If grouting is delayed on a base plate supported by leveling nuts, what should be used to support the base plate according to the AISC Steel Construction Manual?

The use of steel shims as a means to support a base plate when grouting is delayed aligns with best practices outlined in the AISC Steel Construction Manual. Steel shims provide a robust and stable support system that ensures the structural integrity of the base plate.

Steel shims are specifically designed to handle the loads imposed on structural components, minimizing risk of deformation or failure. They can be easily adjusted for height, allowing for precise alignment of the base plate, which is critical for proper performance once the grouting is completed. This method is preferable due to the dimensional stability and strength of steel under load conditions, particularly in applications involving steel structures where rigid and durable supports are essential.

Other options, while potentially usable in less critical or temporary applications, do not offer the same level of reliability and strength as steel shims. For example, wood blocks may compress or warp under load, and cement blocks, while strong, can also crack or deteriorate, leading to instability. Plastic shim plates, though they can offer slight adjustments, typically lack the necessary strength for long-term structural support, especially under heavy loads. Thus, steel shims stand out as the most appropriate choice for ensuring the base plate's stability when there is a delay in grouting.