Simple and explicit formulae are presented for the analyses of the accumulated dead load deflection óda, and the instantaneous live load defection ój; they are applicable to both reinforced and partially prestressed concrete beams under repeated loading. The total deflection at a given number of load repetitions is obtained by summing óda and ój. In the analysis, óda, is computed as the product of the initial dead load deflection, ój, and the intensive creep factor k. For reinforced beams, a semi-empirical formula for k has been presented previously. With the use of the additional deflection data from five partially prestressed box bearns tested herein, a unified equation for k is derived statistically. An interpolation formula developed earlier for estimating the equivalent moment of inertia (hence ój) of reinforced beams is confirmed to be equally applicable to purtiully prestressed beams under repeated loading. In the light of the authors’ own experimental data, and those published by other researchers, comparisons of results are made which indicate that the overall accuracy of the proposed procedure is good. It is also more versatile and more reliable than two other recently published methods of analysis.
Y.C. Loo and Y.W. Wong