Student researcher

Ismail M I Qeshta Research Leader

This student descibes his project in the following way:

Existing reinforced concrete structures are in need for upgrading and retrofitting. Concrete columns are usually strengthened by applying lateral confinement, whereas RC beams and slabs are strengthened in flexure by attaching reinforcement to their soffits (Jones et al., 1986 and Meier,1995). The development of fragility curves for retrofitted bridges are necessary for assessing their vulnerability under the different extreme loading conditions, such as seismic loads and floods. The development of fragility curves offers useful evaluation tools for the different retrofitting measures (Werner et al., 1997 and Basoz and Kiremidjian, 1999). It can also provide a risk assessment of the structures after retrofitting. Although many structures are designed to withstand a certain degree of unforeseen external load, extreme events, such as the earthquake, floods, storms and fires can cause a catastrophic failure of the structure. Therefore, the assessment of the resilience of bridge structures before and after retrofitting will provide valuable data for policy and decision makers in determining the most suitable retrofitting measure for the bridges subjected to flood loads. Hence, this research aims to investigate the effect of different strengthening and retrofitting techniques on the resilience of bridges that are subjected to extreme events, particularly, floods.

 Research aims (objectives)

 1.   To classify the various types of damage of the bridge components.

2.   To provide a definition of the resilience of retrofitted bridge structures under extreme events.

3.   To assess the effectiveness of different strengthening techniques.

4.   To develop a numerical model for the retrofitted bridge superstructure components (i.e. girders and decks).

5.   To evaluate the performance of retrofitted bridges under different extreme events, which can assist the authorities in developing effective decisions.

Research methodology 

A comprehensive literature survey is made to understand the current design methodologies of resilient structures. In addition, the different methods for developing the vulnerability curves are reviewed and discussed. The different retrofitting techniques for bridges subjected to seismic loads are also addressed in the review. These techniques include the FRP and steel plates, restrainer cables, shear extenders and shear keys.

A case study reinforced concrete bridge will be selected. The different strengthening measures will be applied on the bridge. The finite element software ABAQUS will be used to model the different bridge components. The methodology for the development of the vulnerability curves will be established. The series of the developed vulnerability curves for the retrofitted superstructure components will be drawn for the different strengthening schemes and loading conditions. The major failure modes and the different input parameters will be established for the case study bridge. The vulnerability curves will be drawn at the different floods conditions (velocity and flood level). The data obtained from the vulnerability evaluation and damage index (DI) will be used for making decisions and estimating the cost for the suitable strengthening schemes.

 Expected outcomes

  •  Vulnerability models of the different retrofitted elements of the bridge will be developed for varying loading conditions and different strengthening techniques.
  • The suitable strengthening schemes will be identified to assist the decision making for the concrete bridges subjected to natural hazards.
  •  The effect of the retrofitting on the vulnerability of bridge components will be assessed.