With the evolution of global transportation infrastructure towards large span, light weight and long life, high-strength steel bridges have become the preferred solution for complex terrains such as river crossings and mountain valleys due to their excellent mechanical properties and engineering economy. This paper systematically analyzes the core competitiveness of high-strength steel bridges from the dimensions of material innovation, structural design, construction technology and whole life cycle management.

I. Material and process innovation

Application of ultra-high strength steel

The main material adopts Q420D and Q460E high-performance bridge steel, with yield strength ≥420MPa, tensile strength ≥540MPa, and -40℃ low-temperature impact function ≥47J.

The key stress components use S690QL tempered steel (yield strength ≥ 690MPa), the weight of components under the same load is 40% less than that of traditional steel.

Advanced Manufacturing Process

Rolling of steel plate adopts TMCP (controlled rolling and cooling) technology, with grain size of more than 12 grades and Z-direction anti-laminar tearing performance of ≥35%.

Welding process integrates narrow-gap submerged arc welding (NG-SAW) and laser-MAG composite welding, increasing the toughness of weld seam by 50%.

Structural design advantages

Ultra-large span realization ability

Box girder, truss girder, combined girder and other structural systems, single span up to 1800 meters (suspension bridge), compared with the concrete structure span increased by 3 times.

Typical case: the main girder of a sea-crossing bridge adopts double-layer steel box girder, with a dead weight of only 32 tons/extended meter, which is a 28% weight reduction compared with the traditional solution.

Seismic and fatigue resistant design

Energy dissipating dampers are installed in the node area, and the displacement angle is ≤1/250 under the working condition of 0.3g seismic acceleration.

Applying IIW (International Institute of Welding) anti-fatigue design specification, the stress amplitude under 2 million times of cyclic loading is ≤90MPa.

Breakthrough in modular construction

The largest prefabricated unit reaches 60m×40m×12m, the factory manufacturing rate reaches 85%, and the precision of on-site assembling is ±2mm.

A mountain bridge project adopts jacking construction technology, with a single-day advance speed of 15 meters, shortening the construction period by 45%.

Third, the whole scene application field

Sea-crossing passage project

Orthogonal anisotropic steel bridge panels + waterproof pavement system, design life increased to 120 years

A deep-water channel bridge with a navigable clear height of 80 meters, the main girder height-to-span ratio optimized to 1/40, saving 3000 tons of steel.

Urban three-dimensional transportation

Steel-concrete combined girder bridge realizes 45m span unsupported construction, adapting to the complex pipeline environment in the city.

Integrated design of fully enclosed sound barrier reduces traffic noise by 25dB(A).

Heavy Duty Railway Bridge

Variable cross-section continuous steel truss girder under 30-ton axle weight condition, flexure-to-span ratio ≤1/800

Bolt connection nodes account for more than 90%, realizing maintenance-free during operation period

IV. Core technical parameters

Contact

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