Bridge reinforcement judgment

For bridge reinforcement, the first thing to determine is whether the bridge needs to be reinforced or not, the following aspects should be considered:

(1) If there are diseases on the bridge, such as bridge cracks, exposed tendons, etc., and it is found through testing that it can no longer meet the requirements of normal use, the relevant departments will be notified immediately of such specific circumstances, and the organization will take care of these serious damages. Reinforce the area.

(2) When the bridge is still in normal use, the partial or complete lack of bridge stiffness, deflection, and cracks have affected normal use. In order to ensure that the bridge meets the needs of vehicle traffic, relevant departments should be immediately organized to strengthen the bridge.

(3) The traffic volume is increasing with the continuous and rapid development of China's economy. The width of some bridge decks is small, which restricts the traffic capacity of vehicles and restricts the development of the transportation industry. Therefore, relevant departments should be immediately organized to widen the bridge.

(4) In order to ensure the temporary safe passage of vehicles with excessive load on the bridge, the bridge needs to be temporarily reinforced; and the bridge needs to be repaired or reinforced if it is damaged due to natural disasters or mechanical shocks.

(5) If the load-bearing capacity of the bridge does not meet the requirements, check the load-bearing capacity of the bridge according to the current requirements to find that it cannot meet the requirements. The lower load-bearing capacity of individual bridges has become the entire road line for vehicles that smoothly traverse the entire route to deal with this bottleneck that limits the ability of the entire routing load-bearing bridge to be reinforced to improve its load-bearing capacity. Or due to the continuous increase of vehicle load, the construction industry has special needs, large-scale industrial equipment, overweight vehicles are transported through bridge containers, the old bridge has insufficient load-bearing capacity and corruption occurs, and the relevant departments should strengthen the bridge organization.

Attention to reinforcement design

To strengthen different bridges, we put forward the basic principles of strengthening. The basic principles of reinforcement are as follows:

(1) Through the inspection and evaluation report (the old highway bridge carrying capacity evaluation method), its carrying capacity cannot meet the requirements of the current traffic flow, and the bridge structure must be strengthened. Some components will fail and must be replaced immediately. For the content and scope of the reinforcement design involved, either a specific area or bridge component can be selected, or the reinforcement of a complete project can be selected, which is determined based on the evaluation results made by the evaluation method and the subjective requirements of the project owner.

(2) During the construction of steel structure bridges, effective measures should be taken to reduce pollution to the surrounding environment, and attention should also be paid to minimize the impact of the bridge deck and the vehicles passing underneath.

(3) When building bridges to reinforce, the security monitoring of the bridges should be strengthened to ensure the safety of employees and the bridge structure when strengthening the bridges.

(4) When aiming to strengthen the main load-bearing components of the bridge, there should be no less than two schemes for comparison, and the optimal scheme should be selected from them to form the feasibility study report of the reinforcement scheme.

(5) The reinforcement design should comply with the following principles: If the dead load of the bridge increases after reinforcement, the relevant structure and foundation to be strengthened should be calculated to ensure that the structure can adapt to the new load changes. For the calculated cross-sectional area of the reinforced structure, the actual effective cross-sectional area of the newly-added component is used to determine the cooperative work of the reinforced component and the original structure, and the actual stress condition of the structure after reinforcement and the strain hysteresis characteristics of the reinforced part are considered. The internal force of the bridge structure should be calculated based on the actual boundary conditions and actual force conditions of the reinforced bridge.

(6) The original structure can be used for optimized use and unnecessary waste. Don't try to destroy the original structure to produce new design schemes and construction practices.

(7) Strengthen the view of synchronizing the design and construction process, that is, obtain results that can be easily achieved in the current project structure. Once the construction party finds a significant defect in the hidden part of the original bridge structure or related work, it should immediately report it to the relevant authorities and suspend the construction. Discuss with relevant reinforcement parties, after effective treatment of the defective parts, and determine the start time of the next stage of construction.

(8) The reinforcement design should proceed from the perspective of the joint work of the old and the new structure, and the necessary measures should be taken for the construction to allow the effective and reliable connection of the new and old buildings. After the bridge structure is reinforced, it cannot be less than the total duration of the original bridge's construction time and service life.

Principles of comparison and selection of reinforcement schemes 

If two or more reinforcement schemes are compared and selected to be the best, the following principles should be followed:

(1) In the structural reinforcement design calculation analysis, the corresponding selection is relatively easy, the check calculation results after reinforcement should meet the requirements of the specification, and the design experience should be mature and reliable.

(2) The specific construction operation should be less difficult, the quality and construction period should be easy to control, and the construction technology should be mature and reliable. It should be verified by the testing methods of new materials and new processes.

(3) Try to choose a plan with less impact on the environment. Noise, dust, solid or liquid waste and other waste generated during construction are as small as possible.

(4) The reinforced structure still meets the durability requirements of the structure, and the post-maintenance cost is not high. The total expenditure should be economical and reasonable, try to save as much as possible, avoid risk, extravagance, waste and unrealistic investment.

(5) During the construction process, the impact on the personal safety of on-site personnel, as well as on the surrounding traffic safety and the safety and reliability of the structure should be small.

(6) The selection of the scheme should conform to the public's aesthetics, as well as the appearance characteristics and structural characteristics of the steel structure bridge. Follow the purpose and original intention of bridge reinforcement.