2021 Vol. 36, No. 12

Finite Element Analysis on Seismic Behavior of A New Prefabricated Corrugated Steel Plate and Polyurethane Composite Shear Wall
Qiang Xu, Haowen Liu, Wentao Qiao, Chao Wang
2021, 36(12): 1-8. doi: 10.13206/j.gjgS21051102
In addition to good thermal insulation performance, polyurethane has certain caking property, tensile, compressive, and shear strength, can effectively restrict the out-plane buckling of the steel plate. At the same time,the cement board is placed on the outside of the polyurethane and can play a certain role in fire prevention. A new prefabricated corrugated steel plate and polyurethane composite shear wall (SPPSW) is put forward. In order to study the mechanical behavior and failure process of the SPPSW under low cyclic load, and the influence of different parameters on its seismic performance. In this paper, the ABAQUS was used to establish 19 finite element analysis models of SPPSW. The influence of the axial compression ratio, steel plate aspect ratio, wall thickness, steel plate thickness and column flexibility coefficient on the seismic performance of SPPSW is investigated.
The results show:with the increase of the thickness of the steel plate, peak load of the SPPSW increases, but the ductility coefficient decreases and deformation capacity alsodecreases. With the increase of the axial compression ratio, the peak load, ductility coefficient and ultimate displacement of the wall decrease, and the deformation capacity also decreases. Therefore, the axial compression ratio recommendes to be no more than 0.2. With the increase of steel plate aspect ratio, the peak load, ductility coefficient and deformation capacity of the wall increase, but ultimate displacement decreases. In order to make full use of steel plate and play better performance, it is suggested that the aspect ratio of corrugated steel plate should be controlled at 0.8-1.2. Filling polyurethane on both sides of the steel plate can decrease the out-of-plane buckling deformation of steel plate, and with the increase of the filling thickness of polyurethane, the peak load of the wall increases. When the wall thickness is less than 200 mm, the ductility coefficient of the wall increases with the increase of the polyurethane filling thickness.Compared with the wall thickness of 200 mm, when the wall thickness is 240 mm, the ductility coefficient decreases. Therefore, it is suggested that the filling thickness of polyurethane is not more than 200 mm. With the decrease of flexibility coefficient of the column, the peak load and ductility coefficient of the wall increase. However, when the flexibility coefficient is less than 2.87, with the decrease of the flexibility coefficient, the ductility improvement degree of the component decreases.
Influence Analysis of Axial Compression Ratio on the Performance of Core-Grouted Assembled Thin-Walled Steel Tube-Reinforced Concrete Composite Shear Wall
Shuai Xu, Yan Li
2021, 36(12): 9-14. doi: 10.13206/j.gjgS21040602
As a new type of shear wall system, core-grouted assembled thin-walled steel tube-reinforced concrete composite shear wall avoids the difficulty of core pulling of assembly shear wall. Besides, the amount of steel is not increased much, which means it has a good economy while improving the production efficiency. In order to study the influence of axial compression ratio on the performance of thin-walled steel tube reinforced concrete shear wall, the shear wall specimens with the height are 2 600 mm and the section size is 1 100 mm×200 mm are simulated by numerical simulation. The whole specimens are modeled, and it is assumed that the upper and lower ends of the wall are fixed with the loading beam and foundation beam. The load process is applied to the top of the model with vertical uniform load, and the horizontal displacement at the top of the specimen is gradually loaded from 1.3 mm to 26.0 mm. The whole process from elastic force stage to failure is simulated effectively. The difference between failure modes and hysteresis performance of thin-walled steel tube-reinforced concrete composite shear wall in the range of axial compression ratio 0.3-0.5 is compared.
Through the numerical analysis of different models, it is found that the final failure modes of 5 specimens belong to the bending failure of large deflection members under the action of compression bending. Under the reciprocating load, the model near the bottom has a large horizontal deformation, which eventually results in failure due to loss of bearing capacity. According to the stress cloud diagram of the simulated specimens, the thin-walled steel tube at both ends of the test piece yields first, and then the concrete outside the thin-walled steel tube near the bottom begins to reach its tension strength, so the concrete outside the thin-walled steel tube gradually fails. The concrete inside is restrained by thin-walled steel tube, so the specimen can continue to bear the load. Thin-walled concrete-filled steel tube can bear repeated load. During the simulation process, there is no shear slip between thin-walled steel tube and concrete, to maintain a stable state, which makes the specimen have good plastic deformation ability while being subjected to vertical uniform load. The model hysteresis curves are full shuttle shapes, without obvious pinch up. With the increase of axial compression ratio, the envelope area of the hysteresis curve of thin-walled steel tube core filled concrete shear wall is larger, the shuttle curve presented is more fat, the energy dissipated is more, and the ultimate bearing capacity is improved to some extent. From the skeleton curve, when the axial compression ratio exceeds 0.35, with the increase of axial compression ratio, the ductility coefficient decreases. According to the cumulative energy consumption coefficient of each model, the energy consumption capacity of thin-walled concrete-filled steel tubular shear wall will be improved with the increase of axial compression ratio. Under the condition of axial compression ratio of 0.3-0.5, the ductility coefficient of thin-walled steel tube core filled concrete shear wall is more than 3.0, which shows that the structure has good deformation and ductility performance, which can meet the requirements of seismic design.
Research on the Effect of Joint Deviation on the Mechanical Performance of Arc-Shaped Tubular Truss
Jiachen Liu, Jinghai Gong
2021, 36(12): 15-22. doi: 10.13206/j.gjgS20121301
In spatial tubular truss structure, in order to avoid the concentration of weld seams caused by truss chord connections and tubular nodes, the construction method of joint deviation is often used. When segments with different arc curvature exist, joint deviation leads to local changes of the structure and difference from the designed model, which will affect the mechanical performance of the tubular truss with variable arc curvature. To explore the specific influence of joint deviation on the mechanical performance of arc-shaped tubular truss structure, a practical engineering project model is selected, deviation to the chord joint according to the common construction plan is applied, the force of the model before and after the deviation is calculated and compared. Specifically, two representative truss parts at different positions in the structure are analyzed. According to the intersection of diagonal members, the theoretical minimum offset of the appropriate members where the arc curvature changes is calculated. The actual minimum offset at the joint is decided with safety distance and rounded. The model is adjusted to the minimum offset, two times minimum offset, and three times minimum offset respectively. The axial force, bending moment, and stress of upper and lower chord members, diagonal members and the adjacent chord members at the joint are compared under self-weight load condition and the most unfavorable load condition.
The results showed that the axial force of the member was mainly affected by the overall structure design and its cross section, which was not obviously affected by the joint offset. The offset of the joint deviation generates eccentricity between the members at the joint with different arc curvature compared to the designed tubular truss model. The eccentricity caused the axial force on the members at both ends of the joint to generate a bending moment, which would increase the bending moment of the chord members at the joint. When the axial force did not change significantly, the bending moment increased, the stress of the member increased correspondingly. With the minimum offset, the bending moment of the chord members at the joint could increase up to 200% and the stress could increase by 10%-15%. With three times minimum offset, the stress of the chord members at the joint would increase by 70% under the self-weight load condition, and 100% under the most unfavorable load condition. When the eccentricity increased, the bending moment of the members at the joint also increased greatly. At three times minimum offset, the stress ratio of some chord members at the joint exceeded 1, and corresponding joint deviation resulted in an eccentricity of 0.15-0.3 m. Under various working load conditions, the stress of the member increased significantly, which might cause damage under the most unfavorable load condition.
The conclusions are as follows:1) the joint offset has no obvious effect on the axial force of the members in the structure; 2) bending moment increases greatly with the increase of eccentricity caused by joint offset; 3) under the joint action of axial force and bending moment, the joint offset increases the stress correspondingly, causing hidden dangers to the overall structure. During construction, the deviation of the actual chord joint should be checked or the influence of the joint deviation should be considered in the design stage to eliminate the potential danger of the structure.
Finite Element Analysis of Transfer-Bracket Joints of Concrete-Filled Steel Tubular Columns
Junming Jiang, Hongliang Liu, Qiaosheng Chen
2021, 36(12): 23-31. doi: 10.13206/j.gjgS21021802
At present,for the connection of steel box beam,its end is usually directly welded to the surface of supporting steel members.This connection method not only has high technical requirements for welding,but also is easy to produce defects at the weld,resulting in weld cracking.For the problems caused by the installation of traditional steel box beam,a new type of prefabricated connection for steel box beam,a transfer bracket joint,is studied.The steel box beam is installed by bolts instead of welding.The transfer bracket joint is to introduce a transfer bracket between steel box beam and concrete-filled steel tubular column.The basic components of transfer bracket include a short middle coupling beam,and two plates which are welded at both ends of the middle coupling beam,including the front plate connected with steel box beam and the endplate connected with concrete-filled steel tubular column.According to the different connection modes,the transfer-bracket type joint can be divided into two forms:corbel type and extended endplate type.
Firstly,the detailed structure of the joint is given,and the effectiveness of the joint finite element model is verified;detailed parametric analysis is carried out to study the influence of the length of coupling beam,flange thickness and width,and endplate thickness on the joint performance;the failure modes of the two types of joints are compared and analyzed.
The results show that the possible failure modes of transfer-bracket joints include large area yield failure of coupling beam,compression buckling of lower flange,yield failure of steel box girder,tensile failure of front end plate,excessive tensile yield deformation of rear end plate and tensile yield of bolts.The increase of the length of the coupling beam has little effect on the initial stiffness and bearing capacity of the joint,but the length of the coupling beam will affect the stress distribution on the beam.With the increase of the length,the stress level on the beam will decrease.But the long coupling beam can not effectively improve the performance of the joint.The minimum length of the coupling beam should ensure the operation space of the torque wrench,and the maximum length should not affect the mechanical properties of the steel box beam.Increasing the section size of the coupling beam can improve the bearing capacity of the joint.With the increase of the section size,the plastic hinge of the beam will gradually transfer to the steel box beam.By changing the section size of coupling beam,the position of plastic hinge can be controlled.The thickness of the endplate of corbel joints and the front endplate of extended endplate joints has little influence on the joint performance.The thickness of the front plate of corbel joints and the endplate of the extended endplate joints have great influence on the joint performance.When the plate thickness is different,the bearing capacity curve of the joints is often quite different.
Integrated Design of Steel Structure and Metal Roof of Special-shaped Large-span Exhibition Hall in Shaoxing Exhibition Center
Xiang Ye, Lu Li, Hongwei Li, Zhonghua Liu, Shilin Guan
2021, 36(12): 32-43. doi: 10.13206/j.gjgS21012802
The Exhibition Hall 1 of the Phase I Area B Project of Shaoxing International Convention and Exhibition Center has a rhythmic staggered roof with a non-column span of 72 meters.The design and construction of the steel structure and metal roof system are difficult,and the construction period of the Exhibition Hall 1 is extremely tight which is required to be constructed and put into use in the same year.To solve the problems,the project makes full use of the characteristics of EPC mode.The design and construction subjects participate in the design scheme consultation,in which the priority payment requirements,site construction efficiency and inter-professional cohesion are regarded as the key points of design management.The design schemes of the main body and metal roof are finally implemented after study and comparation,and good results are obtained:
1) In view of the large-span special-shaped architectural form,a long-span steel structure scheme suitable for the rhymic staggeredplatformroof is innovatively put forward through the comparison of two form-finding schemes,one of which is the form-finding of roof substructure,and the other one is form-finding of main steel structure.The giant truss is arranged at the staggered platform to improve the overall stiffness and structural efficiency of the roof,through which the organic combination of roof modeling and reliable structure is realized.The analysis and verification show that the structural scheme has strong bearing capacity and excellent seismic performance.The structure greatly reduces the difficulty of design and construction of metal roofs,which is economical,reliable,and beautiful.It lays a good foundation for ensuring the construction period of the project,and can provide a useful reference for the selection of similar (rectangular tooth shaped roof) structure schemes.
2) In view of the slope finding scheme of the main steel structure,in order to further improve the construction efficiency of the roof system,a comparison of the three schemes of reverse installation of metal roof floor,forward installation of overhead floor and forward installation of direct laying floor is conducted,a metal roof system with "separated load-bearing structure of long-span bottom plate and purlin system" is innovatively proposed.The high-wave steel bearing plate leap over the steel structure divisions with a span of 4.5 meters,and is directly laid on the completion surface of the steel structure,which changes the operation mode of the traditional metal roof system.The supporting components of roof bottom plate are integrated into the main steel structure to reduce the aerial working process of roof system.The operation efficiency and construction safety of the metal roof system are greatly improved.The roof bottom plate is separated from the purlin system,and the weight of the structural layer is directly transferred to the main steel structure from the roof bottom plate,so as to improve the utilization rate of the main steel structure.The purlin system bears small force and saves steel,which only supports the roof plate.In addition to the roof purlin,no other parts penetrate the TPO waterproof layer to form a real "two waterproofs" and improve the waterproof effect of metal roof.
The project eventually takes 112 days to complete the construction of steel structure and metal roof system,which is nearly 4 months shorter than that of similar projects.At present,the project,which reflects the great advantages of the EPC mode,has successfully passed the acceptance of the main body and roof engineering,and has achieved the scheduled delivery and trial operation.The project reflects the great advantages of the EPC model.
Comparison of Chinese and US Code
Comparisons Between Chinese and American Standards on End-Plate Connection Design
Yongjiu Shi, Xianglin Yu
2021, 36(12): 44-72. doi: 10.13206/j.gjgS21110202
Bolted end plate connections are one of the main joints in prefabricated steel structures and composite structures. They are widely used in multi-story steel frame structures and portal frame steel structures. Bolted end plate connection has the unique merits of using fewer bolts, easy assembly, and less factory welding. In addition, the on-site erection is fully completed with bolt connection and less affected by weather conditions. Bolted end plate connections are applicable for member splicing, beam-column connection, column base, and steel-plate shear wall connection. Bolted end plate connections can be designed as rigid joints, semi-rigid joints, or hinged joints. The current Specification for Structural Steel Buildings (ANSI/AISC 360-16) and Standard for Design of Steel Structures (GB 50017-2017) actively recommend the application of end plate connections. Other Chinese and American technical standards for steel structures, such as Technical Code for Steel Structure of Light-weight Building with Gabled Frames (GB 51022-2015), Technical Specification for High Strength Bolt Connections of Steel Structures (JGJ 82-2011), Seismic Provisions for Structural Steel Buildings (ANSI/AISC 341-16), and Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications (ANSI/AISC 358-16) specify in details the design method and construction requirements of end plate connection joints. This paper analyzes and compares the provisions and calculation formulas related to the end plate connections in the current Chinese and American technical standards for steel building structures, and discusses in details the structural form, stiffness characteristics, bolt calculation, end plate calculation of end plate connection joints, as well as the local resistance of beam-column joint panel zone, focusing on the realization of the design concept, calculation content, and structural requirements of "strong joints" with end plate connection. Based on summarizing the available design rules of end plate connections in China and the United States, the similarities and differences of the technical standards in the two countries on the regulations of the resistance and stiffness of bolted end plate connections are quantitatively analyzed through examples.
The analysis results show that the current technical standards in China and United States have provided complete design methods of bolted end plate connection applying to steel structures, and they have similar calculation content and structural requirements. However, the design resistance of a single high-strength bolt given by American standards is higher than the result given by Chinese standards. Therefore, thicker end plates and more bolts are required to implement "strong joint" designed according to Chinese standards.
Hot Spot Analysis of Steel Structures
2021, 36(12): 73-73.
2021, 36(12): 74-77.