Calculation Of Capacity Research Articles

Seismic behavior of prefabricated lightweight steel composite frame-sandwich wall with enhanced border structure

An innovative prefabricated lightweight steel composite frame-sandwich wall with an enhanced border structure (LSCF-SW), suitable for low-energy consumption low-rise residences, is proposed. Low cyclic loading experiment were conducted to study its seismic behavior. The main parameters include wallboard border type (composite border, mixed border) and steel reinforcement strength (HRB450, HRB500). One full-scale LSCF specimen and four full-scale LSCF-SW specimens are prepared, and their seismic behavior is investigated in terms of failure mode, hysteretic characteristics, ultimate bearing capacity, stiffness degradation, deformation capacity, energy dissipation, and strain characteristics. The results revealed that the sandwich wall (SW) with an enhanced border and lightweight steel composite frame (LSCF) is the primary and secondary seismic fortification lines of the structure, respectively. The LSCF-SW structure exhibited a damage evolution process with four stages. The failure mode involving concrete crushing at the bolted connection area is observed in the specimens with composite bordered sandwich walls (LSCF-SWC), and dense diagonal cracks are discovered in the specimens with mixed bordered sandwich walls (LSCF-SWM). Compared to LSCF-SWC specimens, the ultimate load of LSCF-SWM specimens increases by 23.0 %–50.3 %, and the initial stiffness improves by 16.3 %–42.3 %. The deformation capacity of LSCF-SWC specimens is superior to that of LSCF-SWM specimens. As the steel reinforcement strength increases, the ultimate bearing capacity and initial stiffness of the LSCF-SW also rise. A shear model for the bolt group and a local bending model for the wallboard border are proposed, establishing an ultimate bearing capacity calculation method for LSCF-SW. The calculation results closely align with the experimental results.

Seismic behavior of innovative reinforced concrete composite shear wall with PEC boundary columns

Considering the inadequate integrity between boundary elements and wall connections in shear walls with PEC columns. A new type of PEC shear wall is proposed to enhance the connection between the PEC columns and the wall by introducing T-section connectors to improve the bearing capacity as well as the deformation capacity. In this study, the seismic behavior of composite shear walls was investigated in terms of the failure process, hysteresis, energy consumption, etc. The test results showed that the specimens had good stiffness and energy dissipation capacity. The combination of PEC columns with RC shear walls under the action of the T-section connector was effective. An increase in the width-to-thickness ratio can lead to shear bonding failure. In the PEC-RCSW structure with a shear-to-span ratio of 1.35, the bearing capacity and deformation capacity of the T-section connectors and PEC columns are slightly higher in the major axis direction than in the minor axis direction. Based on the test results, the finite element model was established and further research was conducted on the shear span ratio and T-section connector size. And provided engineering application suggestions for the innovative composite shear wall shear wall. Finally, flexural and shear capacity calculation formulae of the innovative composite shear wall were proposed.

Pollutant Load Capacity of Rawa Besar Lake, Depok, West Java

Depok City has dozens of lakes and one of them is Lake Rawa Besar. The Depok government gives priority to Rawa Besar Lake to be development as a tourist destination. At this time the waters of Rawa Besar Lake are in a polluted condition caused by domestic waste, land use change, chicken farming and floating net caramba. The study aims to analyze water quality, determine the carrying capacity of pollutant loads and provide recommendations for pollutant load reduction. The calculation of the Pollution Load Capacity refers to Minister of Environment Regulation No. 28 of 2009. Based on water quality analysis, 5 parameters exceed the quality standard, such as BOD, COD, total phosphate, total nitrogen, and total coliform. Using the model and calculation of the pollutant load capacity of lake and/or reservoir. The pollutant load capacity of Lake Rawa Besar for BOD parameters is 50.26 kg/year while the existing load is 262.76 kg/year, COD is 418.81 kg/year existing load is 1150.41 kg/year, phosphate is 0.50 kg/year existing load 26.45 kg/year, nitrogen 12.56 kg/year existing load 85.88 kg/year and total coliform 8.4 x 104 amount/year existing load 9.6x106 amount/year. The burden of incoming pollutants exceeds the pollutant load capacity of Lake Rawa Besar. Pollution control efforts are carried out by implementing communal wastewater treatment systems such as an Anaerobic Baffled Reactor (ABR).

Simulation and Calculation of Temperature Field and Current-Carrying Capacity of Power Cables under Different Laying Methods

Precisely determining how cables distribute their current-carrying capacity and temperature field is crucial for the dependable and cost-effective functioning of power grids. Firstly, the power cable structure and the advantages and disadvantages of different laying methods are analyzed in detail. Secondly, the theoretical model of current-carrying capacity calculation and temperature field of power cables, including heat convection, heat conduction, and heat radiation, is constructed, and the method for calculating cable current-carrying capacity, relying on the double-point chordal interception method, is suggested. Then, the COMSOL multiphysics 6.2 finite element simulation software is utilized to create a simulation model that aligns with the real cable laying technique. Finally, the current-carrying capacity and temperature field of power cables are simulated and analyzed for different arrangements of power cables in three laying modes, namely directly buried, row pipe, and trench. The simulation results show that the cable laying method greatly affects the cable’s carrying capacity; the more centralized the cable distribution, the smaller the flow. The method can be realized in different ways of laying power cables in the real-time rapid calculation of flow as the actual laying of power cables has an important reference and reference significance.

Investigation of Railway Network Capacity by Means of Dynamic Flows

Capacity calculations are essential for the long-term planning of railway infrastructure. Many of the methods currently used in practice calculate characteristic capacity values separately for the single elements (mainly lines and nodes) of a railway network. Approaches that consider the entire network to account for interactions between the elements often rely on many assumptions, which renders a direct practical application difficult. This paper therefore introduces a linear optimization model that comprises railway-specific constraints such as minimum headway times, line capacities, and route conflicts. Under the consideration of these constraints, the developed model permits the calculation of a network-wide capacity. The model is validated on a sample network that is based on a real network of the German railway infrastructure.

Radial compression performance of glass fiber reinforced polyurethane composite tube with open-hole

Glass fiber reinforced polyurethane matrix composite (GFRP) is a novel composite material. GFRP circular tubes are widely used in engineering because of its excellent mechanical properties. It is inevitable to open holes on GFRP circular tubes when connecting with other components due to the use requirements and structural needs. The radial compression test, theoretical analysis, and finite element calculation of GFRP circular tubes produced by the braiding-winding-pultrusion process are carried out, to study the influence of holes on the compression performance of tubes. The GFRP circular tube has four layers with different fiber angles. From the inner to the outer structure layer, they are the inner woven layer, winding layer, longitudinal fiber layer, and outer woven layer. The mechanical properties of a 0° unidirectional plate are better than those of a 90° unidirectional plate according to the mechanical properties test. The radial compression tests are carried out on GFRP circular tubes with a length of 300 mm, an outer diameter of 140 mm, and a wall thickness of 6 mm. The theoretical calculation of the bearing capacity of the GFRP circular tube under the radial compression load in the elastic stage and the failure stage is well matched with the bearing capacity obtained from the test. The theoretical calculation can effectively predict the bearing capacity of the GFRP circular tube. The radial compression test of GFRP tubes is simulated by ABAQUS, which is a finite element software. The good agreement between the finite element calculation results and the test results verifies the feasibility of the finite element. Based on the above research, finite element models are established for different types of GFRP circular tubes to study the influence of opening ratio on the load borne by GFRP circular tubes. The results show that the hole with the opening rate less than or equal to 1/10 has little effect on the load of the GFRP circular tube. This paper studies the influence of opening on the radial compression properties of GFRP tubes, which has certain reference value for the opening of composite tubes in engineering.

Day-ahead electric vehicle charging behavior forecasting and schedulable capacity calculation for electric vehicle parking lot

The Electric Vehicle Parking Lot (EVPL) aims to address the growing demand for EV charging infrastructure. EVs connected to EVPLs have extended access times compared to those at public charging stations. Consequently, EVPL owners can aggregate the schedulable capacity of connected EVs to participate in day-ahead and ancillary service markets, thereby gaining economic benefits. However, achieving this objective is hindered by the lack of accurate day-ahead forecasts of EV charging behavior. To address this issue, this paper introduces a novel day-ahead forecasting method for EV charging behavior at EVPLs, alongside a strategy for calculating EV schedulable capacity based on these forecasts. Unlike existing methods, this paper presents a day-ahead time-of-use clustering forecasting strategy, which provides more detailed and accurate predictions of EV charging behavior, eliminating the need for numerous assumptions during schedulable capacity calculations. The study demonstrates that the proposed method, validated using actual historical data, enables precise forecasting of EV charging behavior. Furthermore, the proposed day-ahead schedulable capacity calculation strategy is shown to be both effective and practical.

Numerical and Theoretical Study on Flexural Performance and Reasonable Structural Parameters of New Steel Grating–UHPFRC Composite Bridge Deck in Negative Moment Zone

As the bridge’s structural component is directly subjected to vehicle loads, the stress performance of the bridge deck has a significant impact on the safety, durability, and driving comfort of the bridge. In order to improve the bending performance of the bridge deck in the negative moment zone, a new type of steel grating–UHPFRC composite bridge deck was proposed in this paper. Firstly, structural details and advantages of the new steel grating-UHPFRC composite bridge deck were introduced. Secondly, the finite element program ABAQUS was used to establish a refined solid finite element model of the new bridge deck. The mathematical program MATLAB (PYTHON) was also used to analyze the effects of the structural parameters on bending bearing capacity and put forward reasonable structural parameters of the new bridge deck, considering the technical and economic indexes. Thirdly, the simplified plasticity theory was applied to analyze the bending bearing capacity of the new bridge deck, and the corresponding formula for bending bearing capacity calculation was derived and verified by numerical model results. In addition, the cost–benefit analysis and environmental impact assessment of the new bridge deck were also conducted. The results show that the bending bearing capacity of the new bridge deck in the negative moment zone increases with the increase of the width of the bridge deck, the thickness of the wing plate, and the height of the web plate, with a trend of increasing and then decreasing when the horizontal inclination of the web plate decreases. The bridge deck width does not have a significant effect on improving the bearing capacity. The bearing capacity calculated by theoretical formulas is close to that calculated by numerical models and the maximum relative deviation is 9.1%. The new steel grating-UHPFRC composite bridge deck proposed in this paper is superior to conventional steel-UHPC composite bridge deck in terms of cost-benefit and environmental impact.

Numerical study on flexural behaviour of sulphate corroded RC beams strengthened with ultra-high-performance concrete

Ultra-high-performance concrete (UHPC) has found extensive application in the strengthening of existing reinforced concrete (RC) structures; however, limited knowledge exists regarding its use in RC structures exposed to sulphate attacks. This study developed a non-linear finite element analysis (FEA) model to predict the flexural behaviour of sulphate corroded RC beams strengthened with UHPC jackets. The FEA model, validated with experimental results, was extended to examine UHPC configurations and thicknesses. Evaluation included ultimate load capacity, serviceability state, and stiffness. Crack patterns, load-deflection behaviour, and strain distribution were analysed for strengthened beams at their respective ultimate loads along the mid-span cross-section height. FEA results showed diverse configurations significantly enhanced the load-carrying capacity of sulphate corroded RC beams by 54.5-88.6%. Strengthened beams exhibited a 64% increase in flexural moment capacity, with notable improvements in cracking and post-cracking stiffness. Strain distribution analysis revealed UHPC strengthening increased strain values, emphasising UHPC jackets’ substantial role in resisting stresses and enhancing flexural behaviour. As expected, the three-sided UHPC configuration outperformed two-sided and bottom-side ones. Increasing UHPC thickness proved most effective in bottom-side strengthening, followed by three-sided, with a lesser effect in two-sided strengthening. Theoretical predictions from the suggested flexural moment capacity calculation aligned well with FEA results.

Design of improved multi-cell L-shaped CFST columns under compression and bending

In recent years, there has been a notable surge in proposals for various forms of special-shaped concrete-filled steel tubular (CFST) columns. Despite various methods developed by researchers for determining the bearing capacity of multi-cell special-shaped CFST columns under different loading conditions, these methods remain lack unified. In this study, FE models were developed to simulate performances of improved multi-cell L-shaped CFST (ML-CFST) column under compression and bending. Parametric analyses have been performed to evaluate impact of various factors, including steel yield strength fy, compressive strength of concrete fcu, steel thickness t, loading direction θ, web height c, and axial load ratio n, on performances of ML-CFST columns. The findings of study indicate that the unidirectional flexural capacity of ML-CFST member exhibits a nearly linear relationship with the variables of t, fy, and c, with a minimal impact observed from fcu on flexural capacity. The width of extended section b, fcu, fy, and t have a certain effect on flexural capacity at any angle, particularly fy, t, and b. While fcu, fy, and t exert some influence on N/Nu-M/Mu correlation curves, their influences are marginal compared to the loading direction, which is the predominant influencing factor. Additionally, Mx0/Mπ/4-My0/M3π/4 curves gradually protrude outward with the increase in n. The effects of t, fy, and fcu on the shape of Mx0/Mπ/4-My0/M3π/4 curve were relatively insignificant. Simplified unidirectional flexural capacity calculation models were proposed based on stress analysis of cross-section under ultimate states. Given that flexural capacities estimated by simplified calculation model are slightly conservative, it is recommended to increase the flexural capacities by 10 %. Furthermore, an elliptical equation was formulated to predict the flexural capacity at any angle, with the predictions being slightly conservative. Based on ultimate equilibrium theory, a simplified calculation method was presented to predict unidirectional eccentric bearing capacities of ML-CFST columns. Through regression analysis, a simplified calculation method expressed as polar coordinate form for biaxial eccentric bearing capacity was established, with calculated values aligning well with FE results.

Hybrid of non-dominated sorting genetic algorithm II and invasive weed optimization for fan duct surface heat exchanger configuration optimization design

In this research, configuration optimization was conducted for FDSHX (fan duct surface heat exchanger) that is a new type of heat exchanger adopted in aero-engine heat management in recent years. Firstly, a method of Taguchi-ANFIS (Taguchi-Adaptive Neuro-Fuzzy Inference System), which can reduce training data volume utilizing orthogonal experimental matrix, was proposed to construct a rapid response mathematical model between three configuration parameters, including fin pitch, fin thickness, and oil passages number, and two design indicators, including heat transfer capacity and operating weight, based on the data prepared by an experimental validated FDSHX heat transfer capacity calculation method using heat transfer unit simulation. Secondly, a hybrid method of NSGA II-IWO (Non-dominated Sorting Genetic Algorithm II-Invasive Weed Optimization), which can simultaneously obtain the strong abilities of exploration and escaping from trap into local optima, was proposed to drive the constructed response mathematical model to enhance heat transfer through adjusting the three configuration parameters. Optimization comparison was performed between NSGA II-IWO and four classic optimization algorithms including GA (Genetic Algorithm), IWO (Invasive Weed Optimization), CA (Cultural Algorithm), and HS (Harmony Search). This research provides an integrated solution to help mechanical engineers improve the applicability and reasonableness of FDSHX design.

Seismic behavior of lightweight steel frame with thin-walled steel skeleton-lightweight concrete wall

In this study, an innovative prefabricated lightweight steel frame with thin-walled steel skeleton-lightweight concrete composite wall structure (LSF-TSLC) is proposed. The proposed LSF-TSLC has the lightweight steel frame (LSF) as the vertical load-bearing system, whereas the thin-walled steel skeleton-lightweight concrete composite wall (TSLC) acts as the main component for horizontal earthquake resistance. A full-scale LSF specimen and three full-scale LSF-TSLC specimens were prepared considering the variables of wall installation method (embedded, external) and thin-walled steel skeleton distribution (frame type, truss type). The corresponding seismic behavior was experimentally investigated by evaluating the hysteretic characteristics, failure mode, ultimate bearing capacity, deformation performance, stiffness degradation, energy dissipation, and strain characteristics. The results showed that the plastic hinges appeared at the beam ends and column bases of LSF. Due to the shear failure, the embedded and external TSLC exhibited grid cracks and diagonal cracks, respectively. The LSF and TSLC had a good coordinating deformation capacity, while the LSF-TSLC structure had two seismic fortification lines. Compared with LSF, the ultimate bearing capacity and stiffness of LSF-TSLC were increased by 2.1 times and 5.1 times, respectively. The deformation capacity and energy dissipation of LSF-TSLC were significantly improved compared to LSF. The self-tapping nail joint of the embedded wall and the high-strength bolt joint of the external wall had reliable connectivity performance. The numerical simulation of LSF were conducted to verify the plastic analysis model for LSF. And the ultimate bearing capacity calculation method for the LSF-TSLC structure was proposed based on the Strut-and-Tie model.

Anti-progressive collapse performance and design method of novel T-stub connections

To address the insufficient anti-collapse capacity of T-stub connections due to premature failure, this study proposes a novel T-stub connection (NTC) by adding four V-shaped laminated plates. Monotonic loading tests are conducted on the T-stub web and V-shaped laminated plate to analyze the influence of geometric parameters on their deformation and load-bearing capacity. The working mechanism of NTC is investigated through the validated numerical models by analyzing the failure mode, impact force history, deformation pattern, internal force development, and energy dissipation. The research results indicate that, compared to the T-stub connection, the NTC exhibits two-phase failure characteristics, which begin with the fracture of the bolt-hole in the T-stub web, followed by the gradual straightening and eventual fracture of the V-shaped laminated plates. NTC undergoes three stages under impact loads: peak, oscillation, and platform stages. The addition of V-shaped laminated plates enhances the ductility of NTC by 93 %−130 % and its energy dissipation capacity by 189 %−235 %. This significant enhancement in deformation and energy dissipation capabilities can be attributed to the addition of the V-shaped laminated plates. The deformation and bearing capacity calculation formulas for both the T-stub web and V-shaped laminated plate are provided. Additionally, a design method for NTC is proposed based on theoretical analysis, and its rationality is verified through numerical examples involving three different sets of beam and column sections.

A review of CO2-injection projects in the Brazilian Pre-Salt — Storage capacity and geomechanical constraints

This review describes the main geological and geomechanical aspects of CO2-injection projects in the Brazilian Pre-Salt reservoirs, focusing on the storage potential and geomechanical aspects of CO2 injection. The Pre-Salt reservoirs in the Santos Basin offer favorable conditions for CCS due to their geological characteristics and existing infrastructure. The thick evaporite caprock, primarily composed of halite, acts as an efficient seal against CO2 migration. The CO2-injection in the Pre-Salt has been active since 2010, with significant amounts of CO2 already stored in the reservoirs. The volumetric assessment estimates the static storage capacity of the Pre-Salt reservoirs to be over 3.3 Gt of CO2, considering only the four fields currently undergoing injection. Geomechanical constraints, including the maximum injection pressure and caprock integrity, are crucial considerations for safe CCS operations. The high stress regime and the hydrostatic state of the caprock minimize the risk of fracturing during injection. Furthermore, dynamic storage capacity calculations indicate the feasibility of injecting CO2 into Pre-Salt reservoirs. This review provides insights into the current state and future prospects of CO2-injection projects in the Brazilian Pre-Salt, contributing to the development of sustainable carbon mitigation strategies in the region.

IoT-based real-time analysis of battery management system with long range communication and FLoRa

In the current scenario, the world is focused on renewable energy generation to achieve sustainability by 2030 regarding clean and affordable energy. Lithium-ion (Li-ion)-based Battery Energy storage (BES) is a prominent approach that is widely adopted for managing large-scale renewable energy generation. Battery Management Systems (BMS) play a critical role in optimizing battery performance of BES by monitoring parameters such as overcharging, the state of health (SoH), cell protection, real-time data, and fault detection to ensure reliability. Previous studies have concluded that the implementation of Internet of Things (IoT) with LoRa ensures effective real-time monitoring of the BMS of Li-ion batteries. This study proposed and implemented a customized LoRa and IoT-based hardware system with a gateway to acquire parameters such as terminal voltage, current, charge voltage, charge current, cycle, temperature, state of charge (SoC), and SoH, and log them into the cloud server. An OMnet++-based Framework for LoRa (FLoRa) simulation was implemented to analyze the power consumption and residual energy of the customized LoRa nodes. The simulation was configured with a spread factor of 7, a carrier frequency of 433 MHz, a bandwidth of 125 KHz, and a transmission power of 2 dBm. The simulation results indicated that Node 3 had the highest mean power consumption (0.028233) and total energy consumption (0.146592), whereas Node 0 exhibited the lowest mean power consumption (0.023413) and total energy consumption (0.070204). Additionally, a comprehensive dataset encompassing voltage, current, and time was created and utilized for precise calculations of the battery's capacity and state of health, with potential use in future predictions.

Research on topology optimization strut-and-tie model and prestress construction for cable-pylon anchorage zone of Fengshuba Bridge

To address the challenges associated with accurate load-bearing capacity calculation and prestress design for the cable-pylon anchorage zone of cable-stayed bridges, a case study focusing on the Fengshuba Bridge is conducted. Utilizing the Solid Isotropic Material with Penalization (SIMP) variable density topology optimization method, a strut-and-tie model (STM) is constructed for the cable-pylon anchorage zone. This model is subsequently employed to verify load-bearing capacity of the struts and nodes within the cable-pylon anchorage zone, as well as to calculate the required quantity of circumferential prestressing tendons. Additionally, a spatial segmental finite element model is established for the cable-pylon anchorage zone to perform a detailed analysis of prestressed structural optimization. This analysis determines various structural details, including the arrangement of prestressing tendons along the height, the design for prestressing blind zones, and the quantity of prestressing tendons. Subsequently, the optimized model is subjected to stress verification. The research results indicate that the adoption of dispersed tendon arrangement results in reduced principal tensile stress within the cable-pylon anchorage zone, in contrast to the concentrated tendon arrangement. The introduction of short prestressing steel bundles within the conduit of prestressing blind zones uniformly enhances the pre-compressive stress on the cable-pylon side wall. Due to the Poisson effect of materials, it is necessary to arrange prestressing tendons appropriately within the cable-pylon anchorage zone. Arranging prestressing steel bundles according to the proposed STM and structural optimization method adequately fulfills the structural force requirements of the cable-pylon anchorage zone.

Methods for ice crossings load capacity calculation

Introduction. The article deals with a problem relevant to the territory of our country – the calculation of the bearing capacity of ice crossings and winter roads. This problem is becoming more and more urgent in connection with the development of the northern territories, an increase in the carrying capacity of road transport and the volume of cargo traffic. At the same time, the construction of permanent roads and bridge crossings requires very large capital expenditures, which are not yet available for the Russian Federation.Methods and materials. A critical analysis of methods for determining by calculation the bearing capacity of ice cover at crossings (the maximum permissible load on the axle of a single car or road train) was carried out.The recommendations of normative and methodological documents on this issue are considered. The presented analysis of domestic and foreign publications made it possible to evaluate mathematical models of different levels of complexity and detail, with a different set of factors influencing the final result.Results. As a result of the research, a summary table, which contains formulas for calculating the bearing capacity of the ice cover, the parameters that are taken into account in these formulas, as well as the values of the bearing capacity calculated using these formulas for two temperatures: 0 °C and minus 20 °C has been compiled.Conclusions. According to the results of the analysis, it can be seen that the largest number of parameters is taken into account in M.M. Kazansky-R.A. Shulman; Q. Wang; ODM 218.4.030-2016 Methodological recommendations for assessing the carrying capacity of ice crossings’ dependencies. At the same time, the value of the bearing capacity, calculated according to the 11th formulas, varies by 2-3 or more times presented. Consequently, the presented mathematical models for predicting the carrying capacity of ice crossings require experimental verification on real objects by dragging the control cargo (with some refinement of this method).

Experimental Investigation on Pure Torsion Behavior of Concrete Beams Reinforced with Glass Fiber-Reinforced Polymer Bars

The failure mechanism of torsional concrete beams with fiber-reinforced polymer (FRP) bars is essential for developing the design method. However, limited experimental research has been conducted on the torsion behavior of concrete beams with FRP bars. Therefore, the pure torsion test of four large-scale FRP-RC beams (2800 mm × 400 mm × 200 mm) was conducted to investigate the influence of the stirrup ratio (0, 0.49%, and 0.98%) and longitudinal reinforcement ratio (3.01%, 4.25%) on torsion behavior. The test results indicated that three typical failure patterns, including concrete cracking failure, stirrup rupturing failure, and concrete crushing failure, were observed in specimens without stirrups (stirrup ratio 0), partially over-reinforced specimens (stirrup ratio 0.49%), and over-reinforced specimens (stirrup ratio 0.98%), respectively. The tangent angle of spiral cracks at the midpoint of the long side of the cross-section was approximately 45° initially for all specimens. The torque–twist angle curves exhibited a linear and bilinear behavior for specimens without stirrups and specimens with stirrups, respectively. As the stirrup ratio increased from 0 to 0.98%, torsion capacity increased from 24.9 kN∙m to 27.8 kN∙m, increased by 12%, ultimate twist angle increased from 0.0018 rad/m to 0.0403 rad/m. As the longitudinal reinforcement ratio increased from 3.01% to 4.25%, the torsion capacity increased from 27.8 kN∙m to 28.3 kN∙m, and the ultimate twist angle decreased from 0.0403 rad/m to 0.0244 rad/m. Based on test results, the stirrup strain limit of 5200 με and spiral crack angle of 45° was suggested for torsion capacity calculation. In addition, based on the database of torsion tests, the performance of torsion capacity provisions was assessed.

Experimental study on axial compression performance of circular CFST columns considering extreme ambient temperature

To examine CFST short columns’ mechanical properties under extreme temps, 14 specimens were designed, focusing on temp’s impact on materials. Axial compression tests revealed temp-dependent changes: concrete strength surged at low temps but ductility diminished, while steel’s properties stayed stable. Concrete strength gains boosted columns’ strength, enhancing steel-concrete synergy. Shear failure dominated at low temps. Ductility improved with thinner diameters or wetter mixes. Calculations underestimated actual capacity, likely due to temperature neglect in design codes, EC4 most notably. Finally, incorporating the experimental results, the bearing capacity calculation formula of CFST based on the unified theory was modified and accounts for ambient temperature.

Research on axial compression performance test and bearing capacity calculation method of newly assembled hollow lattice wallboard

Research on axial compression performance test and bearing capacity calculation method of newly assembled hollow lattice wallboard