Experiments for total of 11 specimens are carried out to observe the behavior of elasto-plastic out-of-plane buckling of the arch structures with open cross section which are subjected to uniform vertical load. The effects of several factors on ultimate strength are investigated, that is, slenderness ratios of arch rib, load directions, types of bracing system and braced length ratios. The experimental results are compared with the theoretical ones. In general, the theoretical predictions show good correspondence with the experimental results in ultimate strength and buckling modes and so on. Validity and efficiency of the theoretical procedure are confirmed.

An incremental equilibrium equation for a beam-cloumn with arbitrary open cross sections is derived in a stiffness matrix form by using a moving element coordinate system and an incremental variational principle. A segmentation method for the cross section is used to analyze the development of plastic zones in the cross section and the effect of initial residual stresses arbitrarily distributed in the cross section. Yielding of the material is judged as a bi-axial stress problem under normal and shear stresses by using the flow theory of plasticity associated with von Mises yield criterion. Validity and efficiency of the present method are shown by illustrative examples.

Elasto-plastic out-of-plane buckling strength of through type and half-through type arch bridges are analyzed by a finite element method which is capable of considering finite displacements and yielding of materials. Examining the numerical results and using an analogy between an arch and a column, we propose a method to determine the slenderness parameter for arch bridges. A designer can use the slenderness parameter to obtain an ultimate stress for arches by substituting it into a column strength formula. The predictions by the proposed procedure are shown to be fairly good correspondence with all of numerical results.

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The present paper discusses the characteristic of hysteresis of member force developed in box type in-ground structures during the 1995 Great Hanshin earthquake, based on numerical simulation. Several case studies including different type structures are carried out using appropriate ground motions for the specific site. In this calculation, dynamic interaction between soil and structure, elasto-plastic behavior, etc, are considered. As a result, the hysteresis of member force of structures, interactive relationship between bending moment and axial force, is expressed as a simple moment-axial force ratio.Key Word : box-type in-ground structure, member force hysteresis, moment-axial force ratio, non-linear seismic analysis