Introduction to bridge reinforcement design and bridge maintenance and reinforcement methods

Bridge reinforcement design is a multidisciplinary system problem involving disease diagnosis, renovation decision analysis, reinforcement material and method selection, reinforcement component design and calculation, maintenance management and construction, etc.
The bridge reinforcement design should fully consider the actual situation of the bridge structure in service and the characteristics of the reinforcement force. The bridge structure has a large dead weight and constant load, and is generally reinforced with load, that is, the structure is reinforced without removing the weight and bearing load of the structure.
The bearing capacity of weak members of bridge reinforcement must be calculated by considering the characteristics of phased stress. The self-weight of the components and the constant load that is not dismantled shall be borne by the original beam.Vehicle loadThe subsequent loading is borne by the reinforced combined section. Compared with the original beam reinforcement, the strain (stress) of the post-reinforcement material is relatively lagging behind, and under normal circumstances, its stress cannot reach the design value of tensile strength in the limit state. The calculation results show that considering the influence of the phased force, the reinforcement components are designed with the tensile stress control of the original beam reinforcement, and the tensile stress of the reinforcement material is small and cannot play a full role. In particular, the passive reinforcement scheme of directly pasting high-strength carbon fiber cloth (plate) is used, and the high tensile performance of the reinforcement material is difficult to play a role, and the "big horse-drawn car" is a great waste. The design and calculation of bridge reinforcement components should consider the graded stress characteristics of load-bearing reinforcement, which is the biggest difference between bridge reinforcement design and new bridge design.
From a technical point of view, there are two main problems in the current bridge reinforcement design in our country:
1. Grassroots units that undertake a large number of maintenance, maintenance, management and reinforcement tasks of medium and small bridges, and the technical strength of bridge disease diagnosis is weakTesting equipmentBackward. Bridge disease diagnosis is the premise and foundation for bridge reinforcement design, and only when the diagnosis is clear can the right medicine be prescribed. Bridge detection is an important means of disease diagnosis and analysis, cracks in concrete structures are a barometer reflecting diseases, and crack analysis is the main content of bridge detection.
In the face of the current situation of grassroots units engaged in bridge maintenance, maintenance and management in our country, it is necessary and urgent to popularize the knowledge of bridge disease diagnosis and improve the ability of crack analysis.
2. Another problem in bridge reinforcement design is insufficient understanding of the particularity of bridge reinforcement designDesign conceptUnclear, the reinforcement design idea is not clear. Some bridge reinforcement designs mechanically apply new bridgesDesign methodology , ignoring the influence of the stress characteristics and structural damage of bridge reinforcement in stages. Individual reinforcement design only does macroscopic qualitative analysis, lacks scientificQuantitative analysis, the design has a lot of arbitrariness.
The following is an introduction to the main methods commonly used for
bridge reinforcement: 1. Increase the section reinforcement method. The enlarged section method is also called the outsourcing concrete reinforcement method. Its definition refers to the adoption of increasing the cross-sectional area of concrete structures or structures for the purpose of improving their load-bearing capacity and meeting the normal use of an effective reinforcement method. When the reinforced concrete is compressed by the bending member and the concrete cast-in-place layer is added, the effective height of the section can be increased, the cross-sectional area can be expanded, and finally the bending resistance of the positive section of the component can be improved, and the shear resistance of the oblique section is also harmoniousSectional stiffness, which plays a role in reinforcement and reinforcement. This reinforcement method can be widely used in concrete structures such as beams, plates, columns, and general structure reinforcement. Under normal conditions, the main methods are to thicken the bridge deck or increase the width of the beam ribs of the main beam.
2. In vitroPrestressed reinforcementlaw. The external prestress reinforcement method is suitable for structures under high stress, especially for the reinforcement of large structures. It can also improve bearing capacity, stiffness and crack resistance, and occupy less space on the bridge after reinforcement. The reinforcement principle of the external prestressing method is that the construction party sets up prestressed materials at the tensile area at the beginning of the lower edge of the beam, and generates eccentric prestress on the beam body by tensioning, so that the beam body arches upwards and offsets the partSelf-weight stress, thus reducing the structural deformation and crack width, improving the structural stress, improving the bearing capacity, stiffness and crack resistance, and the bridge occupying small space after reinforcement. However, the disadvantages of this method are that the local cabling effect is obvious, the number of anchor heads, the complex joint structure, and the high requirements of the construction work surface make the overall economic benefits of the reinforced steel truss not high. This method is mainly suitable for structures under high stress, or for the reinforcement of large structures, or for controlling beam cracks and steel fatiguestress amplitudeand other situations.
3. System conversion and reinforcement method. systemConversion methodIt is a bridge to changeStructural systemAchieve reduced beamsinternal stress, and can improve the bearing capacity, which is an effective method of passive reinforcement into active reinforcement. The reinforcement method of changing the structural system refers to the ability to add additional components or carry out technical transformation, so as to fundamentally change the stress system and stress condition of the bridge, and to reduce the stress of its load-bearing components, and finally achieve the purpose of improving the bearing capacity. At present, the most commonly used system conversion methods are: beam bridge conversion to beam-arch combination system method, addition of auxiliary pier method, multi-spanSimple support beamsto the continuous system method of simplifying the first support and then the bridge deck.
4. Paste steel plate reinforcement method. The pasted steel plate reinforcement method is applied to the reinforcement of the pasted steel plate. Use binders and anchors and paste the steel plate to the concrete structure or other weak parts to achieve the purpose of making the steel plate and the reinforced concrete structure form a whole, and finally improve the bearing capacity of the structure. However, the pasted steel plate reinforcement method has its own shortcomings, such as the necessary surface protection work after the reinforcement of the pasted steel plate, such as epoxy mortar or cement mortar protective layer, the rust degree of the steel plate is difficult to estimate, which reduces the reliability of the reinforcement components and increases the later maintenance cost of the reinforced bridge. However, this method is also often used in the reinforcement of bridges, and such a method still shows some good advantages. For example, the construction is simple, the technology is reliable, the short-term reinforcement effect is good, the process is mature, and the size of the original structure is basically not changed.
5．Composite materialsReinforcement Technology (FRP). It is composed of two parts: fiber and mesh resin. At present, there are three commonly used composite materials: E-glass fiber, carbon fiber, and aromatic fiber, among which carbon fiber (CFRP) materials are the most widely used. adoptedCarbon fiber cloth reinforcementBridge and building structure repair technology is a new type of structural reinforcement technology, which is based onResinsThe cementing material is the matrix, and the carbon fiber cloth is pasted and solidified on the surface of the concrete structure, and the high strength of carbon fiber is usedmodulus of elasticityTo achieve the purpose of reinforcing and reinforcing concrete structures and improving the stress condition of the structure.
6. Wire winding reinforcement method. The wire winding reinforcement method is a direct reinforcement method that winds the annealed steel wire on the surface of the reinforced member to restrain the concrete of the reinforced component, thereby improving its bearing capacity and ductility. This wire winding reinforcement method has the following advantages: first, it improves the bearing capacity of the oblique section of reinforced concrete components; The second is to improve the positive cross-sectional bearing capacity of the axial compression member.
7. SRAP reinforcement method. The SRAP reinforcement method is a new bridge reinforcement method that introduces the concept of prestress. It uses the high strength characteristics of SR reinforcement materials and the characteristics of AP resin mortar to prevent corrosion and waterproofing, and strong adhesion, and applies prestress to SR high-strength materials through special methods, so as to achieve the reinforcement of the bridge. The application of prestress anchored the expansion bolt at both ends of the bottom of the beam, and the two ends of the soft steel wire were fixed to the expansion bolt with spiral buckles, and the prestress was applied by tightening the screw buckle in the opposite direction.

CCCC Road and Bridge Technology Co., Ltd. was established in 2009 and is professionalEngineering inspectionmonitoring, urban safety monitoring, early warning and evaluation, and digital intelligent research and development as one of the composite typesHigh technologyGroup enterprises.

At present, it has obtained the industry testing qualifications issued by the railway industry, highway industry and construction industry, as well as the measurement certification qualification of the Hebei Provincial Technical Supervision BureauChina Transportation Construction Supervision AssociationDeputy Secretary-General Unit of the Test and Testing Committee, Zhongguancun Zhimeng Environmental Civil EngineeringIntelligent detectionThe director unit of the monitoring industry alliance is the only one in the construction and highway testing industry in Hebei Province that has both "specialized, special and new" andHigh-tech enterprises".

Combined with years of advanced experience in the industry, integrating the development needs of the digital economy and national security system, we will build an "engineering hospital + intelligent testing + leading technology + digital empowerment"Brand strategy, forming engineering testing, urban safety monitoring, digital research and development, and wisdomSmart designFour major business segments.

The company has strong technical strength, and currently has a team of high-quality engineering doctors, including railway engineering, urban roads and highways, bridge engineering, tunnel engineering, construction engineering,Water conservancy engineering, engineering geophysical exploration, safety technology, electricity, signal,Integrated circuits, intelligent science and other majors. The company is fully equipped with testing, testing and monitoring instruments, with more than 1,000 sets of instruments and equipment for testing, surveying and mapping, which provides hardware guarantee for the scientific and accurate testing and monitoring data.

Since its establishment, the company's research projects have reached the international advanced and domestic leading level for many times, relying on the enterprise science and technology collaborative innovation center to achieve many new breakthroughs, and have passed for many yearsNational high-tech enterprise recognition, actively participate in the formulation of national and industry standards, and independently innovate a number of thingsIntellectual PropertyTechnology.

The company always adheres to and implements "fair, just, scientific and efficient"Quality policyWith the business philosophy of "integrity based on integrity, innovation and far-reaching", backed by "high standards, high starting point, and modern management", we are committed to building a modern, technological, and compound professional and technical institution based on engineering testing, with urban safety monitoring and digital research and development as the highlights, and is determined to become a modern, technology-based, and compound professional and technical institution with owner satisfaction, employee satisfaction, high partner dependence and high industry recognition.

Some bridge testing cases

1. Static load test and testing of 26 bridges of Inner Mongolia High-grade Highway Construction and Development Co., Ltd.;

2. Static load test and testing of No. 1, 2, 3 permanent bridges and No. 4 temporary bridges of Xinjiang Muzhati River tertiary hydropower station;

3、ZhangjiakouStatic load test and detection of bridges;

4. Static load test and detection of Beijing Fangshan Qiyi Bridge bridge;

5. Inner Mongolia National Highway 110 overpass completion acceptance test and testing;

6. Static load test and testing of the first and second bridges of the Yellow River in Baomao, Inner Mongolia.

7. Static load test test and testing of Pingshan Yehe Bridge.