Research on Stress Performance of Universally Wrapped Assembled Joints of  Lattice Wind Power Tower with Concrete-filled Steel Tube

doi:10.21203/rs.3.rs-1944451/v1

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Research on Stress Performance of Universally Wrapped Assembled Joints of Lattice Wind Power Tower with Concrete-filled Steel Tube

https://doi.org/10.21203/rs.3.rs-1944451/v1

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published 30 Jan, 2023

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With the control parameters of the wall thickness of the ball table and the thickness of the pressure plate of the ball table, four universal wrapped assembled joint models were designed for the research of stress performance via static loading test. The failure mode of the joint, the axial force-displacement curve of the web member, the equivalent stress distribution of the ball table and the pressure plate of the ball table were analyzed, and the ABQAUS finite element software was used for the analysis of parameter expansion of the specimen. The research results show that the failure modes of universally wrapped assembled joints can be divided into the buckling failure of the ball table and the strength failure of the material. The wall thickness of the ball table is the key parameter affecting the failure mode of the joints, and the thickness of the pressure plate of the ball table is the crucial parameter influencing the ultimate bearing capacity of the joints. The maximum equivalent stress of the pressure plate and the ball table at compression zone for all the joints is occurred at the side squeezed by the bolt ball, and the growth rate of the equivalent stress for the ball table at compression zone is more uniform than that at tension zone. According to the finite element analysis results, when the wall thickness of the ball table is greater than 7mm, the thickness of the pressure plate of the ball table is greater than 16mm, the growth rate of the ultimate bearing capacity of the joint is significantly decreased, therefore, it is recommended to use the wall thickness of 7mm and the pressure plate thickness of 16mm in the actual design of the project.

In recent years, China's wind power industry has entered into the stage of high-speed development, which has become an extremely dynamic part of the global renewable energy construction. The installation scale of wind power in China has been leading in the world for many consecutive years^1-2. Cone wind power tower and lattice wind power tower are the two most commonly used tower structures. Compared with the traditional cone wind power tower, the new lattice wind power tower is advantageous at high material utilization, high bearing capacity, good reliability, low cost and so on^3-7. Being the connection part between the web member and the tower column of the lattice wind power tower, as well as the most critical part of the whole structural system, the joint is featured with the complex spatial coupling effect and stress condition^8-11. Nowadays, the intersecting joints and tubesheet joints are mainly researched. However, they are disadvantageous at the site high-altitude welding, lower installation accuracy and greater construction difficulty, which limits the promotion and application of wind power generation. Therefore, the exploratory research on the new joint is of great significance^12-19.

On the basis, a new type of universal wrapped assembled joint featured with no-welding on site, adjustable installation angle, convenient joint transportation, less damage of tower column and suitable for mass production is designed and researched in the paper combined with complex stress of the joint, the feasibility of site construction and the working requirement of the joint. With two control parameters of the thickness of pressure plate and the wall thickness of the ball table, the experimental study and finite element analysis of stress performance are carried out for four specimen models to obtain the influence law, joint stress distribution and failure mode of each factor.

Specimen Design

The four-limb-column lattice wind power tower of concrete-filled steel tube with the prototype of certain 1.5MW wind power tower from Baiyunebo Mining Area is designed by SAP2000 software. Considering the tower internal force analysis, test site, test equipment capacity and others comprehensively, four scale-down joint models with the ratio of 1:1.6 are designed and produced, structure of the specimen can be seen in Figure 1. The wall thickness and pressure plate thickness of the ball table for JD-1~JD-3 are different, and JD-4 is the control test of JD-3. Each part of the specimen is prefabricated by the processing plant with consistent processing technology, and conveyed to the laboratory finally for the on-site assembly.

The tower column is made of 20# seamless steel tube, and the internal is poured with the concrete at the strength grade of C40; the loading plate, web member, cone head, bolt ball, pressure plate of the ball table, ball table, wrapped object and steel tube of tower column are all made of Q235 steel; the bolts of two wrapped objects, and between the plate of ball table and pressure plate are made of M20, and the bolts between the bolt ball and the web member are made of Grade-10.9 M30 high-strength bolts. When processing the material, the welds of loading plate, web member, cone head, ball table and wrapped object are groove welded according to the Steel Structure Design Standard²⁰. The geometric parameters of the components are shown in Table 1, and the mechanical property indexes of steel are shown in Table 2.

Table 1 Geometric Parameters of Components(/mm)

Joint Number	Length of Tower Column	Cross Section of Wrapped Object	Cross Section of Web Member	Length of Web Member	Wall Thickness of Ball Table	Thickness of Pressure Plate
JD-1	1800	φ235×8	φ89×5	700	8	10
JD-2	1800	φ235×8	φ89×5	700	8	16
JD-3	1800	φ235×8	φ89×5	700	4	16
JD-4	1800	φ235×8	φ89×5	700	4	16

Table 2 Mechanical Property Indexes of Steel

Parts	Thickness/mm	f_y /MPa	f_u /MPa	E_s/MPa
Web Member	5	348	482	2.02×10⁵
Pressure Plate of Ball Table	10	332	485	2.05×10⁵
Pressure Plate of Ball Table	16	336	473	2.04×10⁵
Ball Table	4	342	462	1.98×10⁵
Ball Table	8	347	466	2.01×10⁵
Wrapped Object	8	318	466	1.99×10⁵

Test Device and Loading System

Considering the particularity of the joint model structure, the horizontal loading is adopted. One end of the tower column is fixed by the pedestal body, and the other is fixed by the support frame. The web member is connected with the hydraulic servo actuator through the loading plate. Two L-shaped steel plates are used on both sides of the compressive web member to provide lateral support. The steel plate is connected with the steel beam by bolts, the steel beam and the ground groove are fixed by anchor bolts to ensure that the load and the compression rod are always in a straight line and the eccentricity can be avoided. The loading device is shown in Figure 2.

The ultimate bearing capacity of the specimen, the respective compression and tension borne by two web members can be obtained based on the results of SAP2000 internal force analysis. The compression and tension of two web members are loaded at the ratio of 1.2:1. The step-by-step loading is taken for the loading system. The pre-loading stage is conducted initially, which can be divided into three levels. 10% of the predicted ultimate bearing capacity is loaded at each level for 10 min, and it is unloaded at three levels after three-level loading is completed; In the standard loading stage, the load of each level is also 10% of the predicted ultimate bearing capacity step by step. When 75% of the predicted ultimate bearing capacity is reached or there is obvious plastic deformation at the joint, 5% of the predicted ultimate bearing capacity is taken for the loading at each level in order to get the more accurate results until the specimen is loaded to the failure.

1.3 Measuring Content and Measuring Point Arrangement

No.1-4 displacement gauges are set at the end to pull and press the web member in order to obtain the axial force-displacement curve of the web member. A set of rosette gauges are arranged at the pressure plate and the area of the ball table at every 90° to count the strain distribution and growth of the pressure plate and ball table; The layout of displacement gauge and strain gauge is shown in Figure 3 and Figure 4.

Test Phenomenon

There is no obvious test phenomenon at the beginning of loading for JD-1~JD-4. When the tension for specimen JD-1 is added to 154 kN, the out-of-plane deformation of the pressure plate at tension zone increases gradually, and the bolt tends to be pulled out. When the final tension is added to 180 kN, the pressure plate of the ball table at tension zone is pulled into an ellipse, and the bolt ball at tension zone is pulled out, and the test is ended. The case for specimen JD-2 is similar to that of specimen JD-1. When the final tension is increased to 319 kN, the pressure plate mouth of the ball table at tension zone is pulled into an obvious ellipse, and the bolt ball at tension zone is pulled out, and the test is ended. When the tension for specimen JD-3 is increased to 214 kN, there is a clear gap between the table plate and the pressure plate of the ball table at tension zone, and the small deformation is occurred at the axial direction of the tower column at the ball table at compression zone; When the tension is increased to 242kN finally, it is broken suddenly at the crown point of the ball table at tension zone, and the test is ended. The case for specimen JD-4 is similar to that of specimen JD-3. When the tension is increased to 229kN finally, it is broken suddenly at the crown point of the ball table at tension zone, and the test is ended.

Failure Mode

There are two failure modes for the above four joints (Figure 5). Specimen JD-1 and JD-2 are the buckling failure mode of the pressure plate of the ball table, specimen JD-3 and JD-4 are the strength failure mode of the ball table material.

When the wall thickness of the ball table for specimen JD-1 and JD-2 is 8 mm, the damage and large deformation do not occur in the ball table, and the ultimate bearing capacity of the specimen depends on the binding force of the pressure plate of the ball table on the bolt ball at tension zone. Along with the increase of loading, the pressure plate of the ball table at tension zone gradually buckles along the axial direction of the ball table. The pressure plate mouth of the ball table at tension zone is gradually pulled into an ellipse, thus reducing the binding force of the pressure plate of the ball table at tension zone on the bolt ball and finally pulling out the bolt ball. In this process, the deformation of the pressure plate of the ball table develops slowly, therefore, the buckling failure mode of the ball table is a kind of plastic failure. For specimen JD-3 and JD-4, the wall thickness of the ball table is 4 mm and the pressure plate of the ball table is 16 mm. Compared with the thinner wall thickness of the ball table, the thickness of the pressure plate of the ball table is enough to restrict the bolt ball to be pulled out. With the gradual increase of loading, there is no obvious deformation trend for the pressure plate of the ball table. Finally, when the ultimate strength is reached in the ball table, the ball table is pulled off, and the test is ended. It is 35° between the stress direction of the ball table and the axial direction of the ball table, where the ball table is broken quickly with a flat fracture by the greater shearing stress. The failure phenomenon is extremely sudden without obvious failure precursor, therefore, it is a kind of brittle failure for the strength failure mode of the ball table material.

Test Results and Analysis

Axial Force-Displacement Curve of Assembled Joint Web Member

Seen from Figure 6, we can know that it lies in the linear elastic stage for the axial force-displacement curve of the web member at compression zone and tension zone of the specimen at the initial loading stage of JD-1~JD-4, the curve of web member is a straight line, and the slope for the curve of web member at compression zone and tension zone of the joint is similar. With the increase of loading, the curve of web member at compression zone is still a straight line, and the slopes of different curves are still similar; while the curve of the web member at tension zone appears inflection point in succession, and the slope is different at various degrees. There are inflection points in the curve of JD-1 and JD-2 when the tension is increased to 105kN and 126kN respectively; the slope of the curve decreases significantly when the tension reaches 134kN and 254kN respectively; Finally, the slope of the curve approaches zero when the tension reaches 180kN and 319kN respectively, and the test is ended. The slope of JD-3 decreases gradually along with the increase of the tension, and the test is ended until the tension is increased to 242kN. The case of JD-4 is similar to that of JD-3, and the test is ended when the load is increased to 229kN.

Via the comparison among JD-1~JD-4, the wall thickness of the ball table is 8mm, the slope of axial force-displacement curve for the web member at tension zone increases when the thickness of the pressure plate of the ball table is increased from 10mm to 16mm, thus indicating that the increase of the pressure plate of the ball table can improve the ultimate bearing capacity of the specimen greatly, while the deformation capacity of the joint can not be enhanced; When the thickness of pressure plate of the ball table is 16mm, and the wall thickness of the ball table is increased from 4mm to 8mm, the elastic-plastic stage of the curve increases. The increase of the wall thickness of the ball table can effectively improve the overall deformation capacity of the specimen structure.

Equivalent Stress Curve of Ball Table

The ball table plays a vital role for the joint to fix the bolt ball. The ball tables at compression zone and tension zone are severely squeezed by the bolt ball with extremely complex stress mode. The equivalent stress curve of the ball table zone (see Figure 4a for strain measuring points) is shown in Figure 7.

As shown in Figure 7, the maximum equivalent stress of the ball table at compression zone is occurred at No.2 measuring point for JD-1~JD-4, and the values are 139MPa, 154MPa, 259MPa and 243MPa respectively; the maximum equivalent stress of the ball table at tension zone is occurred at No.8 measuring point for JD-1 and JD-2 with the value of 201MPa and 252MPa respectively, which is at No.7 and No.6 measuring points for JD-3 and JD-4 respectively with the value of 311MPa and 313MPa respectively. The minimum equivalent stress of the ball table at compression zone is occurred at No.1 measuring point for JD-1, JD-3 and JD-4 with the value of 17MPa, 81MPa and 73MPa respectively, and that for JD-2 is occurred at No.3 measuring point with the value of 17MPa; the minimum equivalent stress of the ball table at tension zone is occurred at No.5 measuring point for JD-1 and JD-4 with the value of 56MPa and 99MPa respectively, that for JD-2 and JD-3 is occurred at No.6 measuring point with the value of 85MPa and 168MPa respectively. The range (the difference between the absolute value of the maximum and minimum equivalent stress) of equivalent stress for JD-1~JD-4 is 122MPa, 145MPa, 137MPa,167MPa,78MPa,143MPa,170MPa and 214MPa respectively. At the beginning of loading, the equivalent stress distribution and stress growth range of JD-1~JD-4 at compression zone and tension zone of the ball table are relatively uniform. The growth of equivalent stress at No.2 and No.8 measuring points is rapid along with the gradual increase of the compression and tension for JD-1, which is caused by the occurred stress concentration phenomenon when the loading is increased; A slight leap of stress is occurred at No.2 measuring point when the stress is increased to 100kN; With the continuous increase of loading, the equivalent stress increases uniformly until the end of specimen loading; the equivalent stress distribution and stress growth range of the ball table at compression zone and tension zone for JD-2 in the whole loading process are relatively uniform; the growth range of the equivalent stress at No.2 and No.3 measuring points on the ball table at compression zone for JD-3 and JD-4 is greater along with the increase of loading. The leap phenomenon of stress is occurred at the corresponding No.6 and No.7 measuring points when the tension is increased to 150kN and 100kN respectively, for the stress of the ball table at tension zone is rearranged caused by the deformation of the table plate at tension zone. The equivalent stress continues to increase along with the loading increase until the yield strength is reached in the ball table.

Via the comparison among JD-1~JD-4, the maximum equivalent stress of the ball table at compression zone is occurred at No.2 measuring point where the side is squeezed by the bolt ball, the maximum equivalent stress of the ball table at tension zone is occurred at No.8, No.8, No.7 and No.6 measuring point respectively. The growth range of the equivalent stress curve for the ball table at compression zone is more uniform than that at tension zone.

Equivalent Stress Curve of Pressure Plate of the Ball Table

There is less stress for the pressure plate in the ball table at compression zone, which mainly plays a structural role, therefore, the detailed comparison is not displayed in the paper. The equivalent stress curve of the pressure plate (see Figure 4b for strain measuring point) in the ball table at tension zone can be seen in Figure 8.

As shown in Figure 8, the equivalent stress at No.6 measuring point is the maximum of the pressure plate of the ball table at tension zone for JD-1~JD-4 with the value of 341MPa, 329MPa, 122MPa and 107MPa respectively. The minimum equivalent stress for JD-1, JD-3 and JD-4 is occurred at No.5 measuring point with the value of 71MPa, 79MPa and 62MPa respectively. The minimum equivalent stress for JD-2 is occurred at No.7 measuring point with its value of 117 MPa; the equivalent stress range for JD-1~JD-4 is 270 MPa, 212 MPa, 43MPa and 45MPa respectively. At the beginning of loading, the equivalent stress curve at tension zone grows more evenly. A slight leap of stress is occurred at No.6, No.7 and No.8 measuring points when the tension is increased to 70kN for JD-1. The deformation of the table plate and the growth range of the equivalent stress for the pressure plate for the ball table at tension zone are increased gradually along with the increase of loading until the pressure plate yields. The case for JD-2 is similar to that of JD-1. A great leap is occurred at No.5 and No.6 measuring points, a slight leap is occurred at No.7 and No.8 measuring points when the tension is increased to 224kN until the pressure plate yields. The equivalent stress curve for the pressure plate of the ball table at tension zone for JD-3 and JD-4 grows steadily without significant leap phenomenon in the loading process.

Via the comparison among JD-1~JD-4, the wall thickness of the ball table is 16mm, the maximum equivalent stress of the pressure plate of the ball table at tension zone is improved by 1.7 times and the equivalent stress range is increased by 3.9 times when the wall thickness of the ball table is added from 4mm to 8mm. When the wall thickness of the ball table is 8mm, the maximum equivalent stress of the pressure plate of the ball table at tension zone is decreased by 3.5% and the equivalent stress range is decreased by 21.5% when the thickness of the pressure plate of the ball table is added from 10mm to 16mm. The maximum equivalent stress for four joints is occurred at No.6 measuring point where the side of the pressure plate of the ball table at tension zone is squeezed by the bolt ball.

Modelling

Eight-node linear hexahedron element C3D8R is used for core concrete and conventional structural steel parts, and ten-node quadratic tetrahedron element C3D10 is selected for ball table, table plate and pressure plate of the ball table. Steel components such as tower column, wrapped object, ball table and pressure plate of the ball table are simulated by the secondary plastic flow model ²¹given by Han L.H., and the concrete stress-strain relationship model²¹ proposed by Han L.H. is taken for the core concrete in the tower column.

The joint tower column interacts with the core concrete in the form of "hard touching" and "penalty friction", and the friction coefficient is taken as 0.4. The bolt ball interacts with the ball table, pressure plate of the ball table, and the upper wrapped object in the form of "hard touching" and "penalty friction", and the friction coefficient is taken as 0.15. Other contacts are defined by Tie binding.

Seen from Table 3, we can know that the maximum error rate between the test value and the simulated value of the ultimate bearing capacity of the joint is about 10 %, thus indicating that the modelling, material property definition, analysis step establishment, interaction setting, load setting and mesh subdivision are reasonable, therefore, the parameter expansion analysis can be carried out.

Table 3 Comparison of ultimate bearing capacity

Specimen Number	N_ut/kN	N_uc/kN	e/%
JD1	180	183.4	1.8
JD2	318	351.4	10.5
JD3	242	252.5	4.3
JD4	229	252.5	10.2

Parameter Expansion Analysis

Due to the limited test conditions and specimen number, the expansion analysis of key parameter of the joint is conducted by ABAQUS, 40 finite element analysis models are set up to control the change of two parameters, and the other parameters remain unchanged. The results of parameter expansion analysis are shown in Table 4.

Table 4 Parameter Expansion

Thickness of Pressure Plate/mm	Wall Thickness of the Ball Table/mm	N_uc/kN	Model Number		Thickness of Pressure Plate/mm	Wall Thickness of the Ball Table/mm	N_uc/kN
10	4	170.1	1	21	14	8	307.1
10	5	173.4	2	22	14	9	309.7
10	6	176.6	3	23	14	10	314.1
10	7	183	4	24	14	11	319.9
10	8	183.4	5	25	16	4	252.5
10	9	185.4	6	26	16	5	274.7
10	10	186.9	7	27	16	6	313.2
10	11	187.9	8	28	16	7	352.3
12	4	173.9	9	29	16	8	351.4
12	5	192.6	10	30	16	9	365.1
12	6	215.1	11	31	16	10	368.2
12	7	232.4	12	32	16	11	372.3
12	8	240.5	13	33	18	4	255.5
12	9	244.2	14	34	18	5	289.8
12	10	248.9	15	35	18	6	334.1
12	11	252.6	16	36	18	7	368.3
14	4	209.6	17	37	18	8	375.2
14	5	234.4	18	38	18	9	381.1
14	6	264.6	19	39	18	10	385.3
14	7	295.5	20	40	18	11	387.1

Wall Thickness of the Ball Table

According to the relationship curve between the ultimate bearing capacity and the wall thickness of the ball table in Figure 9, we can know that when the thickness of the pressure plate of the ball table is 10mm, 12mm, 14mm, 16mm and 18mm respectively, and the wall thickness of the ball table is increased from 4mm to 7mm, the growth range of the ultimate bearing capacity of the joint is 7.6%, 36.6%, 41%, 39.5% and 44.1% respectively, and the ultimate bearing capacity of the joint is increased by 13.1kN, 39.8kN, 85.9kN, 99.8kN and 112.8kN respectively; When the wall thickness of the ball table is increased from 7mm to 10mm, the growth range of the ultimate bearing capacity of the joint is 2.1%, 7%, 6.2%, 4.5% and 4.6% respectively, and the ultimate bearing capacity of the joint is increased by 3.9kN, 16.5kN, 18.6kN, 15.9kN and 17kN respectively; When the wall thickness of the ball table is increased from 10mm to 11mm, the growth range of the ultimate bearing capacity of the joint is 0.5%, 1.4%, 1.8%, 1.1% and 0.5% respectively, and the ultimate bearing capacity of the joint is increased by 1kN, 3.7kN, 5.8kN, 4.1kN and 1.8kN respectively.

To sum up, when the thickness of the pressure plate of the ball table remains unchanged and the bearing capacity is met, and the wall thickness of the ball table is less than 7mm, the wall of the ball table is thinner, and the failure mode of the joint is the strength failure of the table material. The wall thickness of the ball table is the key parameter affecting the ultimate bearing capacity of the joint, therefore the increase of the wall thickness of the ball table can greatly improve the ultimate bearing capacity of the joint; When the wall thickness of the ball table is greater than 7, the table plate at tension zone is destroyed by the larger loading. At this time, the increase of the wall thickness of the ball table cannot improve the bearing capacity of the table plate at tension zone, and the change of the wall thickness of the ball table has little effect on the ultimate bearing capacity of the joint.

Thickness of Pressure Plate of the Ball Table

It can be seen from Figure 10 that when the wall thickness of the ball table is 4mm, 6mm, 8mm and 10mm respectively, and the thickness of the pressure plate of the ball table is increased from 10mm to 12mm, the growth range of the ultimate bearing capacity of the joint is 2.2%, 21.8%, 31.1%, 33.1% respectively, and the ultimate bearing capacity of the joint is increased by 3.8kN, 38.5kN, 57.1kN and 62kN respectively; When the thickness of the pressure plate of the ball table is increased from 12mm to 14mm, the growth range of the ultimate bearing capacity of the joint is 20.5%, 23%, 27.6%, 26.1% respectively, and the ultimate bearing capacity of the joint is increased by 35.7kN, 49.5kN, 66.6kN and 65.2kN respectively; When the thickness of the pressure plate of the ball table is increased from 14mm to 16mm, the growth range of the ultimate bearing capacity of the joint is 20.4%, 18.4%, 14.4%, 17.2% respectively, and the ultimate bearing capacity of the joint is increased by 42.9kN, 48.6kN, 44.3kN and 54.1kN respectively; When the thickness of the pressure plate of the ball table is increased from 16mm to 18mm, the growth range of the ultimate bearing capacity of the joint is 1.1%, 6.6%, 6.7%, 4.6% respectively, and the ultimate bearing capacity of the joint is increased by 3kN, 20.9kN, 23.8 kN and 17.1kN respectively.

Fig.10 Relationship between ultimate bearing capacity and thickness of pressure plate of the ball table

To sum up, when the wall thickness of the ball table remains unchanged and the table wall meets the bearing capacity, and the thickness of the pressure plate of the ball table is less than 16mm, the pressure plate of the ball table is thinner, and the failure mode of the joint is the buckling failure of the pressure plate of the ball table at tension zone. At this time, the thickness of the pressure plate of the ball table is the key parameter affecting the ultimate bearing capacity of the joint, therefore, the increase of the thickness of the pressure plate of the ball table can greatly improve the ultimate bearing capacity of the joint; When the thickness of the pressure plate of the ball table is greater than 16mm, the table plate at tension zone is destroyed by the greater loading. At this time, the increase of the thickness of the pressure plate of the ball table cannot improve the bearing capacity of table plate at tension zone, and the change of the thickness of pressure plate of the ball table has little effect on the ultimate bearing capacity of the joint.

The failure of the joints can be divided into two modes, namely, the buckling failure of the pressure plate and the strength failure of the table material. The buckling failure of the pressure plate is a kind of plastic failure, and the strength failure of the table material is a type of brittle failure.

The wall thickness of the ball table is the key parameter affecting the failure mode of the joint. When the thickness of the pressure plate of the ball table remains unchanged, increasing the wall thickness of the ball table is an effective way to improve the failure mode of the joint. The pressure plate of the ball table is a key parameter affecting the ultimate bearing capacity of joints. When the wall thickness of the ball table is 8mm and the thickness of the pressure plate of the ball table is increased from 10 mm to 16 mm, the ultimate bearing capacity of the specimen is increased by 77.2%.

The axial force-displacement curve is complete relatively for all specimens with obvious elastic stage and elastic-plastic stage. The increase of the wall thickness of the ball table can enhance the overall deformation capacity of the joint effectively.

The maximum equivalent stress of the pressure plate of the ball table for all joints and the ball table at compression zone is occurred at the side squeezed by the bolt ball. The growth rate of equivalent stress in the ball table at compression zone is more uniform than that at tension zone.

When the wall thickness of the ball table is greater than 7mm, the thickness of the pressure plate of the ball table is greater than 16mm, the growth rate of the ultimate bearing capacity of the joint is significantly decreased. In order to ensure the safety and economy of the joint, it is recommended to use the wall thickness of 7mm and the pressure plate thickness of 16mm in the actual design of the project.

Date availability

The datasets generated and/or analysed during the current study are not publicly available due fund confdentiality but are available from the corresponding author on reasonable request.

Acknowledgements

This work was supported mainly by the National Natural Science Foundation of China (51768056) and it was supported partly by Inner Mongolia Autonomous Region Youth Science and Technology Talents Support Program (NJYT22068). It was supported by Natural Science Foundation Project of Inner Mongolia Autonomous Region (2019MS05038).

Author contributions

Z.L.wrote the text of the main manuscript. Y.W. and W.X.prepared Figs.1,2,3,4and 5.All authors reviewed the manuscript.

Competing interests

The authors declare no competing interests.

Wang,C.L.,Wang,W.G.&Zhang,L.Y.The analysis of China wind power industry.J.Chongqing Univ.38(1) ,148-154(2015).
Shi,W.H.et al.Technology Trend and Development Suggestions for Wind Power Efficient Utilization in China.Str Study.CAE.20(3),51-57(2018).
Li,B.,Yang,X.Y.&Gao,C.Y.Experimental research and comparative analysis on seismic performance of wind turbine frustum tower drum and latticed tower.J.Build.Struct.34(S1),161-166(2013).
Zagubien,A.&Wolniewicz,K.The impact of supporting tower on wind turbine noise emission.Appl.Acoustics.155,260-270(2019).
Liu,X.F.&Yu,L.P.Minimum cost design of the concrete wind turbine tower.Acta Energiae Solaris Sinica.38(3),691-698(2017)．
Huang,X.G.,Li,B.K.,Zhou,X.H.,Wang,Y,H.&Zhu,R.H.Geometric optimisation analysis of Steel-Concrete hybrid wind turbine towers.Struct.35,1125-1137(2022).
Dong,C.H.Research on Mechanical performance of steel-concrete composite structure for wind turbine tower.Harbin Institute of Technology.(2015).
Gao,C.Y.,Li,B.&Shi,Z.H.Nonlinear finiteelement analysis of concrete-filled steel tubular wind turbine tower joints.J.Build.Struct.34(1), 140-146(2013).
Gao,C.Y.et al.Experiment study on the static behavior of the welded tubular K-joints in wind turbine tower. J.Xi an Univ Arc.Tech.46(5),671-675(2014).
Musa,IA.&Mashir,FR.Stress concentration factor in concrete-filled steel tubular K-joints under balanced axial load.Thin-Walled Struct.139,186-195(2019).
Li,F.,Deng,H.Z.&Hu,X.Y.Resistance of gusset-tube DK-joints stiffened by 1/2 annular plates in transmission towers.J.Constr.Steel.Research.159,560-573(2019).
Wen,Y.,Qu,L.L.&Guan,L.P. Experimental study on mechanical behavior of KT-type joints of latticed concrete-filled steel tubular wind turbine tower.J.Build.Struct.36(09),110-116(2015).
Chen,J.,Nie,J.G.&Zhou,C.Y.Study on stress concentration factor of concrete-filled steel tubular T-joints.J.Build Struct.39(3),149-157(2018)．
Gao,C.Y.,ShiI,Z.Y.&Niu,L.H.Experimental study and finite element analysis of concrete-filled circular steel tubular K-type welded tube-gusset joints.J.Ctrl South.Univ.48(3), 769-778(2017)．
Chen,B.C.&Huang,W.J.Experimental study on ultimate bearing capacity of CFST directly-welded K-joints. J.China Civil Engineer.42(12) ,91-98(2019).
Wen,Y.,Meng,C.C.&LIU,S.T. Performance of double-limb splice joints of latticed concrete-filled steel tubular wind turbine tower.J.Southwest Jiaotong Univ.51(6),1113-1120(2016).
Guo,C.X.Computational issues of fillet welds along the intersecting lines of pipe structures.Prog.Steel.Build.Struct.16(1),23-27(2014).
Luo,Y.C.Nonlinear finite element analysis of residual stresses and thermo-harm in direct welded K-joint of steel tubular members.J.Weld Inst.28(3),65-68(2007).
Wang,P.,Wang,Z.,Pan,J.R.&Chen,L.Investigation on mechanical behavior of X shaped welded spatial partition plate tubular joints.J.Buil.Struct.40(3),221-229(2019).
GB 50017-2017.Steel Structure Design Standard(China Construction Industry Press, 2018).
Han,L.H.Concrete filled steel tube structure-theory and practice. 64-71(Science Press,2007)．

No competing interests reported.

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published 30 Jan, 2023

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Editorial decision: Major revision
07 Oct, 2022
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12 Sep, 2022
Reviewers agreed at journal
02 Sep, 2022
Reviews received at journal
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Reviewers agreed at journal
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Editor invited by journal
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You are reading this latest preprint version

Research on Stress Performance of Universally Wrapped Assembled Joints of Lattice Wind Power Tower with Concrete-filled Steel Tube

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Abstract

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Introduction

Testing Survey

Test Phenomenon And Failure Mode

Finite Element Analysis

Conclusions

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References

Additional Declarations

Status:

Journal Publication

Version 1