Do You Know The Structural Classification Of Steel Bridges?

Portal rigid frame bridge

Its legs and beams intersect vertically to form a gate-shaped structure, which can be divided into single-span gate structure, double cantilever single-span gate structure, multi-span gate structure and three-span two-leg gate bridge. The first three types of spanning capacity are not large, and they are suitable for flyover bridges. They require good geological conditions and can be constructed with steel and reinforced concrete structures. A three-span, two-leg portal bridge with abutments at both ends. When constructed with a prestressed concrete structure, the span can reach more than 200 meters.

Inclined leg rigid frame bridge

The piers are rigid frame bridges with diagonal support, the bending moments on the legs and beams are significantly reduced compared to the portal rigid frame bridges of the same span, while the axial pressure is increased; compared with deck arch bridges, no arch is required Go up the building to simplify the structure. The bridge is beautiful, magnificent, and has a large span. It is suitable for canyon bridges and high-grade highway bridges, and is mostly constructed with steel and prestressed concrete structures. For example, the Ankang Han River Bridge (railway bridge), with a distance of 176 meters between the toes, was completed in 1982.

T-shaped rigid frame bridge

It was produced under the influence of cantilever construction on the basis of simply supported prestressed bridges and large-span reinforced concrete box girder bridges. The upper structure can be box girder, truss or truss arch, which is consolidated with the pier to form a whole. The bridge is beautiful, magnificent and light. It is suitable for large-span cantilever balanced construction. It can cross deep water rapids without support to avoid construction difficulties in the lower part or interruption of shipping. , No system conversion is required, and the construction is simple.

T-shaped rigid frame can be divided into T-shaped rigid frame bridge with hanging beam structure and T-shaped rigid frame bridge with shear hinge structure.

Continuous rigid frame bridge

The multi-span rigid frame bridges with continuous beams and the multi-span continuous rigid frame bridges all use prestressed concrete structures. There are two or more main piers that are consolidated by piers and beams, which have the advantages of T-shaped rigid frame bridges. However, compared with similar bridges (such as continuous beam bridges and T-shaped rigid frame bridges): multi-span rigid frame bridges maintain the properties of continuous beams in the superstructure, with large spanning capacity, low construction difficulty, smooth driving, simple maintenance, and relatively low cost. Low, such as the Luoxi Bridge in Guangdong. The multi-span continuous rigid frame bridge is hinged in the middle of the main span, and the spans on both sides are continuous systems. The weight of the continuous beams on the side spans can be used to make the T structure a cantilever of unequal length to increase the span of the main span.

Continuous beam bridge is an ancient structural system, which has the advantages of small deformation, good structural rigidity, smooth and comfortable driving, few expansion joints, simple maintenance, and strong earthquake resistance. However, due to the limitation of construction methods, the spans of continuous beams 50 years ago were all below 100 meters. With the emergence of construction methods such as cantilever and cantilever, T-shaped rigid frames were produced. In the 1960s, almost all large-span prestressed concrete girder bridges with spans ranging from 100 to 200m were the winning solutions. The early typical bridges are the Holmes Bridge built in 1953 in the Federal Republic of Germany and the Koblenz Bridge built in 1954. However, this structure has hinges in the middle and is resistant to creep and shrinkage of the concrete. Insufficient estimation, and due to the influence of temperature and other factors, the structure forms an obvious broken line deformation state at the hinge, which is unfavorable for driving. Therefore, a continuous beam rigid frame bridge type that is advantageous for driving has appeared. The Bendorf Bridge in Federal Germany built in the 1960s has initially embodied the arrangement of the combination of T-shaped rigid frame and continuous beam system, and the thick T-shaped rigid frame piers have been replaced by thin flexible piers. Some of the following famous bridges The example also uses a similar structure. In this way, a flexible thin pier (the thickness of the pier wall is generally 0.2-0.3 fulcrum beam height) and a coupling beam rigid frame system in the form of pier and beam consolidation are gradually formed.