Bearing Capacity Tests Research Articles

Global buckling bearing capacity of corroded H-section steel beams

To understand the effect of seawater corrosion on the stability of steel beams, a global buckling bearing capacity test is conducted on steel beams corroded via an electrochemical method while considering the initial geometric imperfections. The equivalent remaining thickness of the corroded steel beam is calculated based on the yield load obtained from material property tests. Subsequently, this novel approach for calculating the corrosion thickness is utilized to establish a numerical model to simulate the global buckling bearing capacity of the steel beam. Employing this method enables a parameter analysis to be conducted. Furthermore, a new formula for the global buckling of the ultimate bearing capacity of steel beams is proposed based on the differential equilibrium equation of the microdeformation of steel members subjected to bending and torsion. The virtual work principle is employed to develop this formula, which not only simplifies the calculation process, but also assigns clear physical significance to each term.

Analysis of the Application of Static Load Test in Bridge Bearing Capacity Testing

This article uses real engineering projects as examples to analyze how static load test technology is applied in testing the bridge-bearing capacity. The analysis covers aspects such as testing section layout, test load and efficiency coefficient, loading plan, evaluation optimization, test result modification, and result evaluation. The aim is to support the accurate detection and evaluation of bridge-bearing capacity.

Application of the BP neural network algorithm to the ultimate bearing capacity test of building structures

The ultimate bearing capacity test effect directly influences the safety performance of the design of building structures. To enhance the safety of building structures, applying the BP neural network algorithm to their ultimate bearing capacity test is studied to improve the test effect. The shear wave velocity of the building structure during stress is collected using the static probing technique. The input samples of the BP neural network are the building structure’s shear wave velocity and construction parameters. They are processed by dimensionality reduction through principal component analysis. The firework algorithm is used to optimize the weight of the BP neural network. An early termination training method is designed, and the optimal weight is combined to train the BP neural network. After training, the samples are input after dimensionality reduction, and the building structure’s ultimate bearing capacity test results are output. Experimental results show that this method can effectively collect the shear wave velocity of building structures and complete the dimensionality reduction of samples. Under different coaxial stresses, this method can effectively measure the ultimate bearing capacity, about 3800 kN. After parameter optimization, the test value of this method is very close to the target value; that is, the ultimate bearing capacity test precision is high.

Design of press-braked stainless steel C-beams subjected to global-distortional interaction buckling

A detailed finite element (FE) model studying the global-distortional (G-D) interaction of press-braked stainless steel C-beams was reported herein. According to previous bearing capacity tests, the model incorporating measured material characteristics and precise geometric imperfections was validated by comparing to the failure mode, load-vertical displacement curve and bearing capacity. Following the calibration of the model, comprehensive parametric investigations were conducted to investigate the influence of the distribution and amplitude of geometric imperfections, material strain hardening coefficient and effect of cold working. It is found that the distribution of geometric imperfections has significant and complex impacts on the failure mode and ultimate capacity, while the amplitude of imperfection could have positive or negative effects on the ultimate capacity. The accuracy of the design methods provided by EN 1993–1-4, AS/NZS 4673 and ASCE 8–22 was assessed using the test data. All codes are found to account for distortional buckling by employing the Effective Width Method (EWM) to reduce the compression plate area. The calculation results were discrete. Therefore, based on the Direct Strength Method (DSM), a novel and accurate design method was developed for the G-D interaction of stainless steel C-beams. The strong correlation between the ratio of ultimate capacity to global buckling bearing capacity and the G-D interaction slenderness was verified by 260 numerical analyses prior to proposing the new design method. The proposed design method underwent a reliability analysis using first order reliability method to meet the requirement of ASCE 8–22.

Experimental study on axial compression fatigue of grouted connection in jacket offshore wind turbines

The grouted connection (GC) of the offshore wind turbine (OWT) jacket foundation mainly bears axial loads, the wind and wave load in the working environment make the structure prone to fatigue problems. The construction environment of the OWT foundation is relatively harsh, so there will be vertical and horizontal errors during the construction process. In this paper, the fatigue test of 9 specimens were designed to analyze the influence of vertical and horizontal errors, water ingression and other factors on the axial fatigue performance of the GC section. The static ultimate bearing capacity test was carried out to determine the load ranges of the fatigue test. Results of fatigue tests indicate that the fatigue performance of the GC considerably degenerates with the load eccentricity, especially at the end sections of the inner and outer tubes. Water ingression has a significant negative influence on the fatigue performance of the GC section. The presence of water contributes to the propagation and development of cracks in the grout layer. Load range, vertical and horizontal errors and grout material have negligible effect on the fatigue performance of the structure.

The influence of basalt fiber on the mechanical performance of concrete-filled steel tube short columns under axial compression

With rapid economic and social development, both concrete-filled steel tube (CFST) composite structures and basalt fiber (BF) have been widely applied in the field of civil engineering. To investigate the laws and characteristics of the influence of chopped BF on the mechanical properties of CFST columns and further promote the application of BF in CFST structures, the axial compressive bearing capacity test of 18 CFST short columns was carried out, and the influence of BF of different lengths on their structural mechanical properties was analyzed. The test results were compared with the theoretical calculation results and the finite element analysis results to verify the reasonableness of the test results. The results reveal that the axial compressive bearing capacity of the CFST short column after adding BF is significantly improved compared to the ordinary CFST short column, in which the bearing capacity and the ductility coefficient are increased by approximately 8.1% and 31.6%, respectively, on average. In addition, changing the length of BF has less effect on the bearing capacity of CFST short columns, the rate of increase in bearing capacity decreases with an increase in the steel ratio of CFST, and the coefficient of ductility increases with the increase in the steel ratio.

Experimental investigation of global-distortional interaction buckling of stainless steel C-beams

This work reports the test data for press-braked stainless steel C-beams subjected to global-distortional (G-D) interaction. The chemical constituents of austenitic S30408 used in the tests were proved to meet the European (EN 10088–1:2014) and Chinese (GB/T 3280–2015) codes. The tensile test of the material was performed to determine the mechanical properties of the flat and corner areas of the press-braked C-beams. Initial imperfections of each specimen were assessed before conducting the bearing capacity tests. A total of 10 specimens consisting of 20C-beams were subjected to four-point bending. All specimens first underwent distortional buckling and then global buckling. The vertical displacement at the mid-span and the loading points, support rotation, distortional deformation, lateral deformation, strain at the boundary of the upper flange as well as strain of the lower flange were meticulously recorded and analyzed. Based on the observed test phenomena, the recorded displacement and strain data, the failure mechanism of G-D interaction and the development of the buckling waves were unveiled. The test data was employed to evaluate the accuracy of the design methods in accordance to the Direct Strength Method (DSM), EN 1993-1-4, AS/NZS 4673 and ASCE 8–22. All codes are found to account for distortional buckling by employing the Effective Width Method (EWM) to reduce the compression plate area. The evaluation results revealed that DSM could safely and stably make a prediction of the ultimate capacity for G-D interaction in stainless steel beams, while EWM have a lower performance in prediction.

Study on Crack Resistance and Calculation Model of RAC Beams Strengthened with Prestressed CFRP

With the development of recycled aggregate concrete (RAC), the recovery rate of construction waste is improved, and the pollution problem is alleviated. In particular, RAC beams strengthened with prestressed carbon fiber reinforced plastics (CFRP) can exhibit improved mechanical properties, expanding RAC application. Four groups of reinforced RAC beam specimens contained 0%, 40%, 70%, and 100% recycled coarse aggregate, respectively. Each group of beams was first pre-cracked and then strengthened by prestressed CFRP with one layer and two layers respectively. Finally, the bearing capacity tests were performed for these beams. The test results show that as the recycled coarse aggregate content increases, the cracking moment and ultimate load capacity of the beam decrease, while its crack width increases. As the CFRP layer increases, the deformation and crack width of the beam decreases, while the number of cracks increases. The prestressed CFRP also exhibited tensile and peeling failure. A beam deflection calculation model was established by introducing a coefficient k representing the interaction between recycled aggregate and CFRP. The influence coefficient of concrete elongation on the crack width and average crack spacing of the beam was modified, and the crack width analysis model of the beam was established. The calculated results are in good agreement with the experimental observations. It can provide reference for the application and design of recycled concrete beams strengthened with prestressed CFRP.

Study on stability of H-type section aluminum alloy perforated members under axial compression and eccentric compression around weak axis

Aluminum alloy components have the advantages of light weight, high strength, favorable machinability, and good acid corrosion resistance, which can greatly reduce maintenance costs and easy to make the structures with beautiful appearance. Based on the shortcomings of existing research fields, the stability of H-type section 6082-T6 aluminum alloy perforated members under axial compression and eccentric compression around weak axis is studied by combining experimental and numerical simulation methods in this paper. The test results of aluminum alloy members under axial compression and aluminum alloy members under eccentric compression around weak axis with different web opening numbers, opening diameters, slenderness ratios and eccentric distances are analyzed. The verified finite element model is used to carry out the extensive parameter analysis focusing on the key variables. Based on the test and numerical simulation results of the stability bearing capacity of 134 members, the design methods for H-type section aluminum alloy perforated members under axial compression and eccentric compression are proposed and evaluated by reference to the existing specification.

Experimental research and engineering application on bearing capacity of concrete-filled steel tube circular arch

The bearing property and deformation failure law of the CFST circular arch were investigated in order to provide direction for the optimization of the concrete-filled steel tube (CFST) support. The flexural bearing capacity test of the 194 mm × 10 mm CFST was performed initially in this study. It was primarily explored how bearing capacity and deformation of circular arches were affected by the slip of the arch foot and anti-bending strengthening, and the neutral layer migration rule and anti-bending strengthening mechanism of circular arches were examined. The bearing performance of the circular arch under the condition of the concentrated load of the vault and the usual uniform load of the entire span is then simulated in an orthogonal test by numerical simulation in order to extend the experimental investigation. The effect of variables including the steel tube’s outer diameter, thickness, slip of the arch foot, and the ratio of the arch rise to span on the bearing capacity of the circular arch is examined. The study demonstrates that under focused stress on the arch top or full-span normal uniform loading, the arch foot slip is the most important element impacting the CFST support’s bearing capacity. In steel tubes with the same outer diameter and wall thickness, the vector span ratio has a bigger influence than anti-bending strengthening. When the span ratio is the same, the influence of the outer diameter and wall thickness are equal and outweigh the influence of bending strengthening. The circular arch with an outside diameter of 168 mm, a wall thickness of 10 mm, and a rise-span ratio of 0.207 has the best performance characteristics under the influence of concentrated load, and the ultimate failure mechanism is local waist drum deformation failure. Based on the aforementioned study findings, the circular CFST support’s buckling deformation and drum deformation are examined, and a composite support consisting of “anchor net spray + CFST support” is directed for the north three deep track downhill of Yangcheng Coal Mine. Two failure types expose the failure mechanism and provide a technique for optimization. The support had contributed to the circular CFST arc arch’s best bearing performance in the event of waist drum deformation and failure.

Construction of a bearing capacity testing model for reinforced bridges based on material performance deterioration

Reinforced concrete beam bridges have been extensively utilized in transportation engineering due to their advantages such as simplified material selection and low cost. However, the mechanical performance of steel bars and concrete deteriorates over time due to factors such as prolonged bridge service life, fluctuations in environmental temperature and humidity, and other influences. To achieve a precise and effective prediction of the bearing capacity of reinforced concrete structures, this study proposes a method for assessing bearing capacity in the context of material performance degradation. The study commenced by examining the factors that impact the degradation of bridge performance and subsequently utilized material performance test values along with predicted and corrected values to estimate the reduced bearing capacity of the bridge. Additionally, the mechanical and bonding properties of modified reinforced concrete materials were calculated. The experiment results demonstrate that the calculated values from the modified model closely align with the measured values with a differential range of 0.06 to 0.38. At a micro level, nano-SiO2 modification enhances rubber concrete by improving the compactness of the matrix and enhancing bond strength between steel fiber-and-nanosilica-reinforced crumb rubber concrete and deformed steel bars. The revised model in this study exhibits excellent predictive capability for concrete strength, thereby enhancing the accuracy of outcomes in evaluating bridge technical conditions. This method holds potential for practical engineering applications and scientific research on bridge evaluation.

A confined concrete model considering strain gradient effect of CFST column under eccentric load

This paper analyzes the axial and eccentric compression mechanisms of concrete-filled steel tube (CFST) columns and proposes a confined concrete constitutive model that considers gradient effects. The model is based on the gradient effect of stress and strain under eccentric compression to deduce the gradient effect of confinement force, and obtain the calculation formula of confinement force under different eccentricities, so as to obtain the corresponding constitutive model of confined concrete. The model is used to modify the fiber model and Chinese Codes, which are affected by loading eccentricity. Six sets of CFST material constitutive test data are collected to validate the constitutive model. Eight sets of moment-curvature curves of section tests and twelve sets of eccentric compression bearing capacity tests were collected for validation. The data collected from these two sets of experiments were compared with the modified calculation values of the fiber models and the design codes, respectively, to confirm the reliability of the modification effect. The results indicate that the utilization of the model proposed in this paper successfully reflects the influence of eccentric loading on the confined concrete constitutive relationship, improves the prediction accuracy of existing formulas, and facilitates the analysis efficiency of CFST.

Experimental study on fire resistance of high strength Q960 steel columns under axial compression

In order to obtain the mechanical behavior of H-shaped high-strength Q960 steel column under axial compression in fire, the bearing capacity tests of two Q960 steel columns at ambient temperature and fire resistance tests of six Q960 steel columns at elevated temperature were carried out. By considering different slenderness ratios, load ratios, and heating rates of the test columns, the furnace temperature, column temperature, lateral displacement, and axial displacement were measured and recorded. Then, critical temperature, fire resistance, and failure mode of the columns were obtained. The thermal-mechanical coupling analysis model for the Q960 steel column was established by using ABAQUS finite element analysis software. After verifying the accuracy of the model, parameter analysis was carried out to investigate the effects of load ratio, slenderness ratio, geometric imperfection, thermal creep, residual stress, and steel strength on the fire resistance of steel columns. Based on the test data and analysis results, a fire resistance design method for high-strength Q960 steel columns under axial compression is proposed.

Experimental Study on Bonding Performance between Prestressed Concrete Pipe Piles and Core Grout

To make the bearing capacity tests safer and more affordable for prestressed high-strength concrete (PHC) piles, this paper proposes a reaction device for anchor piles filled with core grout based on the geometric and mechanical characteristics of PHC piles. The proposed reaction device has the advantages of convenient construction, strong controllability of the connection quality and low cost. In addition, the pile will not experience prestress unloading or tensile stress under the effect of the upward pulling load. To promote the application of the reaction device developed for PHC pile bearing capacity tests, experimental studies are conducted on the bonding performance between the core grout and the inner wall of the PHC pile. The influence of various factors such as the strength of the core grout, the grouting length, the curing time, and the inner diameter of the PHC pile on the bond strength between the core grout and the inner wall of the PHC pile are investigated. Results show that as the inner diameter of the PHC pile increases, the bond strength between the core grout and the inner wall of the PHC pile decreases with a maximum difference of 5%. The bond strength decreases as the grouting length increases, and gradually stabilizes, with a difference of no more than 10% between the maximum and minimum bond strength values. The higher the strength of the grout is, the greater the bond strength between the core grout and the inner wall of the PHC pile is. The bond strength between the core grout and the inner wall of the PHC pile increases with the increase of the curing time within 28 days of curing, and the bond strength at 3 days meets the requirements of the PHC pile bearing capacity test.

Ultimate strength of CFST-gusset plate joints with ring stiffener plates under tension

Tube-gusset plate joints are increasingly adopted in large lattice towers for wind power, due to the advantages of simple fabrication and clear force transmission path. To investigate the mechanical performance of CFST-gusset plate joints with ring stiffener plates, tensile bearing capacity tests of three tube-gusset plate joints were performed in this study. The test results showed that setting ring stiffener plates and filling concrete could effectively improve the stiffness and tensile bearing capacity of tube-gusset plate joints. In addition, the finite element (FE) models were established in this study, and the accuracy of the FE models was verified by comparing it with the test results. Parameter analysis showed that the increase of the width ratio (R/D) and thickness ratio (tr/t) of the ring stiffener plate and the width ratio (LGP/D) of the gusset plate was a significant method to improve the ultimate strength of tube-gusset plate joints under tension. But when the width ratio and thickness ratio of ring stiffener plates exceeded the limit relationship, the ultimate strength of joints would not be further improved, which was easy to cause waste of materials. Finally, to simplify the calculation of CFST-gusset plate joints with the ring stiffener plates, an equivalent interaction method (EIM) was proposed in this study, which could accurately predict the ultimate strength of CFST-gusset plate joints with ring stiffener plates under tension.

Experimental Research on the Impact Resistance of Partially Precast Concrete Beams Strengthened with Bonded Steel Plates

A structure may be exposed to a range of unexpected loads throughout its full life cycle. Partially precast concrete (PC) beams refer to the process of manufacturing concrete beams in which one part of the component is pre−fabricated in a factory and the other part is completed at the construction site. Through the test, it is possible to better ensure the safety and dependability of the PC composite beams under impact load by examining the reinforcement effect, structural toughness, and damage mode of PC composite beams with bonded steel. Additionally, a scientific basis and practical guidance are provided for the actual project. Their impact resistance can significantly affect the overall safety of a structure when subjected to an impact load. Three of the four PC beams used in this investigation were strengthened with steel plates. Residual flexural bearing capacity tests and drop weight impact tests were then conducted. The impacts of steel plate thickness and U−shaped steel plate hoops on the failure mechanism and dynamic response of the component were investigated. The dynamic responses obtained from the experiments included the displacement–time history curve, impact force, and support reaction force. In order to explore the failure mechanism of the partially precast beam during the impact process, a staged analysis was conducted based on the failure mode and dynamic response characteristic values of each curve. Residual flexural bearing capacity tests were used to examine the residual flexural bearing capacity of PC beams strengthened with bonded steel plates. The results of the research reveal that the failure mechanisms of each test beam are bending–shear failures. With the increase in bonded steel thickness, the peak mid−span displacement reduced by 6.55%, the residual mid−span displacement decreased by 29.53%, and the residual flexural bearing capacity improved by 25.02%. With the adoption of U−shaped steel plate hoops, the residual flexural bearing capacity significantly increased while the peak mid−span and residual mid−span displacements both decreased.

Study of Bearing Capacity of Aluminum Alloy Thin-Walled Circular Tube Filled with Lightweight Filler

In this study, experimental research, a numerical simulation, and a theoretical analysis were performed on the bearing capacity of an aluminum alloy circular tube filled with a lightweight filler (ATLF). Bearing capacity tests were conducted for six ATLF columns and two aluminum alloy hollow tubes (AAHTs), and their local buckling failure modes and mechanical properties were obtained. A finite element model was developed using ABAQUS software (ABAQUS 2016, ABAQUS Inc., Palo Alto, CA, USA) for numerical calculations. Furthermore, a large-scale numerical analysis was performed to investigate the effect of structural parameters, such as the tube thickness, diameter, column length, and initial geometric imperfections, as well as the aluminum alloy’s properties and the lightweight filler’s properties, on the bearing capacity of the ATLF columns and AAHTs under axial compression. Based on the test and numerical analysis results, a formula for calculating the local buckling stress of AAHTs under axial compression is proposed. An improved coefficient of bearing capacity for the ATLF columns caused by the internal lightweight filler was obtained by fitting, and based on the results, a formula for computing the bearing capacity of ATLF columns under axial compression is proposed in this study.

An intelligent model to predict the mechanical properties of defected concrete drainage pipes

Corrosion and cracks are common issues in drainage pipelines. To investigate the mechanical properties of pipes with defects, a series of pipeline bearing capacity tests were carried out. In addition, a prediction model using a combination of self-organizing maps, genetic algorithms, and support vector machines (SOM-GA-SVM) was developed to predict the bearing capacity and circumferential strain of the pipeline. The prediction results obtained using this model were compared with those obtained using three other optimization algorithms. Furthermore, the influence of loading speed and defect volume on the prediction accuracy of the model was analyzed. The results indicated that the MAPE of the prediction results was less than 7%, the RMSE was less than 8, and the R2 was greater than 0.98; Additionally, the prediction accuracy of the SOM-GA algorithm was significantly higher than that of the genetic algorithm, particle swarm optimization algorithm, and grid search method; It was found that removing the loading speed from the variables and changing the defect depth and width to defect volume can improve the prediction accuracy of the model. After removing the loading speed, the average MAPE and average RMSE of the prediction model were reduced by 7.357% and 8.385%, respectively. After changing the defect depth and width to defect volume, the average MAPE and average RMSE of the prediction model were reduced by 4.925% and 5.054%, respectively.

Experimental Study on Bonding Properties between Finishing Rolled Rebar and Grouting Material

In bearing capacity testing of prestressed concrete pipe piles, grouting material is filled up to the bottom of the pipe pile, which is equipped with a finishing rolled rebar. The reaction force of the reaction beam is transferred to the anchor pile through the bonding force between the finishing rolled rebar and grouting material. Therefore, investigating the bonding properties between the finishing rolled rebar and grouting material is essential to remove barriers to the application of the anchor pile method in bearing capacity testing of the prestressed concrete pipe pile. In this study, the bonding properties of 11 groups of specimens were studied through pull-out tests, and the effects of the cover thickness, diameter, and anchorage length of reinforcement on the bond strength between finishing rolled rebar and grouting material as well as on the bond stress-slip curve were explored. The test results showed that the bond stress-slip curve between finishing rolled rebar and grouting material can be divided into two stages, i.e., slip stage and splitting failure stage. In the slip stage, a linear relationship exists between bond stress and slip amount, and microcracks appear in the grouting material around the finishing rolled rebar. In the splitting failure stage, the slip amount increases rapidly under uplift load. Finally, the grouting material around the finishing rolled rebar forms a failure zone, and splitting failure occurs. The bonding capacity and bond strength between finishing rolled rebar and grouting material increase with the increasing cover thickness of the rebar. The bond strength is the maximum for a relative cover thickness of 3.0, and the difference between the maximum and minimum values is more than 9%. The bonding capacity between rebar and grouting material increases slightly with the increasing rebar diameter, but the bond strength decreases with the diameter, and the difference between the maximum and minimum bond strengths is more than 21%. As the contact area between finishing rolled rebar and grouting material increases, the bonding capacity between them increases with the increasing anchorage length of the rebar. However, the bond strength first increases, then decreases, and finally stabilizes with the increasing anchorage length, and the difference between the maximum and minimum bond strengths exceeds 14.64%.

Research and Optimization of Lateral Compressive Performance of the 3-D Printed Beetle Elytron Plate

In this paper, two types of beetle elytron plates (end-trabecular beetle elytron plate (EBEP) and middle-trabecular beetle elytron plate (MBEP)) and honeycomb plate (HP) were manufactured by 3-D printed and applied to large-span spatial structure. The lateral compressive performance of the 3-D printed beetle elytron plate was investigated by lateral compression bearing capacity test and numerical analysis. The influence of number of cylinders, ratio of the radius of the cylinder to the side length of the hexagonal honeycomb core (ratio of radius-length), thickness of core layer and configuration of beetle elytron plate on the lateral compressive performance of the beetle elytron plates were studied and the optimization method for lateral compressive performance of the beetle elytron plates was proposed. The result shows that the lateral compression bearing capacity of EBEP is greater than that of MBEP, and both are greater than of HP. The lateral compression bearing capacity of the beetle elytron plate with six cylinders is about 25% higher than that of the HP without cylinders. The lateral compression bearing capacity of beetle elytron plate can be improved by increasing the thickness of plates. The results of the study will promote the application of beetle elytron plates in large-span spatial structures.