Bolt Connection Research Articles

Bolt loosening angle detection through arrangement shape-independent perspective transformation and corner point extraction based on semantic segmentation results

The identification of loosened bolts is crucial for the early warning of structural damage and maintaining the overall stability of the structure. Most existing two-dimensional computer vision-based bolt loosening detection methods need to rely on the bolt arrangement shape for perspective transformation, to overcome this limitation, this study proposes a bolt loosening angle detection method through arrangement shape-independent perspective transformation and corner point extraction based on semantic segmentation results. First, a dataset of 1748 images containing bolts is collected. Second, a bolt region of interest (RoI) detection is developed to extract the sub-image of the bolt. The results show that the training and validation accuracy of bolt RoI detector are 99.5%, and 99.4%, respectively. Then, the contour corner points are extracted, the automatic and arrangement shape-independent perspective transformation of the image is completed using the planar homography-based image processing algorithm and the regular hexagonal characteristics of the bolt. Finally, automatic estimation of the bolt angle is performed on the corrected bolt image. The proposed method is used to detect bolt images obtained from different shooting distances, perspective angles, and lighting conditions. The results demonstrate that the method can accurately detect the looseness of bolts in bolt connections, and the quantification error is mostly less than 3°, it has the potential for real-time bolt loosening monitoring of multi-type bolted connections.

Research on the Effect of Thermal Coating Temperature on the Fatigue Performance of Wind Turbine Blade Bolts

The bolted connection of wind turbine blades is a bridge for transmitting blade loads. In recent years, with the rapid increase in blade length, the fatigue load at the blade root has also been continuously increasing. The bolt fatigue strength has always been a bottleneck in the interface design between blade and wind turbine hub. However, industry standards still hold conservative values for the S/N curve of bolt fatigue, and there are unclear requirements for thermal coatings, The S/N curves provided by the standards in different periods do not meet the actual processing requirements of bolts. In order to study the effect of thermal coating temperature on the fatigue performance of threads and provide a reasonable basis for the subsequent design of long blade bolt connections. Based on the actual processing technology of bolts, experiments were conducted on the S/N fatigue curves of thermal coated bolts at different temperatures. The experimental results prove that the slope of the inclined part of the low-temperature Dacromet test data and the fatigue strength under 2 million cycles are significantly higher than normal temperature Dacromet coated bolts. Low temperature Dacromet can effectively improve the fatigue strength of bolts.

Seismic performance and skeleton curve model of prefabricated coral aggregate concrete-filled aluminum tube joint

Corrosion-resistant and high load-carrying capacity coral aggregate concrete-filled aluminum tube (CCFAT) structures show promising applications in island construction. However, research on CCFAT joints related to structural safety remains scarce. To advance the engineering application of this structure, a novel prefabricated CCFAT beam-column semi-rigid joint with bolt connections is designed in this study. The seismic performance of the joint is investigated through a pseudo-static method, analyzing the effects of each parameter on failure mode, hysteresis curve, deformation characteristics, and energy dissipation performance, considering the earthquake-prone nature of islands. The primary objective of this study is to explore the influence of different parameters on the seismic performance of the CCFAT joint and establish the moment-rotation relationship of this joint. It is observed that the ultimate moment relationship between the beam and connector significantly impacts the failure mode of the joint, thus affecting its seismic performance. Hence, prioritizing the ultimate moment relationship between the beam and connector in the design phase is crucial to avoid undesirable joint failures. The skeleton curve of CCFAT joints differs significantly from that of steel and reinforced concrete structures, rendering existing joint theories inapplicable to CCFAT joints. Considering joint material, structure, and failure mode, this paper proposes a theoretical calculation method for the initial stiffness and ultimate moment of the CCFAT joints. This method is based on the component method and mechanical model, establishing an exponential three-parameter skeleton curve model for the joint. This model enables an accurate prediction of the moment-rotation relationship of the CCFAT joint, aiding in its seismic performance evaluation.

Experimental investigations of the H-shaped post-tensioned precast frame module with monolithic beam-column connections

ABSTRACT In this study, the evolution of the frame in a structural behavior’s perspective is focused, identifying how cracks influence the degradations of the frame from the camber cracks to plastic hinges. An extensive experimental investigation for the H-shaped post-tensioned precast frame module with monolithic beam-column connections using bolted plate connections is performed to identify the ductile behavior of the H-shaped post-tensioned precast frame module. The inelastic stresses are observed to be redistributed until the failure mechanism with the three plastic hinges are formed in the prestressed beam, which dissipates an inelastic energy in a ductile fashion. No noticeable deformation in plates and bolts for both the first and second floor of the precast frame is found at the final stroke when the experiment was terminated, elucidating that bolted plate connections provide the frame with connections similar to the concrete monolithic joints. Structural behaviors are also investigated using nonlinear finite element analyses based on a damaged concrete plasticity model, unraveling the principles governing crack formations within tested frames. This investigatory approach yields valuable insights for designing post-tensioned precast frames with mechanical column joints. The proposed frame is verified as an option for modular off-site construction to replace cast-in-concrete monolithic frames.

Force Performance Analysis and Numerical Simulation of Assembled Ribbed-Slab Abutments

This study investigates the structural performance of assembled rib-plate bridge abutments (ARBAs) with two different connection methods: bull leg bolt and flange connections. In addition, we explored the bending and shear performance of the connection parts and related areas to assess the damage characteristics and modes of these ARBAs. Utilizing model testing, a numerical analysis was conducted to define the force performance of the ARBA, with reference to a cast-in-place rib-plate abutment. The research results indicate that the bearing capacity and deformation capacity of the cap part of the assembled ribbed slab abutment model with cow leg connections are lower than those of the cast-in-place structure. When the structure fails, a 45° diagonal crack develops from the cross-section at the mid-span joint to the connection between the rib slab and the cap, until the concrete protective layer at the joint is crushed, exhibiting a shear failure mode. The bearing capacity of the assembly rib plate type abutment cap connected by the flange plate is basically the same as that of the cast-in-place structure, and the deformation capacity is weaker than that of the cast-in-place rib plate type abutment. The expansion of structural cracks is consistent with that of the rib plate type abutment connected by the cow leg. When the flange plate at the mid span is damaged, the contact surface between the flange plate and the concrete is pried off, resulting in the inability of the structure to continue bearing, exhibiting a shear failure mode. Through numerical simulation, taking the stress performance of the integral cast-in-place ribbed slab abutment as a reference, the assembled ribbed slab abutment connected by the flange plate is basically consistent with the integral cast-in-place ribbed slab abutment in terms of ultimate load, concrete damage, and steel reinforcement skeleton stress, and the connection device has not yet reached the yield state. The ultimate displacement is slightly weaker than that of the integral cast-in-place ribbed slab abutment. By comparison, it can be seen that the ultimate bearing capacity of the assembled ribbed slab abutment connected by the flange is basically the same as that of the cast-in-place ribbed slab abutment, and the stress performance can reach an “equivalent cast-in-place”, making it the preferred solution for the assembled abutment structure. The finite element parameter analysis of the flanged ARBA revealed that the thickness of the stiffening ribs, the number of bolts, and length of the flange plate anchoring steel plate were proportional to the ultimate load-bearing capacity of the prefabricated ARBA. In the case of no change in the structural damage mode, considering the economic benefits and load-bearing capacity of the structure, the following parameter combinations of the flanged ARBA are recommended: a thickness of 30 mm of the stiffening ribs, the number of bolts is 12, and a length of 50 cm of the length of flange plate anchoring steel plate.

Structural Performance of Reinforced Concrete Beams Retrofitted Using Modularized Steel Plates in Precast Concrete with Bolted Connections

The previous research introduced an innovative retrofitting technique for reinforced concrete beams using modularized steel plates. This technique enhances structural performance, offering a lightweight solution compared to conventional retrofitting methods using steel plates, and accommodates construction errors. However, a challenge arises due to the lack of integrity between unit steel plates. To address this, this study proposes a novel method of connecting each steel plate with bolts. The experimental results show that retrofitted beams achieved a maximum load of 311.9 kN, roughly 1.6 times that of non-retrofitted specimens, with the ductility of retrofitted beams being 3.3 times that of the non-retrofitted beams. Additionally, there was a 25% increase in load capacity for beams retrofitted with interconnected steel plates compared to those without connections between unit steel plates.

Modeling and free vibration analysis of bolted composite flanged cylindrical-cylindrical shells under partial bolt loosening conditions

The bolted composite coupled cylindrical shell is a common substructure in modern engineering, which may encounter the issue of local loosening conditions during service. Meanwhile, the influence of flanges on the structural vibration characteristics is often overlooked in dynamic numerical analysis. In this paper, a semi-analytical dynamic model for the bolted composite flanged cylindrical-cylindrical shell structure under arbitrary connection conditions is established, and the free vibration characteristics of locally loose structures are emphatically studied. In the model, the annular plate modeling method is developed to achieve the simulation of the flange part. To fully reflect the connection characteristics of the bolted joint, a spring surface model and the corresponding parameter determination method based on fractal contact theory are developed. The equations of motion of the structure are obtained utilizing the Lagrange equations. The accuracy of the model and its predictive ability for the vibration characteristics of the bolted composite flanged cylindrical-cylindrical shell under local loosening conditions are fully demonstrated through numerous comparisons with experimental results from other literature and modal test results obtained under various working conditions. Furthermore, the influence of the number and degree of loosening bolts on the free vibration characteristics of the structure and the coupling phenomenon between different modes are discussed. The research in this paper is expected to provide references for the design of bolted composite flanged cylindrical shell structures and the monitoring of bolt connection defects.

Numerical-analytical investigation on bending performance of laminated beams in modular steel buildings

It is well-known that the laminated channel beams can significantly strengthen the combination of adjacent beam components and further enhance the structural integrity of modular steel buildings. In present study, the superimposed bending performance of laminated channel beams was comprehensively investigated using the numerical and analytical methods. Firstly, FE models were developed and validated by the experimental data. Then, a series of numerical parametric studies combining the orthogonal and univariate analysis were successively conducted to identify the sensitivity of design parameters including interfacial bolt number (n), interfacial friction (f), layer height ratio (β), load type (p) and boundary condition (b), and further clarify the influence of key parameters on the cooperative bending properties. Finally, the analytical procedure was proposed to evaluate the equivalent bending stiffness of laminated channel beams. The results showed that the effect degrees of design factors on EIe and Pu were as follows: n > β > f > b > p and p > b > β > f > n, respectively. n and β were selected as the key design parameters for the modular laminated beams. The bending responses were nonlinearly promoted by n, while the linear regularity was observed for β. The influencing mechanism of n indicated that the bolt connections induced the additional internal forces, which caused the transferring of neutral axes and the superimposition effect of laminated beams. Quantifying the neutral axis deviations, the analytical models were developed and reasonably assessed the superimposed bending stiffness of laminated beams in modular steel buildings.

Steel–aluminum screw–thread pair tightening mechanism and fastening axial force conversion efficiency

During the tightening of bolted connection, the tightening torque of the bolt is converted into its fastening axial force. The magnitude of the fastening axial force significantly affects the reliability and fatigue strength of bolted connections. Herein, a theoretical analysis of the tightening process of bolt connection is conducted using a power exponent hardening constitutive model, and the expressions of the tightening angle–fastening axial force and tightening angle–tightening torque during the tightening process are derived. A fine finite element model of steel–aluminum thread connections that can be used to simulate the actual tightening process considering the detailed thread structure is established. The accuracy of the theoretical formula is verified by finite element method and experiment, respectively. Through finite element simulation and experiment, the correctness of the formula is verified. Further, the conversion efficiency of the fastening axial force of the steel–aluminum screw–thread pair is analyzed by combining finite element analysis and theory. The results show that under the same tightening torque, the conversion efficiency of the fastening axial force can be increased by 6.8%–9.3% by appropriately reducing the friction coefficient of the steel–aluminum threaded connection pair. By controlling the fluctuation range of the friction coefficient, the dispersal error of the fastening axial force can be reduced by 26.9%–36.7%. The angle method is more conducive to improving the connection reliability of the steel–aluminum screw–thread pair than the torque method.

Shearing performances of the detachable prefabricated composite beams with different types of connectors

AbstractThe shear performance of precast composite beams with stud connectors and detachable prefabricated composite beams with high‐strength bolt connectors are tested and studied. A total of 12 push‐out specimens were designed for tests, and then the nonlinear finite element models of two kinds of composite beams with different types of connectors were developed. Results show that the failure mode of all push‐out specimens is the shear failure of connectors, but the load‐slip curves of the two connectors are obviously different. It is found that the stiffness of stud connectors is higher, and the ultimate bearing capacity of high‐strength bolt connectors is higher. For stud connectors and high‐strength bolt connectors in this work, the reduction of shear capacity of connectors caused by the group nail effect is not considered. Moreover, the effects of different parameters on the shear performance of stud connectors and high strength bolt connectors were studied by using finite element model. The optimal preload applied to high‐strength bolt connectors with different diameters and strength grades was obtained.

Mechanism and control of preload force loss of precast structural joint bolts under freeze–Thaw environments

Bolt-connected precast buildings are increasingly prevalent, especially due to their efficient force transfer and accelerated construction processes. However, in cold climates, special attention must be directed towards the effects of freeze-thaw (F-T) damage on concrete at bolt connection sites. This study conducted an accelerated F-t-test to investigate how concrete F-T damage influences the preload force of the connection bolts. The changes in bolt preload forces across F-T cycles were monitored using advanced fiber optic sensing technology. To mitigate preload force loss, silicone rubber sleeves were introduced into the bolts. Results indicate a correlation between initial preload force and subsequent preload loss, with lower initial preloads leading to greater losses. Additionally, the concrete's frost resistance significantly affects preload force loss, with less resistant specimens showing marked preload decreases. A notable risk of brittle damage arises after 3 to 6 F-T cycles if a 4 mm gap between the bolt and concrete exists, attributed to water freezing and expansion within the gap. Concrete specimens subjected to our proposed mitigation strategies effectively withstand over 140 F-T cycles, substantially lowering crack damage risks.

Shear performance of high-strength bolt-epoxy bonding composite connector in steel-concrete composite structure

To clarify the shear mechanism of high-strength bolt-epoxy bonding composite connectors in prefabricated steel-concrete composite structures, twenty-one direct shear specimens and six double shear specimens were carried out in this study. The pretension force, interface type, epoxy curing time and loading pattern were considered. Results revealed that the main failure mode of high-strength bolt-epoxy bonding composite connectors was that the large area of epoxy matrix was separated from the steel plate, and the bolt was sheared off. The load-slip curve of composite connector specimens included the elastic stage, epoxy failure stage, frictional slip stage, bolt force transmission stage and failure stage. Compared to the specimens with a bolt connector under recommended pretension, the average initial slip load of composite connector specimens was 437.7% higher. Additionally, the average initial slip load of specimens with 1-day epoxy curing time was 24.4% lower than 7-day curing time, but the average ultimate load and ultimate slip were 12.4% and 29.4% higher, respectively. When the pretension ratio decreased from 1.0 to 0.6, the average initial slip load of specimens with a bolt connector was significantly decreased by 33.0% and the average ultimate slip of composite connector specimens was increased by 18.1%. The average initial slip load and ultimate load of composite connector specimens were comparable under cyclic loading compared to monotonic loading. Upon the experimental results and existing formulas, some equations were proposed for predicting the initial slip load and bearing capacity of steel-concrete composite structures with composite connectors.

Numerical and experimental investigation of a new model of friction damper in diagonal brace under cyclic loading

Owing to the performance of prefabricated friction dampers, which are rapidly increasing, the resistance of structural systems against earthquakes increases and depreciates the energies generated by earthquakes in the structure. It is important to use passive control systems to control the vibrations of a structure at a single level. However, in the design, they cannot depreciate the incoming energy from earthquakes at different levels. Friction dampers focus on displacement variables and are mostly used in steel structures according to the rules of a Coulomb damper or a friction brake that converts kinetic energy into heat through friction. In this study, a new type of friction damper, called a flat cylindrical friction damper, was designed using brake pads in a diagonal brace. The performance and seismic resistance of this system, as well as the amount of energy loss, were investigated. In this study, 18 laboratory tests were conducted using the universal device to check the research variables, their hysteresis diagrams were shown, and the configuration of the damper was designed such that grooved bolt connections and twin steel cables of different sizes and thicknesses were used. Moreover, the way the internal and external components are placed in the damper is such that innovation in tension and pressure has been created. In addition, the movement of the cylindrical element in the damper increased the amount of friction, owing to the presence of two types of brake pads with friction coefficients of 0.11 and 0.16 and the bolt connections. This demonstrates the damper performance under different sliding forces at different friction levels. The geometric dimensions, thickness of the brake pad, number and size of bolts, diameter of cables, sliding force, and location of the damper were among the variables investigated in this study. Brake pads, steel cables, and bolt connections are important and economically affordable. The seismic performance of the intended frame was investigated using 80 different damper models and the placement of the research variables. The desired optimal models were modelled using Abaqus software, analysed, and designed. This system aims to reduce the relative horizontal displacement of floors and increase the amount of energy absorption. An increase in theaxial-force created in multiple loading cycles always causes damage to damper components and frames. In this study, we used a special multi-level geometry to reduce the axial-force created in the damper, the relative displacement of the frame, and damages in the elements, as well as increase the ductility. The results show that the friction surfaces of steel plates and brake pads is very high due to the displacement and damping of the cables. Additionally, with the consumption of energy and its absorption by the damper in cyclic loads, displacement is easily controlled. The seismic response of the structures in terms of frame and damper displacement, base shear forces, and energy absorption is also observed. Numerical studies confirmed that the intended damper is an independent seismic-resistant member in critical building structures when high seismic performance or seismic resilience during moderate and strong earthquakes is desirable.

Phased Array Ultrasonic Method for Robotic Preload Measurement in Offshore Wind Turbine Bolted Connections.

This paper presents a novel approach for preload measurement of bolted connections, specifically tailored for offshore wind applications. The proposed method combines robotics, Phased Array Ultrasonic Testing (PAUT), nonlinear acoustoelasticity, and Finite Element Analysis (FEA). Acceptable defects, below a pre-defined size, are shown to have an impact on preload measurement, and therefore conducting simultaneous defect detection and preload measurement is discussed in this paper. The study demonstrates that even slight changes in the orientation of the ultrasonic transducer, the non-automated approach, can introduce a significant error of up to 140 MPa in bolt stress measurement and therefore a robotic approach is employed to achieve consistent and accurate measurements. Additionally, the study emphasises the significance of considering average preload for comparison with ultrasonic data, which is achieved through FEA simulations. The advantages of the proposed robotic PAUT method over single-element approaches are discussed, including the incorporation of nonlinearity, simultaneous defect detection and stress measurement, hardware and software adaptability, and notably, a substantial improvement in measurement accuracy. Based on the findings, the paper strongly recommends the adoption of the robotic PAUT approach for preload measurement, whilst acknowledging the required investment in hardware, software, and skilled personnel.

Research on seismic behavior of tapered-head bolted inter-module connection of modular steel buildings

Modular steel buildings (MSBs), which comprise prefabricated modular units, are a new type of assembled buildings. The inter-module connection of MSBs plays an important role in the connection between modular units and structural safety. At present, several types of inter-module connections are in use, such as welded, bolted, prestressed, or self-locking. However, they present problems such as poor welding quality, low construction efficiency and no operation space for the internal connection. To solve these problems, this study proposes an innovative tapered-head bolted inter-module connection. Cyclic tests were conducted considering three different parameters: the modular beam section form, axial compression ratio, and thickness of the modular floor beam. Seismic behavior indicators such as stiffness degradation and energy dissipation of the specimens were investigated. Subsequently, a refined finite element model (FEM) was established to verify the corresponding test results. Finally, based on test fitting and nonlinear regression analysis, a restoring force model of the tapered-head bolted connection was established. The results indicated that the calculated ratios of the restoring force model to test results were within 0.07 on the yield, maximum, and failure points and the coefficient of variation (COV) was 0.03, with high accuracy and application. This research provides a reference to some extent for designing MSBs.

STensile behaviour of T-stub to hollow section column using elliptical-head one-side bolts

The Elliptical-head one-side bolt (EOB) is a typical representative of the third generation for one-side bolts, relying on its elliptical head and bolt hole to achieve orthogonal anchorage, and the application scenario is mainly the bolted connection of closed-section members. Studies have been reported for the shear performance of EOBs bolted lap connections and the tensile behaviour of concrete-filled steel tubes, but there is still a lack of the tensile performance of EOBs connecting Hollow section columns (HSCs), which is necessary for the application of the component method for the beam-column joints design. Therefore, numerical simulation and theoretical analysis methods were employed in this paper to demonstrate the feasibility of adopting EOBs for this type of connection, including typical failure modes, novel yield line pattern in the HSC wall, comparison with the Conventional high-strength bolt (CHB) connections, analysis of the parameters related to the elliptical bolt head and hole, and the establishment and validation of the methodology for calculating the HSC bearing capacity. The results show that: The novel trapezoidal yield line pattern tended to show in the HSC wall with the smaller bolt pitch distance and larger gauge distance; The yield strength of the EOBs bolted T-stub to HSC connections was reduced by about 15% compared to the CHBs bolted ones; Vertical layout of bolt holes, accuracy of rough assembly, rotation deviation of bolt shank within 20° and avoidance of bolt offsets in bolt hole were recommended for EOB connections; The novel yield line pattern established in this paper predicted the yield strength of the connections, and the accuracy and stability were verified by comparing with finite element modelling (FEM) results.

Calculation Method of Flange Bolt Preload Based on Finite Element

Flange bolt connection is one of the most important connection modes in bolt connection at present. In this paper, the finite element model of the bolt between the shell and the head flange is established to analyze the influence of different initial preload on the bolt stress state under external load. The results show that according to the bolt stress state, the range of initial preload is divided into the influence area of the external load, the influence area of the resultant force and the influence area of the initial preload. In the influence area of external load, the bending moment exerted on the bolt dominates the stress state of the bolt, and the stress state of the bolt is poor, which is not the safe value area of the initial preload；in the influence area of the initial preload, initial preloads dominates the stress state of the bolt, the average stress of the bolt section is larger, and the bolt safety is smaller, which is not the safe value area of initial preloads; in the influence area of the resultant force, the bolt has better stress state and higher safety coefficient, which is the safety value area of initial preload. The initial preload corresponding to the boundary point between the influence area of the resultant force and the influence area of the external load and the influence area of the external load is the limit of the safe value range of the bolt preload.

Research on the Influence of Disc–Drum Connection Bolt Preloading Rotor Assembly Modal Characteristics and Diagnosis Technology

The drum rotor of an aero-engine is connected by one or multiple mounting edges through bolts, and their dynamics are significantly influenced by the preload state of the bolts. Long working hours in challenging environments can result in the deterioration of bolt pre-tightening during assembly or service, which impacts the rotor’s dynamic stability and overall performance. Currently, there are no available methods for detecting the dynamic characteristics of the drum connection components. This paper analyzes the impact of the natural characteristics of the drum composite structure of a high-pressure aero-engine turbine based on the refined finite element method when the preloading state changes. Two conditions of deviation and uneven stiffness distribution were applied to the connected components of the drum. The analysis focused on the impact of the pre-tightening state on its natural frequency. After analyzing the feasibility of identifying the pre-tightening state, two methods are proposed. These methods focus on changes in natural frequency and mode shape, specifically the sensitive natural frequency change method and the mode step change method. The methods proposed in this paper can serve as a reference for evaluating the quality of assembling complex disc–drum structures with multiple bolt connections.

High-strength preload indicator inner washer forward design method

The preload indicator bolt assembly is a fastener that achieves the desired preload effect by simply tightening the preload nut within a specified range without additional measuring tools. The inner washer is a critical component in this assembly, with its outer diameter and height serving as crucial design parameters. In this paper, an equivalent mechanical model is established for the preload indicator bolt assembly. Utilizing this model, an iterative search process is developed to determine the optimal outer diameter and height of the inner washer. The analytical relationship between the bolt preload force and nut displacement is compared and validated against finite element analysis and experimental results, yielding favorable agreement. Notably, the nut tightening angle can vary within the range of 187°–242°, while the preload force exhibits a minimal variation of only ±2% for type 10-0A bolt connection (Bolt diameter and bolt pitch are φ16 mm and 1.41 mm, respectively. The material of bolt, inner ring, and flat ring are GH4169, 40CrNiMoA, and 30CrMo, respectively). This feature significantly simplifies the installation process of the preload indicator bolt assembly in real-world applications, offering great convenience. The increment in tension force on preloaded bolts under external loads exhibits an almost identical trend for both connection methods. Under the same preload force and the same eccentric working load conditions, the thickness of the connected components follows the same trend as their contact area.

Connection design method of honeycomb plate-rod composite structure: Experimental study and theoretical analysis

The connection design method of plate-rod composite structure is very important for the cooperative work of plate and rod. In this study, ten kinds of plate-rod composite structures of different connection methods, connection spacings, and plate thicknesses were designed to examine the connection performance of composite structure. The applicable finite element analysis methods of three connection methods were obtained by comparing the calculation results of finite element simplification models. The influence of connection spacing, connector diameter and plate thickness on the connection performance of three connection methods was studied by parametric analysis. The optimized shear bearing capacity formula of three connection methods were proposed based on the connection performance test and the design specifications at home and abroad. The bending bearing capacity formula of composite structure were proposed by theoretical derivation and finite element analysis, and the relevant parameters were fitted by the Backward Propagation (BP) algorithm in neural network. The results shown that the connection performance of Self-Piercing Riveting connection is obviously better than that of one-side bolt and core-pulling rivet connection, and the bearing capacity is increased by about 6 % and 10 %. The connector solid (So-1-1), solid simplified beam (So-3-1 and So-3-2), and shell simplified beam (Q-1) modeling method can better simulate the one-side bolt connection, and the error is within 3 %. The connector solid (So-1-2), solid beam (So-2-1), embedded (So-4-1), and shell simplified beam (Q-1) are suitable for core-pulling rivet connection, and the error is within 5 %. All the finite element analysis simplification methods can accurately simulate the Self-Piercing Riveting connection except for the Q-2, and the error is within 2 %. The bearing capacity of the composite structure increases with the increase of the connector diameter, the decrease of the connection spacing and the increase of the plate thickness. The optimized shear bearing capacity formula are more suitable for practical application, and the error of the bending bearing capacity formula of composite structure is within 5 %, which provides a certain reference for the design of honeycomb plate-rod composite structure and the revision of relevant specifications in the future.