Which structural system is suggested for minimizing stress on soil?

Mat or raft slabs are a type of foundation system designed to distribute the load of a building over a large area of soil, thereby minimizing the stress exerted on the soil beneath. This is particularly beneficial in scenarios where the soil has low bearing capacity or is unevenly loaded, as it helps to prevent differential settlement which can lead to structural and performance issues.

By spreading the load over a wider area, mat slabs help to mitigate localized pressure points that might arise with more concentrated footing systems, such as conventional footings. The distribution of load with a mat slab can also reduce the risk of soil failure by ensuring that the foundation remains stable and well-supported, even in challenging soil conditions.

In contrast, conventional footings may concentrate building loads at specific locations, which can result in increased stress on the soil under those footings. Clear span trusses do not directly influence the interaction with soil stress as they are primarily used in structural framing to achieve open spaces, and foundation walls typically support vertical loads directly but may not address soil stress minimization in the same way as mat slabs.

Therefore, when the goal is to minimize stress on the soil beneath a structure, a mat or raft slab is indeed the most effective choice.