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:
“Let’s take the instant by the forward top;
For we are old, and on our quick’st decrees
Th’ inaudible and noiseless foot of time
Steals ere we can effect them.”
—William Shakespeare (1564–1616)
“Each of us, even the lowliest and most insignificant among us, was uprooted from his innermost existence by the almost constant volcanic upheavals visited upon our European soil and, as one of countless human beings, I can’t claim any special place for myself except that, as an Austrian, a Jew, writer, humanist and pacifist, I have always been precisely in those places where the effects of the thrusts were most violent.”
—Stefan Zweig (18811942)
“It is difficult even to choose the adjective
For this blank cold, this sadness without cause.
The great structure has become a minor house.
No turban walks across the lessened floors.
The greenhouse never so badly needed paint.”
—Wallace Stevens (1879–1955)
“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)
“I’ll never forget my father’s response when I told him I wanted to be a lawyer. He said, “If you do this, no man will ever want you.””
—Cassandra Dunn (b. c. 1931)