence of the angle between the load and the center of the minimum segment and the wavelength–diameter ratio on the peak joint force is examined. The results indicate that under the ground shock, shallow tunnel lining is in the impulsive regime, and the force of segment joints is mainly compressed. As the wavelength–diameter ratio increases, the peak values of the lining top displacement and vertical deformation increase significantly, and the proportion of displacement and deformation caused by the inertial force gradually decreases. Sine and cosine functions can be used to preliminarily judge if the bending moment and radial force of the joint are too large or too small, so that the resistance of the lining to ground shock can be improved to a certain extent by setting the positions of lining joints reasonably.

Analysis of Production Cost Calculations Using The Full Costing Method of Mantahukan Fish on Ud. Kerupuk Ikan Kembar


 
 
 
 Abstract : This research was conducted at UD Kerupuk Ikan Kembar which operates in the Mantahukan fish cracker product industry, with the aim of knowing the calculation of the cost of production at UD Kerupuk Ikan Kembar and to analyze the application of the full costing method for calculating the cost of production at UD Kerupuk Ikan Kembar. This type of research uses quantitative descriptive research. Data was collected using documentation, interviews, and data analysis methods in the form of descriptive analysis. The research results show that UD Kerupuk Ikan Kembar still uses a simple production cost calculation method by adding up production costs consisting of raw material costs, direct labor costs, and supporting costs. Application of the full costing method by detailing all production costs that occur, including raw material costs.
 
 
 

Axial deformation of early-age concrete-filled steel tubular columns under multi-stage loading

The continuous construction scheme for concrete-filled steel tubular structures in practice is time-saving and cost-effective in comparison to the conventional moulding construction methods, whilst this also results in complex stress conditions and working mechanisms in the early-age concrete-filled steel tubes (CFSTs) during construction. This investigation aims to explore the influence of continuous construction process on the axial compressive behaviour of early-age CFSTs as subject to multi-stage loading schemes. Eight short square early-age CFST columns are designed and tested. The axial deformation evolutions of CFSTs are analyzed for different load parameters including the initial stress of steel tube, loading time interval and load magnitude. The test results show that the deformation of early-age CFSTs varies significantly with various load parameters. Excessive deformation can be observed during the multi-stage loadings due to the local buckling of the steel tube. Based on the shrinkage and creep model of concrete, a theoretical algorithm for calculating the relationship between the deformation of early-age CFST and the age of concrete is developed. Furthermore, a simplified calculation method for the deformation of early-age CFST under multi-stage loading is proposed that can realistically describe the deformation of early-age CFSTs under continuous construction process. The research findings lay a foundation for the deformation control and safety assessment of CFST under continuous construction scheme.

Modelling and Simulation of Aerodynamic Cylindrical Bearings Using ANSYS Hydrodynamic Bearing Element Types

Modern power engine concepts and environmental restrictions demand oil-free lubrication of rotors, for example, by gas bearings. However, the stiffness and damping properties ruling the rotor’s dynamics are poorly documented for aerodynamic bearings and simple calculation methods are lacking. Based on the similarity between aerodynamic and hydrodynamic journal bearings, it is investigated to what extent the hydrodynamic bearing element types of the commercial FE program ANSYS are also suitable for air bearings. Within these elements, the compressibility of the gas is neglected. After verification of the ANSYS hydrodynamic element types with literature data for cylindrical hydrodynamic bearings, the stiffness and damping coefficients of a cylindrical aerodynamic bearing are calculated by using the ANSYS hydrodynamic element types. In the examined speed range, the results agree well with literature data that consider gas compressibility. Therefore, the FE elements designed for hydrodynamical journal bearings may also be used for simulating cylindrical aerodynamic bearings. The presented calculation approach provides a compact and easy-to-use method for rotordynamic simulations with cylindrical aerodynamic bearings in a single development environment.

Experimental investigation of ultimate bearing capacity of corroded welded hollow spherical joints

The basis for analysing and evaluating the safety performance of space structures in service is investigating the effect of corrosion on the residual bearing capacity of welded hollow spherical joints. Thus, accelerated corrosion tests were conducted in this study on five types of welded hollow spherical joints, where the longest corrosion time is 283 d. Subsequently, axial tension, axial compression, and eccentric compression tests were performed after corrosion. The effects of the corrosion time, joint size, steel strength, and eccentric load on the mechanical properties of the corroded joints were then considered. The test results show that the failure mode and strain distribution of the joints are not influenced by corrosion. For the axial force, the ultimate bearing capacity of the corroded joints fluctuates with the corrosion rate (less than 10%); and under the combined action of the bending moment and axial force, the ultimate bearing capacity of the corroded joints decreases with a decrease in the corrosion rate (maximum reduction of approximately 22%). Finally, a simplified calculation method for the ultimate bearing capacity of welded hollow spherical joints after corrosion was proposed. For the atmospheric environment in Qingdao (over a 50 year period), the corrosion coefficient under axial force is 0.87 considering the joint size and comprehensive corrosion influences. Under the combined action of the axial force and bending moment (within 40 mm of the initial eccentricity), the corrosion coefficient is 0.73.

The effect of temperature actions on single‐sided fillet welds in small‐sized box girders of bridges

AbstractThe use of small‐sized box girders has shown to bring numerous benefits in the design of bridges with short to medium spans. Therefore, it has become an established construction method in Germany. However, the beams are not accessible for inspection due to their small size, requiring the girder to be welded airtight. The limited accessibility also has consequences on the manufacturing process. Two of the four longitudinal fillet welds can only be executed from outside resulting in single‐sided fillet welds. As a result of the airtight construction, temperature actions lead to fluctuation of the internal pressure of the box. The single‐sided fillet welds are consequently subjected to unscheduled bending stress, which has an unclear impact on the weld. Subject of the research project, presented in this paper, is the influence of this unscheduled load case on the load‐bearing capacity of the girder. To quantify the temperature which leads to changes of the internal pressure, numerical studies based on meteorological data are performed. The load‐bearing behavior of single‐sided fillet welds is investigated in experiments. It can be shown that the load‐bearing capacity is underestimated by simplified calculation methods.

Evolution of EC 6—Influence on masonry constructions made from AAC

AbstractWithin the scope of developing a new generation of Eurocodes also the European masonry standards are subjected to an evolution. Thereby new drafts for all four parts of EN 1996 have been elaborated and the final versions are available. Aim of the evolution was to implement the application experiences of the actual version, improving the ease of use and reducing the number of National determined parameters. The most severe changes of the new versions of the standards are the modifications of the calculation methods in EN 1996 parts 1‐1 and 3. Especially for masonry walls with a compressive strength and for constructions with partly supported ceilings the new simplified calculation methods showed a significant difference in the maximum capacities. Basing on this finding the conditions and rules for the design of AAC masonry according to EN 1996‐3 were adapted and thus improved for the final draft. This was a result of a big number of comparing calculations which took into account the special properties and behaviour of AAC masonry especially the ratio between compressive strength and modulus of elasticity. Regarding fire resistance of masonry walls several new test results have been implemented in EN 1996‐1‐2 for revising the tabulated values. The new tables also provide clearer allocations in terms of minimum thicknesses of walls for fulfilling the conditions regarding the different periods of fire resistance.

An evaluation method for quantifying the residual performance of flexible rockfall barriers after impact

Currently, there is no effective analysis algorithm to calculate and evaluate the residual performance of flexible barriers after suffering rockfall impact. To solve this problem, a novel approach for assessing and quantifying the residual performance of flexible barriers through the deflection degree of different components is proposed, based on the substantial experimental database from impact tests that were conducted with impact energies between 750 kJ and 1500 kJ, revealing a high correlation between the three-stage macroscopic deflection characteristics and the residual performance. The approach consists of two significant aspects, one is the calculation method of the residual protection capacity, which was established according to the simplified calculation method of the energy dissipation of the dissipators. The other aspect is the damage identification method for the barrier system based on the deflection of key components, which was determined by comparing the deflection angle of the post and the punching deflection of the net obtained from the analytical geometric model with the ultimate deflection of those components calibrated by tests. Utilizing the ultimate force-deflection relationship calibrated by tests, a method to discriminate the system damage based on the analytical calculation value of the deflection of key components is established. Furthermore, both full-scale tests and numerical simulations were conducted to validate the proposed analytical calculation method. The tested flexible barrier had a nominal energy level of 2000 kJ, and the tests included service energy level (SEL) and maximum energy level (MEL) continuous impacts. The analysis results show that the maximum calculation errors for the energy dissipated by the energy dissipators, elongation of the energy dissipator, elongation of the wire ring, and out-of-plane deflection angle of the post are -3%, 10%, 12%, and -8%, respectively. The evaluation results of the residual performance as well as the damage identification both have satisfied agreement with the test results, confirming the reliability and applicability of the analytical method to engineering maintenance decisions.

Compressive–Flexural Failure Mechanism and Bearing Capacity Calculation of Over-Ranging Tapered CFDST Members for Support Structures of Offshore Wind Turbines

Upon the higher requirement on high-performance structures of large-scale supporting structures of offshore wind turbines, the systematic analysis on the compressive-flexural behavior and ultimate bearing capacity of tapered concrete-filled double skin steel tubular (CFDST) members designed by over-ranging parameters was performed. Investigating the entire-process mechanism, e.g., the moment–deformation response, stress development, interaction stress, and subassembly contribution, was based on the finite element (FE) analysis, where the moment–deformation curve can be distinguished by four characteristic points, and the transverse local buckling of outer tube partly weakens distribution height of interface pressure in compression zone compared to that in tension zone. Influences of material strengths and geometric parameters were examined by the parametric study, e.g., increasing tapered angle (ψ) slightly reduces the bearing capacity; the higher axial compression ratio (n) contributes a noteworthy action on the post-peak behavior and carrying capacity, e.g., the bearing capacities at n = 0.9 and n = 0.5 reduce by 64.14% and 18.44% compared to capacity at n = 0.1, respectively; influence of Do/to ratio is more significant than Di/ti ratio. Subsequently, the modified cross-sectional stress integration (CSI) method was proposed to predict the moment–strain (M-ε) curves of tapered CFDST members; meanwhile, a confined concrete model with transverse confinement stress as an explicit parameter was modified, and influences of different confined concrete models on predicting M-ε curves were compared. Finally, design methods based on the modified CSI method and limit state method were proposed as a simplified calculation method to determine the correlative relationship of axial compressive strength and moment-resisting capacity (N-M curve).