1. Introduction
The role of the steel structure corridor primarily revolves around its function as a connector between buildings [
1]. Serving as a means of passage and illumination, it fulfills the dual purpose of connecting structures on both sides [
2]. The establishment of a steel structure corridor is driven by two objectives. Firstly, it meets architectural requirements such as accommodating sightseeing activities, serving as a scenic corridor, or acting as a peaceful café [
3]. Secondly, it aims to fulfill the aesthetic needs of the architecture by enhancing the impact of the facade and creating a more distinctive appearance [
4]. The steel structure corridor not only assumes the responsibility of supporting its own weight and traffic loads [
5], but also requires coordination with the primary structures on both sides to manage end deformations [
6,
7].
However, wind loads significantly impact the safety and stability of the installation of steel structure corridors between super-tall buildings. Due to the static and dynamic effects of wind loads, twisting, vibration, and deformation of steel structure corridors often occur during lifting and installation, leading to an increasing proportion of safety accidents. This is owing mainly to inappropriate choices made by construction personnel regarding the lifting and installation methods of steel structure corridors, inadequate emergency plans and corresponding measures for potentially unsafe construction projects, and insufficient emphasis by construction management on the stress changes of steel structure corridors under wind loads, without conducting numerical simulation research and analysis on the construction process of steel structure corridors. Therefore, selecting an appropriate steel structure corridor lifting construction method and minimizing the impact of wind loads on the deformation and collisions of super-tall steel structure corridors are essential prerequisites to ensure its safety and reliability for both daily construction and operation [
8].
Numerous techniques exist for the hoisting and elevation of steel structure corridors. Among these, the segmented elevation construction technique is commonly employed, seeking to enhance safety protocols, minimize transportation expenses, and elevate hoisting efficiency during component installation. This is accomplished through the refinement of the construction site’s layout blueprint before commencement, thereby optimizing the construction process [
9]; the high-altitude sliding method is an efficient and economical construction method for large-span reticulated shell structures. The basic operational process involves dividing the lifted items into several units, each of which is hoisted onto the designated sliding track of the building. The sliding operation is then carried out to the specified position. Finally, the units are assembled into a whole [
10]. The cantilever installation construction technique involves gradually extending the installation components outward from the design height. The installed components act as support extensions, gradually expanding toward the periphery until all components are fully installed. Experimental research has demonstrated the sufficient stiffness of this method to meet deformation requirements during construction [
11]; The onsite assembly construction method involves constructing a temporary support platform at the designed height of the steel structure. The pre-assembled components are then directly installed on the platform surface. By proposing a framework to optimize the planning of component sequence and arrangement, geometric variations of components and subsequent rework during the construction process are minimized. This helps avoid risks associated with structure lifting construction, while also shortening the construction period [
12]; and the integral lifting construction method involves transporting structural components to the assembly platform for assembly. The general process of the lifting construction is as follows. Initially, the structural components are transported to the assembly platform and assembled. It should be noted that, to facilitate the installation work after lifting, the assembly platform is typically positioned directly beneath the installation location. Once the assembly is finished, the structure as a whole is lifted to the designated height using lifting equipment. Finally, the components are installed and secured. It is important to note that for ease of installation after hoisting, the assembly platform is generally positioned directly below the installation location [
13,
14,
15,
16]. Once assembly is complete, the entire structure is hoisted to the designated height using lifting equipment. Finally, the components are installed and secured. Through a comparison of finite element numerical simulation and actual construction monitoring results, the safety and applicability of lifting steel structure corridors under wind loads are ensured [
17,
18,
19,
20].
During the actual onsite construction process of steel structure corridor lifting, construction techniques such as segmented elevation, high-altitude sliding, cantilever installation, and onsite assembly involve prolonged high-altitude operations. This significantly reduces construction efficiency, increases construction process risks, and poses a safety challenge to construction personnel. Compared to other methods, the overall lifting and hoisting construction technique involves fewer high-altitude operations, and the speed and duration of hoisting can be controlled, effectively ensuring construction quality. Thus, it is widely applied in practical engineering projects. The installation and construction of the reticulated shell dome in Nagoya, Japan (
Figure 1a) utilized the comprehensive hoisting and lifting method. The lifting weight exceeded 10,000 tons, and the hoisting and lifting heights approached 31 m. Similarly, the comprehensive hoisting and lifting method was employed in the installation and construction of the steel roof at the São Paulo Exhibition Center in Brazil (
Figure 1b), with a lifting weight of approximately 1000 tons and a lifting height of 14 m. A representative case is the reticulated shell roof of the small theater at the Harbin Cultural Center Grand Theater, depicted in
Figure 1c. The versatility of the comprehensive hoisting and lifting method is evident from the aforementioned instances. The weight and height of the lift represent maximum achievable values across all construction methods, with manageable control over construction quality and safety. Therefore, the selected construction approach involves lower platform assembly and subsequent integral lifting. This methodology significantly minimizes high-altitude operations, thereby enhancing construction efficiency and ensuring high construction quality.
In light of the current research status both domestically and internationally, there is a need for further exploration of the safety, stability, and stress conditions of the integral hoisting and construction of steel structure corridors under wind loads. This is crucial to comprehensively guide and ensure the integral hoisting and construction process of steel structure corridors affected by wind loads [
21,
22,
23]. This paper primarily aims to address three main challenges in this regard: (1) Ensuring the safety of the hoisting and lifting process of steel structure corridors under the influence of wind loads. (2) Resolving stability issues encountered during the hoisting and lifting process of steel structure corridors under the influence of wind loads. (3) Addressing the force-related problem of steel structure corridors when subjected to asynchronous lifting under the influence of wind loads. Therefore, this study aims to analyze the safety and stability of hoisting steel structure corridors under wind load.
To achieve this objective, this study takes the integral hoisting and construction of steel structure corridors in two super-tall buildings within the Haiyue Center project in Quanzhou City as an engineering case study. SAP2000 and ANSYS structural finite element software programs are utilized to conduct numerical simulations on the overall hoisting and lifting process of steel structure corridors under wind loads. The obtained numerical simulation results are analyzed to identify the existing problems during the hoisting process. Subsequently, corresponding measures are proposed to address these issues, and the effectiveness of these measures is verified through real-world engineering case studies in conjunction with the simulation results.
2. Methods for the Integral Lifting of Steel Structure Corridors under Wind Load
This study employs a combined approach of theoretical analysis and numerical simulation to investigate the impact of wind loads during the integral hoisting and construction process of steel structure corridors. These two distinct research methods each possess unique characteristics. By integrating and cross validating these two methods, reliable research conclusions can be obtained.
2.1. Theoretical Analysis Methodology
In the realm of studying the influence of wind loads on steel structures, both statics and aerodynamics theories remain applicable. The theoretical analysis method is based on statics and aerodynamics theories, where models and formulas fitting the actual engineering scenarios are established. Mathematical analysis methods are then applied to solve these models, ultimately providing conclusions regarding the stress, deformation, and stability of the steel structure. Theoretical analysis serves as the foundation for other research methods and plays an irreplaceable role.
2.2. Numerical Simulation and Computation
Numerical simulation and computation are based on fundamental principles related to statics and fluid mechanics. They simulate the impact of wind loads on steel structure corridors during the lifting and hoisting process, ultimately yielding calculations for internal forces and displacements of the steel structure corridor. The numerical simulation and computation method simplify the complexity associated with theoretical research. With the continuous advancement of computer technology, the precision and reliability of numerical simulation software have significantly improved. Consequently, this method is widely applied in research under various complex conditions.
Numerical simulation analysis methods primarily encompass three approaches: the time-dependent element method, the topological element method, and the finite element method. Currently, various software options are available for conducting numerical simulations, such as SAP2000, ANSYS, MIDAS, ETABS, and others, and each type of software is suitable for specific engineering conditions and materials. SAP2000 (Structure Analysis Program 2000) is a type of finite element analysis software that not only offers targeted analysis methods for various construction models but also integrates different types of analysis methods, allowing for simultaneous analysis and result output. As a result, it finds extensive applications in the field of structural engineering finite element analysis.
SAP2000 encompasses a comprehensive range of structural analysis methods, including the latest linear, nonlinear, dynamic, and static analysis methods. Its analysis capabilities primarily include static analysis, dynamic analysis, time history analysis, staged construction analysis, static-elastic-plastic analysis, and modal analysis using characteristic vectors. These capabilities are employed to address the gravity second-order effects encountered during numerical simulation research. Specifically, when the lateral stiffness of a structure or component is relatively low, it can experience lateral displacement under horizontal loading. Under vertical loading, this lateral displacement further increases, resulting in additional internal forces within the structure and potentially leading to premature instability phenomena.
4. Construction Procedure for the Case Study of Steel Structure Corridors under Wind Load
The main load-bearing structural system of the steel structure corridor in this project is composed of the three trusses on the first floor and the steel beams positioned in the middle. The remaining structure serves as an additional load during the installation process of the steel corridor, effectively enhancing the out-of-plane stability of the main truss. The force transmission within the force-bearing system of the overall structure is clearly defined, making the adoption of the overall hoisting and lifting construction method highly suitable. Considering the structural characteristics of the steel structure corridor in Haiyue Center project, it can be observed that it predominantly exhibits symmetrical attributes. Consequently, a total of five lifting points are arranged at both ends of each main truss (main steel beam), with an additional lifting point placed near the center. The spatial arrangement of these lifting points is depicted in
Figure 6. The overall hoisting procedure can be outlined as follows: initially, the structural components are transported to the assembly platform and subsequently assembled to form a cohesive structure. To facilitate the hoisting and lifting operations, the assembly platform is directly positioned beneath the designated installation location. Once the assembly process is finalized, the structure can be hoisted directly to the intended height as per the design specifications and ultimately installed in its final position.
The lifting procedure is comprehensively delineated as follows:
- (1)
The steel structure corridor trusses are assembled on the 7th floor of the podium, with a 100 mm offset from the concrete floor, located 115 m away from the office building’s side. Lifting platforms and lifters are installed. Subsequently, the hoist is connected and secured to the lower steel structure corridor using steel strands, as depicted in
Figure 7a.
- (2)
Once the steel structure corridor truss hoisting section is assembled, the hoist is prepared for gradual loading. The steel corridor is lifted as a whole, initially rising by 100 mm and then pausing the lifting operation. The hydraulic cylinder is locked, and the structure, temporary rods, lifting points, and lifting platform undergo a 12-h inspection to assess the normality of welding seams and deformations, as illustrated in
Figure 7b.
- (3)
The entire steel truss structure is lifted comprehensively. The adjusted height of each lifting point serves as the new starting position for hoisting, maintaining this posture until it approaches the desired elevation. The overall lifting speed is approximately 4 m/h, as demonstrated in
Figure 7c.
- (4)
As the overall synchronous lifting nears the design elevation with a 200 mm gap, the lifting speed is reduced. Fine-tuning of the lifter is then performed to accurately position the counterpart, and the hydraulic cylinder is locked, as shown in
Figure 7d.
- (5)
Employing a jack, all the lifter bases, along with the lifter and the truss, are synchronously pushed toward the side of the apartment building for around 400 mm, as depicted in
Figure 7e.
- (6)
Subsequently, butt welding takes place, followed by the installation of back-up rods, as illustrated in
Figure 7f.
- (7)
The lifter is unloaded, and the load is transferred to the prefabricated section. Finally, the temporary structure and the lifter are removed, as shown in
Figure 7g.
The subsequent points outline the essential matters attention throughout the hoisting and lifting procedure:
- (1)
The safety of hoisting and lifting the steel structure corridor under wind load conditions needs to be ensured. With a maximum hoisting height of 128.8 m and a weight of nearly 100 t, the steel structure corridor is susceptible to shaking and potential collisions with adjacent buildings under the influence of wind load. Given the proximity of the corridor to the main buildings, with a minimum distance of only about 200 m during the hoisting process, excessive lifting speed at each point relative to the wind speed onsite could result in collisions. Hence, it is crucial to analyze the safety concerns during the hoisting and lifting process of the steel structure corridor under wind load conditions and develop corresponding solutions.
- (2)
The stability of the hoisting process for the steel structure corridor under wind load conditions is a critical consideration. The presence of wind load during hoisting and lifting can cause beam displacement and excessive stress in the steel structure corridor. This, in turn, leads to uneven deformation of the corridor, thereby affecting its overall stability. It is imperative to conduct a detailed analysis of the impact of wind load on the steel structure corridor and implement targeted control measures.
- (3)
The force distribution problem for the steel structure corridor under wind load conditions during asynchronous lifting requires attention. Due to potential errors in hoisting construction equipment and operational procedures, it is challenging to maintain consistent speed and displacement at each hoisting point. Consequently, stress concentration and localized stress increases may occur at temporary support points. Significant disparities in lifting speed between different points could even result in structural instability. Therefore, it is necessary to evaluate and calculate the internal forces acting on the members of the steel structure corridor during nonsynchronous hoisting and lifting. This analysis will ensure that the structural members’ stress levels remain within allowable limits, provide corresponding limit values, and serve as a reference for the unloading process following the completion of the hoisting operation.
4.1. Preventive Measures against Collisions
To address the potential collision risk during the hoisting process of the steel structure corridor resulting from wind load, a steel structure hoisting anti-collision device was incorporated into the construction process. This device aims to prevent the hoisting structure from experiencing significant arc movements caused by excessive wind speeds, as illustrated in
Figure 8.
On the outer surface of the protective device’s front end, a fastening shaft is positioned. Alignment adjustment mechanisms, assembly shafts, and mounting plates are situated on the outer surfaces of both sides of the steel structure corridor. The alignment adjustment mechanism is located at the upper end of the assembly shaft, while the mounting plate is situated at the lower end. Additionally, a buffer mechanism is installed on one side of the assembly shaft’s outer surface. This protective device effectively safeguards both the hoisting structure and the adjacent buildings throughout the construction process.
In addition to the anti-collision device, this study incorporates wind ropes at the four corners of the structural floors near the steel corridor. These wind ropes employ a 20mm-diameter steel wire rope and a two-ton hoist. One end is connected to the truss corner, while the other is attached to the primary structural column. By applying tension to the steel wire rope using the hoist and reverse chain, the steel corridor remains relatively stable under the influence of wind load, minimizing excessive shaking.
4.2. Process of Corridor Assembly
The assembly of the steel structure corridor is executed employing the onsite tower crane, adhering to the assembly sequence from west to east. Initially, the lower chord of the steel truss and the bottom steel beam are assembled, followed by the assembly of the vertical, oblique webs, and upper chord. Finally, the corridor’s middle and upper steel beams are sequentially assembled. To ensure structural integrity, the temporary reinforcement rods are incorporated alongside the rods of the steel structure corridor.
Figure 9 illustrates the assembly process of the steel structure corridor.
To ensure optimal stability of the steel structure corridor throughout the hoisting process, it is imperative to implement quality control measures during the assembly stage. Through a meticulous analysis of the hoisting and lifting process of the steel structure corridor under prevailing wind loads, it can be deduced that the primary factor influencing stability is the stiffness and precision of the steel structure corridor post-assembly. Therefore, the incorporation of anti-deformation trusses and diagonal web bars, along with appropriate counterbalancing during the hoisting construction process, becomes essential to averting potential destabilization of the corridor. The specific methods employed are as follows:
Firstly, three temporary anti-deformation trusses were erected during the assembly of the corridor. These trusses effectively restrict the out-of-plane deformation of the corridor while simultaneously enhancing its structural integrity. Secondly, crucial control points are designated during the assembly process. These points serve as reference markers during component assembly, and the horizontal projection of these control points is delineated to ensure the utmost accuracy in the assembly process. Thirdly, a specific number of diagonal web bars are installed at the connecting web bars. Simultaneously, tire frames are welded onto the platform. Furthermore, the vertical elevation of the control points is measured to guarantee the precise positioning of the chord bars.
4.3. Linkage between the Corridor and the Lifting Apparatus
The lowering point is mainly in the form of welding a special lifting device on the upper surface of the upper chord member of the steel structure corridor truss. The connection mode and position of the lifting equipment and the upper chord of the truss are shown in
Figure 10.
Based on the preceding finite element simulation, it is evident that the hanger’s connection to the steel structure corridor experiences predominantly tensile stress, while the connection to the sling is primarily subjected to compression. Hence, a thorough inspection of the welding quality at these two connection points is imperative. During the hoisting and lifting process of the steel structure corridor, the spreader material employed is Q345B steel, which adheres to the construction criteria for hoisting and lifting operations.
4.4. Hierarchical Loading and Hoisting
Regular deformation observation of the tower structures on both sides should be carried out before the hoisting and lifting of the steel structure corridor in order to comprehend the development and regulation of its deformation. Throughout the hoisting and lifting process, continual monitoring of the height and height difference of the steel structure corridor is essential to ensure that the height difference of each lifting point remains controlled within L/500 (where L represents the span of the steel structure corridor). In the event that the load or height difference at any lifting point exceeds permissible limits, immediate adjustments or cessation of lifting must be implemented. Resumption of lifting operations is only permitted once the fault has been examined and rectified. The stability of the hydraulic system is guaranteed by adjusting the pressure during the hoisting and lifting of the steel structure corridor. Furthermore, stringent control over acceleration during the initiation and braking phases of the hoisting process is crucial to minimizing the impact of inertial force on the overall lifting procedure.
Figure 11 illustrates the staged loading and lifting process of the steel structure corridor.
Fine adjustments should be made to each lifting point of the corridor to elevate it to the designated position. Subsequently, the work of the hydraulic lifting system equipment should be suspended, and it should be maintained in a stationary lifting state. The chords located in the middle section of the main truss, as well as the chords at both ends, are then subjected to butt welding and secured. Lastly, the diagonal web bar is installed to establish a stable structural system capable of bearing overall forces. This integration is achieved by aligning it with the segmented structures installed at both ends, as depicted in
Figure 12.
4.5. Dismantling of Corridor Support
Once the steel structure corridor has been raised to its designated height through hoisting, the installation of steel trusses follows suit. Subsequently, the hydraulic lifting system equipment is disassembled, and appropriate temporary measures are implemented to ensure the stability of the steel structure corridor. Once the installation of the steel structure truss is finalized, a comprehensive inspection of the entire structure is imperative before removing the supporting frame. The temporary support frame can only be dismantled after the inspection confirms its correctness. As the temporary support frame is gradually dismantled, the load initially borne by it is progressively transferred to the overall structure, ultimately allowing the structure to sustain its own forces.
Figure 13 illustrates the process of horizontal lateral push and installation.
To account for errors arising from construction equipment and personnel operations during hoisting, it is necessary to conduct the unloading of the structure in multiple stages. By means of numerical simulation, the asynchronous lifting of the steel structure corridor has been examined. The results indicate that as long as the asynchronous displacement of each lifting point remains within 25 mm and the asynchronous lifting load is kept at approximately 20%, the stress experienced by all structural members’ remains below the permissible threshold. This ensures that the strength requirements for the components of the steel structure corridor are met even under asynchronous lifting conditions. Thus, it is recommended to maintain control over the asynchronous displacement during the unloading process, limiting it to within 10 mm, and to exercise a 10% threshold for asynchronous unloading during operation.
4.6. Validation of Finite Element Findings
To ensure the precise installation of the steel structure corridor, it is imperative to eliminate errors during the installation process. The primary sources of errors can be attributed to the following two factors: Firstly, the alignment may be compromised due to the downward deflection and deformation of the truss upon lifting into position. As depicted in
Figure 14, a minor deflection of approximately 3 mm is observed at the end of the main truss during the lifting process. Although the deflection value is small, it can be rectified by utilizing welding techniques, thereby mitigating the impact of the downward deflection on the corresponding components. This approach guarantees that the welding quality of the components adheres to the prescribed standards.
Secondly, errors arise from the installation’s positioning. The permissible deflection angle for the steel strand must not exceed 1.5°. During the installation process, it is advisable to begin by installing the lifting platform at the designated hoisting point. Subsequently, the position of the lower hoisting point should be determined in accordance with the location of the hoisting point. This ensures that the verticality of the line connecting the upper and lower hoisting points meets the specified requirements. When lifting the truss into position, any height deviation in the vertical direction can be adjusted by finely tuning the lifter, while the horizontal deviation necessitates the use of a guide chain for pulling purposes. Once the positioning adjustment is promptly completed, a temporary connection is established to prevent any movement during the alignment of the corridor, thereby satisfying the alignment welding criteria. It is crucial to maintain the guide chain in a taut state until the butt welding is finalized, at which point both the guide chain and temporary connection can be removed.
During the hoisting and lifting process, the wind speed onsite ranges from 1.6 to 7.9 m/s, resulting in evident wind load effects on the construction steel structure corridor. Notably, the corridor noticeably oscillates shortly after departing the assembly platform due to the influence of the wind. However, the installation of pre-installed anti-collision devices and wind ropes effectively safeguards the structural integrity.
Based on the aforementioned analysis and calculations of the steel structure corridor’s stability during the hoisting and lifting process under wind load, it is determined that the maximum downward deflection of the corridor throughout the entire lifting procedure amounts to 19.5 mm, measured from the initiation of hoisting until reaching the intended design elevation during final lifting. Onsite measurements indicate a maximum deflection of the steel structure truss at 24.3 mm, which is below the threshold of L/400 = 40 mm, closely aligning with the results obtained from numerical simulations. This demonstrates that the integrity and stability of the steel structure corridor during the hoisting process align with the anticipated design expectations, affirming the effectiveness of the implemented control measures.
5. Conclusions
This study explores the mechanical responses, safety, stability, and construction guidance during the integral hoisting process of steel structure corridors between super-tall buildings under wind load conditions. Through theoretical analysis and numerical simulation methods, the study assesses and addresses the impact of wind loads on collisions and deformations during the hoisting of steel structure corridors. The integral hoisting and construction of steel structure corridors in two super-tall buildings within the Haiyue Center project in Quanzhou City were taken as practical case studies. SAP2000 software was utilized to comprehensively simulate and inspect the cases. This included a detailed analysis of simulation results, encompassing corridor displacement, stress distribution, and overall stability. Significant thresholds for allowable displacement and load differences at each lifting point during the integral lifting process were established. Subsequently, relevant construction control measures were developed to enhance safety and stability during the steel structure corridor lifting process under wind load effects. Scientific recommendations and references for the hoisting and construction process under wind load effects for similar cases were provided. Therefore, the conclusions drawn are as follows:
- (1)
Safety of steel structure corridors hoisting under wind load
Safety during the hoisting process of steel structure corridors under wind load is critical. In the integral hoisting process, the lack of necessary constraints and support within the horizontal plane of the corridor can lead to sensitivity to wind load, especially at heights exceeding 100 m. To prevent structural oscillations due to wind load during the lifting process, safety control measures were taken. Collision-prevention devices were installed on the main structure to avoid collisions resulting from large swings induced by strong winds, thus preventing damage to both sides of the building and the steel structure corridor.
- (2)
Stability of steel structure corridors hoisting under wind load
Issues related to excessive displacement and stress in the beams of steel structure corridors can lead to uneven deformation during the hoisting process. Quality control measures were implemented during assembly to address this concern. Temporary anti-deformation trusses were set up during the assembly to effectively constrain out-of-plane deformations of the steel structure corridor and enhance its overall stability. Key control points were marked during assembly and used as reference points for component assembly to ensure precision during the process. Additionally, diagonal support members were placed at the connection points, and the framework was welded to the platform to maintain vertical alignment, ensuring the correct positioning of tension components. The integration of diagonal support components connecting the upper and lower trusses not only prevents in-plane instability in the steel structure corridor but also ensures the stability of the entire hoisting operation.
- (3)
Stress issues of steel structure corridors during asynchronous hoisting under wind load
Structural unloading should be carried out in a graded manner. Numerical simulations have revealed that when the asynchronous displacement at each lifting point is around 25 mm and the asynchronous lifting load is kept at approximately 20%, the stress in the members remains below the allowable limit. Furthermore, during the unloading process, the asynchronous displacement should be controlled within 10 mm, and the asynchronous unloading should be controlled within 10%.