Zhuojin Pipe Fitting Co., LtdInfluencing Factors of Wave Attenuation in Steel Pipe Tire Floating Breakwaters
Literature Overview
This paper by Wu Weideng, Zhong Husui, and Huang Jun from Hohai University (2002) investigates the wave-dissipation performance of floating breakwaters constructed with a steel pipe and tire composite structure. The research is grounded in physical model testing and addresses a practical coastal engineering challenge: designing floating breakwaters that maintain high wave attenuation efficiency even under unfavorable incident wave conditions. The study identifies four key structural parameters—raft stiffness, tilt angle, wave-blocking area, and natural frequency—and proposes an improved configuration achieving a minimum wave height transmission coefficient of 0.22.
Core Technical Analysis
The steel pipe serves as the primary structural skeleton, providing buoyancy and structural integrity, while the tire elements contribute energy dissipation through their inherent hysteresis and damping characteristics. From a metallurgical and materials perspective, the steel pipe selection is critical: the material must withstand long-term marine corrosion, cyclic wave loading, and impact from tire components. Typical pipe specifications for such applications include API 5L Grade B or X42 steel, with wall thicknesses ranging from 6 mm to 12 mm depending on the design wave height and pipe diameter.
The four influencing factors identified in the study can be understood through the following framework:
| Parameter | Role in Wave Attenuation | Engineering Consideration |
|---|---|---|
| Raft stiffness | Controls structural deformation under wave load | Higher stiffness reduces hydrodynamic drag but may increase reflected wave energy |
| Tilt angle | Affects wave energy absorption and reflection balance | Optimal tilt angle depends on incident wave period and height |
| Wave-blocking area | Directly relates to the frontal area intercepting wave energy | Larger area increases attenuation but also increases mooring loads |
| Natural frequency | Determines resonance behavior relative to wave frequencies | Must be tuned away from dominant wave frequencies to avoid resonance |
The wave height transmission coefficient of 0.22 achieved by the improved design represents a significant engineering improvement. For context, conventional floating breakwaters typically achieve transmission coefficients in the range of 0.40 to 0.60 under similar conditions, meaning the proposed structure reduces transmitted wave energy by approximately 55 percent compared to conventional designs.
Connection with Engineering Practice
In marine and offshore engineering, the structural integrity of floating breakwater systems is paramount. The steel pipe elements must be fabricated and inspected in accordance with relevant standards such as ISO 15590 for steel pipes or GB/T 8163 for structural steel pipes. Welding quality is particularly critical at the pipe-to-connection joints, where fatigue cracking can initiate under cyclic wave loading. From a quality control standpoint, the following practices should be applied:
- All circumferential and longitudinal welds should be subjected to 100 percent radiographic testing (RT) or ultrasonic testing (UT) in accordance with ISO 17635 or NB/T 47013.
- Magnetic particle testing (MT) or penetrant testing (PT) should be performed on all welds to detect surface-breaking defects.
- Hydrostatic pressure testing at 1.5 times the design pressure should be conducted on each pipe section prior to assembly.
- Corrosion protection systems, including internal coatings and external cathodic protection, should be verified through coating thickness measurements and holiday detection.
The tire elements introduce an additional quality challenge: the rubber-tire interface with the steel pipe requires careful attention to bonding quality. Adhesive bonding or mechanical fastening methods must be evaluated for long-term durability under UV exposure, salt spray, and cyclic mechanical loading. Accelerated weathering tests in accordance with ASTM G154 or GB/T 14522 should be conducted to validate the durability of the tire-to-pipe interface.
Study Insights and Reflections
This paper demonstrates a systematic approach to structural optimization through experimental investigation. The identification of natural frequency as a critical parameter is particularly insightful, as it highlights the importance of dynamic design in floating structures. Engineers should always verify that the natural frequencies of the breakwater structure fall outside the spectral energy concentration band of the local sea state. The proposed improved structure, which increases both wave reflection and energy dissipation while reducing self-generated waves, represents a balanced design philosophy that addresses multiple performance criteria simultaneously. The practical implication is clear: floating breakwater design should be treated as a multi-objective optimization problem where structural stiffness, geometric configuration, and dynamic characteristics must be coordinated rather than optimized independently.