126 Websjournal of Science and Engineering Application//Lyon _ AIGEN Websjournal of Science and Engineering Application/Lyon _ AIGEN VARIATION STRENGTH ANALYSIS OF CONCRETE BRIDGE STRUCTURE REINFORCED WITH STEEL BARS AND SHAPE MEMORY ALLOY WIRES S. O. Odeyemi 1, and A. A. Adedeji 2 1 Department of Civil Engineering, Federal Polytechnic, Offa, Offa 2 Department of Civil Engineering, University of Ilorin, Ilorin ABSTRACT This research work focused on investigating the appropriate percentage of shape memory alloy and steel reinforcements for the least deflection in the column-beam of a 2-span reinforced concrete (RC) bridge subjected to seismic load. A reinforced concrete bridge of double span of 10m per span was modelled over Iyemoji River in Ijebu Ode with coordinates 607159.00mE and 746997.00mN and analyzed using SAP2000 Structural Engineering Software under Elcentro earthquake of 1946. A time history method of seismic analysis was used to determine the deflection in the bridge column and capping beam.The data used for the analysis include physical measurement at the bridge location and experimental data on SMA by Moochul (2012). It was discovered that African countries like Algeria, Rwanda and Ghana have experienced various degrees of earthquakes while several tremors had been experienced in some parts of Nigeria in areas such as Ijebu-Ode, Ibadan and Lagos where the magnitudes of some of these earthquakes ranged between 4.3 and 4.5. The double span model bridge over Iyemoji river subjected to the Elcentro earthquake of 1946 experienced the least deflection in its column when 75% steel and 25% SMA were combined as reinforcement. This combination reduced the deflection of the bridge’s column by 65.66%. The combination of SMA with steel reinforcement in the beam element of the model bridges did not reduce its deflection. The use of SAP2000 gave the advantage of checking the deflections at intervals of the columns and the capping beam during computations. The reliability of the results produced by analytical modelling was validated by comparing a bridge column model simulated with SAP2000 with the experimental model of Moochul (2012). The results obtained were closely related. Based on this research work, Shape memory alloy has a high resistance to seismic loads when combined with steel reinforcement. The Shape memory effect and the Superelastic effect of the alloy also give it an additional advantage. It can therefore serve as a secure means of reducing the effect of earthquakes on structures in earthquake prone areas. Key words : Earthquake, Shape Memory Alloy, Iyemoji River, Bridge, SAP2000, Steel reinforcement, Elcentro earthquake, Time History Analysis. 1. INTRODUCTION Insuring the resilience of lifeline infrastructures against high seismic events in highly populated areas is of high priority in any seismic design and mitigation plan. Bridges are among the most critical elements in any transportation infrastructure network. Therefore, a large number of studies focus on identifying the main causes of the collapse of bridges during earthquakes. These studies showed that many of the bridge failures that occurred during past earthquakes were due to the collapse of one or more of the bridge reinforced concrete (RC) columns or piers (Moochul, 2012). Smart structural materials are gaining acceptance for use as different form of braces in concrete structures. A conventional structural system is designed to achieve a set of intended functions under pre- selected loads and forces. Such a conventional system cannot successfully develop its ability against unexpected loads and forces unless a large factor of safety is provided for safety limit states to take into account various uncertainties in load, force amplitude and structural responses. The traditional method of anti-seismic technique is to increase the stiffness of structures by enlarging the section of columns, beams, shear walls, or other elements, which will accommodate the seismic load because of the added mass to structures. The traditional anti-seismic technique causes an increase in the cost of the structure while the safety level of such structures is less improved (Emmanuelle, 2013). Another disadvantage of the traditional anti - seismic technique is that it focuses on the protection of the structure but neglects the facilities inside the structure. Hence, it cannot be used in some structures. WEBSJOURNAL OF SCIENCE AND ENGINEERING APPLICATION WESEA ISSN: 1974-1400-X Vol 2, No 3, 2013, 126-142