Deflection Creep of Pultruded Composite Sheet Piling

The time-dependent creep behavior of pultruded composite sheet piling was investigated. Two panels were tested under equally spaced third point bending at a span to depth ratio of 48; one was subject to a constant load of 50% of $P_{\max }$ and the other 25% of $P_{\max }$. Tensile creep, shear creep, and deflection creep were recorded over 1 year. The time-dependent tensile and shear moduli were obtained using the simplified Findley’s model, and the deflection creeps were predicted based on both Findley’s model and Timoshenko’s equation. It was found that the time exponents in Findley’s model for tensile, shear and deflection creep were of close value and could therefore be averaged to provide a viscoelastic material constant for the composite sheet piling. With the averaged viscoelastic parameters, Timoshenko’s equation resembled the Findley’s power law model for the prediction of deflection creep and agreed well with experimental results up to 1 year. Over 30 years, it is estimated that the viscoelastic tensile and shear moduli will be reduced to 68 and 36% of their respective initial values and the creep deflection will reach 50% of its static deflection.