Title:
Initial and Time-Dependent Deformation of Progressively Cracking Nonprestressed and Partially Prestressed Concrete Beams
Author(s):
Susanto Tengand Dan E. Branson
Publication:
Structural Journal
Volume:
90
Issue:
5
Appears on pages(s):
480-488
Keywords:
beams (supports); camber; computer programs; deflection; cracking (fracturing); creep properties; flexural strength; loads (forces); modulus of elasticity; one-way slabs; partial prestressing; shrinkage; prestressed concrete; reinforced concrete; structu
DOI:
10.14359/3975
Date:
9/1/1993
Abstract:
An accurate time-step procedure for computing the initial and time-dependent deformation of progressively cracking nonprestressed and partially prestressed concrete flexural members is presented. The procedure is based on the I-effective method, which has been applied to many different cases and has been proven worldwide to be very reliable for predicting the initial deformation of cracked prestressed and nonprestressed members. The extension of the I-effective method to the time-dependent deformation of cracked prestressed and partially prestressed members has so far been achieved by using long-term multipliers. In the proposed procedure, the I-effective method is used in combination with the effective centroidal axis formula Y e to perform the time-dependent analysis on the effective section, taking into account the effects of progressive cracking and tension stiffening. Experimental data from different groups of researchers have been used to verify the accuracy of the proposed procedure. From these comparisons, it can be seen that the proposed procedure gives accurate predictions of the initial and time-dependent deformation of progressively cracking concrete members for all prestressing range. Discussions on the effect of prestress force on the value of the effective-I, and lower limits on the effective-I, etc., are also presented to clarify these concepts.