RC bridge

This dissertation work describes a methodology for the analysis and design of Reinforced Concrete (RC) tall bridge piers with various cross sections (Solid Circular and Double Cylindrical) and its foundation, which are typically used in deep valley bridge viaducts. Piers are usually considered tall when the shaft has a height of 30 m or more. Three different cross sections of tall piers have been studied for road bridges varying 30m and 100m in height and also varying grade of concrete from M40, M50, M60 and M70 of pier. Cost comparison has been carried out of tall pier road bridges. The aim of this study is to generate database for preliminary design of tall pier R.C. bridges under seismic loading. Using the database, the user would be able to establish design of the bridges, given the structural scheme and other design parameters, Understanding the behaviour of tall pier bridges under seismic condition and also Design of Pier as per IRC: 112-2011 (Limit State) and Design of Pile Foundation as per IS: 2911-2010 part-II. The study report contains charts that represent material quantities and cost for initial estimates for different types of pier forms for tall bridges. From the study it seems that most suitable pier height for tall bridges is in between 70 m to 80 m. It also represent that most efficient L/D Ratio is in between 21 to 22.5.

Bridges are lifeline structures and their performance is critical during and after the earthquake. The RC Bridge decks, supported on unanchored elastomeric pad bearings are free to move over substructure during an earthquake. Excessive deck displacement causes unseating and sometimes complete collapse of the deck leading to closure of the bridge for long periods. The problem worsens for irregular bridge with significant variations in the pier/pile heights. For that type of bridges base isolation techniques are the best method to protect it from earthquake and for a partially damaged building retrofitting techniques are best to protect further damages for working condition. We are here to discuss the rehabilitation assessment of seismically damaged irregular bridge namely changappa bridges by isolation technique and retrofitting technique.

The paper presents a model for chloride ingress into concrete. The model accounts for two mechanisms which control the chloride ingress-diffusion and convection. Using one-dimensional (1-D) formulation of the model, the influence of chloride binding and ambient humidity on chloride ingress into concrete has been investigated. Based on results of this investigation parameters for probabilistic analysis have been selected. Probabilistic evaluation of the time to corrosion initiation has then been carried out for a reinforced concrete (RC) wall (1-D problem) and a RC column (2-D problem) in a marine environment. Results of the analysis show that for the same thickness of the concrete cover the probability of corrosion initiation in the corner reinforcing bars of the RC column is much higher than in reinforcing bars in the middle part of the RC wall. The results demonstrate the importance of 2-D modelling for correct prediction of corrosion initiation in such RC elements as columns and beams. r