Long-term behaviour of beams prestressed with aramid fibre cables: Part 2: an approximate solution

In a previous paper a general method to analyse PC and PPC compact cross-sections, prestressed by means of aramid fibre composite cables, was suggested. This method is complex and cumbersome, not suitable for common practice. This paper suggests an approximate approach to the problem (i.e. the Age Adjusted Effective Modulus Method) that leads to simple, recurrent algebraic formulas. Together with it, the aging coefficient for two cables (industrial products) reinforced with aramid fibres, computed adopting a long-term constitutive law already discussed in the previous paper, are given in tables. These tables, together with those already available for concrete, allow to easily compute the time-dependent losses due both to creep and shrinkage of concrete and aramid fibre relaxation. algebraic formulas bring with them a crude approximation that consists in the assumption that the long-term behaviour of both concrete and cable are linear functions of their own creep coefficients, that is the behaviour of the cable (after bond has become effective) is independent of the creep coefficient of concrete and vice versa. isons with the outcome of the general method allow to evaluate the error gathered by these formulas and therefore guarantee their reliability.