Development of steel arch bridges aimed to cut the construction costs

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This study is aimed to clarify 3-dimension seismic behavior of deck-type bridge arches which is composed of parallel twin ribs and pair curved ribs with lateral members. The first, the restoring force model and the interaction curves of stiffened short arch ribs subjected to compression and both in-plane and out-of-plane bending moments were examined. The dimensions of stiffened steel box cross-section of short-arch ribs were obtained from those of real deck-type bridge arches with 100〜200m span lengths. Numerical analyses were conducted using FEM program (MARC) by changing axial force, in-plane and out-of-plane bending moment and the width-to-thickness ratio parameters of the plates of a stiffened steel box cross-section. Based on the numerical results, the interaction curves for yield resultant forces (N, My Mz and T) of stiffened short arch ribs are derived. Strength and ductility of single steel arch bridges were studied experimentally and theoretically. The kind of specimens, that is, one with ordinary stiffener, one of unstiffened sections were tested under equivalent distributed vertical load and cyclic horizontal loads. Numerical analyses were carried out using the FEM program.Furthermore, the nonlinear seismic response analysis of the deck-type steel bridge arch is carried out using restoring force model and the interaction curves. A nonlinear seismic response analysis of a deck-type steel bridge arch is carried out taking into account the effect of interaction strength curves and changing of the axial force. It has been shown that the effect of the taking into account of interaction curves for yield resultant forces on the seismic behavior of deck-type bridge arches is large. Validity of approximated bending moment-curvature relations using proposed restoring force model were shown.