Category Archive : Design

October 26, 2015

Slip-Critical Connections and Turn-of-Nut Pretensioning: Practical Specs for Bridge Applications

Slip-Critical Connections and Turn-of-Nut Pretensioning: Practical Specs for Bridge Applications

As explained in our article published on July 23, 2015, entitled Slip-Critical Connections: Use of the Turn-of-Nut Method, this pretensioning method is based on the relative rotation between the nut and bolt head in order to develop the necessary preload tension force in the bolt. This preloading generates a normal force between the faying surfaces and as a result, the required frictional resistance in the slip-critical connection is achieved. While the principle is simple, several…

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July 23, 2015

Slip-Critical Connections: Use of the Turn-of-Nut Method

Slip-Critical Connections: Use of the Turn-of-Nut Method

Bolted connections in bridge structures are almost all installed using a torque-controlled tightening method. The use of controlled tightening enables the development of friction force between the plates of the bolted connections; they are therefore slip-critical connections. The resulting friction force allows for an enhanced performance of connections in fatigue conditions, reduces deflections in the structure and prevents bolts from loosening when subjected to impact loads and vibrations. The Turn-of-Nut method is widely used to obtain…

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