You can also refer to the following link, quite well summarized for the horizontal behavior of soil and subgrade reaction along with the references. So we can simply estimate the vertical stiffness based on the horizontal subgrade reaction.Īgain, this is just definition of Ko, nobody should ask where we can find the reference, who suggested the equation. In case of D x I (Diameter X Length) is just the area (the equivalent area of pile tip supported). Ko is the earth pressure coefficient which can define the relation between normal stress and horizontal stress of the soil (Horizontal = Ko x Normal). Basically it must come from lap, or field test like SPT(Standard penetration test). I believe that the engineer must know about this how we can get this value. Regardless of the soil type, we can simply define the stiffness based on the horizontal subgrade reaction, Kh, called k-value. The equation which is described in the manual is as the following. We, in general, do not take the nonlinearity into account, because this is about the settlement of pile within the elastic range in terms of behavior. Software will generate the vertical and horizontal spring automatically when you use this function.įirst of all, the vertical spring is a linear elastic one which doesn’t consider the nonlinearity of soil material. Midas Civil or midas Gen defines the nonlinear spring along with the pile, when we use the pile spring function. To account for this characteristic of the soil, lateral springs are modeled as compression-only springs and vertical springs are modeled as linear elastic springs.
If cycles are repeated infinitely, the modulus of subgrade reaction of backfill becomes constant. Due to the repeated backfill compaction and soil slide, the modulus of subgrade reaction and the pressure distribution of backfill vary with depth.Ī Cycle is the period from a deck expansion to a deck contraction.
Backfill compaction due to a deck expansion and soil slide due to a deck contraction is repeated.
Expansion and contraction of the bridge deck affects the backfill soil adjacent to the abutments. The prime concern in integral bridges is the effects of temperature variations on the deformation of bridge deck. An integral bridge is one in which the bridge deck and its supporting abutments and piers are integrated without expansion joints to absorb the deformation of the bridge deck using the flexibility of the abutments and piers. Midas Civil has a function called the Integral Bridge Spring Support. Function Location: Boundary > Spring Supports > Integral Bridge.
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