What is the maximum sweep and camber allowed for a welded plate girder that is 40 feet long?

The maximum sweep and camber allowed for a welded plate girder that is 40 feet long is indeed 1/2" (12mm). This specification is rooted in the structural integrity and performance standards outlined in welding and construction codes.

Welded plate girders are designed with particular tolerances to ensure they can effectively handle the stresses and loads placed upon them. The allowed maximum camber and sweep is a way to account for variability and imperfections that can occur during the fabrication and installation processes. A tolerance of 1/2" is considered adequate to maintain the structural performance of the girder while allowing for any unavoidable deviations in the manufacturing process.

Tighter tolerances, such as those found in the other options, may not provide sufficient allowance for the variations encountered in actual construction scenarios. Thus, they are less practical in real-world applications where a balance between manufacturing capabilities and structural performance must be achieved.