Effect of Soil Structure Interaction On Structural Response
It has conventionally been considered that soil-structure interaction has beneficial effect on the seismic response of a structure. Many design codes have suggested that the effect of SSI can reasonably be neglected for the seismic analysis of structures. This myth about SSI apparently stems from the false perception that SSI reduces the overall seismic response of a structure, and hence, leads to improved safety margins. Most of the design codes use oversimplified design spectra, which attain constant acceleration up to a certain period, and thereafter decreases monotonically with period. Considering soil-structure interaction makes a structure more flexible and thus, increasing the natural period of the structure compared to the corresponding rigidly supported structure. Moreover, considering the SSI effect increases the effective damping ratio of the system. The smooth idealization of design spectrum suggests smaller seismic response with the increased natural periods and effective damping ratio due to SSI. With this assumption, it was traditionally been considered that SSI can conveniently be neglected for conservative design. In addition, neglecting SSI tremendously reduces the complication in the analysis of the structures which has tempted designers to neglect the effect of SSI in the analysis.
This conservative simplification is valid for certain class of structures and soil conditions, such as light structures in relatively stiff soil. Unfortunately, the assumption does not always hold true. In fact, the SSI can have a detrimental effect on the structural response, and neglecting SSI in the analysis may lead to unsafe design for both the superstructure and the foundation.
Read more about this topic: Soil Structure Interaction
Famous quotes containing the words effect, soil, structure, interaction, structural and/or response:
“The first general store opened on the ‘Cold Saturday’ of the winter of 1833 ... Mrs. Mary Miller, daughter of the store’s promoter, recorded in a letter: ‘Chickens and birds fell dead from their roosts, cows ran bellowing through the streets’; but she failed to state what effect the freeze had on the gala occasion of the store opening.”
—Administration in the State of Sout, U.S. public relief program (1935-1943)
“There will be mud on the carpet tonight
and blood in the gravy as well.
The wifebeater is out,
the childbeater is out
eating soil and drinking bullets from a cup.”
—Anne Sexton (1928–1974)
“Slumism is the pent-up anger of people living on the outside of affluence. Slumism is decay of structure and deterioration of the human spirit. Slumism is a virus which spreads through the body politic. As other “isms,” it breeds disorder and demagoguery and hate.”
—Hubert H. Humphrey (1911–1978)
“Just because multiples can turn to each other for companionship, and at times for comfort, don’t be fooled into thinking you’re not still vital to them. Don’t let or make multiples be parents as well as siblings to each other. . . . Parent interaction with infants and young children has everything to do with how those children develop on every level, including how they develop their identities.”
—Pamela Patrick Novotny (20th century)
“The reader uses his eyes as well as or instead of his ears and is in every way encouraged to take a more abstract view of the language he sees. The written or printed sentence lends itself to structural analysis as the spoken does not because the reader’s eye can play back and forth over the words, giving him time to divide the sentence into visually appreciated parts and to reflect on the grammatical function.”
—J. David Bolter (b. 1951)
“Parents’ accepting attitudes can help children learn to be open and tolerant. Parents can explain unfamiliar behavior or physical handicaps and show children that the appropriate response to differences should be interest rather than revulsion.”
—Dian G. Smith (20th century)