Toshitaka Yamao

Steel bridge piers with inner cruciform plates under cyclic loading

The strength and ductility of steel bridge piers with inner cruciform plates were studied experimentally and theoretically. Three types of specimens were investigated, one with an ordinary stiffener, one with inner cruciform plates and one where the section is unstiffened, were tested under a constant compressive axial load and cyclic horizontal loads. Elasto-plastic and large displacement numerical analyses were carried out using the finite element package MARC. The effects of using inner cruciform plates on the strength and ductility of steel bridge piers were investigated where the height of the inner cruciform plate was varied in the box section bridge piers. It was found that piers with inner cruciform plates show better performance than ordinary piers with regard to ductility and energy absorption capacity.

Effect of two directional loading on ductility and ultimate strength of steel bridge piers with inner cruciform walls

Publisher Summary The chapter presents the ductility and ultimate strength of steel bridge piers with inner cruciform walls subjected to two directional loading under a constant vertical load. Specimens with various radius-to-thickness ratios and slenderness ratios are used, and FEM analyses are carried out considering the effect of the loading method. Numerical analyses are carried out using a type of four-node thick-shell element in the finite element package MARC (2001). To check the validity of the numerical analyses, numerical results were compared with previous experimental results. Effects of the radius-to-thickness ratio and the slenderness ratio on the ductility and the ultimate strength of the steel bridge pier with inner cruciform walls are studied in the chapter.

Ductility of stiffened steel box member

Publisher Summary Ductility of structures depends on the ductility of key members like the end member of an arch bridge or the lower part of bridge piers. The chapter clarifies the effect of buckling parameters, the number of stiffeners in a flange plate, and patterns of repeated loading on the ductility behavior of members. FEM analyses were carried out on various box-section members changing such parameters under several repeating patterns of bending. The ductility of a member is studied on an equivalent stress-strain relation, where the equivalent strain is defined to include the shortening of a stiffened flange plate due to local buckling deformation. From these numerical results, one proposes a suitable load pattern for the cyclic load analysis and provides information about how to increase the ductility of the member by controlling the buckling parameters and the number of stiffeners. Seismic design method for complex steel structures like arch bridges is neither studied enough nor developed well. Engineers should set up new design specifications, and should realize and ascertain an expected performance of structures.

NONLINEAR SEISMIC RESPONSE ANALYSIS OF A DECK-TYPE STEEL ARCH BRIDGE

Publisher Summary The seismic behavior of a deck-type steel arch bridge composed of parallel twin ribs with lateral members is investigated in this chapter. The restoring force model incorporating the interaction curves of stiffened short arch ribs subjected to compression by in-plane and out-of-plane bending moments is analyzed numerically using MARC. A nonlinear seismic response analysis of a deck-type steel bridge arch is carried out, by which the effects of a RC floor slab stiffness and interaction curves are examined. The influence of interaction curves on the interpretation for yield resultant forces is shown to be a significant factor in the seismic behavior of arches. The 3-dimensional seismic analysis of a deck-type arch bridge composed of parallel twin ribs with lateral members subjected to ground acceleration is theoretically analyzed. A parametric study is conducted using the finite element method (FEM) analysis and nonlinear seismic response analysis methods by considering the effect of interaction curves on yield resultant forces and the nonlinear seismic behavior of a deck-type arch bridge.