The Moanalua trestle spanned over Moanalua Stream, Honolulu, HI and was designed to accommodateconstruction of five 10 feet diameter cast in drilled hole (CIDH) piers as a part of Honolulu Authority forRapid Transportation (HART) project. Due to the proximity of piers to the existing bridge, the trestle waselevated 20 feet above grade. Stratigraphy of the site consisted of shallow depth of fill and 150 feet of looseto very loose recent alluvium (soft clay) underlain with stiff to hard old alluvium (stiff clay). CIDH casingswere installed by a rotator or oscillator depending on the diameter of the piers. The challenge was to designthe trestle, not only for heavy gravity loads, but also to resist significant lateral loads from rotator andoscillator with minimal deflection. Series of piles, called reaction piles, were integrated into the trestle ateach CIDH pier location to provide adequate lateral support for the rotator/oscillator. Due to the lack ofinformation regarding soil Young’s modulus (E), a methodology was developed to calibrate and calculateE with two methods. Extensive analyses using LPILE and finite element analysis program, PLAXIS, wereperformed to model reaction piles and calculate lateral deflection.
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