The fundamental reason for choosing prestressing FRP system technology to reinforce bridges is that it actively and efficiently solves the core problems of bridge structure - insufficient crack resistance and bearing capacity.

The following is a detailed explanation, divided into several levels:

1. Core principle: From "passive" reinforcement to "active" reinforcement

Traditional (passive) reinforcement: such as pasting steel plates or carbon fiber cloth (non prestressed). These methods involve patching the structure after it has been subjected to stress and deformation. They can only share the subsequent additional loads, but cannot eliminate existing cracks, deformations, and stresses. The structure is actually working with defects, and the efficiency of reinforcing materials is relatively low.

Pre stressing (active) reinforcement: It is like injecting a reverse energy into the structure before reinforcement. By tensioning high-strength materials (steel strands or FRP), a beneficial prestress is actively applied to the structure.

It can be metaphorically described as follows:

Passive reinforcement: like sticking a book with loose pages together with tape.

Pre stressing reinforcement: It's like using a rubber band to tightly tie up a book, giving it a continuous "holding force" before it falls apart.

2. Why is this' proactive 'force so effective?

The "reverse load" generated by prestressing can directly solve several major problems of bridges:

a) Significantly improve stiffness and crack resistance

The root cause of excessive downward deflection (downward bending) of the bridge under load is the excessive tensile stress at the bottom of the concrete beam, which leads to cracking. Pre stressing reinforcement effectively counteracts the tensile stress generated by the load by applying a reverse pressure at the bottom of the beam.

Result: The crack width is reduced or even completely closed, the stiffness of the bridge is restored, and the deflection deformation is significantly reduced. When the vehicle passes by, it feels more "tough" and the smoothness of driving is greatly improved.

b) Fully utilize the properties of high-strength materials

Pre stressing technology forces high-strength reinforcement materials (such as carbon plates and steel strands) to be in a high stress state from the beginning, allowing them to fully exert their extremely high tensile strength throughout the entire stress process. In contrast, non prestressed reinforcement materials can only gradually come into play when the bridge undergoes significant deformation, resulting in a low utilization rate.

c) Significantly increase the carrying capacity

Due to the prestress offsetting most or even all of the stress generated by external loads, the structure can withstand much larger loads than before before before reaching its stress limit. This means that the load-bearing capacity of the bridge, such as its ability to withstand heavier vehicles, has been fundamentally improved.

d) Realize stress redistribution and improve structural stress performance

Pre stressing can alter the internal force flow of a structure, transferring forces from weak areas to stronger areas, and even improving the stress state of other parts of the bridge (such as piers and supports), optimizing overall structural performance.

3. Advantages compared to other reinforcement methods

4. Unique advantages of prestressed FRP reinforcement

The prestressed FRP (fiber-reinforced composite material) you mentioned in Horse in Action combines the advantages of traditional prestressing technology with the advantages of new materials:

High strength and lightweight: FRP material has extremely high strength and light weight, which will not significantly burden the bridge.

Corrosion resistance: Compared with traditional prestressed steel strands, FRP materials such as carbon fiber never corrode and are very suitable for harsh environments such as humidity, de icing salt, etc., with low life cycle cost.

Convenient construction: A single FRP laminate is lightweight and does not require large lifting equipment. It can be manually transported and tensioned, making it very suitable for construction on busy bridges without interrupting traffic or short-term flow restrictions.

In summary, choosing prestressing (especially prestressed FRP) to strengthen bridges is because it:

• Transforming from passive to active, fundamentally improving the stress state of the structure.

• Efficiently and thoroughly solve core diseases such as insufficient stiffness, excessive deflection, and wide cracks

• Significantly increase the bearing capacity, allowing the old bridge to meet the load requirements of modern transportation.

• High material utilization and cost-effectiveness, providing long-term durability and lower maintenance costs.

• The construction has minimal impact and is an advanced solution for achieving rapid reinforcement without or with minimal interruption to traffic.