Proceso constructivo y cálculo de flechas. Estudio experimental

Construction process and deflection design. Experimental study

An experimental plan has been designed in order to study the influence of the construction process of structures on their service behaviour. The construction process has been simulated by appliying three successive load steps to three beams whose dimensions are (b x h x L) = (15 x 20 x 450) cm, until reaching the characteristic service load, unloading then until reaching a load similar to the self weight of a real structure. Other three similar beams have been subjected to an analogous load process, this time with a difference: the loads of the first three steps have generated bending moments 23Fo higher than in the previous case. The total deflections registered in each one of the beams ar the end of each load step as well as those existing after the unloading are shown. The simplified method of EHE spanish code for the deflection design allows an excellent accuracy, even better if it takes into account the correction factor of the modulus of elasticity according to the type of aggregate. The relation of the bending moments applied between the two load histories is always inferior to the relation between deflections and that of the instantaneous recoverings after unloading. This seems to indicate that the damage level accumulated during the construction of the structure is maintained.