Enhancing the load capacity of pultruded GFRP beams via discrete load redistribution

The paper addresses whether or not equal sub-division and re-distribution of the total load on a beam as a series of discrete loads enables load ratios (target ratios), similar to those between uniformly loaded and mid-span point loaded simply supported and clamped beams, to be achieved, assuming either equal deflection or strength limits. This is pertinent to the design of pultruded GFRP beams, which behave linear elastically and have inherently low flexural stiffness. Simply supported and clamped beams subjected to four symmetric, equally spaced groups of equal point loads are analysed and formulae for their maximum deflections and moments are presented. These are then converted to load ratios for equal deflection and strength limits. It is shown that load ratios similar to the target ratios are achievable and the corresponding load spacing ratios λλ are given. The investigation is then extended to consider whether the effects of varying the load magnitudes and load spacing ratios, whilst keeping the total load constant, allow the target load ratios to be achieved. It is shown that the target ratios can be achieved, and the corresponding load spacing ratios are given for a range of load and spacing factors, δδ and γγ.