Title: A Rational Approach to the Analysis of Structural Effects due to Creep

Author(s): M. A. Chiorino

Publication: Symposium Paper

Volume: 227

Issue:

Appears on pages(s): 107-142

Keywords: aging; compliance; concrete; creep analysis; delayed restraints; prediction models; redistribution function; relaxation; static system; stress redistribution; structural analysis; viscoelasticity

DOI: 10.14359/14428

Date: 3/1/2005

Abstract:
The long-term service behavior of modern reinforced or prestressed concrete structures, whose final static configuration is frequently the result of a complex sequence of phases of loading and restraint conditions, are influenced largely by creep. Creep substantially modifies the initial stress and strain patterns, increasing the load induced deformations, relaxing the stresses due to imposed strains, either artificially introduced or due to natural causes, and activating the delayed restraints. The resulting influences on serviceability and durability are twofold, creep acting both positively and negatively on the long-term response of the structure. The paper shows that use of the four fundamental theorems of the theory of linear viscoelasticity for aging materials, and the related fundamental functions, offers a reliable and rational approach to estimate these effects. Extremely compact formulations are obtained, which are particularly helpful in the preliminary design, as well as in the control of the output of the final detailed numerical investigations and safety checks, and suitable for codes and technical guidance documents. Particular attention is dedicated to the problem of change of static system.