Development of a Stress-Dependent Finite Element Slab Model.
Annual rept. 6 Jan 82-30 Apr 83,
ILLINOIS UNIV AT URBANA DEPT OF CIVIL ENGINEERING
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The concept of the Resilient Modulus of Subgrade Reaction, K sub R, developed to account for the stress dependent behavior of typical fine-grained subgrade soils. This new subgrade support parameter is defined as plate pressureresilient deflection in an impulse plate load test simulated using finite element program ILLI-PAVE. The resilient modulus of subgrade reaction, K sub R, is expressed in the same units as the standard static modulus of subgrade reaction, K, but the value of the former is significantly higher. This indicates increased stiffness in response to rapidly moving loads. The finite element model presented in this report is a modified and expanded version of ILLI-SLAB, developed in 1977 for the study of jointed, slab-on-grade pavements. A number of modifications to the original code are described. The most important of these is the incorporation, through an iterative procedure, of the deflection dependent Resilient Modulus of Subgrade Reaction K sub R. This parameter is considered more appropriate in modeling nonlinear subgrade response to rapidly moving loads. Other changes include generation of contour plots of system response introduction of specification of loaded areas in terms of global coordinates and, free-form input capability. To illustrate the impact of these innovations, results from several demonstration runs are summarized. The major effect of the proposed model is due to the higher values of K sub R, compared to the commonly used static k.
- Civil Engineering