Bridge Engineering Basics

10 Questions

What is the primary function of diaphragms in a slab-on-girder bridge superstructure?

To connect the girders and form a frame

What is the typical material used for the girder in a slab-on-girder bridge superstructure?

Either steel or precast-prestressed concrete beams

What is the primary advantage of using prefabricated primary members in a slab-on-girder bridge superstructure?

It allows for quick erection and an economy of materials

What is the typical maximum span length for a slab-on-girder bridge superstructure with steel girders?

300 ft

What is the primary purpose of the concrete slab in a slab-on-girder bridge superstructure?

To resist the wear of traffic and support the traffic load

What is the disadvantage of using a slab-on-girder bridge superstructure?

It is only suitable for short-to-medium span lengths

What is the purpose of the wearing surface in a slab-on-girder bridge superstructure?

To provide a durable surface for traffic

What is the typical maximum span length for a slab-on-girder bridge superstructure with prestressed concrete girders?

160 ft

What is the primary benefit of using a slab-on-girder bridge superstructure with a thicker slab to create an integrated wearing surface?

It eliminates the need for a separate wearing surface

What is the advantage of using readily available materials in a slab-on-girder bridge superstructure?

It provides an economy of materials

Study Notes

Bridge Engineering

Bridge engineering is a branch of civil engineering that involves the planning, design, construction, operation, maintenance, and rehabilitation of bridges to ensure safe and effective transportation of vehicles, people, and goods.
A bridge is a key element in a transportation system, and balance must be achieved between handling future traffic volume and loads and the cost of a heavier and wider bridge structure.
Strength and measures to prevent deterioration are crucial considerations in bridge engineering.

Importance of Bridge Engineering

Bridge engineering is important because a bridge's failure can cause system failure, and it has the highest cost per mile.
The designer of new bridges must make wise decisions to balance capacity and cost, and ensure safety is not compromised.

History of Bridge Engineering

The modern highway bridge originated from the Industrial Revolution, which began in the last half of the eighteenth century and saw the emergence of cast iron, wrought iron, and finally steel for bridges.
The use of reinforced concrete in bridges began in 1824 with Joseph Aspdin's production of Portland cement.
Prestressing construction techniques were first developed by the French engineer Ernest Freyssinet in the 1920s.

Origins of the Modern Highway Bridge

The development of bridges began with the stone arch by the Roman engineers of the second and first centuries BC.
The Renaissance period saw the building of beautiful bridges across Europe during the fourteenth through seventeenth centuries.

Bridge Engineering Terms

Appurtenances and Site-Related Features: any part of the bridge or bridge site that is not a major structural component yet serves some purpose in the overall functionality of the structure (e.g., guardrail).
Major Appurtenances and Site-Related Features: include slope protection, which provides for proper drainage and erosion control, and underdrain, which is a drainage system that transports runoff away from the structure.

Structure Types

Slab-on-girder: a bridge superstructure consisting of a concrete slab resting on a set of girders, which are connected by diaphragms to form a frame.
Advantages of slab-on-girder: simple design, uniform design that can be standardized easily, and economical repair methods.
Disadvantage of slab-on-girder: suitable for short-to-medium span lengths (up to 300 ft [91 m] for steel girders and 160 ft [49 m] for prestressed concrete girders).