Parallel Three-Dimensional Crossing Construction Method for Steel Tube Concrete High-Rise Buildings and the Influence of Construction Initial Stress

Literature Overview

This 1998 paper by Zha Xiaoxiong, Tang Jiaxiang, and Zhong Shantong, published in Industrial Construction (Vol. 28, No. 11, pp. 32-34), addresses a critical construction methodology issue in steel tube concrete (SRC) high-rise and super high-rise buildings. The authors introduce the parallel three-dimensional crossing construction method (parallel stereoscopic crossing method) and analyze how initial stresses generated during construction affect the overall load-bearing capacity of the structure. This work emerged from a period of rapid urbanization in China when SRC composite columns were increasingly adopted for their superior ductility, load capacity, and fire resistance compared to conventional reinforced concrete columns.

Core Technical Content

The parallel three-dimensional crossing construction method is designed to overcome the sequential construction constraints that typically plague SRC structures. In conventional construction, the steel tube is erected first, concrete is poured inside, and then the surrounding reinforced concrete core wall or shear wall is constructed. This sequential approach creates a mismatch in stiffness development between the SRC column and the surrounding structure, leading to unintended stress redistribution.

The parallel method allows the steel tube concrete column and the surrounding reinforced concrete structure to be constructed simultaneously along different axes in three-dimensional space. This means that the steel tube is erected and filled with concrete on one axis while the adjacent structural elements are being formed on perpendicular axes, minimizing the differential stiffness development between composite and non-composite structural members.

Initial Stress Analysis

The construction initial stress refers to the residual stress state that develops in the structure due to the time-dependent construction sequence, even before any external loads are applied. The authors identify several sources of initial stress:

The key finding is that construction initial stress can reach 10-25% of the ultimate load-bearing capacity in certain structural configurations, which is a non-negligible fraction that can significantly affect the structural performance envelope.

Engineering Practice Implications

From a steel pipe manufacturing perspective, this paper highlights an important consideration: the mechanical properties of the steel tube at the time of concrete filling matter more than the properties at the time of final service. The steel tube must have adequate stiffness and yield strength at the early construction stage to properly confine the concrete during its curing period. This has direct implications for the selection of steel grade and wall thickness.

For steel tube suppliers, the following points deserve attention:

• The steel tube should be delivered with certified mechanical properties that are traceable to the heat number, because the initial stress analysis depends on accurate material property data.
• Surface quality of the steel tube is critical because poor surface condition (scale, rust, dents) can reduce the bond between the steel tube and the infill concrete, weakening the composite action that the parallel construction method relies upon.
• Ovality and out-of-roundness of the steel tube must be controlled within tight tolerances because geometric imperfections concentrate stress and can trigger premature local buckling under the combined initial and service loads.

Welding Considerations

The construction joints in SRC columns typically involve welding the steel tube segments together. The welding process introduces its own residual stresses, which superimpose on the construction initial stresses. For typical SRC column diameters of 400-800 mm with wall thicknesses of 8-16 mm, the following welding practices are recommended:

• Use of low-hydrogen shielded metal arc welding (SMAW) with E7018-type electrodes or gas metal arc welding (GMAW) with ER70S-6 wire for the main structural welds.
• Preheating to 100-150°C for wall thicknesses exceeding 12 mm to control hydrogen-induced cracking.
• Post-weld heat treatment (PWHT) at 550-650°C for critical joints to relieve welding residual stresses.
• Full-penetration butt welds with radiographic testing (RT) to UT Level II per ASME Section V.

Study Insights and Reflections

This paper is notable for its early recognition that construction sequence is not merely a scheduling concern but a structural engineering variable that directly affects the safety margin of the final structure. The parallel three-dimensional crossing method represents a sophisticated approach to managing this variable. However, the paper is somewhat limited in its quantitative analysis; it provides qualitative descriptions and general magnitude estimates but does not present a comprehensive parametric study with detailed finite element modeling.

The relevance of this work extends beyond the specific construction method described. Any steel tube concrete structure where the construction sequence creates differential stiffness development should be evaluated for construction initial stresses. In modern practice, this means that steel tube suppliers should provide not only material certificates but also guidance on the expected mechanical behavior during the construction phase, particularly for projects where the construction schedule is tight and the concrete may not reach full strength before additional loads are applied.