How do welded connections compare to bolted connections in steel bridges in terms of stiffness, inspection, and fatigue risk?

• A. Welded connections are easier to fabricate and require less inspection.
• B. Bolted connections always have no fatigue concerns.
• C. Welded connections provide a continuous load path and high stiffness but require stringent quality control and NDT; bolted connections ease fabrication and inspection but can have fatigue concerns at bolt holes and require proper detailing.
• D. Bolted connections cannot transfer shear effectively.

Answer: (C)

The main idea is how the two connection types behave in stiffness, how we verify them in practice, and where fatigue risk shows up. Welded joints create a continuous load path across the connection, so bending moments flow through the welds and the joint tends to have high stiffness with limited rotation. That stiffness makes welded connections very effective for transferring moments, but it also means that any weld defect directly affects performance. Because small cracks or lack of fusion can act like crack starters, fabrication quality must be tightly controlled and verified with non-destructive testing and careful inspection.

Bolted connections are much easier to fabricate and assemble in the field; you can fit up parts, pre-tension bolts, and inspect the interface without specialized welding. However, their stiffness is more sensitive to the bolt preload and potential slip at the joint, so they can be less stiff than a fully welded connection unless details are chosen carefully. Fatigue risk mainly arises at bolt holes and bearing areas where cyclic loading causes stress concentrations and potential crack initiation or bolt loosening if not properly designed. Good detailing—proper bolt type and pattern, edge distances, bearing length, and, when needed, slip-critical design—helps control these concerns.

So the best description is that welded connections give a continuous load path and high stiffness but require stringent quality control and non-destructive testing; bolted connections simplify fabrication and inspection but can have fatigue concerns at bolt holes and require proper detailing.