A parametric study is conducted to investigate the effect of lead rubber bearing (LRB) isolator and ground motion characteristics on the response of seismic isolated bridges. The purpose was to investigate the most favorable parameters of the LRB for minimum earthquake response of the isolated bridge system for different ground motions. The important parameters included are: ground motion characteristic by considering peak ground acceleration to peak ground velocity, PGA/PGV ratio as damage index; characteristic strength, Q d of the LRB isolator normalized by the weight acting on the isolator; flexibility of isolator by varying post yield time period, T d ; and yield stiffness to post yield stiffness, K u /K d ratio. The performance of seismic isolated bridge is measured by the variation of maximum isolator displacement (MID), maximum isolator force (MIF), deck acceleration and pier base shear. For a specified ground motion, smaller MID and MIF are regarded as indicator of better seismic performance. It is found that there exists a particular value of Q d /W, T d and K u /K d for which the MID, MIF, deck acceleration and pier base shear attain the minimum values. Finally the recommendations are made which are useful for the design engineers at the preliminary seismic isolation design of the bridges with LRB isolator for the ground motion having different characteristics.

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Sufficient deformability can be achieved in concrete while maintaining segregation resistance either by using a chemical viscosity-modifying admixture (VMA) or increasing the fine content in the concrete. Using VMA, the initial cost of self-compacting concrete (SCC) increases, making it unsuitable for general construction. As a result, alternative methods for lowering the cost of SCC must be investigated. In this study, we assess the effectiveness of fly ash (FA) as a viscosity-modifying agent in the production of cost-effective and durable SCC. We also forge new pathways for sustainable development. The percentage of FA, superplasticizer dose, and water/binder ratio were varied, whereas the amounts of cement and water, as well as fine/coarse aggregate content were kept constant. Fresh properties, such as flow, filling and passing abilities, viscosity, and segregation resistance, were measured. Compressive/flexural strength, density, water absorption, and rate of water absorption of hardened SCC were also determined. The test results showed that fly ash can be used as an alternative to a VMA to produce cost-effective, self-compacting concrete. The slump flow of the various fresh-state concrete mixes ranged from 200 to 770 mm, with an L-box ratio of 0 to 1 and a flow time of 2.18 to 88 s. At 28 and 56 days, the compressive strengths of the concrete mixes with fly ash were found to be comparable to those of the control concrete mixes with VMA. The cost of ingredients for a specific SCC mix is 26.8% lower than the price of control concrete, according to a cost comparison assessment.