Calculation Method Of Bearing Capacity Research Articles

Experimental analysis on the out-of-plane structural performance of single-face superposed shear walls with different horizontal connections

Single-face superposed (SFS) shear wall is a novel precast concrete sandwich panel (PCSP) wall that can be used as load-bearing walls in high-rise buildings and underground structures in seismic zones. This paper investigates the out-of-plane structural performance of SFS shear walls with different horizontal connections. Three SFS shear walls with different lap-spliced rebar connection configurations at the horizontal connections were designed and tested to compare their out-of-plane structural performance with that of a cast-in-place specimen, in terms of failure modes, cracking patterns, load-displacement curves, stiffness degradation curves, ductility, and force transfer mechanism of lap-spliced rebar connections. The test results showed that the SFS shear wall specimens exhibited and maintained a high level of composite action until failure, and the studied three different horizontal connections can allow effective force transfer between the upper shear walls and the lower. The stiffness, ductility, and ultimate bearing capacities of SFS shear walls under out-of-plane monotonic loading were significantly higher than those of cast-in-place shear walls. The bearing capacity was found to depend to a large extent on the location of additional vertical connecting rebar, the displacement mainly caused by rigid body rotation and related to crack width at joint. A calculation method of the ultimate bearing capacity of a SFS shear wall under out-of-plane horizontal loads was proposed. Finally, some suggestions on the setting of the vertical connecting bar are put forward.

Analysis of Shear Model for Steel-Fiber-Reinforced High-Strength Concrete Corbels with Welded-Anchorage Longitudinal Reinforcement.

According to the shear capacity test results of six steel-fiber-reinforced high-strength concrete (SFHSC) corbels with welded-anchorage longitudinal reinforcement under concentrated load, the effects of shear span ratio and steel fiber volume fraction on the failure mode, cracking load and ultimate load of corbel specimens were analyzed. On the basis of experimental research, the shear transfer mechanism of corbel structure was discussed. Then, a modified softened strut-and-tie model (MSSTM), composed of the diagonal and horizontal mechanisms, was proposed, for steel-fiber-reinforced high-strength concrete corbels. The contributions of concrete, steel fiber and horizontal stirrups to the shear bearing capacity of the corbels were clarified. A calculation method for the shear bearing capacity of steel-fiber-reinforced high-strength concrete corbels was established and was simplified on this basis. The calculation results of the model were compared with the test values and calculation results of the GB50010-2010 code, the ACI318-19 code, the EN 1992-1-1 code and the CSA A23.3-19 code. The results showed that the concrete corbel with small shear span ratio mainly has two typical failure modes: shear failure and diagonal compression failure. With the increase in shear span ratio, the shear capacity of corbels decreases. Steel fiber can improve the ductility of a reinforced concrete corbel, but has little effect on the failure mode of the diagonal section. The calculated values of the national codes were lower than the experimental values, and the results were conservative. The theoretical calculation values of the shear capacity calculation model of the corbels were close to the experimental results. In addition, the model has a clear mechanical concept considering the tensile properties of steel-fiber-reinforced high-strength concrete and the influence of horizontal stirrups, which can reasonably reflect the shear transfer mechanism of corbels.

Experimental study on the performance of shear connections between local UHPC slabs and GFRP girders

This paper proposes a novel fiber-reinforced polymer (FRP)-concrete hybrid system with local ultrahigh-performance concrete (UHPC) in key parts to accelerate construction and reduce the cost of UHPC. Fifteen push-out specimens were tested to investigate the shear behavior of the UHPC-FRP hybrid interface embedded with bolts in a local UHPC slab. The parameters varied were the local UHPC width, types of concrete slabs, bolt diameter, bolt number and bolt embedding length in concrete. Push-out test results showed that (1) the increase in bolt embedding length substantially reduced the bearing capacity, with a maximum reduction of 25.8%; (2) the interfacial bearing capacity and rigidity increased significantly with increasing bolt diameter, while the excessive diameter may cause the failure of GFRP flange shear-out; (3) the increase of the number of bolts improved the interface performance, but decreased the efficiency of a single bolt utilization; (4) the employment of local UHPC increased the slip stiffness by 16.9%, which had similar shear performance to that of the whole UHPC slab; (5) further changing the local UHPC width had little effect on the shear performance of the push-out specimens. Finally, the calculation method of the bolt shear bearing capacity considering the influence of the embedded length was proposed by modifying the existing formula.

Practical temperature calculation and fire-resistant design of special-shaped concrete-filled steel tubular columns

The fire performance of special-shaped concrete-filled steel tubular (SCFST) columns under axial load was investigated in this paper. The ABAQUS based finite element models were conducted for heat transfer and structural analysis. Twelve fire tests on SCFST columns under the ISO-834 standard fire curve by the authors' research were used to verify the model. In addition, heat transfer and fire-resistant mechanism of full-scale SCFST columns were studied; and extensive parametric studies were investigated to examine the influence of fire protection layer thickness, column limb thickness, slenderness ratio and other factors on temperature distribution and fire behavior of SCFST columns. Through the calculation and analysis of temperature field and fire resistance, a simplified temperature calculation method for steel tube, tension reinforcement, and inner steel plate are proposed along with the modularization temperature calculation method for special-shaped concrete sections. Moreover, the ultimate bearing capacity calculation method for SCFST columns under the standard temperature rise curve is proposed allowing for the influence of high temperatures on material properties, which can also be applied to determine fire resistance of SCFST column. Finally, the calculation method for the thickness of fire protection layer and the corresponding fire design is proposed based on the delaying temperature mechanism.

Static behavior of TOBs bolted endplate connection to strengthened HSST with fixed thread length

Five thread-anchored one-side bolts connected endplate connections to Hollow Square Steel Tube (TOBEC-HSSTs) with various strengthening measures were tested to investigate the structural performance under monotonic loads. The thread anchored length was 1.2 times the bolt diameter for all specimens. The connection behaviour were influenced by the endplate thicknesses and the strengthening measures (i.e. the internal polygonal tube, the internal polygonal tube with infilled concrete, and the cross-H section stiffener with infilled concrete). The failure patterns, moment-rotation curves, and strain response of joints were obtained through tests. It was found that (1) 1.2 times the bolt diameter was taken as the safe thread assembled length, which can avoid the premature failure of hole threads not before the fracture of other components under monotonic loads. (2) The presence of the infilled concrete can improve the rigidity and strength of the connection by 84% and 23%, respectively, compared to the reference joint without the infilled concrete, and the thickness of the column wall can be reduced when the concrete was infilled into hollow steel tube. (3) For the connections with thin endplates, the cross-H section stiffener exhibited 8.8% and 3.5% higher preliminary stiffness and yield bending moment than the inner polygonal tube, but the cross-H section stiffener had 14.3% lower rotation capacity. (4) Thickening endplates can change the failure modes of the connections to beam plastic hinge formation, enhance the preliminary stiffness and yield bending moment of joints by 2.4% ∼11%, but decrease the rotation capacity of joints by 54% compared to thin endplates. Based on experimental results, the calculation methods of the bending moment bearing capacity for TOBEC-HSSTs considering the strengthening effect of internal stiffeners and infilled concrete under different failure patterns were proposed with errors no greater than 15%.

Experimental study on seismic behavior of steel angle truss reinforced concrete columns under compression-bending-shear-torsion combined action

This study discusses the seismic behavior of steel angle truss reinforced concrete (SARC) columns under compression-bending-shear-torsion combined action. Ten SARC columns were designed and tested to investigate the influence of the axial compression ratio, torsion-bending ratio, shear span ratio, volume ratio of steel plates, and cover thickness. The failure modes and hysteretic curves of specimens were obtained in the test. The important performance parameters of the specimens were compared to evaluate the seismic performance of the specimens, including bearing capacity, stiffness degradation, ductility, and energy dissipation. The results show that the failure modes of SARC columns could be classified as bending failure, bending-torsion failure, shear-torsion failure, and torsional failure depending on the torsion-bending ratio and shear span ratio. An obvious “pinch” effect can be observed in the middle of the T-θ hysteresis curves of specimens, but the P-Δ hysteresis curves are full. The torsional capacity of SARC columns can be improved by adding the axial compression ratio, torsion-bending ratio, and volume ratio of steel plates, but the effect is adverse when increasing cover thickness and shear span ratio. Moreover, a calculation method of torsional bearing capacity of SARC columns under compression-bending-shear-torsion combined action was proposed.

Local compression capacity of steel fiber reinforced ultra-high performance concrete containing coarse aggregate

Steel fiber reinforced ultra-high performance concrete containing coarse aggregate (CA-UHPFRC) can significantly reduce cost and shrinkage compared to conventional ultra-high performance concrete (UHPC). The application of CA-UHPFRC to prestressed concrete structures is a novel exploration. However, the existing prediction models are generally suitable for ordinary-strength concrete, which may generate a large error when applied to UHPC because of the insufficient consideration of the effects on concrete strength and ducts. To explore the anchorage zone mechanism and fill the blank of local bearing capacity calculation method in prestressed CA-UHPFRC structures, 22 specimens were tested. The failure characteristics, crack patterns and the relationships between load versus deformation were discussed. The results indicated that CA-UHPFRC exhibited ductile failure modes under local pressure, where the ratios of cracking load to ultimate load ranged from 57.2 % to 84.1 %. The wedge cleaving theory was still followed by CA-UHPFRC, and the integrity and fine post-peak performance can be maintained. Besides, the effects of concrete strength, local area aspect ratio and duct diameter were fully discussed. Finally, prediction equations were developed and experimentally verified, which comprehensively considered the multiple factors. This research provided a novel insight into the accurate bearing capacity calculation methods for CA-UHPFRC in anchorage zones.

Calculation Method of Stable Bearing Capacity of Fastener-Type Steel Pipe Formwork Support Upright Rod

In this paper, the torsional moment of the right-angle fastener bolt is taken as the main research parameter, and the torsional stiffness performance of the right-angle fastener under different working conditions is studied experimentally. By establishing the moment–rotation relationship model of the node, the mechanical performance and rotation characteristics of the semirigid connection of the node are studied. According to the joint stiffness value determined by the experimental study and the theory of semirigid connection frame with lateral displacement, the calculation formulas of the stiffness correction coefficient αu of the transverse bar and the constraint coefficient K at the end of the vertical bar are derived, and the effective length coefficient μ of the vertical bar and the theoretical value of the stable bearing capacity of the vertical bar under different working conditions are given. Compared with the current standard values, it is found that the theoretical calculation results of the percentage increase of the stable bearing capacity of the vertical bar are 3 to 4 times larger than the standard calculation results when the step distance is reduced. The theoretical calculation method can better consider the semirigid characteristics of the joint and the influence of adjacent members on the stable bearing capacity of the vertical bar.

Experimental and Theoretical Studies on Hysteretic Behavior of Friction Energy Dissipation Composite Chord under Quasi-Static Tests

To improve the seismic performance of a staggered truss steel framing system, the basic force unit in the truss system is replaced by a friction energy dissipation truss. The difference between a friction energy dissipation truss and an ordinary truss is that the upper chord is a friction energy dissipation composite chord. In this paper, we investigate the effects of the number of bolts and the friction surface on the energy dissipation capacity of the chord by a quasi-static test on six composite chord specimens at a scale of 1:2. The results show that the hysteresis curves of friction energy dissipation composite chords are ideal rectangles, and the energy dissipation capacity is excellent. The more bolts there are in the specimen, the slower the energy dissipation capacity of the chord decreases. Among the different friction surface specimens, the energy dissipation capacity of the aluminum friction plate specimen decays the fastest, while the energy dissipation capacity of the shot-blasted treated specimen decays substantially after the first cycle. Friction plates can improve the stability of the hysteresis properties. Based on the test results, this paper proposes a calculation method for the ultimate bearing capacity of the composite chord, which provides a basis for the design of a friction energy dissipation truss. In addition, we studied the effects of different bolt clamping forces and slotted bolt hole lengths on the energy dissipation capacity of composite chords by establishing a finite element analysis. It was shown that as the clamping force of the bolt increases, the energy dissipation capacity of the specimen becomes stronger but the stability decreases. The energy dissipation capacity of the chord is close to a linear relationship with the slotted bolt hole lengths; thus, increasing the slotted bolt hole lengths within the allowable range of inter-story drifts can enhance the energy dissipation capacity of the chord. Finally, we propose the design method of the angle steel by analyzing the force of the chord.

Seismic performance of circular concrete-filled steel tube columns reinforced with inner latticed steel angles

The seismic behavior of circular concrete-filled steel tube (CFST) columns with inner latticed steel angles under combined axial load and reversed cyclic horizontal load was studied in this paper. A total of 8 specimens was tested, including two CFST specimens and six latticed steel angles reinforced CFST specimens. The main parameters studied were the diameter-to-thickness ratio of steel tube, the cross-sectional area of inner latticed steel angles and the axial compression ratio. Firstly, the load-displacement curves and load-strain curves were obtained experimentally; secondly, the failure modes, hysteretic behavior, skeleton curves, stiffness degradation, ductility index, hysteretic energy dissipation capacity were analyzed; thirdly, the seismic performance of the tested specimens were simulated by the established finite element (FE) models, and parametric studies were subsequently performed; finally, the modified calculation method for the horizontal bearing capacity was proposed. The research results showed that the failure of the composite columns was caused by the local buckling of the latticed steel angles and steel tube, and the latticed steel angles could effectively participate in the overall loading process. It was also found that latticed steel angles are able to improve the energy dissipation capacity.

Study on axial compression performance of original bamboo-fiber reinforced phosphogypsum composite walls

In this article, a kind of original bamboo-fiber reinforced phosphogypsum composite wall was proposed. The axial compression tests of eight walls and finite element analysis were carried out. The failure modes and mechanical properties of the walls were explored, the influence of parameters on the axial compression performance of the walls was studied, and the calculation methods of the axial compression capacity and stiffness of the composite walls were proposed. The results show that the phosphogypsum cracked first in the composite walls during the loading process, the cracks gradually spreaded through and widened, and the bamboo tubes inside the composite walls were crushed. The buckling failure occurred in the pure original bamboo wall. The bearing capacity of the composite wall control specimen is 140% and 38.46% higher than that of the pure phosphogypsum wall and the pure original bamboo wall, respectively. The number of dovetail nails has no significant effect on the axial compression performance of the composite wall. The bearing capacity and stiffness of composite wall increase with the increase of bamboo number, wall thickness, bamboo wall thickness and phosphogypsum strength. The calculation method of axial bearing capacity and stiffness of composite wall based on bamboo content is proposed. The finite element simulation results are in good agreement with the experimental and theoretical calculation results. The theoretical calculation method has high accuracy. The composite wall realizes the complementary advantages of original bamboo and phosphogypsum, which provides reference for the development and application of green buildings.

Seismic behavior of novel modular structural joint with grouted channel connection

This study proposes an innovative joint with grouted channel steel connection that can satisfy the complete decoration requirements of modular steel buildings (MSB) and adequate allowable installation tolerances to accommodate imperfections. Quasi-static testing of four full-size T-shaped joints was carried out, and the seismic properties of the grouted joints were evaluated in detail through initial stiffness, bearing capacity, ductility and energy dissipation capacity. The results show that the axial force ratio has little effect on the seismic properties of the joints; the bearing capacity of the joints with stiffener is increased by 12.6%. The stiffness and bearing capacity of the joints are analyzed. Both beams can achieve full-section yielding, and the joint can meet the requirements of full-strength joints. Finally, through theoretical analysis and numerical simulation, the bearing capacity calculation method of grouted connection is obtained, and the corresponding design methods and suggestions are given, which provide the basis for the use of grouted connections in MSB.

Numerical investigation and design of suction caisson for on-bottom pipelines under combined V-H-M-T loading in normal consolidated clay

The length-to-diameter ratio of suction caisson used as the foundation of the pipeline system in deep-water oilfields in the South China Sea is usually between 1 and 2. Suction caisson will bear combined V-H-M-T loading, including vertical force, horizontal force, moment and torsion from the upper manifold structure during pipeline installation and operation. The failure envelopes equation is generally used for caisson design, but existing equations are mainly suitable for suction caissons under combined V-H-M loading. This study uses a finite element numerical investigation to study the combined V-H-M-T bearing capacity calculation method. The torsion influences on vertical force, horizontal force, moment bearing capacity and combined VHM bearing capacity are discussed. The results showed that the primary function of torsion is to share the tangential force around the cylinder wall, which causes the VHM composite envelope surface of the suction caisson to decrease. This impact is quantified through regression analysis of the calculation results. The design method of suction caisson for on-bottom pipelines under combined V-H-M-T loading in normal consolidated clay is summarized.

Calculating the ultimate strength of a tube–gusset KT joint with 1/4 ring stiffener plates

In this study, experiments, numerical simulations, and theoretical analyses were performed on tube–gusset KT joints with 1/4 ring stiffener plates, which are frequently used in electrical transmission line towers. The failure modes and mechanisms of the joint were determined to comprise either ‘chord failure’, in which the chord exhibits obvious deformation while the stiffener plate exhibits little deformation, or ‘stiffener plate failure’, in which the chord exhibits obvious concave deformation and the stiffener plate exhibits obvious warping deformation. An increase in chord axial compression caused the ultimate bearing capacity of the joint to decrease, though when the ratio of axial chord force to plastic limit was less than 0.2, this effect of was not obvious. Furthermore, an equation for the ultimate strength of a joint was proposed based on the conservation of energy, which was subsequently verified against test and finite element model results. In this equation, the influence of the chord axial compression on the bearing capacity of the joint is considered using the coefficient β, which is dependent on the ratio of the chord diameter to the chord thickness. Finally, the proposed bearing capacity calculation method was shown to reproduce the numerical analysis results more accurately than the Japanese code or CIDECT code. Thus, the proposed calculation method can be confidently used to guide joint design in electrical transmission line tower projects.

Mechanical properties and automatic design method for rural residences with hinged frames and cold-formed thin-walled stiffened walls

At present, the overall construction quality of rural residences is still relatively poor, and the seismic performance of their structural systems is insufficient. In this study, quasi-static tests were carried out on three cold-formed thin-walled stiffened steel plate wall (CFSW) specimens infilled in a single-span two-story 1/2 scale hinged special-shaped column frame. The seismic performance of each specimen was evaluated by comparing the bearing capacity, ductility, stiffness degradation, energy dissipation capacity, and strain. The results show that the filling of concrete and gypsum in the column helps improve the bearing capacity of the structure but has no notable effect on the stiffness. The brittle failure phenomenon in the filled concrete specimens is obvious, and those specimens either without filler or whose columns are filled with gypsum show better ductility and energy dissipation capacities. A finite element (FE) model was established and validated, and the influence of parameters such as the connection method between the wall and frame, the shear-span ratio of the wall, the thickness of the stiffened wall, and the number of hat-section cold-formed steel (HCFS) stiffeners upon the structural system was analyzed. In combination with the test and the FE analysis results, the calculation method for horizontal bearing capacity of CFSW restrained by HCFS stiffeners and engineering design suggestions were put forward. In addition, an automatic program for the forward generation of the CFSW was designed, and the application of the system in practical engineering was verified using Midas software.

Theoretical study of earthquake resilient beam-column joint in high-strength steel

This paper proposes the web angle connection joint and carries out the relevant theoretical derivation, finds out the design method and the bearing capacity calculation method. The calculation results are verified by simulation results. Finally, the advantages of the web angle connection joint are verified by comparing with the common joint. The results show that the thickness of damage element should not exceed 1.3 tflang in the joint design; Through the analysis of the bearing capacity and energy consumption, it is found that the error between the calculated and simulation results about bearing capacity is within 5%; The development law of the energy consumption of each part is consistent with the theoretical calculation, which reveals the validity of the joint design theory; Through parameter analysis, it is found that under the premise of considering steel damage, the spacing of intermediate bolts will significantly affect the cyclic loading times of joints. In consideration of recoverability, bearing and energy dissipation performance and steel damage, it is recommended that the thickness of flange connecting plate is 1.2tflange, and the spacing between intermediate bolts is 21.5tcov, f. Compared with ordinary earthquake-resilient joints, it is found that the bearing capacity of web angle connection joints can be increased by 50.3%, the energy dissipation capacity can be increased by 35.8%, and it's plastic development of damage elements is more uniform, which is conducive to the replacement after earthquake. The proposed joint in this paper can provide reference for the development of earthquake resilient structures.

Mechanical behavior of semi‐grouting sleeve and steel bar connection

AbstractA series of pull‐out tests were conducted on semi‐grouting sleeve and steel bar connections to investigate the mechanical behavior of the connectors. Taking the steel bar diameter, anchorage length, and grouting material strength as the parameters. The test results showed that when the anchorage length was small and the grouting material strength was low, sufficient anchorage strength cannot be provided, specimens were subjected to bond slip failure, which belongs to the brittle failure. When the anchorage strength between the steel bar and the grouting material was sufficient, the steel bar breaking occurred on the specimens, which belongs to the ductile failure. Then, the semi‐grouting sleeve and steel bar connection was modeled by finite element software, and the bond slip between the steel bar and grouting material was simulated by COMBIN39 element. The results indicated that the failure mode of the specimen obtained by finite element simulation was the same as the test result. The ultimate bearing capacity of the specimen was highly similar to the test result, which verified the feasibility of the modeling method in this paper. Next, the number of specimens and parameter levels were increased through finite element modeling, and the influences of steel bar diameter, anchorage strength, and grouting material strength on the ultimate bearing capacity of semi‐grouting sleeve and steel bar connections were analyzed. The results testified that the ultimate bearing capacity of the specimen increased with the increase of steel bar diameter. In a certain range, the ultimate bearing capacity of the specimen increased with the raising of anchorage length and grouting material strength. While the anchorage length increased, the ultimate bearing capacity of the specimen did not necessarily increase because of the uneven distribution of stress. The steel bar diameter had the most significant influence on the ultimate bearing capacity of the specimen, while the grouting material strength had the most negligible impact, that was, increasing the steel bar diameter is the most effective method to improve the ultimate bearing capacity of the specimen. Finally, according to the results of finite element analysis, the calculation method of ultimate bearing capacity with different failure modes was obtained, and it has been proved to be effective and accurate by the comparison of calculated results and test results. The results of this paper have great significance for improving the calculation theory and design method of relevant engineering.

Mechanical properties of steel reinforced reactive powder concrete columns under axial compression

With the continuous development of building structures and the increasing demand for use, the composite structure of steel reinforced reactive powder concrete (SRRPC) with excellent bearing capacity, stiffness, ductility, fire resistance and seismic performance was proposed. In this paper, the SRRPC column model was established by finite element software ABAQUS to investigate mechanical characteristics, and consistency within the model and the test results were verified from the aspects of failure phenomenon, load-displacement curve and bearing capacity. On this basis, the influence of calculated length, section steel strength, reinforcing bar strength, stirrup ratio and concrete strength on the mechanical characteristics of SRRPC columns was investigated. The consequences show that: (1) The bearing capacity rose with the rise of concrete strength, section steel strength, reinforcing bar strength and stirrup ratio, and decreased with the rise of calculated length. (2) On the basis of sensitivity analysis of parameters, bearing capacity is highly sensitive to concrete strength and section steel strength, generally to stirrup ratio and calculated length, and minimally to reinforcing bar strength. (3) The load entering the elastic-plastic stage increased with the rise of concrete strength, section steel strength and stirrup ratio, and decreased with the increase of calculated length. (4) The stiffness increased in each phase with the rise of concrete strength, section steel strength, reinforcing bar strength and stirrup ratio, and changed the most in phase C (0.5–0.75 Pu). The stiffness in each phase decreased with the increase of the calculated length, and changed the most in phase B (0.25∼0.5 Pu). Finally, the calculation method of bearing capacity was proposed.

Deflection calculation method for UHPC composite beams considering interface slip and shear deformation

The mid-span deflection is an essential index for evaluating the safety of bridge safety and service life. In contrast, the existing deflection calculation methods cannot accurately predict the deflection of ultra-high performance concrete (UHPC) composite beams. The flexural behavior of steel-glass fiber reinforced polymer (GFRP) strips-UHPC composite beam under a positive bending moment was investigated and compared with that of the steel-UHPC composite beam. The flexural behavior of UHPC composite beam was analyzed and discussed in terms of failure mode and mechanism, mid-span load-deflection response, changing laws of cross-section strain and interface slip. The deflection calculation method for the UHPC composite beams considering interface slip and shear deformation was derived. Moreover, a calculation method of ultimate bearing capacity for the UHPC composite beams is developed. The results showed that all the UHPC composite beams failed because of yielding of steel beam, and the influence of GFRP strips on the flexural behavior of steel-UHPC composite beam was very small. The theoretically calculated results of the mid-span deflection and ultimate bearing capacity for the UHPC composite beams were in good agreement with the experimental results and have higher accuracy.

Ultimate strength of multiplanar KT-type tube–gusset plate joint with half-ring stiffener plates

In this study, full-scale tests, numerical simulations, and theoretical analyses on double KT (DKT)-type tube–gusset plate joints (TGPJs) stiffened with half-ring stiffener plates were performed. The failure modes and mechanisms of DKT-TGPJ under the opposing action of multiplanar loading (e.g., compression vs. tension) were determined to comprise ‘chord failure’, ‘stiffener plate failure’, and ‘combined failure’. The incidence of each failure mode was clearly related to the stiffness of the stiffener plate. When the stiffener plate had low stiffness, the TGPJ exhibited ‘stiffener plate failure’; when the stiffener plate had high stiffness, the TGPJ exhibited ‘chord failure’; and lastly, when the stiffness of stiffener plate is moderate, the TGPJ exhibited ‘combined failure’. A method for calculating the ultimate bearing capacity in the case of stiffener plate failure was proposed based on the yield-line theory. According to the deformation mode of TGPJ in the case of chord failure, a leverage model was established, and a method for calculating the ultimate bearing capacity was obtained. The minimum value obtained from the above two methods was taken as the ultimate load bearing capacity of DKT-TGPJ, which was subsequently verified against the test and finite element model results. The proposed bearing capacity calculation method was shown to reproduce the test and numerical analysis results more accurately than the Japanese and Committee for International Development and Education on Construction of Tubular Structures (CIDECT) codes.