Lowering and heightening of existing girders refers to the process of adjusting the vertical position of a girder (a structural beam) after it has been installed. This might be necessary to accommodate changes in the structure, correct for errors, or meet new design requirements.

Lowering a Girder:

Structural Assessment:

A thorough analysis is needed to determine the feasibility and methods for lowering the girder without compromising its structural integrity or the stability of connected elements.

Support System:

A temporary support system, such as jacks and temporary beams, is installed to bear the girder's weight during the lowering process.

Controlled Descent:

The girder is carefully lowered in a controlled manner using the support system, ensuring uniform movement and preventing stress concentrations.

Re-establishment of Connections:

Once the girder is at the desired height, connections to adjacent structural elements are re-established, and the temporary support system is removed.

Heightening a Girder:

Structural Assessment:

Similar to lowering, a detailed assessment is required to determine the impact of heightening on the overall structure.

Temporary Supports:

Temporary supports are installed to hold the girder in its current position while modifications are made.

Girder Modification:

This may involve adding a section to the girder (e.g., a steel plate or concrete extension) or modifying the connection points. In some cases, the entire girder might be replaced with a taller one.

Re-establishment of Connections:

The modified girder is then reconnected to the structure, and the temporary supports are removed.