The bridge is an important traffic project connecting the two sides of the river, and its construction requires precise design and construction to ensure the safety and beauty of the bridge.
However, sometimes due to various reasons, the bridge may not be aligned in the middle during the construction process, can such a bridge be used normally?If not, what should be done?
There are several reasons why the middle of the bridge is not aligned:
Design errors. If the design drawings of the bridge do not take into account the topography, geology, hydrology and other factors, or are not reviewed and checked in accordance with the specifications, it may lead to deviations in the axis, elevation, slope and other parameters of the bridge.
Measurement errors. If the surveyors of the bridge do not use accurate instruments and methods, or do not carry out re-inspection and review, it may lead to errors in the data of the bridge's lofting, elevation, control points, etc.
Construction errors. If the construction personnel of the bridge do not operate in strict accordance with the design drawings and technical specifications, or do not carry out quality inspection and adjustment in time, it may lead to problems such as offset, deformation, and cracks in the foundation, pier columns, beams and other components of the bridge.
Environmental impact. If the environment of the bridge has changed, such as natural disasters such as floods, landslides, or human factors such as human interference and destruction, it may lead to loosening, fracture, falling off and other phenomena in the support, anchorage, connection and other parts of the bridge.
Misalignment in the middle of the bridge can have a variety of effects.
Affect security. If the middle of the bridge is not aligned too much, it can lead to a decrease in the structural strength and stability of the bridge, and even accidents such as collapse or fracture, bringing danger to pedestrians and vehicles.
Affect the aesthetics. If the middle of the bridge is not aligned too much, it can cause the shape and alignment of the bridge to lose coordination and balance, giving people an uncomfortable and unsightly feeling.
Affect functionality. If the middle of the bridge is not aligned too much, it can lead to a reduction in the capacity and comfort of the bridge, causing inconvenience and discomfort to pedestrians and vehicles.
Affect the economy. If the middle of the bridge is not aligned too much, it may lead to an increase in the cost of bridge maintenance and renovation, and bring economic losses to the builder and the manager.
There are also many remedies for misalignment in the middle of the bridge.
Blow it up and rebuild. This is the most thorough and expensive method, and is only suitable if the middle of the bridge is not too misaligned to be repaired by other means. This method requires the bridge to be demolished by blasting and then redesigned and constructed, which is time-consuming, labor-intensive, and costly.
Adjust the connection. This is the most common and economical method, which is suitable for situations where the misalignment in the middle of the bridge is small, and it can be repaired by adjusting the supports, connectors, prestressing, etc.
This method requires first measuring the actual deviation of the bridge, and then adjusting accordingly according to the calculation results to make the bridge reach a reasonable connection state.
Widening and heightening. This is a compromise and flexible approach that is suitable for situations where the bridge is not aligned in the middle, but can be transitioned by increasing the width or height of the bridge deck.
This method requires the addition of steel or concrete structures on both sides or up and down the bridge, and then the corresponding connection and paving are carried out to make the bridge achieve a reasonable shape and function.
Design corners. This is an innovative and complex approach that can be achieved when the bridge is not aligned in the middle, but can be achieved by changing the alignment of the bridge.
This method needs to design a certain curve or turning back at both ends of the bridge, and then carry out the corresponding construction and decoration to make the bridge achieve a reasonable form and effect.
We can strengthen the design. In the bridge design stage, it is necessary to fully consider the topography, geology, hydrology and other factors, select the appropriate bridge type and structure, review and check in accordance with the specifications, and ensure the accuracy and rationality of the design drawings.
Rigorous measurements. In the bridge measurement stage, it is necessary to use accurate instruments and methods, and carry out mutual inspection and review in accordance with the specifications to ensure the accuracy and reliability of the measurement data.
Standardize construction. In the bridge construction stage, it is necessary to operate in strict accordance with the design drawings and technical specifications, and carry out quality inspection and adjustment in accordance with the specifications to ensure the qualification and stability of the construction quality.
Monitor the environment. In the use stage of the bridge, it is necessary to regularly monitor the deformation, cracks, anchorage and other conditions of the bridge, find and deal with abnormal phenomena in time, and prevent environmental factors from causing damage to the bridge.
Case study of misalignment in the middle of a bridge, a steel girder bridge in a Croatian gorge. The bridge was pushed outwards after steel structures were built on both sides of the canyon, and when it was about to connect, it was found that the top and bottom were not aligned.
Since the bridge is a flexible steel structure and is pushed out after the structure is completed in the tunnel, the connection can be achieved by small adjustments up and down, left and right.
Taishun Wenxing wooden arch bridge. The bridge was built on both sides of the bridge and then docked to the middle, and when approaching, it was found that the left and right sides were not aligned.
Since the bridge is a timber structure and is docked after the structure is completed on the water, the connection cannot be achieved by adjustment.
In the end, the engineers adopted the method of widening and heightening, adding a wooden arch structure in the middle of the bridge, so that the bridge achieved a reasonable shape and function.
San Francisco Bay Bridge, USA. The bridge was built on both sides of the reinforced concrete structure and then butted to the middle, and when approaching, it was found that the front and back were not aligned.
Since the bridge is a reinforced concrete structure that is relatively sturdy and docked after the structure is completed at sea, the connection cannot be achieved by adjustment.
Finally, the engineers adopted the method of designing curves, and designed certain curved sections at both ends of the bridge, so that the bridge achieved a reasonable form and effect.
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