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Construction Technology
Research on Design and Construction Technology of Width-Narrowing Multi-Layer Interval High-Level Connected Structure
Feng Yao, Jiantao Zhang, Liu Wang, Yongjian You
2024, 39(4): 1-9.   doi: 10.13206/j.gjgS23091301
Abstract(4) PDF (14202KB)(0)
Abstract:
A newly built hospital has a total height of 79. 6 meters and 18 floors above ground. Two symmetrical inpatient buildings are arranged, and three aerial corridors are set at intervals between the 9th and 10th floors, 12th and 13th floors, and 15th and 16th floors respectively. The span of each corridor is 25. 2 meters. The main tower adopts a steel frame braced structure system, and the frame beams of the three steel corridors act as chord members, with center supports between upper and lower levels to form a plane truss. The width of the corridors narrows from 24. 3 meters to 7. 8 meters compared to the main tower structure. The structure is complex, and the corridors have high seismic performance requirements. Additionally, the order of dismantling the scaffolding not only causes additional effects on the structure but also affects on-site construction efficiency. Therefore, key technical issues and solutions in the design and construction process of multi-layered high-rise connected structures with narrowing widths have been summarized. By comparing and analyzing the differences in modal vibration modes, lateral and torsional stiffness, and joint construction forms between the connected structure and the main tower using strong and weak connections, a strong connection scheme for the connected structure was established. Based on seismic performance-oriented design objectives, a seismic non-yielding verification was performed on the highrise connected structure, and the results showed that the load-bearing capacity of the members and floors met the established seismic performance targets. Depending on the stage of scaffolding removal, two construction schemes were analyzed for additional internal forces and deformations caused to the connected structure. Considering on-site construction efficiency, it was determined to adopt a construction plan that involves removing the corresponding scaffolding immediately after each floor’ s corridor installation is completed. The analysis results indicated that the high-rise corridors symmetrically located on both sides of the main towers should adopt a strong connected structure form. To ensure the stiffness of the strong connected structure and coordinate the two side towers, the shear bearing capacity within the plane of the connected structure should be larger than the standard value of the maximum shear force of the floor under fortify against earthquake. During the construction phase, the connecting truss can be used as a support for the upper connection scaffolding, and additional stresses and deflections can be released through reasonable construction steps. Additional deflections can be compensated for by adjusting the height of the scaffolding based on construction simulation analysis.
Uniaxial Rotation Method for Long Span Special-Shaped Curved Surface Structures Based on Optimization Theory
Zhihao Zhang, Shangrui Jia, Dongchen Ye, Zunsheng Xing
2024, 39(4): 10-16.   doi: 10.13206/j.gjgS22121901
Abstract(3) PDF (13997KB)(0)
Abstract:
In the past decade, a large number of airports, high-speed rail stations, exhibition centers and other projects have been constructed in China, which have novel architectural designs, generally free form surface shapes, large plane dimensions, and characteristics such as super wide face, super deep depth, and large height differences. Therefore, the construction process of in-situ assembly lifting or cumulative lifting is generally adopted. The above construction methods have problems such as high assembly height, large high-altitude operations, and complex processes, resulting in low construction efficiency, high safety risks, and difficult quality control. Although the rotary lifting method has a significant effect on reducing the assembly of jig frames, it is often used in structures with small spans, regular structures, and a small number of lifting points. At the same time, the synchronization of the rotation process is poor, often leading to excessive bending and damage of the elevator cylinder and even local members. The construction of large-span special-shaped curved steel structures is still in a technical blank period, and there are applicability limitations. Based on the Hangzhou West Station project, the article systematically introduces two methods for determining the rotation axis and angle of large-span special-shaped curved steel structures, namely the double axis repeated rotation method and the single axis rotation method based on optimization theory. The two methods and the in-situ assembly and lifting method are compared in terms of economy, safety, and practicality. In terms of economy, the single axis rotation method based on optimization theory saves 5. 8% of the usage of tire racks compared to the double axis repeated rotation method, and improves the saving of tire rack usage compared to in-situ assembly by 406. 8% ; In terms of safety, the difference in stress ratio between single axis rotation construction and in-situ assembly lifting construction is less than 0. 05, while the difference in stress ratio between double axis rotation construction ( before pole replacement) and in-situ assembly lifting construction is 1. 31. This is because using double axis rotation construction requires the structure to rotate in two directions, and there is a significant difference in the configuration between the rotation process state and the structural design state, resulting in uneven distribution of internal forces in the members, As a result, some components have relatively high stresses, which can be solved by replacing rods for reinforcement, but the design and construction costs will correspondingly increase. Although the stress ratio of components during structural construction is not significantly different between the single axis rotation method and the in-situ assembly lifting method, the height of the jig frame set by the in-situ assembly lifting method is high, and there is a large area of high-altitude work, resulting in poor construction safety for workers. In terms of practical operation, the use of rotary lifting can effectively solve the construction complexity problems caused by the high installation height of the assembly jig frame and frequent high-altitude operations caused by insitu assembly lifting.compared to the dual axis repeated rotation method, the single axis rotation method based on optimization theory can obtain the optimal solution of rotation lifting parameters in one step through self programming, saving time and effort. And due to the unique rotation axis and angle determined, the structure only needs to rotate around a single axis during construction, making the operation more convenient. The results indicate that the single axis rotation method based on optimization theory is better, which effectively compensates for the technical defects and shortcomings of the in-situ assembly lifting method and the double axis repeated rotation method in the application of large-span special-shaped curved steel structures, and provides reference for the construction of similar curved roof structures in the future.
Optimization Analysis of Lifting Scheme for Multilayer Connected Structure with Discontinuous Bottom Floor
Rong Zong, Zhihao Zhang, Chuanlin Liu, Li Ding, Fei Yang, Di Wu, Weichong Lu
2024, 39(4): 17-25.   doi: 10.13206/j.gjgS23082102
Abstract(5) PDF (28221KB)(0)
Abstract:
With the development of steel structures in buildings, high-rise building clusters have sprung up like mushrooms after a rain, and setting up steel connections between two high-rise buildings is a common structural form. At present, for the installation of conventional high-altitude connected structures, the installation method mostly uses ground assembly and overall lifting to the design position. However, for multi-layer connected structures with discontinuous bottom layers, on the one hand, the ground assembly jig frame is high, which leads to high-altitude operations, which is not economical and not safe; on the other hand, the bottom structure needs to be reinforced during assembly, which is cumbersome to construct. Therefore, how to develop a more economical, safe, and fast construction method is a consideration for construction plan developers. The article takes the Hangzhou Yunmen project as an example and provides two construction plans: cumulative lifting and layered lifting. The two are compared in terms of structural deformation, construction economy, safety, and timeliness. In terms of stress, using the above two schemes for construction, for the tower, the difference in the maximum stress value of the member is small, but the additional stress of the construction component using layered lifting is smaller, making the stress more reasonable; for connected bodies, the maximum stress values of the members are basically the same, but the overall stress of the members using layered lifting is relatively small; for the lifting reinforcement rod, the maximum axial force of the reinforcement rod using the layered lifting scheme is 10 905. 27 kN, while the maximum axial force of the reinforcement rod using the cumulative lifting scheme is 12 615. 81 kN, which is reduced by about 13. 6% compared to the latter. Therefore, using the layered lifting scheme can reduce the demand for its cross-section and facilitate removal after the lifting is completed. In terms of deformation, using the above two schemes for construction, the maximum vertical deformation of the structure is located in the middle of the connected span, and the difference in deformation values is not significant; while the maximum horizontal deformation of the structure is located at the top layer of the tower, there are some differences in deformation values. The deformation value of layered lifting is relatively small, which is due to the use of layered lifting. Before the secondary lifting, the upper structure of the connecting body and the tower have already been integrated, with a certain level of horizontal stiffness. In terms of construction, when the cumulative lifting scheme is adopted, the lower structure is installed at low altitude, the upper connected structure has a longer suspension time and poor timeliness, and the connected structure does not form an effective connection with the tower, resulting in poor construction safety; while by adopting a layered lifting scheme, the upper connected structure is directly reinforced after being lifted in place, forming an effective connection between the connected structure and the tower. At that time, the assembly work of the lower triangular area structure can be carried out simultaneously, with better timeliness and safety. In terms of economy, there is a small difference between the two, and hierarchical upgrading has a high demand for increasing the number of equipment. The results indicate that for the construction of multi-layer connected structures with discontinuous bottom layers, the layered lifting method performs better in terms of structural stress and deformation, construction economy, safety, and timeliness.
Analysis on the Influence of Ambient Temperature on Integral Lifting Construction Technology for High-Rise Connected Structure
Chuanlin Liu, Dongchen Ye, Rong Zong, Zunsheng Xing, Fei Yang, Changsen Xu
2024, 39(4): 26-33.   doi: 10.13206/j.gjgS23071101
Abstract(6) PDF (6360KB)(0)
Abstract:
The construction process is an important stage to ensure the reliable performance of the structure and to meet the quality standards. With the development of social economy, the requirements for construction quality are gradually improved. Ambient temperature is the key factor which affects the construction accuracy and maintains the construction quality. It is widely concerned in long-span structures judge the influence of temperature difference on the additional stress of the structure. For the lifting stage of Yunmen steel structure, the analysis results show that when the ambient temperature at the time of lifting is 27. 6 ℃ lower than during assembly, the amount of misalignment between the connected structure and the tower is the lowest. The temperature difference is too large to occur in the real environment. It can be seen that with the decrease of the ambient temperature, the amount of misalignment between the connected structure and the tower during lifting decreases, which is conducive to the construction accuracy assurance. Therefore, it is recommended that the docking should be carried out early in the morning or late afternoon as much as possible. such as railways and bridges, but there is less research in the construction stage of building structures. With the increasing complexity of building structure design and the increasing structure dimension, the impact of ambient temperature on construction begins to appear. Therefore, based on the integral lifting technology, which is widely applied in high-rise connected structures, this paper discusses the influence of ambient temperature on the two important construction process, assembling and lifting stage. In the assembly stage, the connected structure is constrained by the tire frame and support frame, so that it produces additional internal forces and deformation under the action of temperature. The structure of the supporting measures are considered under two extreme conditions: minimal horizontal constraint and rigid connection. In the lifting stage, the connected structure has no horizontal constraint and can be freely deformed in the horizontal direction, which will significantly affect the influence of the connected structure docking accuracy with the tower structure at high altitude. In this paper, the temperature deformation and construction deformation are superimposed and it is proposed to comprehensively consider the influence of the temperature deformation and the construction deformation on the lifting accuracy of connected structure. In the specific analysis, based on the finite element simulation, the relationship between the deformation of the key linking point and the temperature is obtained by linear fitting. The relationship between the temperature and the amount of docking is further calculated, so as to obtain the temperature difference with the smallest misunderstanding. Therefor time schedule of the lifting construction with this temperature difference could be guided. After that, taking Hangzhou Yunmen steel structure project as an example, the influence of ambient temperature in the project was analyzed. If the horizontal constraint of the tire frame is not considered in the assembly stage, the additional stress of the ambient temperature on the structure is small. On the contrary, it will cause greater additional stress, even more than the yield stress of the steel. The calculation result is based on the calculation in extreme cases, which means the temperature difference changes greatly and the constraint is strong. The probability of actual engineering conditions is low. Therefore, it is suggested that in the stress analysis, reasonable temperature difference and boundary conditions should be selected for analysis according to the real environment of the project and the use of measures, so as to
Research on Key Technologies of Cantilever Lifting of Large Cantilever Spoke Truss Structure with Inner Support
Li Ding, Shangrui Jia, Chuqiao Wu, Changsen Xu
2024, 39(4): 34-40.   doi: 10.13206/j.gjgS23013101
Abstract(2) PDF (16324KB)(0)
Abstract:
In the conventional implementation projects using hydraulic lifting construction methods, the lifted structures have bilateral or multilateral lifting support boundary conditions, good structural stability. For cantilevered structures, especially cantilevered structures with particularly high heights, it is difficult to adopt the lifting construction method because it is impossible to set a balanced lifting point. The Xi’ an Silk Road Happy World Center Tower project is an all-steel special-shaped tower, consisting of an inner cylinder steel frame, an outer cylinder mesh shell, a large cantilever hub-and-spoke skirt truss, a top Mobius ring and an outer barrel shaped ribbon. Taking the Xi’ an Silk Road Tower project as the object, the cantilevered lifting construction technology used in the steel structure construction of the large cantilever hub-and-spoke skirt truss with inner support was studied. Through numerical analysis, the influence of different temporary reinforcement ( a circumferential bar or truss for reinforcement) on the structure during the lifting process is compared, a circumferential truss reinforcement is recommended for the lifting structure according to the comparison results. The influence of different lifting points on the structure during the lifting process was studied, and the recommended number of lifting points was given the number of 5 was optimal for this project. The technical points in the construction process were discussed and the experience was summarized, and the key points that need to be paid attention to in the lifting construction and temporary measures design of the steel structure of the large cantilevered spoke skirt truss were expounded. It expands the application scope of hydraulic lifting construction technology.
Research on Key Techniques of Unsupported Construction of Three-Way Grid Structure
Jianhong Zhang, Peizhao Wang, Wenyan Zhao, Qiang Wang, Daxian Chen, Wenzhi Pan, Weiqing Wang
2024, 39(4): 41-48.   doi: 10.13206/j.gjgS240201
Abstract(5) PDF (15516KB)(0)
Abstract:
The space grid structure is increasingly utilized in modern architecture due to its unique architectural design. With the growing complexity of space grid structure and the main structure below it, the structural installation technology is continuously improving and evolving. For a single-layer three-way grid structure with a complex lower supporting structure, the conventional method of installing insitu block installation using temporary supporting frameworks or erecting full-height scaffolding for high-altitude bulk installation poses challenges such as excessive measures, high costs, and long dismantling times. New construction methods like hydraulic overall synchronous lifting, jacking, and skidding not only face issues of cost and efficiency but also involve higher construction difficulty. Addressing the mentioned issues, the key technology of unsupported construction is studied, taking the saddle-shaped single-layer three-way grid dome structure in the sunken plaza of Shenzhen’ s “ Internet+” Future Science and Technology City Lot DY01-04 as an example, aiming to achieve fewer temporary support measures and increased construction efficiency. Unsupported construction involves using a specific blocking method to fully utilize the previous lifting unit as the support structure for the next unit and complete the installation in a staggered manner without temporary support. The key to the construction is that each block divided by the specific blocking method can form a stable structural system with the previous installation structure post-lifting completion, preventing excessive displacement and stress compared to the one-time design pattern. Through simulation analysis of the entire construction process and onsite monitoring data, and considering safety, convenience, and cost-effectiveness of the construction process, a comparative study of three unsupported construction methods-spiral, unidirectional staggered, and symmetric staggered is conducted. The study indicates that unsupported construction for single-layer three-way grid structures is safe, reliable, and close to the design state in terms of structural stress and deformation after completion, with minimal overall structural stress and no stability issues in the construction process of the ring girder, showing sufficient safety margin. Unsupported spiral construction has a shorter segment length, better structural stress and deformation of the total structure compared to unsupported interlocking construction, while unsupported symmetric staggered construction effectively reduces the additional stress and deformation caused by the “ see-saw ” effect in the construction process, making it superior to unsupported unidirectional staggered construction. By placing deformation and stress monitoring points where simulated structural displacements and stresses are significant, monitoring the structural deformation and stress during the construction process reveals that the actual structural deformation and stress align closely with MIDAS simulation and analysis results in trend and numerical value, demonstrating the rationality of the unsupported spiral construction scheme.
Design Discussion
Strength Reduction Factor of Framed Columns Supporting Leaning Columns
Genshu Tong
2024, 39(4): 49-51.   doi: 10.13206/j.gjgS23032720
Abstract(3) PDF (1400KB)(0)
Abstract:
This paper investigated the stability coefficient of columns which provide lateral support to leaning columns. The present paper revealed that, the stability coefficient of framed columns should not only be determined by an amplified effective length, but also the column curve used should be lower, in the case of the leaning column carrying the same axial load as the framed column, the column curve should be changed from the curve b to the curve c in Eurocode 3. Using the well-known Jezek model, the above conclusions were verified.
Hot Spot Analysis of Steel Structures
2024, 39(4): 52-52.  
Abstract(3) PDF (391KB)(0)
Abstract: