The method of determining the implementation unit of bridge construction monitoring

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The construction precamber of each section of the main beam provided by the design is based on the design parameters determined by the specification requirements, but there is a certain error between the actual construction situation and the specification requirements, (such as the specific gravity of concrete material, the elastic modulus of concrete, the elastic mode of prestressed steel beam, the prestress loss, the difference between the construction environment temperature and the design, the difference between the load and the design consideration during construction, etc.), this error often leads to a certain difference between the design calculation and the actual construction. At the same time, the continuous rigid frame bridge usually adopts cantilever segment construction, is a complex construction process, the stress condition is complex, the bridge state is closely related to the construction process, in the construction process, the geometric characteristics of the structure, the material characteristics, the load and the supporting conditions are constantly changing, the structural system is often converted, and the construction process directly affects the internal force and the linear shape after the bridge. The construction process includes construction stages such as pier body, main beam support section, main beam hanging section and closing section.

The standard cantilever section construction of the main beam is generally divided into several processes, including hanging basket walking, vertical formwork, steel bar binding, concrete pouring, prestressed beam tensioning and grouting and other processes, and the increase of each beam section has a certain impact on the linear shape and internal force of the existing structure. In the construction process of continuous rigid frame bridge, each construction stage is continuous with each other, is a complete system, and the current construction state directly affects the result of the later stage, and because of the characteristics of the continuous rigid frame bridge itself, if the deviation occurs and is not corrected in time, when the deviation is too large or even beyond the control range, it is difficult to make up for it in the construction of the subsequent section, and it is very possible.

The content of bridge construction monitoring mainly includes the determination of the ideal state of the bridge, the determination of the ideal construction state and the timely control and analysis of construction.

Supplement]: The ideal state of the bridge refers to the design alignment and ideal stress state of the structure under the action of dead load; The ideal state of construction takes the ideal state of the bridge as the initial condition, and gradually dismantles the influence of each construction item on the structure according to the steps of the actual construction reversal, so as to determine the state parameters (axis elevation and stress) of the structure in each stage of construction, which is generally determined by the regression analysis method; Timely control of construction is to adjust according to the ideal state of construction and according to certain criteria during construction, and to correct the main design parameters that affect structural deformation and internal force by identifying them, so that the structural performance and internal force can reach the target state.

Resources.

You asked in a general way, what about the schedule, safety, quality or cost......It is similar to the main body, although there are many differences, not all of them are cofferdams, underwater cast-in-place piles or other pile foundation construction-cushion-foundation cap-column-beam plate construction ......Now it is generally ...... to be constructed by the tension methodPrestress.

Bridge construction control used to be regarded as scientific research work, but now it is counted as technical service work. The preparation of the construction control scheme is aimed at different bridge structure forms, and its focus is very different. But in general, the scheme of construction control should include the following parts:

1. Project overview;

2. Understanding of the bridge construction control;

3. Construction control purposes;

4. Construction control basis;

5. Construction control content;

6. Construction control management system;

7. Construction control technology system;

8. Monitoring methods;

9. Intermediate process and final result submission format.

Personnel, materials, machinery, and on-site scheduling.

It is necessary to find a construction unit, find a bridge major, and colleges and universities should ask some school bridge engineers to do monitoring.

Main monitoring items:

1) The stress of the bridge should be monitored with skin shouting;

2) Bridge deflection monitoring and field measurement;

3) Bridge temperature monitoring;

4) Bridge crack monitoring;

5) Bridge support seat transfer supervisor grip carrying test;

6) Bridge pier tilt monitoring;

7) Bridge vibration monitoring;

According to the actual situation of the bridge, the increase or decrease can be selected.

Bridge monitoring is to measure the internal force and line type of the bridge structure according to the actual construction conditions during the construction of the new bridge, and then correct and adjust to achieve the design goal as much as possible after error analysis. Bridge monitoring, also known as bridge construction monitoring or bridge construction control. In the balanced cantilever pouring construction of long-span suspension bridge, cable-stayed bridge, arch bridge and continuous rigid frame bridge, the latter piece is connected with the previous piece by prestressed tendons and concrete, therefore, each construction stage is closely related.

Construction monitoring engineering monitoring refers to the technical means of using monitoring instruments to monitor the control indicators of key parts in the construction process of the building, and send out an alarm when the monitoring value is close to the control value, which is used to ensure the safety of the construction and can also be used to check whether the construction process is reasonable.

Using a variety of monitoring technology and signal transmission processing methods, the establishment of the best monitoring expert system, the formation of intelligent control system. At present, Qingye Engineering and Business Consortium have developed and completed a number of visual monitoring software for monitoring content, the response time can be controlled within the range of 1s, and the sampling frequency can reach 100Hz, which can fully achieve real-time monitoring and truly provide information support for engineering construction.

Bridge inspections are divided into frequent inspections and periodic inspections, and the requirements are different. General bridge inspection includes: general inspection and special inspection.

General inspection refers to visual inspection, line inspection, etc. Special tests include non-destructive testing, static load testing, dynamic load testing, and so on. Non-destructive testing also includes concrete strength testing, crack testing, steel corrosion, carbonization and so on.

For details, please refer to the "Regulations for Testing and Evaluation of the Bearing Capacity of Highway Bridges".

1. Routine regular inspection: including bridge deck system inspection, superstructure inspection, and substructure inspection. 2. Regular inspection of the structure:

Including concrete strength testing, concrete carbonization depth testing, rebar position and concrete protective layer thickness inspection and seepage testing. 3. Detection of underwater components: Investigate and record the underwater pile foundation concrete falling off, cracks, exposed ribs, cavities, mechanical damage and other diseases.

Fourth, the bearing capacity appraisal: through the bearing capacity appraisal to determine whether the bearing capacity of the bridge at this stage can meet the design requirements. 5. Long-term monitoring point layout and first observation:

In order to observe the displacement of the bridge pier and girder under the action of the vehicle for a long time, so as to analyze the safety of the bridge, the monitoring point was arranged at the key position of the bridge Guanling, and the monitoring point was observed for the first time. With the development of our national highway bridges, more and more bridges, while many existing bridges have gradually entered the maintenance and repair stage, relevant experts believe that bridges, more than 25 years of use will enter the aging period, according to statistics, 40% of the total number of bridges in China has belonged to this category, are "old" bridges. And as time goes on, their number continues to grow, and bridge managers have paid more and more attention to the maintenance of bridges.

In order to meet the requirements of the continuous development of road transport load capacity, make full use of the existing highway bridges, so that they can continue to serve road transport safely, according to the requirements of the "Technical Specifications for Highway Maintenance" promulgated by the Ministry of Communications, the bridge must be identified.

Bridge safety monitoring content: (1) geometric linear monitoring and construction measurement, including: arch rib linear monitoring, main beam linear monitoring, main beam deflection monitoring, axis offset measurement and tremor, arch displacement measurement.

2) Stress and strain monitoring of arch ribs. (3) Observation of stress and strain of steel box girder. (4) Stress and strain monitoring at the stress concentration position of the anchor end of the tie rod.

5) Tie rod cable force monitoring. (6) Temperature monitoring, including: control the temperature value of the section and the ambient temperature value during the construction process.

7) Material parameter testing, etc. (8) Monitoring the stability of the construction process. With the development of China's public bridges, more and more bridges, while many existing bridges have gradually entered the maintenance and repair stage, relevant experts believe that the bridge is used for more than 25 years and enters the aging period, according to statistics, 40% of the total number of bridges in China has belonged to this category, all belong to the "old" bridge.

And with the passage of time, its number is still growing, and bridge managers have paid more and more attention to the maintenance of bridges. In order to meet the requirements of the continuous development of road transport load capacity, make full use of the existing highway bridges, so that they can continue to serve road transport safely, according to the requirements of the "Technical Specifications for Highway Maintenance" promulgated by the Ministry of Communications, the bridges must be identified. With the development of bridges in full swing in various places, the ensuing bridge construction accidents have also frequently sounded the alarm bell of safety production.

The detection is to evaluate the bridge according to the actual situation, so the main work in the early stage is to start from the existing status quo and characteristics, have a general grasp of the entities to be detected, and clarify the direction of the subsequent work, which is the investigation and calculation.

The scope of data collection here is broader than that of cracking, including not only design data, but also construction data and related maintenance, repair and reinforcement data.

There are many details involved in data collection, such as calculation books, design drawings, modified drawings and geological data in the design data; The construction materials include the completion drawings, completion instructions, material test data and construction records of each stage, and the completion acceptance materials. Other maintenance and maintenance materials include historical vehicle types, loads, traffic conditions, maintenance information, etc. There are also information related to the natural environment or natural disasters (floods, **, permafrost, mudslides, etc.) that should be collected from the relevant authorities if necessary.