Existing pad foundation loaded is to be extended in order to consider load bearing sharing between existing base and extension. Can it be considered that the post-installed rebars will be 100% efficient for transferring the loads to the extension as per profis calculations or a percentage only of the stress captured in the existing slab will be transferred to the unloaded extension?
thanks
Hi, thanks for your question.
No, 100% load transfer to the foundation extension should not be assumed from the PROFIS Engineering calculation alone. Load distribution between the existing and new foundation must be established by the structural engineer, considering the construction sequence, relative stiffness, soil response and differential settlement. Loads already carried by the existing foundation will not automatically redistribute to the unloaded extension.
The post-installed rebars should then be designed in PROFIS Engineering for the interface forces obtained from this analysis. Their role is to provide reinforcement continuity and transfer the specified forces, not to determine the proportion of foundation load sharing.
Shear transfer across the old-to-new concrete interface must also be verified separately, considering the surface roughness, friction and rebar dowel action in accordance with the applicable design standard.