Determining the reliability of an arch-shaped, steel fiber reinforced shotcrete (SFRS) culvert, built via the inflatable form process

In order to improve understanding of the performance of large diameter culverts built via the inflatable form construction process, a ten foot radius, arch-shaped, shotcrete culvert was constructed in Elyria, Ohio, and its behavior was monitored with the use of strain gages, pressure cells, and observation bolts. In general, it was found that the field results compared favorably with the finite element results except where arching or stress relaxation was evident. Proper planning and management are necessary to minimize possible problems of construction related to the setting of reinforcement, and the emplacing of shotcrete on the inflatable form and around reinforcement. Delamination between shotcrete layers as a result of freeze-thaw cycles is another major concern. To alleviate these concerns, it was determined that the use of steel fibers (instead of wire mesh) for the reinforcement of shotcrete would be advantageous.;A research and testing program was developed to determine the reliability of an arch-shaped, steel fiber reinforced shotcrete culvert, built via the inflatable form process, without the actual construction of the structure. Using data obtained from conventional ASTM strength and durability tests for concrete, ASTM laboratory and field tests for soil, and an updated finite element analysis; the reliability (safety) of the culvert was determined via reliability based design analysis (AASHTO-LRFD). Relevant performance data from the existing culvert was used for a comparison between the reliability of the existing construction process and the reliability of the proposed construction process (using steel fiber).;It was found that steel fibers will aid in preventing delamination between shotcrete layers subjected to repeated freeze-thaw cycles. A theoretical explanation for the phenomenon is presented based on the Composite Material Approach and the Law of Mixtures. Also, a steel fiber reinforced, silica fume enhanced, shotcrete culvert built via the inflatable form process will be more reliable (with regard to strength, performance, and durability) than the wire-mesh reinforced shotcrete culvert, and at the same time be as cost effective. The results may be used for the analysis of future culverts built via the inflatable form process, and for modifications and additions to AASHTO-LRFD specifications for cast-in-place concrete arch culverts.