During long-term use, steel structure parts may deform due to various factors, which will affect their structural safety and normal use. Therefore, deformation monitoring and correction are extremely important.
First of all, there are many deformation monitoring methods. Level measurement is one of the commonly used methods. By setting observation points at key parts of steel structure parts and using a level to measure the elevation changes of each point, it is possible to determine whether the structural parts have vertical settlement or uplift deformation. For example, observation points are set on the piers and spans of large bridge steel structures, and their elevation differences are measured regularly, which can timely detect deformation caused by foundation settlement or vehicle loads. Total station measurement can simultaneously obtain the plane coordinates and elevation information of the observation points on the steel structure parts, comprehensively reflect the three-dimensional deformation state of the structure, and is suitable for deformation monitoring of steel structure buildings or structures with complex shapes and spatial positions, such as overall deformation monitoring of high-rise steel structure buildings. In addition, strain gauge measurement also plays an important role. Strain gauges are pasted on the key stress-bearing parts of steel structure parts. When the structure deforms and causes stress changes, the resistance value of the strain gauge changes. By measuring the resistance change, the strain size can be converted, and then the deformation of the structure can be deduced. This method is very accurate for deformation monitoring in local stress-complex areas.
Secondly, in terms of deformation correction methods, mechanical correction methods are more common. For steel structure parts with smaller deformation, jacks, presses and other equipment can be used to apply external force for correction. For example, when a steel beam undergoes local bending deformation, a jack can be set on the convex surface of the deformed part, and the top force can be slowly applied to gradually restore the steel beam to its normal shape. The flame correction method is also widely used. Flame is used to locally heat the deformed parts of steel structure parts. Due to the thermal expansion and contraction characteristics of metals, the heated area will shrink after cooling, thereby offsetting the original deformation. If the steel plate undergoes wavy deformation, triangle or strip heating can be performed on the convex part, and then it can be allowed to cool naturally to achieve the purpose of correction. However, the heating temperature, range and cooling rate must be strictly controlled during flame correction to avoid adverse effects on steel properties.
Furthermore, for the correction of complex deformation or large steel structure parts, a comprehensive correction method is sometimes required. First, use mechanical correction to preliminarily adjust the overall shape of the structure, and then combine flame correction to finely process the local parts that are difficult to correct. For example, in the correction of the steel structure of a large gantry crane, first use the crane's own lifting equipment or a large jack to reset the large deformation of the overall structure, and then use the flame correction method to repair some local distortions caused by welding residual stress to ensure that the overall structure is restored to the shape and accuracy required by the design, and to ensure its safe and reliable operation.
Finally, a sound system and process should be established for deformation monitoring and correction. Formulate a regular monitoring plan, determine the monitoring cycle according to the type, use environment and importance of steel structure parts, and record and analyze the monitoring data in a timely manner. Once it is found that the deformation exceeds the allowable range, immediately start the correction plan, and conduct a review after correction to ensure that the correction effect meets the requirements, thereby extending the service life of the steel structure parts and ensuring the safe and stable operation of related engineering facilities.
