Steel Tube Concrete Pumping Principle and Pulsating Pressure Analysis

Literature Overview

This paper by Feng Yonggang, Wang Xin, and Yang Shirong, published in Construction Technology in 2009, addresses a practical and often overlooked aspect of steel tube concrete (CFST) construction: the determination of pumping pressure required to fill large-diameter steel tube columns in industrial plant structures. The authors conducted on-site pressure measurement experiments at the Baosteel Stainless Steel Project and proposed a methodology for calculating the pump truck outlet pressure based on the observed pulsating pressure characteristics.

Core Technical Findings

The study identified that the pump truck outlet pressure is not a steady-state value but rather takes the form of a pulsating pressure. This finding is significant because conventional pumping calculations assume steady-state flow conditions, which can lead to underestimation of the actual pressures experienced in the steel tube. The authors proposed a calculation method that treats the pump truck outlet pressure as a steady-state pressure multiplied by a pulsating amplification factor λ.

The on-site measurements revealed clear pressure variation curves with height in the steel tube columns, providing a more accurate understanding of pressure loss mechanisms during the pumping process. The pressure loss is influenced by multiple factors including concrete rheology, pipe roughness, flow velocity, and the pulsating nature of the pump discharge.

Process Analysis and Engineering Practice

The pumping of concrete into large-diameter steel tubes presents unique challenges compared to conventional reinforced concrete column construction. The steel tube acts as a smooth, rigid boundary that eliminates the friction contribution from rough concrete formwork, but the large internal diameter can lead to concrete segregation and aggregate settlement if the pumping process is not properly controlled.

From a steel pipe fabrication and quality control standpoint, the pumping process imposes significant internal pressures on the steel tube wall. For thin-walled tubes, this can lead to local buckling or ovalization, particularly if the tube-to-concrete interface is not properly prepared. The pulsating nature of the pump pressure introduces cyclic loading on the tube wall, which must be considered in the structural design of the tube column during the construction phase.

The proposed calculation method, while practical, relies on the empirical determination of the pulsating amplification factor λ. This factor is influenced by pump type, discharge rate, pipeline configuration, and concrete rheological properties. Engineers should not apply a universal value but should calibrate λ through site-specific measurements, particularly for critical structures where overpressure could damage the steel tube or where underpressure could lead to incomplete concrete filling.

Study Insights and Reflections

This paper addresses a gap in practical construction methodology that is often overlooked in academic research but is critical in field operations. The recognition of pulsating pressure as a distinct phenomenon, rather than a mere fluctuation, represents a meaningful advancement in pumping technology for CFST structures.

For engineers involved in steel tube fabrication, the key implication is that the tube wall thickness and material grade must be selected not only for the final structural loads but also for the construction-phase pumping pressures. A tube that is adequate for service loads may be susceptible to deformation during concrete placement if the pumping pressure is not properly managed. The integration of pumping pressure analysis into the design process, alongside weld quality control and tube dimensional accuracy checks, is essential for ensuring the integrity of CFST columns in large-scale industrial projects.