In the field of modern bridge engineering, structural safety, durability, and span breakthroughs have always been the core goals pursued by the industry. With the increasing traffic load and the extension of bridge construction towards long spans and complex terrains, the drawbacks of traditional concrete structures—such as proneness to cracking and insufficient stiffness—have become increasingly prominent. The emergence and application of prestressed technology have provided a key solution to this problem. As an advanced technology that optimizes structural stress states by pre-applying stress, prestressed technology not only significantly improves the crack resistance and bearing capacity of concrete components but also effectively saves materials and reduces construction costs, making it one of the core technologies driving the high-quality development of bridge engineering. This article will explore the basic principles, construction characteristics, application scope, and common problems of prestressed technology, aiming to provide a reference for an in-depth understanding of its practical value in bridge engineering.

1. Basic Principles of Prestress

Prestress refers to the stress pre-applied in structural design to offset or reduce the impact of future loads on the structure. Its basic principle is to pre-apply a certain degree of stress to the structure, enabling it to better adapt to load requirements when bearing future loads, thereby improving structural safety and durability. In prestressed concrete structures, the core idea is to pre-apply a certain pressure to the tensile zone of the structure before it bears external loads. This pre-compression measure is intended to effectively offset the concrete tensile stress caused by external loads, thereby reducing the tensile stress, ensuring that the component maintains its structural integrity and stability during service, delaying or even avoiding cracking, and thus significantly enhancing the component’s crack resistance and overall stiffness.

2. Characteristics of Prestressed Construction Technology

Prestressed construction technology is mostly applied to concrete structures. It mainly involves pre-applying a certain pressure to the concrete structure before it bears loads, so that the concrete in the tensile zone can generate corresponding compressive stress under external loads, thereby offsetting or reducing the tensile stress caused by external loads. Due to its advantages of light self-weight, high strength, large stiffness, and excellent bending resistance, shear resistance, and fatigue resistance, prestressed concrete technology has demonstrated significant advantages in long-span and heavy-load structures. According to different tensioning methods, prestressed concrete technology can be divided into pre-tensioning method and post-tensioning method, each with its own construction process and characteristics.

3. Application Scope and Importance in Bridge Construction

Prestressed technology is one of the key technologies in highway bridge construction, with unique advantages and value. Applying prestressed technology to handle flexural and tensile components of highway bridge structures can fully enhance component performance, improve structural stability, and ensure project quality. The application of prestressed technology can fully tap the potential of bridge materials, alter the intrnal micro-structure of the bridge, and allow various components to adapt to pressure in advance, thereby effectively improving the bridge’s stability and rigidity. Addietionally, prestressed technology can effectively save materials used in bridge construction and reduce construction costs. In practical construction, for highway bridge projects with high construction difficulty and long spans, prestressed technology can effectively improve the tensile capacity of concrete components, reduce the load on concrete, thereby reducing the possibility of concrete cracking, enhancing the stability of highway bridges, and improving project quality.

4. Common Problems in Prestressed Construction of Bridge Engineering

4.1 Excessive Prestress Loss

Excessive prestress loss is a common and urgent problem in the prestressed construction of bridge engineering. The occurrence of this problem often results in the actual stress value of prestressed tendons being much lower than the design expectation, which in turn affects the bearing capacity and durability of the bridge structure. The causes of excessive prestress loss are complex and diverse: it may stem from anchor slippage or wire breakage inside the steel strands, preventing effective transmission of prestress; it may also be due to the relaxation rate of the steel bundles exceeding the specified range, leading to a gradual decrease in prestress under long-term action. Errors in measuring equipment and prestress release caused by local concrete damage can also induce excessive prestress loss. This problem not only increases construction difficulty and costs but also may pose potential threats to the safe use of the bridge.

4.2 Duct Blockage

Duct blockage is a common and intractable problem during the prestressed construction of bridge engineering. As a key channel for threading and tensioning prestressed tendons, the unobstructed nature of the duct is crucial to ensuring the effect of prestress application. In practical construction, duct blockage may be caused by various factors: for example, the damage or displacement of duct-forming materials such as corrugated pipes during installation or concrete pouring, or the infiltration of concrete slurry into the duct due to excessive vibration during concrete pouring. Duct blockage not only affects the normal threading and tensioning of prestressed tendons, resulting in ineffective transmission of prestress to the entire structure but also may cause damage to the prestressed tendons, seriously affecting the bearing capacity and service life of the bridge.

In summary, relying on its unique stress optimization principle and significant engineering advantages, prestressed technology has become an indispensable key technology in modern bridge engineering. Its application not only effectively solves the structural problems of long-span and heavy-load bridges but also promotes the dual improvement of bridge engineering in economy and durability. However, common problems such as excessive prestress loss and duct blockage in the prestressed construction process still require continuous exploration and optimization of solutions in practice. To further exert the application value of prestressed technology, the next article will focus on the specific applications of prestressed technology in bridge construction.