classification of bridges and types of span structures.
Span structures are distinguished constructively, according to the design scheme of the facility and the material of manufacture. For each specific case, a certain type is selected, taking into account the terms of reference and the existing conditions.
Depending on the initial data and operating conditions for each concrete structure, engineers select the optimal design that determines the type of bridge and its main physical and operational characteristics and makes up a scheme of span structures.
constructions of span structures.
- A beam span structure. Differences consist in the features of overlapping of span of beams and perceived loads. The forces on the supports are predominantly vertical.
- Fermen span structure. Distinguish split and continuous farms, the differences are in the features of overlapping spans of farms and perceived loads. And also the farms are distinguished by the level of the location of travel for vehicles, farms with driving at the bottom, at the top and in the middle.
- Arched span structure. The span is made in the form of an arch that holds loads. Horizontal forces are converted into vertical forces, the bridge works on compression.
Combined type constructions. Combine the same arched and girder principle design schemes. They have universal application. Frame span structure. Can have a T- or U-shaped appearance, span structures – crossbars, supports – construction sites. Hanging span structure. Intermediate supports are not installed, the supporting structure of flexible units, the fastening is made to the pylons.
Hanging span structure. Intermediate supports are not installed
By the mutual arrangement of the arches (arches) and the roadway, bridges with riding over the top are distinguished – when the carriageway is located above the arches, with the ride below – when the carriageway is located under the arches, and with the ride in the middle (for this type there is also the name “with a lower ride” ) – when the carriageway is located between the arches.
Arched bridges with lower ride often do with a tightening, perceiving the archway. This allows instead of massive support supports, perceiving and transmitting to the ground, in addition to vertical loads, also the spacing forces of the arch, to use lighter supports, on which only vertical loads act. Arched bridges with a tightening can be installed on weak grounds.