Aims and Scopes
Conventional seismic design of soil–foundation structure interaction is still based on the “prudent” conservative approach inherited from static geotechnical engineering: through the use of “overstrength” factors plus (explicit and implicit) factors of safety, FS ≥ 1, the engineers aspire to avoid exceeding those thresholds that lead to the creation of failure mechanisms in the supporting soil or the footing–soil interface. This is the “Conventional Wisdom”.
However, a growing body of evidence suggests that soil–foundation plastic yielding under seismic excitation is unavoidable, and at times even desirable. Our research will help break away with the very philosophy of the conventional approach for seismic loading. It will contribute in a decisive way towards a soil–foundation–structure design that can survive seismically while operating at the verge of failure. And survive with “dignity” (i.e. experience permanent displacements and rotations within acceptable limits).
Three are the fundamental objectives of DARE :
- To explore (theoretically and experimentally) the potential consequences of allowing “below ground” support systems (foundations) to respond to strong shaking by going beyond conventional failure thresholds, and thereby experiencing, (i) sliding at the soil–foundation interface, (ii) separation and uplifting of a shallow foundation from stiff supporting soil, (iii) bearing capacity “failure”, alternatingly under each uplifting edge of a foundation on soft soil, (iv) a combination of two or more of the above, (i) structural plastic “hinging” and severe cracking of piles.
- To develop reliable methods of analysis and design of foundation–soil systems developing such “plastic hinging” under strong seismic shaking. Two types of methods are envisaged : (i) nearly rigorous methods, based on advanced numerical tools calibrated experimentally, and (ii) simplified physically–inspired engineering methods.
- To develop an integrated procedure for seismic analysis of structure–foundation–soil systems, which may lead to optimum design by allowing the two sub-systems (structure and foundation) to compatibly respond in their truly inelastic (“failure”) range.