Connection Performance of Threaded Sleeve Grouting in Prefabricated Steel Tube Concrete Shear Walls

Literature Overview

The paper by Yan Wenshang, Chen Jianwei, and Su Youpo, published in 2014 in Engineering Earthquake Resistance and Retrofitting (Volume 36, Issue 6, pages 13–19), presents a quasi-static test study on steel tube connection nodes for prefabricated steel tube concrete shear walls. Funded by the National Natural Science Foundation of China (Grant 51278164) and the Hebei Provincial Natural Science Foundation (Grant E2014209221), the research was conducted at Hebei United University's School of Architectural Engineering. This work addresses a critical gap in prefabricated structural engineering: the reliable joining of precast steel tube concrete shear wall panels through threaded sleeve grouting connections.

Connection Method Description

The proposed connection method employs a threaded sleeve grouting technique. The prefabricated steel tube concrete shear wall panels are joined at their interfaces through threaded sleeves embedded in the steel tubes, with high-strength grout material injected to create a monolithic bond. The study investigated two key variables: the presence or absence of local reinforcement zones at the connection interface, and different grouting methods. Five test specimens were fabricated and subjected to quasi-static loading to evaluate the connection performance.

The following table summarizes the specimen configurations:

Specimen	Reinforcement Zone	Grouting Method	Key Variable
Specimen 1	Without reinforcement	Standard grouting	Baseline
Specimen 2	With reinforcement	Standard grouting	Reinforcement effect
Specimen 3	Without reinforcement	Bottom-up grouting	Grouting method effect
Specimen 4	With reinforcement	Bottom-up grouting	Combined optimization
Specimen 5	Additional configuration	Additional configuration	Supplementary validation

Key Findings and Technical Analysis

The test results confirm that the threaded sleeve grouting connection method is structurally reliable and capable of meeting design requirements for prefabricated steel tube concrete shear walls. A particularly important finding is that bottom-up grouting is more effective in improving the load-bearing capacity of the specimens compared to standard grouting methods. This is attributed to the gravity-assisted filling of the grout, which minimizes voids and ensures complete encapsulation of the threaded sleeve interface.

The ultimate bond strength between the grout material and the steel tube at the connection seam was calculated to be approximately 0.33 to 0.34 times the compressive strength of the internal grout material. This empirical relationship provides a practical design parameter for engineers specifying grout grades and connection dimensions. The bond strength ratio is consistent with the general behavior of cementitious grouts bonded to steel surfaces, where the interfacial adhesion is typically governed by the weaker of the two materials.

Process Analysis and Quality Control Considerations

From a welding and fabrication quality control perspective, several critical process parameters govern the reliability of threaded sleeve grouting connections. The threaded sleeve must be precisely manufactured with tight dimensional tolerances to ensure proper engagement with the grout. The grouting process itself requires careful control of injection pressure, temperature, and mix ratio to prevent honeycombing or incomplete filling.

The following table presents key quality control parameters for the grouting process:

Parameter	Recommended Range	Control Method
Grout compressive strength	Per design specification	Cube test per ASTM C109
Bond strength ratio	0.33–0.34 × grout compressive strength	Pull-out test per ASTM C1044
Grouting temperature	15–30 °C	Thermometer monitoring
Injection pressure	Per manufacturer specification	Pressure gauge
Sleeve dimensional tolerance	±0.1 mm	CMM or micrometer

The study's finding that bottom-up grouting is superior has direct implications for construction methodology. Engineers should specify bottom-up grouting in construction drawings and provide detailed method statements for field crews. Quality assurance protocols should include ultrasonic testing of the grouted joints to verify complete filling and absence of voids.

Engineering Practice Integration

For prefabricated steel tube concrete shear wall systems, the threaded sleeve grouting connection offers several advantages over welded or bolted alternatives. The connection provides a monolithic joint that maintains structural continuity under seismic loading, which is essential for shear wall performance. The prefabrication approach reduces on-site construction time and improves overall construction quality by shifting critical fabrication work to controlled workshop environments.

However, engineers must carefully consider the interaction between the connection and the overall shear wall behavior. The connection stiffness should be compatible with the shear wall design to avoid unintended stress concentrations. The study demonstrates that reinforcement zones at the connection interface improve performance, suggesting that local thickening or additional steel reinforcement should be incorporated into the prefabricated panel design near connection locations.

Critical Reflection and Study Insights

This research provides valuable experimental data on a practical prefabricated connection method for steel tube concrete shear walls. The empirical bond strength ratio of 0.33–0.34 is a useful design parameter, though it should be validated for different grout compositions and steel surface conditions. The study's limitation lies in its focus on quasi-static loading; seismic performance under dynamic loading conditions requires further investigation through shake table testing or dynamic analysis. Nevertheless, the work establishes a foundation for the practical application of threaded sleeve grouting connections in prefabricated steel tube concrete structures, and the findings directly inform construction methodology and quality control protocols.