What Is a Highway Bridge?

Highway bridges are built for highway vehicles and pedestrians. The highway bridge is made of steel, reinforced concrete or wood, and it is designed for heavy-duty rolling loads of up to 0.8 million tons (80,000 tons) to crowds. The width of the driving part depends on the expected intensity and speed of the traffic and the shape and span of the bridge (usually 7-21 meters). The sidewalk is at least 1 meter wide.

Classified by use

Divided into highway bridges, highway and railway bridges, pedestrian bridges, machine-cultivated bridges, and water bridges by use;

Classified by useful life

It can be divided into permanent bridge, semi-permanent bridge and temporary bridge according to the service life;

Classification by structural system

Based on the main load-bearing members, it can be divided into five categories: beam bridges, arch bridges, rigid frame bridges, cable-stayed bridges, and suspension bridges.

1) Beam bridge

The main beam is the main load bearing ^[1]

With the development of bridge seismic engineering ^[3] and the summary of earthquake damage experience, the method of seismic vulnerability assessment of highway bridges has been revised several times. The main purpose of this work is to identify the seismic weak points of these highway bridges without complicated calculations at the site.

Through statistical analysis, the factors affecting the seismic resistance of highway bridges are divided into two categories for measurement and research. The damage degree is classified according to high weakness (A grade), medium weakness (B grade), and low weakness (C grade) (as shown in Table 1). An analysis of previous earthquake damage identified 15 projects that affected the seismic vulnerability of bridges. These 15 items are mainly composed of four factors, namely: ground motion intensity; superstructure and foundation structural characteristics; superstructure anti-slump facilities; site components. Each item is divided into several levels.

Table 1 Division of seismic vulnerability

grade	Vulnerability to earthquake damage	Destruction Degree
Class A high vulnerability	The probability of encountering damage or the degree of damage is large	5 Superstructure falling beam 4 Serious damage
Class B high vulnerability	The probability of encountering damage or damage is medium	3 Moderate damage
Class C low vulnerability	Less probable or destructive	2 Minor damage 1 Minor damage 0 No damage