Answer:
In the Steel Joints add-on, the option 'Pretensioned Bolt' can be selected.
When this option is selected, the pretension force Fp,C is assigned to the bolt. In the computational model, known as the submodel, a pretensioned joint is thus generated. In the calculation of the joint, the bolt tension forces Ft,Ed, which arise from the acting internal forces, are simultaneously applied with the pretension force Fp,C. As a result of the calculation, the bolt tension force is given as "Design Tensile Force Ft,Ed" in the verification details. This represents a value from the combined effect of the pretension and the acting internal forces, with the pretension force being considered as an action.
The utilization ratio of the pretensioned bolt results from the quotient of the aforementioned design tensile force Ft,Ed and the limit tensile force Ft,Rd. The degree of pretension is determined by the pretension coefficient kp. In the case of full pretension, correspondingly high values for the bolt's tension utilization are obtained. However, this generally does not allow a conclusion about the ratio between the acting tensile force (without pretension) Ft,Ed,NP and the design tensile force Ft,Ed. For analyzing the tensile reserve capacity of the bolt, the following approach is suitable: In the verification details for the slip resistance, the tensile force from the acting internal forces, calculated without pretension, is output under the designation Ft,Ed,NP. By comparing this value with the design value of the tensile capacity Ft,Rd, information about the tensile reserve capacity of the used bolt can be obtained.
