Static and fatigue tests on SFTC arch ribs: Fid-Bau Portal

Static and fatigue tests on SFTC arch ribs

Lee, M.K. / Barr, B.I.G. / Penny, C. / Browne, P.

The paper reports on the application of steel fibre reinforced concrete (SFRC) in arch ribs subjected to static and fatigue loading. A theoretical study was carried out prior to the experimental programme in order to identify the worst loading conditions for use in the experimental study and to identify the locations for instrumentation at the two additional hinges formed in the arch at failure. Two types of arch ribs were used in the study: solid rectangular sections (300mm wide x 145mm deep) and U-shaped channel sections (with overall dimensions of 300mm wide x 250mm deep). Four solid sections and five channel sections were used in the study. Initial test results were obtained under static loading and thereafter each section type was subjected to fatigue loading. The fatigue tests were interrupted at regular intervals in order to carry out static tests corresponding to the minimum, mean and maximum loads in the fatigue test. Deflections and crack opening deformation were monitored in this way throughout the fatigue test. The arch ribs showed good performance in the static tests where the failure in the solid arch ribs were primarily via the development of four hinges. The solid arch rib tested under fatigue loading (between 10% and 70% of ultimate load) failed after approximately 16000 cycles. The cross-section of the channel arch ribs were significantly deeper and improvements had to be made to the loading method. After succeeding in doing so, the channel arch rib tested under fatigue loading (between 10% and 60% of ultimate load) failed after approximately 7.7 x 105 cycles. The fatigue tests were carried out after the arch ribs had reached their ultimate load capacity in the pre-cracking exercise. The test programme shows that the SFRC arch ribs performed well under both static and fatigue loading conditions since the tests carried out represents the worst loading case that could be encountered by the arch rib system. In reality, the nature of the applied load would not be as severe which increases the attractiveness of the SFRC arch rib.