What factors influence the choice between concrete and steel in a bridge?

A concrete building inherently has a 1- to 3-hour fire rating without special fireproofing or other details. Structural steel or timber buildings must be fireproofed to attain similar fire ratings. 4. Rigidity.

Why were the twin towers made of steel?

It was designed to resist a wind load of 2 kPa—a total of lateral load of 5,000 t. In order to make each tower capable of withstanding this wind load, the architects selected a lightweight “perimeter tube” design consisting of 244 exterior columns of 36 cm square steel box section on 100 cm centers (see Figure 3).

What made the twin towers unique?

The twin towers were built as a steel tubular structural system that differed radically from other structures of that time. The exterior walls were built of closely spaced steel columns to perform as load bearing walls and the interior columns were located only in the core area containing the elevators.

Why is concrete good for bridges?

Concrete as a locally-sourced material with low environmental and social impacts, it lends itself to structures with a typical design life of at least 100 years with low maintenance requirements, thereby providing a sustainable solution for bridge construction.

What are the advantages of steel over concrete?

Steel is a highly durable metal. It can withstand a considerable amount of external pressure. Hence, steel structures are earthquake resistant whereas concrete structures are brittle. Concrete is not as resistant as steel.

Why steel is used in bridges?

Steel is an ideal material for bridges. It is an essential part of modern bridges because it is strong, can flex without fracturing and has a long life, even in the harshest conditions. It can be used to build bridges of any length because of its durability and ease of manufacture and maintenance.

How is concrete used in bridges?

Concrete is commonly used for many bridge superstructure members such as decks, pre-stressed concrete beams, curbs, sidewalks and parapets (side traffic barrier walls). It can also be used for cast-in-place or precast concrete piles to support the abutments and piers.

What is the difference between concrete and steel?

Concrete is a conventionally used material for construction while steel is now gaining momentum for its flexibility and reduced construction time. However, steel needs fire protection whereas within concrete this is inherent. Prefabrication of steel can allow thin film intumescent coatings to be applied offsite.