Comparative Assessment of Soil-Structure Interaction Regulations of ASCE 7-16 and ASCE 7-10

TL;DR

This study compares the impact of ASCE 7-16 and ASCE 7-10 soil-structure interaction regulations on seismic performance, revealing that the new provisions often lead to similar or more conservative responses depending on soil and structure type.

Contribution

It provides a comprehensive evaluation of the effects of the updated SSI regulations in ASCE 7-16 on various building types and soil conditions, highlighting their practical implications.

Findings

SSI regulations often increase structural response on soft soils.

ASCE 7-16 provisions are closer to fixed-base responses for stiff structures.

On very soft soils, ASCE 7-16 tends to produce conservative designs.

Abstract

This paper evaluates the consequences of practicing soil structure interaction (SSI) regulations of ASCE 7-16 on seismic performance of building structures. The motivation for this research stems from the significant changes in the new SSI provisions of ASCE 7-16 compared to the previous 2010 edition. Generally, ASCE 7 considers SSI as a beneficial effect, and allows designer to reduce the design base shear. However, literature shows that this idea cannot properly capture the SSI effects on nonlinear systems. ASCE 7-16 is the first edition of ASCE 7 that considers the SSI effect on yielding systems. This study investigates the consequences of practicing the new provisions on a wide range of buildings with different dynamic characteristics on different soil types. Ductility demand of the structure forms the performance metric of this study, and the probability that practicing SSI provisions, in lieu of fixed-base provisions, increases the ductility demand of the structure is computed. The analyses are conducted within a probabilistic framework which considers the uncertainties in the ground motion and in the properties of the soil-structure system. It is concluded that, for structures with surface foundation on moderate to soft soils, SSI regulations of both ASCE 7-10 and ASCE 7-16 are fairly likely to result in a similar and larger structural responses than those obtained by practicing the fixed-base design regulations. However, for squat and ordinary stiff structures on soft soil or structures with embedded foundation on moderate to soft soils, the SSI provisions of ASCE 7-16 result in performance levels that are closer to those obtained by practicing the fixed-base regulations. Finally, for structures on very soft soils, the new SSI provisions of ASCE 7-16 are likely to rather conservative designs.