Zhuojin Pipe Fitting Co., LtdConstruction Technology of Steel Tube Concrete Rigid Frame Structure for Shenzhen World Trade Center
Literature Overview
The article by Xue Feng (2001), published in Building Technology, documents the construction technology applied to the steel tube concrete (STC) rigid frame structure of the Shenzhen World Trade Center building. This project, executed by Jiangsu First Construction and Installation Engineering Corporation, represents one of the early large-scale applications of STC rigid frame systems in China's high-rise construction industry. The article provides practical insights into the construction sequence, welding procedures, formwork systems, and quality control measures employed in the execution of this significant structural project.
Structural System and Construction Sequence
The STC rigid frame system combines the advantages of steel tube columns (high strength-to-weight ratio, rapid erection, excellent seismic ductility) with the benefits of rigid frame connections (moment resistance, reduced lateral displacement, improved overall structural stiffness). The construction sequence followed a bottom-up approach, with the steel tube columns erected first and then concreted to form the composite STC columns, followed by the connection of steel beams to form the rigid frame.
| Construction Phase | Key Activities | Quality Control Focus |
|---|---|---|
| Foundation and column base | Column base plate installation, anchor bolt positioning | Base plate flatness, anchor bolt alignment |
| Steel tube column erection | Column segment fabrication, lifting, splicing | Verticality, weld quality at splices |
| Column concreting | Formwork assembly, concrete placement, curing | Concrete strength, compaction quality |
| Beam connection | Beam fabrication, welding to columns | Weld penetration, joint rigidity |
| Shear wall integration | Shear wall reinforcement, concrete placement | Reinforcement spacing, concrete integrity |
The construction technology emphasized the importance of precise column fabrication and erection, as the STC columns serve as the primary vertical load-bearing elements and must maintain dimensional accuracy throughout the building height. The steel tube columns were fabricated in segments at the fabrication shop, with longitudinal welds inspected using ultrasonic testing (UT) and surface defects checked using magnetic particle testing (MT).
Welding Technology and Quality Assurance
Welding was a critical construction activity in this project, with multiple welding applications including steel tube longitudinal welds, column splice butt welds, beam-to-column connection welds, and reinforcement welds in shear walls. The welding procedures were qualified in accordance with applicable Chinese standards, and welders were certified to the required skill levels.
For the steel tube fabrication, the longitudinal welds were produced using submerged arc welding (SAW) processes, which provide deep penetration and high-quality welds suitable for structural applications. The weld procedure specifications (WPS) included parameters such as welding current, voltage, travel speed, and filler material composition, all of which were optimized to ensure weld quality and mechanical properties. Column splice connections used full-penetration butt welds with backing bars or root reinforcement to ensure complete fusion at the root of the weld.
The welding quality control program included:
- Pre-weld inspection of base material and filler material certification
- Welding procedure qualification testing (WPQT) including tensile, bend, and impact tests
- In-process monitoring of welding parameters and visual inspection
- Post-weld non-destructive testing (NDT) including UT for volumetric defects and MT/PT for surface defects
- Destructive testing of coupon welds for mechanical property verification
Formwork and Concrete Construction
The formwork system for STC column concreting was designed to accommodate the cylindrical or square geometry of the steel tube while providing access for concrete placement and vibration. For circular steel tubes, the formwork was typically omitted, with concrete pumped directly into the tube through a filling port at the top. For square steel tubes, removable formwork panels were used to contain the concrete and ensure proper compaction. The concrete mix design was optimized for pumpability and workability, with appropriate admixtures to achieve the required slump and setting time.
The concrete placement sequence was critical to ensure proper compaction and avoid voids or honeycombing within the tube. The concrete was placed in lifts of approximately 500-800 mm, with each lift vibrated using internal vibrators before the next lift was placed. For tall columns, the concrete was pumped continuously to avoid cold joints, and the pumping rate was controlled to prevent excessive pressure on the formwork.
Shear Wall and Reinforcement Integration
The rigid frame structure also incorporated shear walls for additional lateral resistance. The integration of shear walls with the STC columns required careful coordination of reinforcement details and construction sequencing. The shear wall reinforcement was installed before the STC column concrete was placed, with the column steel tube passing through the shear wall reinforcement cage. This required precise positioning of the steel tube within the reinforcement cage and the use of temporary supports to maintain the tube's position during concrete placement.
The reinforcement welding in shear walls was performed using electric arc welding or flash butt welding, with weld quality inspected using MT or PT. The reinforcement detailing followed applicable standards such as GB 50010, with particular attention to lap splice lengths, hook details, and anchorage lengths in high-seismicity regions.
Study Insights and Concluding Remarks
This construction technology documentation provides a practical reference for engineers and contractors involved in STC rigid frame construction, highlighting the key technical challenges and quality control measures that must be addressed during execution. The emphasis on welding quality, formwork design, and construction sequencing reflects the practical realities of large-scale high-rise construction. The article also demonstrates the importance of integrating structural design requirements with construction feasibility, as the STC rigid frame system demands precise fabrication and erection tolerances that must be achieved within the constraints of site construction conditions. For future projects, the lessons learned from this construction experience should be incorporated into more detailed construction method statements and quality assurance plans, particularly regarding welding procedure optimization, concrete placement logistics, and the coordination of multiple construction activities within tight construction schedules.