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Research
Static Behavior Research for New Spherical Suspendome Structures of Non-Circular Architectural Plan
Xiangyu Yan, Hao Gong, Qiwu Zhang, Jinghai Yu, Zhihua Chen, Shaohua Wang, Zhengkai Wang
2021, 36(4): 1-10.   doi: 10.13206/j.gjgS20052702
Abstract(0) PDF (18041KB)(0)
Abstract:
The existing spherical suspendome structure is mainly suitable for buildings whose plane projection is standard circle. The supports around the structure are at the same elevation. When the plane required by the building is polygon or irregular curve shape composed of multiple arcs with different diameters, the existing conventional arrangement of spherical suspendome cannot meet the needs of this kind of building. In order to study the applicability of the spherical suspendome in the non-standard circular building whose plane projection is polygon or multiple arcs, this paper introduces a new type of spherical suspendome structure system, which is suitable for the plane of non-circular building. The spherical suspendome structure with good mechanical performance is applied to the building with irregular plane projection by using supports located in different elevations. The axis of the plane projection profile is composed of eight arcs, the dimension of the long axis is 89.89 m, the dimension of the short axis is 82.674 m, the height of the short axis is 4.104 m, and the height of the long axis is 4.876 m. The upper single-layer reticulated shell is arranged in K8+grid, with five ring cables and struts. In this paper, the effects of rise-span ratio, strut length, initial tension of ring cable, cross-sectional area of ring cable and horizontal stiffness of support on the structural displacement, internal force of member and reaction force of support of the new suspendome are studied. The results show that:1) the maximum vertical displacement of the new spherical suspendome decreases with the increase of the short axis rise span ratio, the length of the strut, the initial tension of the ring cable, the cross-sectional area of the ring cable and the horizontal stiffness of the support. 2) The maximum axial force decreases with the increase of the brace length, the initial tension of the ring cable, the cross-sectional area of the ring cable and the horizontal stiffness of the support, and does not vary with the short axis rise span ratio. The internal force of brace and ring cable decreases with the increase of short axis rise span ratio and horizontal stiffness of support, increases with the increase of initial tension of ring cable, and changes with brace length and ring cable section area are complex. The unbalanced force of ring cable joint decreases with the increase of short axis rise span ratio, strut length and support horizontal stiffness, and increases with the increase of ring cable initial tension and ring cable section area. 3) With the increase of the short axis rise span ratio, the horizontal reaction of the support is basically unchanged, while the vertical reaction of the support decreases; with the increase of the length of the strut and the cross-sectional area of the ring cable, the horizontal reaction of the support decreases, while the vertical reaction of the support increases; with the increase of the initial tension of the ring cable, the horizontal reaction of the support and the vertical reaction of the support decrease; with the increase of the horizontal stiffness of the support, the horizontal reaction of the support increases, while the vertical reaction of the support increases.
Performance of Dovetail Profiled Steel Concrete Sandwich Composite Members Subjected to Axial Compression
Zhenfeng Huang, Sumei Zhang, Lanhui Guo, Jie Chen
2021, 36(4): 11-19.   doi: 10.13206/j.gjgS21010601
Abstract(0) PDF (11279KB)(0)
Abstract:
Dovetail profiled steel concrete sandwich composite members (DPSC) are composed of two dovetail profiled steel sheets and filled concrete in between. The dovetail-shaped profiled ribs embedded in concrete can not only function as connectors for steel sheets and concrete, but also effectively reduce the steel sheet's width to thickness ratio and improve the buckling capacity of steel sheet. Compared with the traditional double steel plate concrete composite member, the steel sheets and concrete of DPSC can work together without additional connectors, which increases the convenience and efficiency of construction, while maintaining the performance advantages of double steel plate concrete composite member, and has a broad application prospects in engineering.
The mechanical response of the DPSC subjected to axial compression is analyzed by employing finite element method, the stress distribution of concrete section, the stress development process and the buckling behavior of the steel strips between ribs. Based on the above analysis, the embedment effect of rib in concrete is clarified. Finally, the influence of the positioning of the steel ribs, concrete strength grades, steel strength, sheet thickness (strip width to thickness ratio) and width of the members on axial compression performance of DPSC is analyzed.
The following conclusions can be drawn through the analysis:the dovetail-shaped ribs divide the steel sheets into several strips to bear the axial compression load, and each strip develops the compression buckling wave independently, which changes the overall compression buckling mode of the steel plate; the infill concrete provides enough anchorage for the ribs to realize the composite action and make the steel sheets and concrete working together; the anchored ribs offer solid boundary support and anchorage for the steel strips, which lead the strips to full development of post-buckling strength; the post-buckling strength of the strips shall be considered in calculation of the DPSC bearing capacities; the anchored dovetail-shaped ribs, under axial compression, affect the concrete stress distribution nearby and cause some confinement for the concrete between two ribs, but there are no obvious constrained region and unconstrained region; the DPSC axial compressive bearing capacities can be evaluated by the summation of the concrete compressive capacity, steel ribs reaching yielding and the post-buckling strength of strips; the parameter analysis results show that the positioning of the steel ribs has no significant effect on the axial compression bearing capacity of the DPSC, however, the material strength, wall thickness and profiled steel plate thickness have significant effects on the axial compression bearing capacity and ductility.
Construction Technology
Research on the Key Construction Techniques of Precast Assembly for New Type Steel-Concrete Composite Girder Bridge
Yao Yang, Shu Zhou
2021, 36(4): 20-25.   doi: 10.13206/j.gjgS19102103
Abstract(0) PDF (4108KB)(0)
Abstract:
The precast assembly technology of steel-concrete composite girder bridge is a new type of construction technology, in which piers, caps, steel girders and concrete decks are prefabricated in factories and then transported to the construction site for assembling rapidly.At present, there are many researches on the precast assembly of the main girder of steel-concrete composite girder bridge, but few comprehensive analysis researches on the precast assembly of piers, caps and main girders. Therefore, it is of great significance to research the key construction techniques of the full precast assembly of the main structure of the bridge.
Taking the first multi-girder steel-concrete composite girder bridge in China as an example, this paper researches the key construction techniques of piers, caps and steel-concrete composite girders, such as fabrication, transportation and assembly.Through summarizing the construction experience, the standardized construction technology of the main structure for the steel-concrete composite bridge is determined. Construction technology of steel-concrete composite girders:temporary supports erection,girders hoisting on-site, precise adjustment and positioning for composite girders, construction for the top concrete of bridge deck, grouting construction for anchor bolt holes of permanent bearing, welding for composite girders, girders falling to permanent bearing and concrete construction for beams on pier.Construction technology of piers:surface cleaning for cushion caps, installation for baffle plate of grouting, turning over and hoisting for piers, alignment for piers, precise adjustment for piers, grouting on top of cushion caps, fine adjustment for piers and sleeve grouting. Construction technology of caps:temporary supports installation, installation for baffle plate of grouting, caps installation, grouting on top of piers, cap beam fine adjustment for caps and sleeve grouting, construction for wet-joint, prestressing construction. The conclusions are as follows, the main girder of the bridge is composed of 11 I-shaped steel girders and precast concrete slabs, which reduces the weight of the bridge structure and solves the transportation problem,and it is an optimum design for the structure of steel-concrete composite girders.Standardized temporary support structure, hoisting scheme and construction procedure have been developed in construction of piers, caps and steel-concrete girders, which improves the management level of construction site and promotes the refinement of management.Grouting sleeve connections are adopted between piers,cushion caps and cap beams, and standardized construction technology has been developed, then key technical problems in precast assembly construction have been solved. The main structure of the bridge adopts precast assembly technology, which changes the traditional construction technology and produces good social benefits, which is the inevitable trend of bridge development.
Unsupported Overhead In-Situ Installation Technology for Large Cantilever Steel Structure
Jian Ma, Chuang Ye, Wencai Xia
2021, 36(4): 26-31.   doi: 10.13206/j.gjgG20052501
Abstract(0) PDF (13437KB)(0)
Abstract:
Based on the installation for the large cantilever steel structure of Podiums in Wuhan Optics Valley Science and Technology Mansion, The paper introduced the application of the unsupported overhead in-situ installation technology in the installation of cantilever steel structure. The installation of cantilever steel structure in this project need to be implemented after the completion of installation of non cantilever structure in podiums. At that time, the narrow construction site and difficultly of lifting points setting cannot meet the assembling on the ground and integral lifting. In addition, the high-position of installation of cantilever structure caused high-cost to set temporary support frame and the stability of support frame cannot be ensured. In concrete construction, using without support overhead in-situ installation technology, analyzing and utilizing stress characteristics of cantilever steel structure, assisting location and stability of super heavy components by means of temporary pull rod and imitating the internal force and deformation in hoisting process by means of finite element software, according to the principle materials first and then auxiliary materials and inside-out lifting sequence making the scientific lifting sequence and forming the own stress system of cantilever structure step by step. The installation of cantilever steel structure in this project ensure construction security and economize the cost. Also, quality control and monitor, arrangement of construction procedures and security measures were discussed in the paper. The accuracy of cantilever steel structure after completion meet the design and standard requirements, the scientific nature and security of programme were verified in concrete construction.
Comparison of Chinese and US Code
Comparison of End Plate Connection Design Between AISC DG4 and GB Codes
Dan Guo, Wenxing He
2021, 36(4): 32-49.   doi: 10.13206/j.gjgS20071302
Abstract(0) PDF (1921KB)(0)
Abstract:
End plate connection is commonly used in multi-story buildings, which is widely used in American Standard Design, but rarely in Chinese Standard Design. In response to that, the comparison between American and Chinese standard design is conducted, through which it's found that the American Standard has been deeply investigated, such as AISC DG4, DG16. The DG4 design procedure suits to extended end plates yielding to wind and seismic design (rigid joint). For the beam-column joint of extended end plate, refer to DG13. DG16 suits to flush end plate and extended end plates yielding to non-seismic or wind design (semi-rigid joint). In contrast, associated calculation procedure per Chinese Standard is quite preliminary. Both JGJ 82-2011 Technical Specification for High Strength Bolt Connections of Steel Structures ("Bolt Regulations" hereinafter) and GB 51022-2015 Technical Code for Steel Structure of Light-weight Building with Gabled Frames ("Gabled Frames Specifications" hereinafter) provide clauses dealing with end plate connection design, but the plate thickness calculation method is not given in the Bolt Regulations, only with a mandatory term of plate thickness no less than 16mm nor less than the bolt diameter being identified. Meanwhile, calculation method of bolt arrays is not given in Gabled Frames Specifications, but only providing the end plate thickness calculation. Neither of these standards integrates the end plate connection design procedure.
In order to rationalize the bolt and end plate design of the connection, also to valid the end plate connection as rigid joint in Chinese Standard Design, the article presents what distinctively different between AISC DG4 and GB/JGJ since the researching history, calculation theory, assumptions, case studies and analysis.
The connection tension member design concurs between AISC DG4 and GB/JGJ, the bolt sizing procedures are basically the same, but the calculation of the end plate thickness varies drastically in between, Yield Line Theory was adopted by American Standard considering the controllable plastic development, in contrary, the Chinese Standard proceeds extremely conservatively, all the calculations are limited within the elastic theory.
Looking into Appendix B of AISC DG4, the end plate thickness is less than the bolt diameter in majority of the cases, especially for end plate of 50 ksi (equals to 345 MPa) and above, this criteria prevails. Even though the Chinese Standard leads a safe end plate connection design via mandatory requirements of end plate thickness no less than bolt diameter, column flange thickness no less than end plate thickness, stiffening of the extended end plate, and so forth, but obviously the AISC DG4 leads to reasonable design, especially for cases yielding to seismic requirements.
By comparing above research, we find that the theory of AISC DG4 is relatively clear, and can be supported by engineering and test data. In seismic design, if the engineers determine that the theory of GB code is not applicable, they can design according to AISC DG4. In non-seismic condition, the construction measures required in GB code are safe enough.
Hot Spot Analysis of Steel Structures
2021, 36(4): 50-53.  
Abstract(0) PDF (763KB)(0)
Abstract: