Comment sont construits les ponts modernes à poutres d'acier ?

The whole process is led by high-precision processing in the factory, and high-strength structural steel beams are prefabricated in the factory using BIM modeling, with a precision of at least millimeters. At the same time, the site of the construction site is not idle, and the substructure-that is, the reinforced concrete abutments and piers-must be laid at the same time. This is the foundation.

We will use huge crawler cranes or bridge erecting machines to hoist steel beams to predetermined positions. After the hoisting is in place, they are locked with advanced bolt connection and welding technology. Here I usually stare at torsion shear high-strength bolts and field splicing joints. Bridge decks are laid on the steel beams, and expansion joints, drainage systems and crash barriers are installed to ensure that the structure is stable.

Factory Finishing And BIM Digital Simulation

Modern bridge construction actually began long before the steel arrived. Cutting steel and welding beams in the controlled environment of the factory is much more stable than in the field.

Large projects can’t work without BIM (Building Information Modeling). We have to make a “digital twin” model first, and accurately align the bolt hole position and web thickness of each beam section, and the error must be controlled within a few tenths of a millimeter. You won’t stop work because of rain, and every piece of steel can pass strict stress tests, which is directly related to the bearing capacity of the bridge in the future.

Substructure Foundation And Site Casting

When welding beams in the factory, the substructure is equivalent to the “foundation system” of the bridge “.

Abutment: This thing is installed at both ends of the bridge. It not only has to eat the longitudinal and lateral thrust of the whole bridge, but also has to smoothly connect with the road behind it.

Piers: If it is a multi-span bridge, the middle is all supported by these reinforced concrete piers.

At the scene, I have been staring at the binding quality of high-strength concrete and steel cage. These components have to withstand the earthquake force and the usual environmental corrosion. If the foundation is unstable, it is useless to make the steel structure on it beautiful.

Erection Stage-Lifting And Placement

This step is the most eye-catching and technical content in the whole construction period. After the steel beams are delivered to the site, the real erection begins.

Depending on the terrain, we usually choose different machines:

Crawler crane: as long as the ground is large enough and flat enough, use crawler crane. Strong and stable, it can directly carry heavy steel beams from flatbed trucks or barges to bridge pier supports.

Bridge erecting machine: If you are in a deep mountain valley or where the crane cannot be parked on the ground, you have to rely on the bridge erecting machine. The machine can move between piers like a tightrope, sending steel beams forward section by section.

The accuracy of hoisting is life-saving, and now it all depends on GPS and laser leveling. The steel beam must fit tightly when it falls on the support.

Deep Connection-Bolt And Welding

Now the construction, we attach great importance:

Torsional shear type high-strength bolts : This kind of bolt has a special tail, which will automatically break when screwed to a predetermined torque. The quality control was very intuitive.

Field welding: Some core stress parts must rely on certified welders for deep penetration welding. After welding, I will also arrange ultrasonic flaw detection to ensure that there are no bubbles or cracks in it.

Only when these connection points are made solid, the bridge force will be symmetrical and will not produce local fatigue.

Bridge Deck And Final End

The last big move is to install the bridge deck. Now the mainstream design is “modular concrete slab”. We will first support metal permanent formwork or precast slab between the steel beams, which becomes the mold of cast-in-place concrete.

When the concrete strength comes up, it will work together with the steel beam below “2 into one. Finally, close the end:

Expansion joint: the bridge will expand with heat and shrink with cold, and the road will crack without it.

Drainage system: Don’t let rainwater accumulate, or the steel beams will corrode quickly.

Safety guardrail: reinforced concrete or steel guardrail, that is life-saving things.

Auteur : Robert Sterling
I have specialized in transforming complex structural blueprints into enduring physical landmarks through precision engineering and rigorous site safety. My passion lies in bridging the gap between academic theory and real-world construction, helping the next generation of engineers master the intricacies of modern steel assembly and site management.