Fatigue and Durability of Laminated Carbon Fibre Reinforced Polymer Straps for Bridge Suspenders

Abstract

Steel cables and suspenders in bridges are at high risk of corrosion-fatigue and in some cases of fretting-fatigue in their anchorages. These factors greatly limit the service stresses of a specific cable system and involve expensive protection measures. In order to investigate the above limitations, the fretting fatigue behaviour of pin-loaded carbon fibre reinforced polymer (CFRP) straps was studied as models for corrosion-resistant bridge suspenders. Two types of straps were tested: small model straps with a sacrificial CFRP ply and large full-scale straps. In a first phase, five fully laminated and carbon pin-loaded CFRP model straps were subjected to an ultimate tensile strength test. Thereafter, and in order to assess their durability, 20 model straps were subjected to a fretting fatigue test, which was successfully passed by 4 straps. An S-N curve was generated for a load ratio of 0.1 and a frequency of 10 Hz. In a second phase, one full-scale strap was tested for its ultimate tensile strength and two full-scale straps were fatigue-tested. The influence of fretting fatigue loading on the residual mechanical properties of the straps was also assessed, and although fretting fatigue represented an important limitation for laminated CFRP straps, it could be shown that the investigated CFRP tension members can compete with the well-established steel suspenders.

Influence of Temperature on the Mechanical Performance of Unidirectional Carbon Fiber Reinforced Polymer Straps

“…Baschnagel et al further investigated the fretting fatigue behavior of laminated CFRP straps intended for use as bridge suspenders [ 20 , 21 ]. In their work, the residual mechanical properties of CFRP straps subjected to tensile fatigue loading with a frequency of 10 Hz (R = 0.1) were assessed and the fatigue limit stress was observed to be reached after 3 million loading cycles at 46% of their ultimate tensile strength (UTS) (i.e., 750 MPa).…”

“…The stress distributions in pin-loaded laminated straps under static tension was studied in [8], and the critical failure-triggering region was identified as the transition region between the pin and the straight part (i.e., the 'shaft'). Baschnagel et al further investigated the fretting fatigue behavior of laminated CFRP straps intended for use as bridge suspenders [20,21]. In their work, the residual mechanical properties of CFRP straps subjected to tensile fatigue loading with a frequency of 10 Hz (R = 0.1) were assessed and the fatigue limit stress was observed to be reached after 3 million loading cycles at 46% of their ultimate tensile strength (UTS) (i.e., 750 MPa).…”

A New Multiparameter Model for Multiaxial Fatigue Life Prediction of Rubber Materials

“…As explained in Sections 2 and 3, there is not a general model available in the literature which can be applied to obtain the fatigue life prediction in every type of rubber material. The difficulty arises due to the complex mechanical behavior of rubber materials and the large number of parameters influencing their durability [75].…”

“…The fatigue life prediction for rubber materials requires, on the one hand, a precise characterization of stress, strains and strain energy fields of the entire component along the complete load history and, on the other hand, a considerable effort is needed to carry out the corresponding fatigue tests, defining a fatigue model capable of correlating the selected fatigue parameter with the lifetime of each of the samples tested [36,75,76]. would represent the predictions that coincide with the real life of the sample and the dashed lines represent the real life multiplied and divided by 2.5, respectively.…”

Development of a Mechanical Wedge–Barrel Anchor for CFRP Rods: Static and Fatigue Behaviors

“…The relative displacement between the wedges, CFRP rod, and barrel could generate heat during fatigue tests, depending on the loading frequency (Baschnagel et al 2018). The draft guideline for FRP PT tendons (Rostásy 1998) recommends that the loading frequency in the fatigue tests not be greater than 2 Hz.…”