Bolted structural anchor bolts are 1920mm, manufactured in two sections, and the lower part is buried in reinforced concrete. For example, the bolt stiffness c1 considers that the following section is buried in concrete and has less deformation, so only the deformation of the above section is calculated. Bolt strength check bolt performance grade is 1219 (GB3098.1-82), its nominal yield limit R0.2 is 1080MPa, guaranteed stress Sp is 970MPa (permissible stress), R is less than Sp, that is, maximum working stress, maximum installation The stress is less than the allowable stress and the strength of the anchor bolt is acceptable. In-production inspection and overhaul During the production process, when the gap bolts are used to check whether the anchor bolts are loose, they can also be stretched by tensioning cylinders. During maintenance, the residual preload force is Pvc, and the residual deformation is vLc=Pvc(1C1+1C2+1C3). When the tensile force P is equal to Pvc, the deformation increment of the bolt is in a critical state, that is, P is less than or equal to Pvc, and v is 0; When P is greater than or equal to Pvc, v increases significantly. From this sudden change, the residual preload can be judged. When the pulling force is increased by a small value, the displacement is also increased by a smaller value. When the displacement increases more (ie, a sudden change occurs), it can be judged that the actual residual preload of the bolt is here, and the bolt at this time should preferably be replaced. (1) The theoretical preload force required for the anchor bolt is 158.3kN. The original design indicator (220kN) meets the actual requirements. When installing bolts, the tensioning cylinder is pre-tensioned by the extension method, and the force is used as the control index. The construction process based on the displacement is reasonable. (2) The safety factor of the ground screw inspection is only 1188, and the strength is not rich. In the production operation, the pre-tightening force should be checked regularly to prevent equipment accidents.
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