Service Life and Influencing Factors of Steel Trestle Bridges

Steel trestle bridges, widely used in temporary or semi-permanent projects such as bridge construction, mining operations, and disaster relief, play a critical role in modern infrastructure. Their service life, typically designed for 10–30 years, is determined by a combination of material properties, environmental conditions, load effects, design quality, and maintenance practices. Understanding these factors is essential for optimizing longevity and ensuring structural safety.

1. Material Properties
The durability of steel directly impacts a trestle bridge’s lifespan. Corrosion resistance is a primary concern, especially in humid, coastal, or industrial environments. For instance, carbon steel in coastal zones may corrode 3–5 times faster than in inland areas due to chloride exposure. Weathering steel (e.g., ASTM A588) or galvanized coatings can reduce corrosion rates by over 20%. Fatigue strength is another key factor; cyclic loads from traffic or machinery induce micro-cracks. Studies show that high-strength steel (e.g., Q345) loses up to 30% of its fatigue resistance after 10⁶ load cycles. Material selection and surface treatments are thus foundational to longevity.

2. Load Conditions
Both static and dynamic loads affect structural integrity. Overloading, such as frequent heavy vehicle traffic, accelerates fatigue damage. A case study revealed that a 20% overload reduced a bridge’s lifespan by 40% due to weld fractures. Impact loads from sudden braking or vibrations also induce stress concentrations. Installing shock-absorbing components (e.g., rubber bearings) can mitigate these effects.

3. Environmental Exposure
Harsh environments significantly shorten service life. Chloride ions from seawater or de-icing salts penetrate protective coatings, causing pitting corrosion. In industrial areas, acid rain (pH <5.6) can erode steel at 0.1–0.3 mm annually. Extreme temperature fluctuations, common in regions with 60°C annual variations, lead to thermal expansion-induced deformations. Effective countermeasures include epoxy coatings, cathodic protection, and expansion joints.

4. Design and Construction Quality
Design flaws or poor workmanship compromise durability. Inadequate drainage systems allow water accumulation, accelerating corrosion; a 1–3% slope design is recommended for efficient runoff. Structural details, such as bolted-welded hybrid joints, reduce stress concentrations at connections. During construction, welding defects (e.g., porosity) can halve fatigue life, necessitating strict quality control via ultrasonic testing. Additionally, hot-dip galvanizing (≥85 μm thickness) extends coating life to over 20 years.

5. Maintenance Strategies
Proactive maintenance is vital for lifespan extension. Regular inspections using drones and AI-based crack detection improve efficiency by 70%. Recoating with fluorocarbon paints every 3–5 years enhances corrosion resistance threefold compared to conventional paints. Replacing components with >10% corrosion loss prevents cascading failures.
The service life of steel trestle bridges hinges on an integrated approach combining corrosion-resistant materials (e.g., S355J2W steel), optimized design, real-time load monitoring, and predictive maintenance. Emerging technologies like IoT sensors for stress-corrosion monitoring offer new avenues for lifecycle management. With systematic strategies, these structures can exceed design expectations, delivering sustainable value for engineering projects.