Bridge

A bridge is a structure built to span physical obstacles such as rivers, lakes, roads, railways, ravines, or other geographic or artificial barriers. Its primary purpose is to provide passage over the obstacle, facilitating the movement of automobiles, trains, and pedestrians, but it may also accommodate pipelines, utility lines, buildings, wildlife crossings, and even canals.

Bridges are classified into several structural types based on their design and construction. The principal styles include arch, truss, beam, cantilever, suspension, and cable-stayed. Less common forms include moveable bridges, double deck bridges, pontoon bridges, and military bridges. Bridges can also be categorized by their materials, which include wood, brick, stone, iron, steel, and concrete.

The history of bridge building reflects the evolution of engineering knowledge, materials, and construction techniques across different civilizations and eras. The greatest bridge builders of antiquity were the ancient Romans, who built numerous semicircular arch bridges. The Renaissance in 1500s Europe brought a new emphasis on science and engineering, leading to stronger bridges with longer spans. With the advent of the Industrial Revolution, iron became an important construction material for bridges. The abundance of inexpensive lumber in Canada and the United States caused timber bridges to be the most common type of bridge in those countries from the late 1700s to the late 1800s. In the late 1800s, concrete replaced stone and masonry as the primary material for bridge foundations. Steel became a common building material for bridges in the late 1800s, leading to suspension bridges and cable-stayed bridges that spanned long distances.

The designer of a bridge must address a wide range of functional, structural, environmental, and aesthetic requirements to ensure safety, efficiency, and durability. Fundamental requirements include structural strength, stability, and the capacity to provide safe passage for users. In addition to these core functions, designers must consider factors such as cost, aesthetics, expected lifespan, the time frame for construction, client or governmental preferences, and the experience and capabilities of the construction team. To address these complex demands, engineers employ methodologies such as Limit State Design, which ensures that bridges remain functional under both normal and extreme conditions. The finite element analysis method enables detailed modeling of stresses and deformations within the structure. Provided by Wikipedia