NOMOGRAPHS FOR THE DESIGN OF CRCP STEEL REINFORCEMENT

The purpose of this study was to develop graphical procedures (nomographs) for the design of continuously reinforced concrete pavement (CRCP) for implementation by the Texas State Department of Highways and Public Transportation for a range of specified local conditions. Use of this set of nomographs as a design tool supplementary to the CRCP-2 computer program model will facilitate the design of CRCP, substantially reducing both the time and cost involved in the design process, and at the same time accounting for the effect of regional and local environment. Regression equations were developed for the prediction of three design parameters and then principles of nomography were applied to these mathematical relationships to prepare three corresponding nomographs. The choice of equations was made following multiple linear and nonlinear least squares fits to a fractional factorial of simulated observations which were output from the CRCP-2 computer program. Theoretical models developed at the Center for Highway Research and the variations of the three design parameters with each of the relevant input variables over the range of the simulated data were considered in deciding on the form of the regression equations. "Standard error of residuals" and "R2" (proportion of variance explained by the regression equation) statistics were considered in the final choice of coefficients for the regression equations. Confidence prediction limits were determined using multiple linear regression techniques for application to nomograph predictions. A recommended procedure for the use of the nomographs with appropriate limiting criteria has been outlined along with an example. (FHWA)