When pretension is required, steel sleeves should be installed. There the steel tendons are stressed past the yield point to ensure that the concrete (weak in tension) is always subjected to compression and to reduce the deflections. There are five approved methods to pretension bolts
Spookykins
The specific requirements of each method are described in rcsc sections 8.2.1 through 8.2.5.
Bolts are tightened such that a high tension, usually above yield strength, is developed in the bolts, these are called preloaded bolts
The plates of the connection are thus clamped together and shear transfer between the plates is achieved through friction. The initial anchor bolt tension does not increase the maximum bolt tension caused by wind or earthquake This initial tension will only clamp the base ring to the concrete. One of the practices that i have gone back and forth on in my career is specifying a preload for anchor bolts
The idea is that inducing tension in an anchor rod as part of the installation process will avoid load reversal in the rod under transient loading (wind, seismic, etc.) conditions. In the every day anchor bolt construction, the anchor bolt is tighten before all of the service loads are placed on the column Since the anchor bolts are tighten they are pretensioned before the loads are placed. Structural engineers think of preloading (pretensioning) as those steel tendons in prestressed concrete design
