2019 https://repo.nzsee.org.nz/xmlui/handle/nzsee/80 2026-04-19T01:23:51Z 2026-04-19T01:23:51Z Plotnikova, A. Wotherspoon, L. https://repo.nzsee.org.nz/xmlui/handle/nzsee/82 2019-07-27T03:00:23Z 2019-04-04T00:00:00Z

Dynamic behaviour of reinforced-concrete bridges in freezing conditions Plotnikova, A.; Wotherspoon, L. The strong influence of ambient temperature variation, and especially freezing of near-surface soils, on the transverse modal response of the bridges in cold earthquake-prone regions has been shown in previous research. This paper extends this work and presents an analytical investigation of the modal characteristics of the range of reinforced concrete continuous beam bridges with integral pile-column systems with various geometries over a range of temperatures. The numerical bridge models were geometric modifications of previously validated finite element models of a soil–pile-bridge system representing a prototype three-span bridge located in Anchorage, Alaska. Frozen conditions increased the fundamental modal frequencies across all the bridge schemes. The mode shapes of the short bridges with a few spans undergo significant transformation mainly due to the changes in the stiffness of the pier-foundation-soil system in winter. More flexible, high column and multi-span bridges are less susceptible to these significant mode shape variations. The findings reveal the need for further assessment of the seismic design code requirements for the bridge stock in the cold regions, given that changes in modal parameters may increase the design seismic lateral loads along with potential redistribution of the loads across the structure due to stiffening of the pile-soil system in winter.

2019-04-04T00:00:00Z Dashti, F. Dhakal, R. P. Pampanin, S. https://repo.nzsee.org.nz/xmlui/handle/nzsee/81 2019-07-27T03:00:25Z 2019-04-04T00:00:00Z

FEM prediction of failure mechanisms in RC structural walls: parametric investigation Dashti, F.; Dhakal, R. P.; Pampanin, S. This study investigates the ability of a microscopic (finite element) model based on curved shell element formulation in predicting nonlinear behavior of planar RC structural walls, identifying the strengths and limitations of this modeling approach. For this purpose, a parametric validation is conducted in addition to verification of the model simulation against experimental results of several wall specimens tested in literature. The effects of variations in total length, thickness, shear-span ratio, axial load ratio, confinement, as well as the horizontal and vertical reinforcement ratios are investigated at both global and local levels. The capabilities and deficiencies of the modelling approach are discussed in detail in light of the numerical vs experimental as well as parametric verifications. The model is found to be able to predict most of the experimentally observed failure mechanisms of rectangular walls including global out-of-plane instability under in-plane loading, concrete crushing at the base, diagonal tension and diagonal compression as well as sliding shear. The model is not able to represent bar buckling, bar fracture and the potential subsequent secondary failure modes such as instability of the compression boundary zone due to progressive asymmetric concrete crushing at the base. The parametric study indicated sensitivity of the model response to the variation of the parameters known to be influential on the in-plane and out-of-plane responses of RC walls.

2019-04-04T00:00:00Z