For what purpose shall thermally cut surfaces be ground smooth?

Thermally cut surfaces are required to be ground smooth primarily to ensure the integrity and performance of cyclically loaded joints. When steel components are connected through welding or bolting in applications subject to repeated loading, such as bridges and structures experiencing vibration or dynamic forces, the quality of the joint becomes critical.

Rough edges created by thermal cutting can act as stress concentrators, leading to potential fatigue failures over time. By grinding these surfaces smooth, the distribution of stress is improved, which enhances the overall durability and strength of the welded or bolted connection. This practice is essential in maintaining the structural integrity and longevity of components that will experience fluctuating loads, thereby preventing premature failure due to fatigue.

While the other options may provide some validity in certain contexts—such as aesthetic or ease of installation considerations—the primary concern in structural applications, especially those involving cyclic loads, rests on the mechanical performance and safety of the joint. This highlights why attention to surface preparation is vital in load-bearing connections.