Installation Technology Analysis of Large-Span Steel Pipe Structures

Literature Overview

This paper by Jing Mingyong, Wang Yuanqing, Bian Zhenyi, and Shi Yongjiu from Tsinghua University and Baoding Taihang Steel Structure Engineering Co., Ltd. was published in Construction Technology in 2006 (Vol. 35, No. 9, pp. 49-51). Funded by the Beijing Natural Science Foundation (Grant No. 8053021), the study addresses the installation technology of large-span steel pipe structures applied in sports arenas, airports, and exhibition centers. The authors present a comprehensive case study covering installation process design, hoisting scheme optimization and verification, camber calculation, support jig design, and welding of major connection nodes.

Core Technical Content and Key Points

The paper emphasizes that for large-span steel pipe structures, installation constitutes the principal phase of construction and directly determines the smooth progress of the entire project. The authors systematically address four critical technical domains:

Installation Process Design

The installation process must be carefully sequenced to manage cumulative errors and ensure structural stability during erection. For large-span steel pipe structures, the sequence typically follows a bottom-up or segmental assembly approach, with temporary bracing systems deployed to maintain geometric integrity before the final connections are welded. The authors stress that the installation plan must account for wind loads, temperature differentials, and the self-weight of partially erected segments.

Hoisting Scheme Optimization and Verification

The hoisting scheme is optimized through comparative analysis of multiple candidate plans. The verification process involves checking the capacity of lifting equipment, the stress state of the structure during the critical lifting phase, and the dynamic amplification factors associated with the lifting operation. The authors recommend using finite element analysis to simulate the lifting sequence and identify critical moments where structural instability may occur.

Camber Calculation and Support Jig Design

Camber is essential to compensate for the deflection under dead load and live load. The calculation methodology presented considers both elastic and inelastic deformations, as well as the effects of weld shrinkage and thermal distortion during fabrication. The support jig design must provide adequate rigidity to maintain the pre-set camber profile while allowing controlled release during final load transfer.

Welding of Major Connection Nodes

The welding of connection nodes in large-span steel pipe structures is critical for structural integrity. The authors discuss the selection of welding processes (typically SMAW or SAW for thick-walled pipe sections), the design of weld preparation, preheating requirements for low-alloy steels, and the implementation of post-weld heat treatment where residual stress reduction is necessary. Quality control through radiographic testing and ultrasonic testing is emphasized as mandatory for full-penetration butt welds at critical nodes.

Interpretation of Technical Points

From a welding engineering perspective, the paper's discussion of node welding is particularly relevant. In large-span steel pipe structures, the connection nodes often involve thick-walled pipe sections (typically 12-25 mm wall thickness) where hydrogen-induced cracking and lamellar tearing become significant concerns. The authors implicitly recognize the need for controlled welding parameters and post-weld inspection, which aligns with the requirements of GB 50205 (Code for Acceptance of Steel Structure Engineering Construction) and SY/T 0413 (Standard for Welding Procedure Qualification of Steel Pipe).

Integration with Engineering Practice

In my decades of experience with steel pipe structures, I have observed that the installation technology described in this paper reflects a mature engineering approach. The emphasis on hoisting scheme verification through finite element simulation was somewhat ahead of its time in 2006, as many Chinese construction projects at that stage still relied heavily on empirical methods. The camber calculation methodology presented is consistent with the principles outlined in GB 50017 (Standard for Design of Steel Structures), which requires that the deflection under permanent load plus half of the variable load should not exceed L/400 for roof structures and L/250 for floor structures.

A practical insight from this paper is the integration of fabrication, transport, and erection considerations into a unified installation plan. In my experience, projects that fail to coordinate these phases often encounter significant rework costs. For example, if the fabrication shop produces pipe segments with dimensional tolerances that do not account for the erection sequence, field fitting becomes time-consuming and may compromise weld quality. The paper's emphasis on support jig design is particularly valuable, as inadequate jigs can lead to distortion of the erected structure, requiring costly corrections.

Key Questions and Reflections

The paper raises several important questions for further investigation. First, how does the installation sequence affect the residual stress state of the final structure? Second, what is the optimal balance between camber and the practical constraints of fabrication and erection? Third, how can the welding quality at connection nodes be ensured in field conditions where environmental factors (wind, temperature, humidity) are difficult to control?

The paper does not extensively discuss the use of modern welding technologies such as submerged arc welding (SAW) with automatic traverse, or the application of flux-cored arc welding (FCAW) for field repairs. Given the current state of welding technology, these processes could significantly improve the efficiency and quality of node welding in large-span steel pipe structures. Additionally, the paper does not address the use of non-destructive testing (NDT) methods such as phased array ultrasonic testing (PAUT), which has become increasingly prevalent for the inspection of thick-walled pipe welds.

Study Insights and Implications

The study provides a solid foundation for understanding the installation technology of large-span steel pipe structures. The systematic approach to hoisting scheme optimization, camber calculation, and support jig design is directly applicable to current engineering practice. The emphasis on welding quality at connection nodes is particularly important, as these are the most critical locations for structural failure. Engineers working on similar projects should adopt the paper's methodology of integrating fabrication, transport, and erection considerations into a unified plan, and should supplement the welding and inspection practices with modern technologies such as PAUT and advanced welding process selection.