Non-linear three-dimensional analytical models of bridges with laminated-rubber seismic bearing devices upgraded with multi-directional space-flange energy-dissipation (SF-ED) devices were experimentally validated under multi-directional seismic action by shaking table tests of large-scale prototypes. The experimentally verified hysteretic models were used to model the upgraded seismic isolation (USI) system. The seismic protection benefits of the USI were demonstrated through a comparative analysis of bridge prototypes with both standard and upgraded systems. It was confirmed that the SF-ED devices provided a qualitative contribution under very strong earthquakes in all directions. The variation of the structural characteristics of the devices illustrates the technological options for qualitative seismic upgrading of various types of isolated bridges with complex plane geometries under multi-directional seismic actions.

In this paper is describes a non-linear static (pushover) analysis method for reinforced concrete structures that predicts real nonlinear (both material and geometrical) behavior including all stages of loading, starting from the initial application of loads up to and beyond the collapse of building. In other words from appearance of first plastic hinge until last hinge which represent collapse of building. Some important aspects which are implemented in EC8, FEMA-273/356 and ATC-40 documents regarding to pushover analysis and performance evaluation of buildings are discussed. Modeling of structural elements is made by linear elements approach. Nonlinear behavior of structural elements is made by plastic hinges when inelastic behavior is concentrated at plastic hinge locations in both ends of elements. For monitoring structural degradation of beams, bilinear Moment-Rotation relationship is considered. For monitoring structural degradation of columns, PMM interaction surface is considered. Nonlinear geometrical effects are taken into account by incorporating both local (P-δ) and global (P-Δ) in analysis. An eight story reinforced concrete building is analyzed. Distribution of lateral loads is accepted by first mode of free vibration. Results are given in terms of Global Capacity Curve, sequences of plastic hinge formation, plastic hinge distribution in structure, performance levels in terms of local behavior of structural elements and global behavior of structure.

Fibre-reinforced polymer (FRP) bars are important replacements for reinforcements made of ordinary steel because the former offer structural durability, electromagnetic neutrality and a high strength/weight ratio, as well as being lightweight and flexible. In the present study, six concrete columns with a diameter of 29·7 cm, a height of 1·5 m but with different percentages of steel and glass FRP bars were tested for endurance under a combination of an axial load and a reversed cyclic bending load up to failure. The experimental and numerical results in terms of force–displacement hysteresis are presented and discussed in this paper. Theoretical analysis was devoted to the refined modelling of the complex hysteretic response of experimentally tested columns with ordinary and composite reinforcement. Finite-element models of the specimens were formulated using a modelling concept of refined fibre sections.

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