January 9, 2026
As the main bridge type of highway traffic construction in our country, simple support T-beam bridge has become the most widely used prefabricated bridge structure by virtue of its simple structure, convenient construction and clear stress. Its standardized design significantly improves construction efficiency, and the main beams are connected by 4~6 meters spacing transverse beams, which reduces the difficulty of construction while ensuring integrity. This bridge type has significant economic advantages within the span range of 10~25 meters (reinforced concrete beams 10~16 meters, prestressed concrete beams can reach 25 meters), and provides important support for the construction of our country's road network.
However, with the increase of operating life, the disease problem of T-beam bridges has become increasingly prominent, and engineering accidents caused by structural defects are not uncommon. The results show that such diseases are mostly related to material aging, load exceedance and early design limitations. In order to ensure the safety of bridge service, it has become a top priority to systematically analyze the causes of diseases and formulate targeted reinforcement plans.
Common diseases and causes of T-beam bridges
According to the location of common diseases, it can be divided into T beams, webs, diaphragms, and bearings, and their specific diseases and causes are as follows.
Cracks in the beam end and wing plate
The oblique cracking of the beam end and the longitudinal cracking of the wing plate may be defective in the design or caused by excessive shear force on the web during later maintenance and improper management of overrun vehicles. The shear resistance of the beam end near the support is insufficient, and finally the beam end is cracked diagonally.
Transverse cracks in the flange plate
The beam end deteriorated
It mostly occurs on the side of the abutment, because the expansion joint is in disrepair, resulting in rainwater and other intrusion into the expansion joint, and the corrosion of the concrete by the water flow or caused by construction defects.
Deterioration of the baseplate
The diaphragm is cracked
One reason is that the position of the diaphragm is not installed in place due to improper operation during construction, and the transverse beam is weak in transverse connection, and the diaphragm is prone to cracking. Another reason is improper management and maintenance in the later stage.
Broken diaphragm (left) and cracking (right)
The support is empty
It mostly occurs in bridges with simple support first and then continuous structure, because the longitudinal slope of the bridge is large, and the T beam itself is not set up with steel plates to adjust the bearing to balance the force, or the adjacent bearings are placed roughly in the construction, so they cannot be stressed together, so the bearing is hollowed. It can be seen that the bridge disease caused by improper construction can be reasonably avoided.
The shear deformation of the bearing is too large
Common diseases such as excessive shear deformation of bearings on continuous beam end bearings are caused by improper management and maintenance of the bridge in the later stage, resulting in large shear deformation and impact load at the beam end support, which can easily lead to concrete bulging and cracking at the beam bearing.
Concrete fracturing, spalling
Some T-beams have concrete fracturing and spalling caused by the death of the beam end, which may be due to the length exceeding the design length or installation misalignment during the prefabrication of the beam.
The mud on the beams peeled off
The bridge deck cracks longitudinally
The longitudinal cracking of the T-beam bridge deck is often dewelded by the welding of the lower flange plate at the splicing of the diaphragm, resulting in the beam not being able to become a complete whole, and the transverse parts have large mobility and dislocation cracks.
The bridge deck cracks longitudinally
Reinforcement methods for T-beam bridge diseases
Nowadays, the management, maintenance and reinforcement of bridge structures have gradually become a focus of structural engineering. Most of the T-beam bridges use prefabricated assembly structures, which are spliced together by various prefabricated components to form a structural whole, so the reinforcement methods commonly used for T-beam bridges are as follows.
Paste reinforcement method
This method mainly solves the tensile problem of the bridge and improves the integrity of the structure, thereby enhancing the bearing capacity and durability of the bridge. The calculation process and construction process of the reinforcement of the old stone arch bridge by the pasted steel plate method illustrate the applicability and effectiveness of the pasted steel plate method in reinforcement.
Paste reinforcement method
This reinforcement method can be applied to the reinforcement and repair of different parts of the structure, through the actual engineering fiber material reinforcement construction case, the carbon fiber cloth reinforcement method is simple and fast, and the reinforcement effect is good. The characteristics of this reinforcement method are that it will not complete the damage to the original structure; The construction quality is easy to control; Cost-effective and short construction periods; The problem is that if there is a problem with the binder, this method will fail.
Prestressed carbon fiber cloth reinforcement method
Carbon fiber materials have high strength, high elastic modulus, low density, and small linear expansion coefficient. It can greatly improve the ductility and bearing capacity of the components while increasing the dead weight almost without increasing the dead weight. Usually, carbon fiber cloth is pasted on the bottom and both sides of the T-beam web, and the carbon fiber cloth is tensioned and prestressed, which can give full play to the high strength characteristics of the material, improve the stress performance in the structural use stage, and solve the problem of stress hysteresis of carbon fiber cloth reinforcement.
The experiments show that the strength of the carbon fiber cloth is fully utilized to reinforce the beam with prestressed carbon fiber cloth, which improves the structural properties of the beam and significantly improves the reinforcement effect. Wan Qiushi et al. use prestressed CFRP to reinforce concrete beams, which can reduce deflection, enhance stiffness, and increase yield load.
Prestressed carbon fiber cloth reinforcement method
Increase the cross-sectional reinforcement method
The cross-section is often enlarged at the horseshoe position of the T-beam, and longitudinal steel bars are implanted at the increased horseshoe position. The results show that the stiffness, stability and overall stress performance of the bridge are improved after the reinforcement of the piers by this method.
Outer steel reinforcement method
This method can improve the strength, stiffness and stability of the component, and can effectively reduce the crack width. The bridge parts it is applicable to include beam bridges, piers, steel frame bridges and bridge foundations. However, the method of increasing the cross-section reinforcement method will increase the dead weight of the structure and have a certain gravitational effect on the whole structure. And the existence of stress hysteresis leads to the reduction of the bearing capacity of the new part and reduces the durability of the structure. Therefore, it can only be used if certain conditions are met.
Fig.3 Enlarged section reinforcement method
Extracorporeal prestress reinforcement method
The bridge becomes a self-balancing system by external prestress tensioning, thereby offsetting the deflection and stress generated by the structure under its own weight and automobile load. At present, with the vigorous development of our country's transportation industry, highways and bridges have been seriously damaged, and the planting capacity has declined. Existing practice has proved that the use of extracorporeal prestress can greatly improve the bearing capacity of highway bridges, have application and promotion value, provide strong technical support for the development of bridge engineering in our country, accelerate the sustainable development of the transportation industry, and contribute to the economic construction of a modern society.
The advantages of using this reinforcement method are:
(1) When the structure has little self-weight or the external load has little effect on its self-weight, this method can adjust and improve the stress condition of the original structure, so as to improve its stiffness and crack resistance.
(2) Economy, the structure has a small weight, and the load transmitted to the pier or foundation is small, and the cost of reinforcing the pier is small;
(3) The reinforcement time does not occupy the opening operation time and improves social benefits;
(4) The treatment of prestress can be arbitrary, that is, its prestress can be retained or released. Therefore, it is very convenient to temporarily reinforce the traffic of heavy vehicles, and at the same time, it can also permanently reinforce the bridge to improve its bearing capacity. The external prestress reinforcement method is suitable for defects in beams, plates, columns and trusses to improve the bearing capacity of the parts.
Extracorporeal prestress reinforcement method
Prestressed steel wire-polymer mortar reinforcement method
This reinforcement method is the perfect combination of the internal prestress reinforcement method and the MPC composite reinforcement method, and the process flow is to thread the prestressed steel bundle at the bottom of the T beam, tension the prestressed steel bundle, pour MPC high-toughness polymer concrete at the bottom of the beam, and also use MPC high-toughness polymer concrete to pour the anchor head after curing. Relying on the Zhongxing Bridge in Fangzheng County, the prestressed steel wire-polymer mortar reinforcement method was used to reinforce it, and the load test results showed that the reinforcement method could effectively improve the bending bearing capacity of the T-beam bridge and significantly reduce the structural deflection.
Fig.5 Reinforcement method of prestressed steel wire-polymer mortar
Steel-UHPFRC combined reinforcement method
This reinforcement method is reinforced with concrete and steel plates at the horseshoe and web position of the T beam. Steel-UHPFRC combined reinforcement test of flexural bearing capacity of full-foot concrete T beam The steel-UHPFRC combined reinforcement method uses ultra-high performance fiber concrete (UHPFRC), and the compressive strength of the concrete is about 150MPa~200MPa, and the tensile strength is about 7MPa~11MPa.
Schematic diagram of concrete T-beam bending reinforcement structure
Through these reinforcement methods, it can be clarified that the cause of defects should be clarified before reinforcement, and then the specific reinforcement methods should be clarified for the requirements of different disease locations, different bearing capacities, structural types and applications of bridges. The paste reinforcement method can be applied to the reinforcement and repair of damage to different parts of the structure due to tension. Carbon fiber reinforcement can be used for the bending and oblique section shear reinforcement of concrete beams, as well as the reinforcement of columns with insufficient compressive bearing capacity, the reinforcement to increase seismic ductility, and the repair and reinforcement after earthquake damage. The bridge parts applicable to the enlarged section method include beam bridges, piers, steel frame bridges and bridge foundations. The prestressed wire-polymer mortar reinforcement method is used for defects caused by bending, compression and tension.
The large-scale application of simple-supported T-girder bridges in our country provides important support for transportation development, but the problem of diseases during operation also exposes the shortcomings of design, construction and maintenance. At present, the application of new material technologies such as prestressed steel wire-polymer mortar reinforcement method and steel-UHPFRC combined reinforcement method has further improved the reinforcement effect and durability.
In the future, bridge maintenance work needs to focus on intelligent detection, such as UAV inspection, three-dimensional modeling, standardized construction, reducing bearing voiding, etc., which can avoid diseases, material innovation to promote the application of materials such as UHPFRC, and full-cycle management to establish a closed-loop data platform, with the iteration of technology and management upgrades, the service safety and economy of our country's T-beam bridges will continue to be optimized, providing a more reliable guarantee for the high-quality development of transportation infrastructure.
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Westcoast New Area, Qingdao City ,Shandong Province ,China
