Definition of existing cracks
The Pre-cracking lift joints command (see Figure 82) opens the Pre-cracked joint(s) window which allows the user to assign a cracked length to a defined joint. The uplift pressures in these cracks are considered as an initial loading condition in all load combinations. Cohesion is considered to be zero along a crack and only the uncracked ligament is considered when determining the area and inertia of the joint.
The user can specify crack length values (m or ft) or as a percentage of joint length. To assign a crack length, one or more joints are selected from the Pre-Cracked Joint(s) list where the desired upstream and downstream crack lengths are entered. Once this step is complete, the Set crack lengths to selected joints button confirms the input values (see Figure 120).