Calculation Of Capacity Research Articles

Slenderness effects on concrete-filled square steel tube columns strengthened with CFRP grid-reinforced ECC matrix

This study presents an experimental investigation aim at evaluating the slenderness effects on concrete-filled square steel tube columns strengthened with a carbon fiber-reinforced polymer (CFRP) grid-reinforced engineered cementitious composite matrix. Thirteen columns were subjected to axial compression, with the studied parameters including the length-to-width (L/B) ratio, CFRP grid layer number, concrete strength grade, and width-to-thickness ratio of the steel tube. Test results revealed that slender columns experienced an increase in load-bearing capacity ranging from 27.1 % to 32.4 % after strengthening, while the ductility enhancement reached a peak of 52.0 %. A column with an L/B ratio of 5.87 exhibited slight bending deformation in a localized region upon failed, with CFRP grid ruptured at the corner. While columns with L/B ratios of 7.83 and 9.78 failed due to the loss of stability, displaying overall bending deformation. The increase in L/B ratio accelerated the loss of stability, resulting in a decrease in the ultimate load. As the L/B ratio increased from 2.97 to 5.93, 7.91 and 9.89, the ultimate loads of the strengthened columns decreased by 7.4 %, 9.2 %, and 15.4 %, respectively. A load-bearing capacity calculation model of slender strengthened columns was developed using the fiber element method. Through numerical analysis, a stability coefficient was introduced, and a simplified calculation formula was proposed to predict the stability bearing capacity.

Axial compressive performance of thin-walled square steel tube concrete short column with built-in steel slag block

In the process of iron and steel production, steel slag is produced as waste. The steel slag processing method generally produces steel slag cement as a substitute for gravel and fine aggregates. Steel slag aggregates replace natural aggregate concrete used in concrete components. In addition, steel slag expansion can compensate for the shrinkage characteristics of concrete and steel pipes inside closed wet environments, and the outer steel tube hoop constraint can avoid late hydration expansion structure cracking. Through orthogonal testing, the wall thickness of the steel pipe (3 mm, 3.75 mm, 4.5 mm), content of the steel slag blocks (10 %, 15 %, 20 %) and particle size of the steel slag blocks (40–60 mm, 60–80 mm) were used as experimental variables to conduct axial compression tests on 9 groups of short columns made of slag aggregate concrete-filled thin-walled square steel tubes. Based on the analysis of the test process and displacement, strain, ductility and ultimate bearing capacity results, the failure pattern and mechanism of the short column specimens under axial compression were obtained, and a bearing capacity calculation formula was obtained according to the existing theoretical methods. The results indicate three failure patterns: local convexity, shearing and circumferential bulging. The factors influencing the bearing capacity, from most influential to least influential, are the particle size of the steel slag, the wall thickness of the steel pipe and the amount of steel slag. The Poisson's ratio of core concrete has an important effect on its passive binding force, which affects the longitudinal displacement and load-bearing capacity of the component. The deduced formula can be used to accurately calculate the ultimate bearing capacity of the square steel tube and steel slag concrete. This article transforms the drawbacks of steel slag concrete into advantages and, by combining the characteristics of steel tube concrete, proposes a new type of composite component that has a certain degree of innovation and application value.

Flexural behavior of historical RC beams strengthened with hybrid FRP sheets

Historical reinforced concrete (RC) buildings are culturally and aesthetically significant and require conservation due to aging. Strengthening RC buildings often requires the use of Fiber Reinforced Polymer (FRP) sheets, however distinct material properties of historical RC buildings have not been systematically considered yet. This study investigates the flexural behavior of historical RC beams strengthened by hybrid FRP sheets. A total of 11 beam specimens with varying FRP sheet configurations were tested using a four-point bending test to assess their flexural behavior, including failure mode, cracking pattern, load-deflection behavior, strain distribution, and ductility. The results showed that hybrid FRP sheets increased the maximum bearing capacity of strengthened specimens up to 30.2 %. An optimal fiber sheet configuration (T-3) is identified. 45-degree incline installation contributes to a 4.5 % increase in the bearing capacity of specimens. The average ductility loss of hybrid FRP sheets strengthened specimen (except for double-layer strengthened specimen) is 42 %, while an increase of sheet layer post adverse effect on ductility. Strain distribution conforms to the plane-section assumption. Additionally, a maximum bearing capacity calculation model was proposed, aiding the understanding of FRP strengthening in historical RC buildings.

Axial compressive performance and finite element analysis on spirally reinforced seawater sea-sand concrete-filled aluminum alloy tube columns

Axial compression experiment and finite element analysis were used in this research to explain the mechanical properties of spirally reinforced seawater sea-sand concrete-filled aluminum alloy tube (SR-CFAT) columns. The diameter and spacing of the spiral stirrup, the quantity and diameter of the longitudinal reinforcement, and the ratio of the spiral stirrup to longitudinal reinforcement (rhv) were used as the variation parameters in the design of 16 SR-CFAT columns and 1 seawater sea-sand concrete-filled aluminum alloy tube (CFAT) column. The results demonstrated that both the SR-CFAT columns and the CFAT column experience shear failure, while the former exhibited greater axial compression bearing capacity and deformation capacity. The ultimate bearing capacity, ductility, and energy absorption value of this composite column increase with an increase in rhv, then decrease under the same reinforcement content. The specimens perform best under axial compression when rhv is 2.20. Among the others, specimens with "fine and dense" spiral stirrups and "less and coarse" longitudinal reinforcement have higher ultimate bearing capacities, ductility, and energy absorption values. An FE model is created for the SR-CFAT columns, followed by a parameter extension analysis. Based on test and finite element results, a high-accuracy axial compression bearing capacity calculation algorithm is provided using cylinder theory.

Application of ZnS:Ni Loaded on Sponge‐Activated Carbon as an Efficient Adsorbent for Dye Removal

AbstractIn the present work, a ZnS:Ni loaded on sponge‐activated carbon (SAC) was synthesized and applied as an effective adsorbent to remove bromophenol blue (BPB) dye from aqueous solutions. Various techniques such as Fourier‐transform infrared, X‐ray diffraction, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and Brunauer‐Emmett‐Teller (BET) were used to characterize ZnS:Ni–SAC. The effective parameters such as BPB concentration, amount of ZnS:Ni–SAC, ultrasonic time, and pH of the aqueous solution were investigated and optimized by response surface methodology. To investigate the accuracy and reliability of the proposed method, the analysis of variance was used based on p‐values and F‐test. The optimal values of the parameters were obtained using the desirability function, and they were as follows: 15 mg L−1 BPB concentration, 20 min sonication time, 18 mg of ZnS:Ni–SAC, and pH = 7. To evaluate the adsorption mechanism and calculation of maximum adsorption capacity, different adsorption isotherms were studied, and according to the obtained results, the Langmuir isotherm model showed the highest compatibility due to its higher R2 (0.997). Also, the proposed adsorbent represented good adsorption capacity (125 mg g−1). Moreover, kinetic studies proved the applicability of the pseudo‐second‐order model (R2 = 0.986) compared to other models. The achieved results confirmed the applicability of ZnS:Ni–SAC as a versatile adsorbent for the removal of BPB.

Research on the Scale Fire Test and Fire Resistance of the One-Way Slab of a Metro

To address the difficulty in conducting fire tests to verify the fire-resistance limit of large one-way slabs with heavy loads in a metro, a scale fire test method is proposed based on the bearing capacity calculation of the one-way slab under fire. The scale fire test method adapted the hypothesis that the deflection of the one-way slab under fire is close to a half-sine function and the plane section hypothesis. The validity of this hypothesis is verified through fire tests and finite element simulations. The scale fire test method achieves a similar temperature field and mechanical behavior between the scaled model and full-scale model of the one-way slab. The results of the fire tests showed that the temperature field and mechanical behavior of the scaled model were consistent with those of the full-scale model, with an error in fire resistance of 4.7%. The calculation results and fire test results are essentially consistent, with an error of 6.5%, and according to the calculation of the one-way slab fire-resistance limit, the key factor affecting the fire resistance of the one-way slab under fire is the temperature of the bottom rebars. Using the scale fire test method, the size effect of the one-way slab under fire still exists, and larger slabs have a greater deformation capacity.

STUDI KOMPARASI KAPASITAS DUKUNG RENCANA DAN KAPASITAS DUKUNG AKTUAL FONDASI TIANG PANCANG PADA KONSTRUKSI SLAB ON PILE JALAN TOL SEMARANG – DEMAK SEKSI 2

Semarang - Demak Toll Road Section 2 with a length of 16.31 km crosses the North Coast of Java. The regional geological map shows that the North Coast of Java has alluvial soil layers with clay and silt characteristics. The results of soil investigations show that the depth of the soft layer reaches more than 60 m. This condition triggers construction engineering to support the Highway above it. One of the efforts to fulfill the elevation plan (finish grade) is the flyover concept with slab on pile construction. The planned traffic lane is laid on a concrete slab which is supported by piles with a diameter of 600 mm. With sufficiently deep soft soil layers, the bearing capacity of the foundation piles is borne by the frictional resistance provided by the soil along the piles. This comparative study compares the planned carrying capacity calculated by the empirical formula with the actual carrying capacity of the field as a result of the PDA Test. Calculations were made on 5 test poles for later comparisons were made with the PDA test record data. For the case of 14 days driving at the research location, the pile bearing capacity from the PDA test results is still below the design bearing capacity. The average actual carrying capacity obtained from the 5 test piles is 278 tons. This value is below the planned carrying capacity of the Shio & Fukui method of 381 tons, Meyerhoff's 355 tons, Biaud et al's 777 tons, and Luciano Decourt's 605 tons. At the age of the pile 14 days after the erection was completed, the results of the calculation of the bearing capacity of the Meyerhoff method are closest to the actual bearing capacity of the PDA test results with a ratio of 1.26. The next method is Shio & Fukui with a ratio of 1.36, Luciano Decourt (2.16), and Biaud et al (2.81). Some of the results of previous studies showed a positive correlation between the age after completion of the pile and the frictional carrying capacity. For this type of friction pile, this is of course very influential, so that it is possible that when it is realized that it is carried out with a longer service life, the actual bearing capacity obtained will increase. This requires further research to obtain a time relationship with an increase in pile bearing capacity, especially for locations that have deep soft soil layers such as in this study location.

Bearing Capacity Equations for Intact Argillaceous and Arenaceous Rocks in Malaysia Derived from P-Wave Velocity

This paper presents the derivation of the bearing capacity equation of shallow foundations using P-wave velocity based on the seismic refraction method on argillaceous rocks (shale) and arenaceous rocks (sandstone). Various theories of bearing capacity equations were developed over the years for the calculation of bearing capacity under vertical central loading. But, the most widely used on rock is the Mohr-Coulomb failure criterion given by Meyerhof (1963). Based on this theoretical development, the empirical equation of ultimate bearing capacity was obtained. The detailed derivation of these parameters is comprised of the results from Uniaxial Compressive Strength (UCS) and P-wave velocity values. The proposed empirical equation of bearing capacity derived from P-wave velocity herewith can be used as an alternative method in designing shallow foundations. There is a good agreement on the bearing capacity determination from P-wave velocities.

EV Battery Management using Adaptive Kalman Filter and ECC

This initiative addresses the critical concerns of enhancing battery management and easing the calculation of battery capacity in electric vehicles. By using Coulomb counting method, the State of Charge (SoC) of Electric Vehicle (EV) batteries is estimated by analysing real-time battery data through simulations and interpolation techniques. The primary objective is to offer precise SoC estimation to mitigate the range anxiety. Furthermore, this research proposes methods of estimating the SoC of Lithium-Ion batteries and an enhanced coulomb counting model with Adaptive Kalman Filter to estimate the state of charge with higher accuracy. This comprehensive approach seeks to address critical challenges in EV battery management contributing significantly to the electric vehicle technology for the society.

Modeling load distribution for rural photovoltaic grid areas using image recognition

Expanding photovoltaic (PV) resources in rural-grid areas is an essential means to augment the share of solar energy in the energy landscape, aligning with the “carbon peaking and carbon neutrality” objectives. However, rural power grids often lack digitalization; thus, the load distribution within these areas is not fully known. This hinders the calculation of the available PV capacity and deduction of node voltages. This study proposes a load-distribution modeling approach based on remote-sensing image recognition in pursuit of a scientific framework for developing distributed PV resources in rural grid areas. First, houses in remote-sensing images are accurately recognized using deep-learning techniques based on the YOLOv5 model. The distribution of the houses is then used to estimate the load distribution in the grid area. Next, equally spaced and clustered distribution models are used to adaptively determine the location of the nodes and load power in the distribution lines. Finally, by calculating the connectivity matrix of the nodes, a minimum spanning tree is extracted, the topology of the network is constructed, and the node parameters of the load-distribution model are calculated. The proposed scheme is implemented in a software package and its efficacy is demonstrated by analyzing typical remote-sensing images of rural grid areas. The results underscore the ability of the proposed approach to effectively discern the distribution-line structure and compute the node parameters, thereby offering vital support for determining PV access capability.

Study on current carrying capacity calculation model for dynamic capacity increase of carbon fiber reinforced composite core conductor

Abstract With the “dual-carbon” as the goal of the new power system construction gradually in-depth, transmission lines must have energy-saving capacity for the direction of development. A new type of large-capacity overhead transmission conductor is the carbon fiber reinforced composite core (CFCC) conductor. The conductor has high capacity, low loss, high-temperature resistance, low high-temperature sag, and other characteristics. It is one of the key technologies and equipment applied to the transformation of old overhead transmission lines to enhance its capacity. At the same time, it can also realize the dynamic transmission capacity regulation of the overhead line. The application of the prospect is very promising. The accurate assessment and calculation model for the conductor’s allowable current carrying capacity is the key core technical problem of the overhead transmission line dynamic capacity increase capability. The paper establishes a maximum allowable current capacity calculation model for carbon fiber-reinforced composite core conductors based on Morgan’s formula. The results of the load flow calculation are compared with the actual load flow test results to verify the calculation model, and the maximum error is 3.59%, which proves the reliability of the calculation model. On this basis, the influence of external environmental factors (ambient temperature, sunlight intensity, wind speed, and direction) on the maximum allowable current capacity of the conductor is discussed. The correlation coefficient of the model is analyzed.

Axial Compressive Tests and Bearing Capacity Calculations for Short Circular Concrete Columns Strengthened with Woven Carbon Fiber Mesh and Polypropylene Fiber-Reinforced Cement-Based Composite Materials

Axial Compressive Tests and Bearing Capacity Calculations for Short Circular Concrete Columns Strengthened with Woven Carbon Fiber Mesh and Polypropylene Fiber-Reinforced Cement-Based Composite Materials

Research on seismic performance of prefabricated composite shear wall with end steel plate connection

Chinese construction industry is gradually transforming to industrialization, which promotes the development of prefabricated buildings. As an efficient lateral force resisting system, prefabricated steel-plate concrete composite shear wall structure has become a research hotspot in the field of architecture at home and abroad. Based on the mechanical characteristics of the shear wall, this paper proposes a end steel plate connection prefabricated composite shear wall structure. Through numerical simulation and analysis of the prefabricated composite shear wall with different connection areas and the cast-in-place composite shear wall, which verified the feasibility and reliability of end steel plate connection. Based on the above verification, the influence of different parameters on the seismic performance of the prefabricated composite shear wall with end steel plate connection has been further studied, and the theoretical calculation of bearing capacity is carried out. The results show that the length of the connector should be controlled within a reasonable range. The tie bars in the node connection area can improve the strength and ductility of the prefabricated composite shear wall. The aspect ratio and axial pressure ratio have obvious influence on the seismic performance of the wall, which should be reasonably selected in design.

Research on bearing capacity and stability of deep-water novel combined wellhead based on experimental methods

The combined wellhead has the advantage of high bearing capacity and broad prospects for application in the construction of deep water surface wells; therefore, it is important to conduct relevant research to guide the construction of combined wellheads. The aim of this paper is to study the mechanical characteristics of the combined wellhead in the longitudinal direction and establish the method for real-time calculation of the bearing capacity of the combined wellhead taking into account the effects of installation. The variations of external wall pressure and internal soil pressure during installation and the waiting process of the combined wellhead were investigated by indoor experiments. The installation efficiency of the combined wellhead at different negative pressure conditions was also compared. The experimental results show that the pressure on the outer wall of the combined wellhead facility gradually increases as the depth of the combined wellhead facility increases, and the closer it is to the bottom, the greater the soil pressure. The pressure on the inner soil will increase rapidly during the installation process to almost the same level, while the pressure on the outer soil will increase slightly. During the waiting process of the combined wellhead, as the waiting time increases, the soil damaged during the installation process gradually recovers, and the external wall pressure gradually rises. Moreover, the pressure on the outer wall gradually increases, the pressure on the inner soil decreases slightly leveling off within about 24 h. An appropriate increase in suction pressure facilitates the installation of the combined wellhead, and approximately 2.0 L/min is the optimal option for installation. The computational model developed in this paper and the experimental measurements corroborate each other. These combined wellheads significantly improve the stability of deep water soft-soil well construction and provide a theoretical benchmark for developing oil, gas and hydration in deep water.

Theoretical evaluation of a hybrid buoyancy-compressed air energy storage system

Energy storage plays a pivotal role in the emerging green economy. This study, for the first time, presents the theoretical evaluation of a buoyancy power generator combining with the compressed air energy storage (CAES-BPG) system. A theoretical model that satisfies conservation laws and does not involve any adjustable parameters is developed for the calculation of system efficiency and power generation capacity. To accurately predict drag acting on the buoy, the low Reynolds number κ-ω SST model with a locally refined mesh (y+~1) is applied to fully resolve the viscosity affected regions including the viscous sublayers, whilst the surrounding flow is modelled by LES. The refined mesh moves passively with the buoy and does not change, whilst mesh in other regions undergoes smoothing and remeshing to accommodate the buoy's motion. Correlations of drag coefficients are then developed as a function of buoy shape, Reynolds number, and vessel-to-buoy size ratio. The aerofoil shape yielded a substantially smaller drag coefficient compared to the square, hex, and bullet shapes. System efficiency showed independency on buoy volume and shell material but decreased as the water level in the vessel increased, reaching 64 % for a water level of 1.5 m. Similarly, as the water level increased, the system output power decreased. The output power increased as the buoy volume increased, reaching ~22 kW for a buoy volume of 2 m3 at a water level of 1.5 m. This CAES-BPG system is highly automatic and fully green, and can operate continuously once compressed air is connected, showing great potential for implementation as an energy storage / utilisation system of small to medium capacities.

ОЦЕНКА МЕТОДИК РАСЧЕТА ЖЕЛЕЗОБЕТОННЫХ ЭЛЕМЕНТОВ ПО ПРОЧНОСТИ ПРИ ДВУХОСЕВОМ ДЕЙСТВИИ ПОПЕРЕЧНЫХ СИЛ

The current design standards for reinforced concrete structures in the Russian Federation do not contain methods for calculating bending elements subjected to biaxial action of shear forces. However, methods for calculating such structures exist and are given in the works of domestic and foreign researchers, as well as in the design standards of past years. This article selects data on the results of 33 tests of beams subjected to action of biaxial shear forces. The results of selected tests were compared with the results of theoretical calculations of the bearing capacity of elements under the biaxial action of shear forces using various analytical methods. A brief overview of existing analytical techniques is provided. A comparison of test results and theoretical calculations is presented in tabular and graphical form. The purpose of the work is to identify existing methods for calculating reinforced concrete bended elements under biaxial action of transverse forces, allowing to obtain load-bearing capacity calculation results that are as close as possible to the test results.

Bearing capacity evaluation of embedded circular footing considering presence of an overload adjacent

The bearing capacity of axially loaded embedded foundations has been widely studied using analytical and numerical methods. However, there are many discrepancies in the literature results regarding the bearing capacity factors and depth factors of circular embedded footings proposed by different authors. Terzaghi's hypothesis has been used to assess the bearing capacity of shallow foundations and several analytical solutions have been proposed for computing bearing capacity factors, even though a superposition of individual contributions may lead to some error in the computed bearing capacity. This assumption has sometimes been criticized as being more conservative. This article aims to study two problems; The first part is focuses on the numerical evaluation of the superposition hypothesis in the calculation of the bearing capacity for rough circular foundations embedded in sand. In this section, the bearing capacity factors contributing to the conventional solution have been evaluated and superposition errors are indicated and compared with those found by different authors. The latter part of the work is devoted to studying the depth effect on the estimation of the bearing capacity of a rough circular footing embedded in the sand considering presence of an overload adjacent. For both analyses, the finite-difference code Flac2d (FLAC 2007) was used to reach the bearing capacity for embedded circular footings, the ground friction angles are between 25° and 40° and a depth ratio Df/D varies from 0.1 to 2. The calculation results are presented in tables and graphs and compared to previously published results available in the literature.

Experimental investigation and simulation analysis of cast-steel joints under vertical pressure

The joint made of cast steel is frequently utilized within a treelike column structure to ensure a smooth transition. It is of great significance in ensuring the overall structural safety, but currently, the mechanical property and bearing capacity of this type of joint cannot be fully understood. This study investigates the load characteristics of three-forked cast steel joints through concrete experiments, finite element analysis, and regression method formula derivation, filling the gap in mechanical properties and calculation formulas of forked cast steel joints. Initially, a comprehensive model of the cast-steel joint, sourced from a practical engineering, underwent vertical load testing. Detailed scrutiny of stress distribution and vertical displacement of the tested joint was conducted based on the experimental outcomes. Subsequently, a finite element model of the tested joint was constructed using SolidWorks and subjected to analysis via ANSYS. The numerical findings were juxtaposed with experimental data and extrapolated to encompass other parametric scenarios. Ultimately, a regression analysis method was employed to derive a calculation formula for the load-carrying capacity of branch-bearing cast-steel joints. The regression analysis method can accurately obtain the load-bearing capacity calculation formula for tree-shaped joint models and can be extended to determine corresponding branch and main pipe dimensions, as well as the deviation angle between branches and the main pipe, under known load conditions. This improves design efficiency and accuracy. Comparative analysis reveals a substantial concurrence among experimental, finite element analysis, and formula-based predictive outcomes. The maximum error between experimental results and those obtained from finite element analysis is 9.02%. The maximum error between the results calculated using the load-bearing capacity formula derived from regression methods and those from finite element analysis is only 1.9%.

Concrete and reliability of existing prestressed bridge structures

A large number of post-tensioned concrete bridges were built in the second half of the last century. They have often been insufficiently maintained during their lifetime (usually around 50 years). Nowadays, these structures exhibit significant deterioration, mainly due to leakages and also due to various other deficiencies such as a small concrete cover. Their load-bearing capacity needs to be verified. This paper focuses on estimating the load-bearing capacity calculation of existing post-tensioned concrete bridges. In the engineering practice, this is carried out using the partial factor method according to the currently valid standards (Czech standards ČSN and the Eurocodes), which often impose more stringent requirements than the original standards. The partial factor method then often leads to low load-bearing capacities. This study deals with the bridge for which a very low load-bearing capacity has been determined. For this reason, a comparative probabilistic analysis was performed, allowing for a better description of the uncertainties in the resistance and load effect variables. The probabilistic approach appears to be less conservative and yields a higher load-bearing capacity.

Study on the Mechanical Performance of RC Beams under Load Reinforced by a Thin Layer of Reactive Powder Concrete on Four Sides

To repair reinforced concrete beams efficiently in a limited building space, the four-sided application of a reinforcing thin layer of reactive powder concrete (“RPCTL”) was proposed to improve the bending capacity of the members. Static flexural tests of one comparison beam and five reinforced beams were completed on a four-point centralized loading device. Changes in deflection, cracks, stresses, and damage characteristics of the specimens were measured under various levels of loading. The test results showed that the damage patterns of the reinforced specimens were dominated by the yielding of longitudinal tensile reinforcement at the bottoms of the beams and the crushing of the cementitious material in the top compression zones of the beams. The cracking load greatly increased by 1.42 to 7.12 times, and the ultimate bearing capacity increased by 0.29 to 1.41 times. The distribution characteristics and dynamic changes in the displacement, stress, and damage of the specimens were dynamically simulated by finite element software. The effects of reinforcement and initial load-holding level on the reinforcement effect were investigated. A bending capacity calculation formula for RPCTL reinforcement technology is proposed that aligns with the test results and can provide a reference for the design of RPCTL reinforcement.