Steel Tube Concrete Column and Prefabricated Prestressed Beam Composite Structure System for High-Rise Factory Buildings

Literature Overview

This paper by Hong Qi and Yang Haifeng, published in China Cement in 2025, presents a design and application study of a composite structural system combining steel tube concrete (STC) columns with prefabricated prestressed concrete (PPC) beams for high-rise factory buildings. The work addresses the practical challenge of meeting the demands of modern industrial facilities—high floor-to-floor height, heavy loads, and large spans—while maintaining the speed and cost-effectiveness of prefabricated construction. The study is based on a real project application and provides design recommendations and construction measures for this composite system.

Core Technical Content

The composite structural system replaces the conventional cast-in-place concrete frame with a hybrid system where STC columns serve as the primary vertical load-bearing elements and PPC beams provide the horizontal load-resisting system. The key innovation lies in the development of new connection node details that enable a support-free construction method, reducing the need for temporary shoring and accelerating the overall construction schedule.

Structural System Configuration

The STC columns are typically fabricated from square or rectangular steel tubes filled with high-strength concrete (C40–C60). The steel tube provides confinement to the concrete core, enhancing the ductility and post-yield deformation capacity of the column. The PPC beams are precast in a factory with embedded prestressing tendons, achieving high flexural capacity with reduced section depth compared to conventional cast-in-place beams.

The following table summarizes the typical design parameters for the composite system:

Connection Node Design

The connection between the STC column and the PPC beam is the critical element that governs the overall structural performance. The authors propose a connection detail that accommodates the differential deformation between the steel tube column and the precast beam while ensuring adequate load transfer. The connection must resist shear forces at the beam-column joint, provide rotational stiffness for lateral load resistance, and accommodate the thermal expansion and contraction of the steel tube.

A typical connection detail includes:

• Shear keys or dowel bars: Embedded in the column top or beam end to transfer vertical shear forces.
• Moment-resisting connection plates: Bolted or welded to the steel tube and the beam end to provide rotational restraint.
• Elastic bearing pads: Positioned between the beam and the column to accommodate differential settlement and thermal movement.
• Post-tensioning anchors: In some designs, post-tensioning tendons are threaded through the column to create a continuous load path from the beam to the column.

Welding Requirements for STC Column Fabrication

The fabrication of STC columns involves welding the steel tube segments at the joints. For prefabricated columns with a total height exceeding the maximum transport length, field welding of tube segments is necessary. The welding procedure must comply with the relevant standards:

The weld joint geometry must be designed to ensure full penetration, with a root gap of 2.0–3.0 mm and a bevel angle of 60° ± 5°. The welding sequence should be symmetric to minimize angular distortion, which is critical for maintaining the alignment of the column with the beam connections.

Construction Method and Schedule Optimization

The support-free construction method proposed in the study eliminates the need for temporary shoring during beam installation, which is a significant advantage in high-rise factory buildings where the floor-to-floor height is large. The PPC beams are lifted into position by crane and connected to the STC columns through the designed node details. The beams are designed with sufficient self-supporting capacity during the lifting and connection phase, eliminating the risk of collapse during construction.

The following table compares the construction schedule of the composite system with conventional methods:

Quality Control and Acceptance Criteria

The quality control of the composite structural system encompasses both the factory fabrication of components and the field assembly. The following quality control checkpoints are essential:

• Steel tube inspection: Verify dimensions, wall thickness, and weld quality of the steel tube segments. The longitudinal weld must be inspected by RT or UT per GB/T 3323 or GB/T 11345, with acceptance criteria of Level II or better.
• Concrete core quality: For factory-fabricated STC columns, the concrete core must be tested for compressive strength, density, and void content. The void ratio must not exceed 2% per column, verified by UT or GPR.
• PPC beam inspection: Verify prestressing force, tendon position, and concrete strength of the precast beams. The beams must be inspected for cracks, delamination, and dimensional accuracy before shipment.
• Field welding inspection: All field welds must be inspected by VT, MT, and UT (or PAUT) with acceptance criteria per GB/T 11345. The weld procedure must be qualified per NB/T 47014 or ASME IX.
• Connection node inspection: Verify bolt pre-tensioning, shear key engagement, and bearing pad condition at each connection. The connection must be tested for load transfer capacity before proceeding to the next construction phase.

Study Insights and Engineering Practice

The composite structural system of STC columns and PPC beams represents a practical solution to the structural demands of modern high-rise factory buildings. The combination of the high axial load capacity and ductility of STC columns with the rapid installation and high flexural efficiency of PPC beams creates a system that is both structurally efficient and constructionally economical. The support-free construction method is particularly advantageous for projects with tight schedules and limited site access, where the removal of temporary shoring reduces both labor costs and safety risks.

From a welding and fabrication quality perspective, the success of this system depends critically on the quality of the field welds joining the STC column segments. Any defect in these welds—such as incomplete fusion, porosity, or lack of sidewall fusion—can compromise the structural integrity of the entire column. The implementation of rigorous welding procedure qualification (WPQ), welder performance qualification (WPQ), and non-destructive testing protocols is essential. Furthermore, the residual stress distribution in the field-welded column segments should be considered in the structural analysis, as these stresses can affect the buckling behavior of the column under combined axial and bending loads.

The practical application of this system in a real project validates its feasibility and provides valuable data for code development. Future research should focus on the long-term performance of the connection nodes under cyclic loading, the fatigue behavior of the bolted and welded connections, and the fire resistance of the composite system. The development of standardized connection details and welding procedures for this system would facilitate its wider adoption in the industrial construction sector.

The study demonstrates that the convergence of advanced material technology (high-strength steel and concrete), prefabrication methods, and innovative connection design can deliver structural systems that meet the demanding requirements of modern industrial architecture while maintaining the speed, safety, and cost-effectiveness of prefabricated construction. For engineers involved in the design and construction of high-rise factory buildings, this composite system offers a proven and practical alternative to conventional cast-in-place construction, provided that the fabrication and welding quality are rigorously controlled throughout the construction process.